build: move package sources from src/pkg to src

Preparation was in CL 134570043.
This CL contains only the effect of 'hg mv src/pkg/* src'.
For more about the move, see golang.org/s/go14nopkg.

22 files changed, 5767 insertions, 0 deletions

diff --git a/src/strconv/atob.go b/src/strconv/atob.go
new file mode 100644
index 000000000..d0cb09721
--- /dev/null
+++ b/src/strconv/atob.go
@@ -0,0 +1,35 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package strconv
+
+// ParseBool returns the boolean value represented by the string.
+// It accepts 1, t, T, TRUE, true, True, 0, f, F, FALSE, false, False.
+// Any other value returns an error.
+func ParseBool(str string) (value bool, err error) {
+	switch str {
+	case "1", "t", "T", "true", "TRUE", "True":
+		return true, nil
+	case "0", "f", "F", "false", "FALSE", "False":
+		return false, nil
+	}
+	return false, syntaxError("ParseBool", str)
+}
+
+// FormatBool returns "true" or "false" according to the value of b
+func FormatBool(b bool) string {
+	if b {
+		return "true"
+	}
+	return "false"
+}
+
+// AppendBool appends "true" or "false", according to the value of b,
+// to dst and returns the extended buffer.
+func AppendBool(dst []byte, b bool) []byte {
+	if b {
+		return append(dst, "true"...)
+	}
+	return append(dst, "false"...)
+}
diff --git a/src/strconv/atob_test.go b/src/strconv/atob_test.go
new file mode 100644
index 000000000..28f469f58
--- /dev/null
+++ b/src/strconv/atob_test.go
@@ -0,0 +1,91 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package strconv_test
+
+import (
+	"bytes"
+	. "strconv"
+	"testing"
+)
+
+type atobTest struct {
+	in  string
+	out bool
+	err error
+}
+
+var atobtests = []atobTest{
+	{"", false, ErrSyntax},
+	{"asdf", false, ErrSyntax},
+	{"0", false, nil},
+	{"f", false, nil},
+	{"F", false, nil},
+	{"FALSE", false, nil},
+	{"false", false, nil},
+	{"False", false, nil},
+	{"1", true, nil},
+	{"t", true, nil},
+	{"T", true, nil},
+	{"TRUE", true, nil},
+	{"true", true, nil},
+	{"True", true, nil},
+}
+
+func TestParseBool(t *testing.T) {
+	for _, test := range atobtests {
+		b, e := ParseBool(test.in)
+		if test.err != nil {
+			// expect an error
+			if e == nil {
+				t.Errorf("%s: expected %s but got nil", test.in, test.err)
+			} else {
+				// NumError assertion must succeed; it's the only thing we return.
+				if test.err != e.(*NumError).Err {
+					t.Errorf("%s: expected %s but got %s", test.in, test.err, e)
+				}
+			}
+		} else {
+			if e != nil {
+				t.Errorf("%s: expected no error but got %s", test.in, e)
+			}
+			if b != test.out {
+				t.Errorf("%s: expected %t but got %t", test.in, test.out, b)
+			}
+		}
+	}
+}
+
+var boolString = map[bool]string{
+	true:  "true",
+	false: "false",
+}
+
+func TestFormatBool(t *testing.T) {
+	for b, s := range boolString {
+		if f := FormatBool(b); f != s {
+			t.Errorf(`FormatBool(%v): expected %q but got %q`, b, s, f)
+		}
+	}
+}
+
+type appendBoolTest struct {
+	b   bool
+	in  []byte
+	out []byte
+}
+
+var appendBoolTests = []appendBoolTest{
+	{true, []byte("foo "), []byte("foo true")},
+	{false, []byte("foo "), []byte("foo false")},
+}
+
+func TestAppendBool(t *testing.T) {
+	for _, test := range appendBoolTests {
+		b := AppendBool(test.in, test.b)
+		if !bytes.Equal(b, test.out) {
+			t.Errorf("AppendBool(%q, %v): expected %q but got %q", test.in, test.b, test.out, b)
+		}
+	}
+}
diff --git a/src/strconv/atof.go b/src/strconv/atof.go
new file mode 100644
index 000000000..286206481
--- /dev/null
+++ b/src/strconv/atof.go
@@ -0,0 +1,540 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package strconv implements conversions to and from string representations
+// of basic data types.
+package strconv
+
+// decimal to binary floating point conversion.
+// Algorithm:
+//   1) Store input in multiprecision decimal.
+//   2) Multiply/divide decimal by powers of two until in range [0.5, 1)
+//   3) Multiply by 2^precision and round to get mantissa.
+
+import "math"
+
+var optimize = true // can change for testing
+
+func equalIgnoreCase(s1, s2 string) bool {
+	if len(s1) != len(s2) {
+		return false
+	}
+	for i := 0; i < len(s1); i++ {
+		c1 := s1[i]
+		if 'A' <= c1 && c1 <= 'Z' {
+			c1 += 'a' - 'A'
+		}
+		c2 := s2[i]
+		if 'A' <= c2 && c2 <= 'Z' {
+			c2 += 'a' - 'A'
+		}
+		if c1 != c2 {
+			return false
+		}
+	}
+	return true
+}
+
+func special(s string) (f float64, ok bool) {
+	if len(s) == 0 {
+		return
+	}
+	switch s[0] {
+	default:
+		return
+	case '+':
+		if equalIgnoreCase(s, "+inf") || equalIgnoreCase(s, "+infinity") {
+			return math.Inf(1), true
+		}
+	case '-':
+		if equalIgnoreCase(s, "-inf") || equalIgnoreCase(s, "-infinity") {
+			return math.Inf(-1), true
+		}
+	case 'n', 'N':
+		if equalIgnoreCase(s, "nan") {
+			return math.NaN(), true
+		}
+	case 'i', 'I':
+		if equalIgnoreCase(s, "inf") || equalIgnoreCase(s, "infinity") {
+			return math.Inf(1), true
+		}
+	}
+	return
+}
+
+func (b *decimal) set(s string) (ok bool) {
+	i := 0
+	b.neg = false
+	b.trunc = false
+
+	// optional sign
+	if i >= len(s) {
+		return
+	}
+	switch {
+	case s[i] == '+':
+		i++
+	case s[i] == '-':
+		b.neg = true
+		i++
+	}
+
+	// digits
+	sawdot := false
+	sawdigits := false
+	for ; i < len(s); i++ {
+		switch {
+		case s[i] == '.':
+			if sawdot {
+				return
+			}
+			sawdot = true
+			b.dp = b.nd
+			continue
+
+		case '0' <= s[i] && s[i] <= '9':
+			sawdigits = true
+			if s[i] == '0' && b.nd == 0 { // ignore leading zeros
+				b.dp--
+				continue
+			}
+			if b.nd < len(b.d) {
+				b.d[b.nd] = s[i]
+				b.nd++
+			} else if s[i] != '0' {
+				b.trunc = true
+			}
+			continue
+		}
+		break
+	}
+	if !sawdigits {
+		return
+	}
+	if !sawdot {
+		b.dp = b.nd
+	}
+
+	// optional exponent moves decimal point.
+	// if we read a very large, very long number,
+	// just be sure to move the decimal point by
+	// a lot (say, 100000).  it doesn't matter if it's
+	// not the exact number.
+	if i < len(s) && (s[i] == 'e' || s[i] == 'E') {
+		i++
+		if i >= len(s) {
+			return
+		}
+		esign := 1
+		if s[i] == '+' {
+			i++
+		} else if s[i] == '-' {
+			i++
+			esign = -1
+		}
+		if i >= len(s) || s[i] < '0' || s[i] > '9' {
+			return
+		}
+		e := 0
+		for ; i < len(s) && '0' <= s[i] && s[i] <= '9'; i++ {
+			if e < 10000 {
+				e = e*10 + int(s[i]) - '0'
+			}
+		}
+		b.dp += e * esign
+	}
+
+	if i != len(s) {
+		return
+	}
+
+	ok = true
+	return
+}
+
+// readFloat reads a decimal mantissa and exponent from a float
+// string representation. It sets ok to false if the number could
+// not fit return types or is invalid.
+func readFloat(s string) (mantissa uint64, exp int, neg, trunc, ok bool) {
+	const uint64digits = 19
+	i := 0
+
+	// optional sign
+	if i >= len(s) {
+		return
+	}
+	switch {
+	case s[i] == '+':
+		i++
+	case s[i] == '-':
+		neg = true
+		i++
+	}
+
+	// digits
+	sawdot := false
+	sawdigits := false
+	nd := 0
+	ndMant := 0
+	dp := 0
+	for ; i < len(s); i++ {
+		switch c := s[i]; true {
+		case c == '.':
+			if sawdot {
+				return
+			}
+			sawdot = true
+			dp = nd
+			continue
+
+		case '0' <= c && c <= '9':
+			sawdigits = true
+			if c == '0' && nd == 0 { // ignore leading zeros
+				dp--
+				continue
+			}
+			nd++
+			if ndMant < uint64digits {
+				mantissa *= 10
+				mantissa += uint64(c - '0')
+				ndMant++
+			} else if s[i] != '0' {
+				trunc = true
+			}
+			continue
+		}
+		break
+	}
+	if !sawdigits {
+		return
+	}
+	if !sawdot {
+		dp = nd
+	}
+
+	// optional exponent moves decimal point.
+	// if we read a very large, very long number,
+	// just be sure to move the decimal point by
+	// a lot (say, 100000).  it doesn't matter if it's
+	// not the exact number.
+	if i < len(s) && (s[i] == 'e' || s[i] == 'E') {
+		i++
+		if i >= len(s) {
+			return
+		}
+		esign := 1
+		if s[i] == '+' {
+			i++
+		} else if s[i] == '-' {
+			i++
+			esign = -1
+		}
+		if i >= len(s) || s[i] < '0' || s[i] > '9' {
+			return
+		}
+		e := 0
+		for ; i < len(s) && '0' <= s[i] && s[i] <= '9'; i++ {
+			if e < 10000 {
+				e = e*10 + int(s[i]) - '0'
+			}
+		}
+		dp += e * esign
+	}
+
+	if i != len(s) {
+		return
+	}
+
+	exp = dp - ndMant
+	ok = true
+	return
+
+}
+
+// decimal power of ten to binary power of two.
+var powtab = []int{1, 3, 6, 9, 13, 16, 19, 23, 26}
+
+func (d *decimal) floatBits(flt *floatInfo) (b uint64, overflow bool) {
+	var exp int
+	var mant uint64
+
+	// Zero is always a special case.
+	if d.nd == 0 {
+		mant = 0
+		exp = flt.bias
+		goto out
+	}
+
+	// Obvious overflow/underflow.
+	// These bounds are for 64-bit floats.
+	// Will have to change if we want to support 80-bit floats in the future.
+	if d.dp > 310 {
+		goto overflow
+	}
+	if d.dp < -330 {
+		// zero
+		mant = 0
+		exp = flt.bias
+		goto out
+	}
+
+	// Scale by powers of two until in range [0.5, 1.0)
+	exp = 0
+	for d.dp > 0 {
+		var n int
+		if d.dp >= len(powtab) {
+			n = 27
+		} else {
+			n = powtab[d.dp]
+		}
+		d.Shift(-n)
+		exp += n
+	}
+	for d.dp < 0 || d.dp == 0 && d.d[0] < '5' {
+		var n int
+		if -d.dp >= len(powtab) {
+			n = 27
+		} else {
+			n = powtab[-d.dp]
+		}
+		d.Shift(n)
+		exp -= n
+	}
+
+	// Our range is [0.5,1) but floating point range is [1,2).
+	exp--
+
+	// Minimum representable exponent is flt.bias+1.
+	// If the exponent is smaller, move it up and
+	// adjust d accordingly.
+	if exp < flt.bias+1 {
+		n := flt.bias + 1 - exp
+		d.Shift(-n)
+		exp += n
+	}
+
+	if exp-flt.bias >= 1<<flt.expbits-1 {
+		goto overflow
+	}
+
+	// Extract 1+flt.mantbits bits.
+	d.Shift(int(1 + flt.mantbits))
+	mant = d.RoundedInteger()
+
+	// Rounding might have added a bit; shift down.
+	if mant == 2<<flt.mantbits {
+		mant >>= 1
+		exp++
+		if exp-flt.bias >= 1<<flt.expbits-1 {
+			goto overflow
+		}
+	}
+
+	// Denormalized?
+	if mant&(1<<flt.mantbits) == 0 {
+		exp = flt.bias
+	}
+	goto out
+
+overflow:
+	// ±Inf
+	mant = 0
+	exp = 1<<flt.expbits - 1 + flt.bias
+	overflow = true
+
+out:
+	// Assemble bits.
+	bits := mant & (uint64(1)<<flt.mantbits - 1)
+	bits |= uint64((exp-flt.bias)&(1<<flt.expbits-1)) << flt.mantbits
+	if d.neg {
+		bits |= 1 << flt.mantbits << flt.expbits
+	}
+	return bits, overflow
+}
+
+// Exact powers of 10.
+var float64pow10 = []float64{
+	1e0, 1e1, 1e2, 1e3, 1e4, 1e5, 1e6, 1e7, 1e8, 1e9,
+	1e10, 1e11, 1e12, 1e13, 1e14, 1e15, 1e16, 1e17, 1e18, 1e19,
+	1e20, 1e21, 1e22,
+}
+var float32pow10 = []float32{1e0, 1e1, 1e2, 1e3, 1e4, 1e5, 1e6, 1e7, 1e8, 1e9, 1e10}
+
+// If possible to convert decimal representation to 64-bit float f exactly,
+// entirely in floating-point math, do so, avoiding the expense of decimalToFloatBits.
+// Three common cases:
+//	value is exact integer
+//	value is exact integer * exact power of ten
+//	value is exact integer / exact power of ten
+// These all produce potentially inexact but correctly rounded answers.
+func atof64exact(mantissa uint64, exp int, neg bool) (f float64, ok bool) {
+	if mantissa>>float64info.mantbits != 0 {
+		return
+	}
+	f = float64(mantissa)
+	if neg {
+		f = -f
+	}
+	switch {
+	case exp == 0:
+		// an integer.
+		return f, true
+	// Exact integers are <= 10^15.
+	// Exact powers of ten are <= 10^22.
+	case exp > 0 && exp <= 15+22: // int * 10^k
+		// If exponent is big but number of digits is not,
+		// can move a few zeros into the integer part.
+		if exp > 22 {
+			f *= float64pow10[exp-22]
+			exp = 22
+		}
+		if f > 1e15 || f < -1e15 {
+			// the exponent was really too large.
+			return
+		}
+		return f * float64pow10[exp], true
+	case exp < 0 && exp >= -22: // int / 10^k
+		return f / float64pow10[-exp], true
+	}
+	return
+}
+
+// If possible to compute mantissa*10^exp to 32-bit float f exactly,
+// entirely in floating-point math, do so, avoiding the machinery above.
+func atof32exact(mantissa uint64, exp int, neg bool) (f float32, ok bool) {
+	if mantissa>>float32info.mantbits != 0 {
+		return
+	}
+	f = float32(mantissa)
+	if neg {
+		f = -f
+	}
+	switch {
+	case exp == 0:
+		return f, true
+	// Exact integers are <= 10^7.
+	// Exact powers of ten are <= 10^10.
+	case exp > 0 && exp <= 7+10: // int * 10^k
+		// If exponent is big but number of digits is not,
+		// can move a few zeros into the integer part.
+		if exp > 10 {
+			f *= float32pow10[exp-10]
+			exp = 10
+		}
+		if f > 1e7 || f < -1e7 {
+			// the exponent was really too large.
+			return
+		}
+		return f * float32pow10[exp], true
+	case exp < 0 && exp >= -10: // int / 10^k
+		return f / float32pow10[-exp], true
+	}
+	return
+}
+
+const fnParseFloat = "ParseFloat"
+
+func atof32(s string) (f float32, err error) {
+	if val, ok := special(s); ok {
+		return float32(val), nil
+	}
+
+	if optimize {
+		// Parse mantissa and exponent.
+		mantissa, exp, neg, trunc, ok := readFloat(s)
+		if ok {
+			// Try pure floating-point arithmetic conversion.
+			if !trunc {
+				if f, ok := atof32exact(mantissa, exp, neg); ok {
+					return f, nil
+				}
+			}
+			// Try another fast path.
+			ext := new(extFloat)
+			if ok := ext.AssignDecimal(mantissa, exp, neg, trunc, &float32info); ok {
+				b, ovf := ext.floatBits(&float32info)
+				f = math.Float32frombits(uint32(b))
+				if ovf {
+					err = rangeError(fnParseFloat, s)
+				}
+				return f, err
+			}
+		}
+	}
+	var d decimal
+	if !d.set(s) {
+		return 0, syntaxError(fnParseFloat, s)
+	}
+	b, ovf := d.floatBits(&float32info)
+	f = math.Float32frombits(uint32(b))
+	if ovf {
+		err = rangeError(fnParseFloat, s)
+	}
+	return f, err
+}
+
+func atof64(s string) (f float64, err error) {
+	if val, ok := special(s); ok {
+		return val, nil
+	}
+
+	if optimize {
+		// Parse mantissa and exponent.
+		mantissa, exp, neg, trunc, ok := readFloat(s)
+		if ok {
+			// Try pure floating-point arithmetic conversion.
+			if !trunc {
+				if f, ok := atof64exact(mantissa, exp, neg); ok {
+					return f, nil
+				}
+			}
+			// Try another fast path.
+			ext := new(extFloat)
+			if ok := ext.AssignDecimal(mantissa, exp, neg, trunc, &float64info); ok {
+				b, ovf := ext.floatBits(&float64info)
+				f = math.Float64frombits(b)
+				if ovf {
+					err = rangeError(fnParseFloat, s)
+				}
+				return f, err
+			}
+		}
+	}
+	var d decimal
+	if !d.set(s) {
+		return 0, syntaxError(fnParseFloat, s)
+	}
+	b, ovf := d.floatBits(&float64info)
+	f = math.Float64frombits(b)
+	if ovf {
+		err = rangeError(fnParseFloat, s)
+	}
+	return f, err
+}
+
+// ParseFloat converts the string s to a floating-point number
+// with the precision specified by bitSize: 32 for float32, or 64 for float64.
+// When bitSize=32, the result still has type float64, but it will be
+// convertible to float32 without changing its value.
+//
+// If s is well-formed and near a valid floating point number,
+// ParseFloat returns the nearest floating point number rounded
+// using IEEE754 unbiased rounding.
+//
+// The errors that ParseFloat returns have concrete type *NumError
+// and include err.Num = s.
+//
+// If s is not syntactically well-formed, ParseFloat returns err.Err = ErrSyntax.
+//
+// If s is syntactically well-formed but is more than 1/2 ULP
+// away from the largest floating point number of the given size,
+// ParseFloat returns f = ±Inf, err.Err = ErrRange.
+func ParseFloat(s string, bitSize int) (f float64, err error) {
+	if bitSize == 32 {
+		f1, err1 := atof32(s)
+		return float64(f1), err1
+	}
+	f1, err1 := atof64(s)
+	return f1, err1
+}
diff --git a/src/strconv/atof_test.go b/src/strconv/atof_test.go
new file mode 100644
index 000000000..ba4933218
--- /dev/null
+++ b/src/strconv/atof_test.go
@@ -0,0 +1,430 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package strconv_test
+
+import (
+	"math"
+	"math/rand"
+	"reflect"
+	. "strconv"
+	"strings"
+	"testing"
+	"time"
+)
+
+type atofTest struct {
+	in  string
+	out string
+	err error
+}
+
+var atoftests = []atofTest{
+	{"", "0", ErrSyntax},
+	{"1", "1", nil},
+	{"+1", "1", nil},
+	{"1x", "0", ErrSyntax},
+	{"1.1.", "0", ErrSyntax},
+	{"1e23", "1e+23", nil},
+	{"1E23", "1e+23", nil},
+	{"100000000000000000000000", "1e+23", nil},
+	{"1e-100", "1e-100", nil},
+	{"123456700", "1.234567e+08", nil},
+	{"99999999999999974834176", "9.999999999999997e+22", nil},
+	{"100000000000000000000001", "1.0000000000000001e+23", nil},
+	{"100000000000000008388608", "1.0000000000000001e+23", nil},
+	{"100000000000000016777215", "1.0000000000000001e+23", nil},
+	{"100000000000000016777216", "1.0000000000000003e+23", nil},
+	{"-1", "-1", nil},
+	{"-0.1", "-0.1", nil},
+	{"-0", "-0", nil},
+	{"1e-20", "1e-20", nil},
+	{"625e-3", "0.625", nil},
+
+	// NaNs
+	{"nan", "NaN", nil},
+	{"NaN", "NaN", nil},
+	{"NAN", "NaN", nil},
+
+	// Infs
+	{"inf", "+Inf", nil},
+	{"-Inf", "-Inf", nil},
+	{"+INF", "+Inf", nil},
+	{"-Infinity", "-Inf", nil},
+	{"+INFINITY", "+Inf", nil},
+	{"Infinity", "+Inf", nil},
+
+	// largest float64
+	{"1.7976931348623157e308", "1.7976931348623157e+308", nil},
+	{"-1.7976931348623157e308", "-1.7976931348623157e+308", nil},
+	// next float64 - too large
+	{"1.7976931348623159e308", "+Inf", ErrRange},
+	{"-1.7976931348623159e308", "-Inf", ErrRange},
+	// the border is ...158079
+	// borderline - okay
+	{"1.7976931348623158e308", "1.7976931348623157e+308", nil},
+	{"-1.7976931348623158e308", "-1.7976931348623157e+308", nil},
+	// borderline - too large
+	{"1.797693134862315808e308", "+Inf", ErrRange},
+	{"-1.797693134862315808e308", "-Inf", ErrRange},
+
+	// a little too large
+	{"1e308", "1e+308", nil},
+	{"2e308", "+Inf", ErrRange},
+	{"1e309", "+Inf", ErrRange},
+
+	// way too large
+	{"1e310", "+Inf", ErrRange},
+	{"-1e310", "-Inf", ErrRange},
+	{"1e400", "+Inf", ErrRange},
+	{"-1e400", "-Inf", ErrRange},
+	{"1e400000", "+Inf", ErrRange},
+	{"-1e400000", "-Inf", ErrRange},
+
+	// denormalized
+	{"1e-305", "1e-305", nil},
+	{"1e-306", "1e-306", nil},
+	{"1e-307", "1e-307", nil},
+	{"1e-308", "1e-308", nil},
+	{"1e-309", "1e-309", nil},
+	{"1e-310", "1e-310", nil},
+	{"1e-322", "1e-322", nil},
+	// smallest denormal
+	{"5e-324", "5e-324", nil},
+	{"4e-324", "5e-324", nil},
+	{"3e-324", "5e-324", nil},
+	// too small
+	{"2e-324", "0", nil},
+	// way too small
+	{"1e-350", "0", nil},
+	{"1e-400000", "0", nil},
+
+	// try to overflow exponent
+	{"1e-4294967296", "0", nil},
+	{"1e+4294967296", "+Inf", ErrRange},
+	{"1e-18446744073709551616", "0", nil},
+	{"1e+18446744073709551616", "+Inf", ErrRange},
+
+	// Parse errors
+	{"1e", "0", ErrSyntax},
+	{"1e-", "0", ErrSyntax},
+	{".e-1", "0", ErrSyntax},
+	{"1\x00.2", "0", ErrSyntax},
+
+	// http://www.exploringbinary.com/java-hangs-when-converting-2-2250738585072012e-308/
+	{"2.2250738585072012e-308", "2.2250738585072014e-308", nil},
+	// http://www.exploringbinary.com/php-hangs-on-numeric-value-2-2250738585072011e-308/
+	{"2.2250738585072011e-308", "2.225073858507201e-308", nil},
+
+	// A very large number (initially wrongly parsed by the fast algorithm).
+	{"4.630813248087435e+307", "4.630813248087435e+307", nil},
+
+	// A different kind of very large number.
+	{"22.222222222222222", "22.22222222222222", nil},
+	{"2." + strings.Repeat("2", 4000) + "e+1", "22.22222222222222", nil},
+
+	// Exactly halfway between 1 and math.Nextafter(1, 2).
+	// Round to even (down).
+	{"1.00000000000000011102230246251565404236316680908203125", "1", nil},
+	// Slightly lower; still round down.
+	{"1.00000000000000011102230246251565404236316680908203124", "1", nil},
+	// Slightly higher; round up.
+	{"1.00000000000000011102230246251565404236316680908203126", "1.0000000000000002", nil},
+	// Slightly higher, but you have to read all the way to the end.
+	{"1.00000000000000011102230246251565404236316680908203125" + strings.Repeat("0", 10000) + "1", "1.0000000000000002", nil},
+}
+
+var atof32tests = []atofTest{
+	// Exactly halfway between 1 and the next float32.
+	// Round to even (down).
+	{"1.000000059604644775390625", "1", nil},
+	// Slightly lower.
+	{"1.000000059604644775390624", "1", nil},
+	// Slightly higher.
+	{"1.000000059604644775390626", "1.0000001", nil},
+	// Slightly higher, but you have to read all the way to the end.
+	{"1.000000059604644775390625" + strings.Repeat("0", 10000) + "1", "1.0000001", nil},
+
+	// largest float32: (1<<128) * (1 - 2^-24)
+	{"340282346638528859811704183484516925440", "3.4028235e+38", nil},
+	{"-340282346638528859811704183484516925440", "-3.4028235e+38", nil},
+	// next float32 - too large
+	{"3.4028236e38", "+Inf", ErrRange},
+	{"-3.4028236e38", "-Inf", ErrRange},
+	// the border is 3.40282356779...e+38
+	// borderline - okay
+	{"3.402823567e38", "3.4028235e+38", nil},
+	{"-3.402823567e38", "-3.4028235e+38", nil},
+	// borderline - too large
+	{"3.4028235678e38", "+Inf", ErrRange},
+	{"-3.4028235678e38", "-Inf", ErrRange},
+
+	// Denormals: less than 2^-126
+	{"1e-38", "1e-38", nil},
+	{"1e-39", "1e-39", nil},
+	{"1e-40", "1e-40", nil},
+	{"1e-41", "1e-41", nil},
+	{"1e-42", "1e-42", nil},
+	{"1e-43", "1e-43", nil},
+	{"1e-44", "1e-44", nil},
+	{"6e-45", "6e-45", nil}, // 4p-149 = 5.6e-45
+	{"5e-45", "6e-45", nil},
+	// Smallest denormal
+	{"1e-45", "1e-45", nil}, // 1p-149 = 1.4e-45
+	{"2e-45", "1e-45", nil},
+
+	// 2^92 = 8388608p+69 = 4951760157141521099596496896 (4.9517602e27)
+	// is an exact power of two that needs 8 decimal digits to be correctly
+	// parsed back.
+	// The float32 before is 16777215p+68 = 4.95175986e+27
+	// The halfway is 4.951760009. A bad algorithm that thinks the previous
+	// float32 is 8388607p+69 will shorten incorrectly to 4.95176e+27.
+	{"4951760157141521099596496896", "4.9517602e+27", nil},
+}
+
+type atofSimpleTest struct {
+	x float64
+	s string
+}
+
+var (
+	atofRandomTests        []atofSimpleTest
+	benchmarksRandomBits   [1024]string
+	benchmarksRandomNormal [1024]string
+)
+
+func init() {
+	// The atof routines return NumErrors wrapping
+	// the error and the string.  Convert the table above.
+	for i := range atoftests {
+		test := &atoftests[i]
+		if test.err != nil {
+			test.err = &NumError{"ParseFloat", test.in, test.err}
+		}
+	}
+	for i := range atof32tests {
+		test := &atof32tests[i]
+		if test.err != nil {
+			test.err = &NumError{"ParseFloat", test.in, test.err}
+		}
+	}
+
+	// Generate random inputs for tests and benchmarks
+	rand.Seed(time.Now().UnixNano())
+	if testing.Short() {
+		atofRandomTests = make([]atofSimpleTest, 100)
+	} else {
+		atofRandomTests = make([]atofSimpleTest, 10000)
+	}
+	for i := range atofRandomTests {
+		n := uint64(rand.Uint32())<<32 | uint64(rand.Uint32())
+		x := math.Float64frombits(n)
+		s := FormatFloat(x, 'g', -1, 64)
+		atofRandomTests[i] = atofSimpleTest{x, s}
+	}
+
+	for i := range benchmarksRandomBits {
+		bits := uint64(rand.Uint32())<<32 | uint64(rand.Uint32())
+		x := math.Float64frombits(bits)
+		benchmarksRandomBits[i] = FormatFloat(x, 'g', -1, 64)
+	}
+
+	for i := range benchmarksRandomNormal {
+		x := rand.NormFloat64()
+		benchmarksRandomNormal[i] = FormatFloat(x, 'g', -1, 64)
+	}
+}
+
+func testAtof(t *testing.T, opt bool) {
+	oldopt := SetOptimize(opt)
+	for i := 0; i < len(atoftests); i++ {
+		test := &atoftests[i]
+		out, err := ParseFloat(test.in, 64)
+		outs := FormatFloat(out, 'g', -1, 64)
+		if outs != test.out || !reflect.DeepEqual(err, test.err) {
+			t.Errorf("ParseFloat(%v, 64) = %v, %v want %v, %v",
+				test.in, out, err, test.out, test.err)
+		}
+
+		if float64(float32(out)) == out {
+			out, err := ParseFloat(test.in, 32)
+			out32 := float32(out)
+			if float64(out32) != out {
+				t.Errorf("ParseFloat(%v, 32) = %v, not a float32 (closest is %v)", test.in, out, float64(out32))
+				continue
+			}
+			outs := FormatFloat(float64(out32), 'g', -1, 32)
+			if outs != test.out || !reflect.DeepEqual(err, test.err) {
+				t.Errorf("ParseFloat(%v, 32) = %v, %v want %v, %v  # %v",
+					test.in, out32, err, test.out, test.err, out)
+			}
+		}
+	}
+	for _, test := range atof32tests {
+		out, err := ParseFloat(test.in, 32)
+		out32 := float32(out)
+		if float64(out32) != out {
+			t.Errorf("ParseFloat(%v, 32) = %v, not a float32 (closest is %v)", test.in, out, float64(out32))
+			continue
+		}
+		outs := FormatFloat(float64(out32), 'g', -1, 32)
+		if outs != test.out || !reflect.DeepEqual(err, test.err) {
+			t.Errorf("ParseFloat(%v, 32) = %v, %v want %v, %v  # %v",
+				test.in, out32, err, test.out, test.err, out)
+		}
+	}
+	SetOptimize(oldopt)
+}
+
+func TestAtof(t *testing.T) { testAtof(t, true) }
+
+func TestAtofSlow(t *testing.T) { testAtof(t, false) }
+
+func TestAtofRandom(t *testing.T) {
+	for _, test := range atofRandomTests {
+		x, _ := ParseFloat(test.s, 64)
+		switch {
+		default:
+			t.Errorf("number %s badly parsed as %b (expected %b)", test.s, x, test.x)
+		case x == test.x:
+		case math.IsNaN(test.x) && math.IsNaN(x):
+		}
+	}
+	t.Logf("tested %d random numbers", len(atofRandomTests))
+}
+
+var roundTripCases = []struct {
+	f float64
+	s string
+}{
+	// Issue 2917.
+	// This test will break the optimized conversion if the
+	// FPU is using 80-bit registers instead of 64-bit registers,
+	// usually because the operating system initialized the
+	// thread with 80-bit precision and the Go runtime didn't
+	// fix the FP control word.
+	{8865794286000691 << 39, "4.87402195346389e+27"},
+	{8865794286000692 << 39, "4.8740219534638903e+27"},
+}
+
+func TestRoundTrip(t *testing.T) {
+	for _, tt := range roundTripCases {
+		old := SetOptimize(false)
+		s := FormatFloat(tt.f, 'g', -1, 64)
+		if s != tt.s {
+			t.Errorf("no-opt FormatFloat(%b) = %s, want %s", tt.f, s, tt.s)
+		}
+		f, err := ParseFloat(tt.s, 64)
+		if f != tt.f || err != nil {
+			t.Errorf("no-opt ParseFloat(%s) = %b, %v want %b, nil", tt.s, f, err, tt.f)
+		}
+		SetOptimize(true)
+		s = FormatFloat(tt.f, 'g', -1, 64)
+		if s != tt.s {
+			t.Errorf("opt FormatFloat(%b) = %s, want %s", tt.f, s, tt.s)
+		}
+		f, err = ParseFloat(tt.s, 64)
+		if f != tt.f || err != nil {
+			t.Errorf("opt ParseFloat(%s) = %b, %v want %b, nil", tt.s, f, err, tt.f)
+		}
+		SetOptimize(old)
+	}
+}
+
+// TestRoundTrip32 tries a fraction of all finite positive float32 values.
+func TestRoundTrip32(t *testing.T) {
+	step := uint32(997)
+	if testing.Short() {
+		step = 99991
+	}
+	count := 0
+	for i := uint32(0); i < 0xff<<23; i += step {
+		f := math.Float32frombits(i)
+		if i&1 == 1 {
+			f = -f // negative
+		}
+		s := FormatFloat(float64(f), 'g', -1, 32)
+
+		parsed, err := ParseFloat(s, 32)
+		parsed32 := float32(parsed)
+		switch {
+		case err != nil:
+			t.Errorf("ParseFloat(%q, 32) gave error %s", s, err)
+		case float64(parsed32) != parsed:
+			t.Errorf("ParseFloat(%q, 32) = %v, not a float32 (nearest is %v)", s, parsed, parsed32)
+		case parsed32 != f:
+			t.Errorf("ParseFloat(%q, 32) = %b (expected %b)", s, parsed32, f)
+		}
+		count++
+	}
+	t.Logf("tested %d float32's", count)
+}
+
+func BenchmarkAtof64Decimal(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		ParseFloat("33909", 64)
+	}
+}
+
+func BenchmarkAtof64Float(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		ParseFloat("339.7784", 64)
+	}
+}
+
+func BenchmarkAtof64FloatExp(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		ParseFloat("-5.09e75", 64)
+	}
+}
+
+func BenchmarkAtof64Big(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		ParseFloat("123456789123456789123456789", 64)
+	}
+}
+
+func BenchmarkAtof64RandomBits(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		ParseFloat(benchmarksRandomBits[i%1024], 64)
+	}
+}
+
+func BenchmarkAtof64RandomFloats(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		ParseFloat(benchmarksRandomNormal[i%1024], 64)
+	}
+}
+
+func BenchmarkAtof32Decimal(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		ParseFloat("33909", 32)
+	}
+}
+
+func BenchmarkAtof32Float(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		ParseFloat("339.778", 32)
+	}
+}
+
+func BenchmarkAtof32FloatExp(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		ParseFloat("12.3456e32", 32)
+	}
+}
+
+var float32strings [4096]string
+
+func BenchmarkAtof32Random(b *testing.B) {
+	n := uint32(997)
+	for i := range float32strings {
+		n = (99991*n + 42) % (0xff << 23)
+		float32strings[i] = FormatFloat(float64(math.Float32frombits(n)), 'g', -1, 32)
+	}
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		ParseFloat(float32strings[i%4096], 32)
+	}
+}
diff --git a/src/strconv/atoi.go b/src/strconv/atoi.go
new file mode 100644
index 000000000..9ecec5a58
--- /dev/null
+++ b/src/strconv/atoi.go
@@ -0,0 +1,198 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package strconv
+
+import "errors"
+
+// ErrRange indicates that a value is out of range for the target type.
+var ErrRange = errors.New("value out of range")
+
+// ErrSyntax indicates that a value does not have the right syntax for the target type.
+var ErrSyntax = errors.New("invalid syntax")
+
+// A NumError records a failed conversion.
+type NumError struct {
+	Func string // the failing function (ParseBool, ParseInt, ParseUint, ParseFloat)
+	Num  string // the input
+	Err  error  // the reason the conversion failed (ErrRange, ErrSyntax)
+}
+
+func (e *NumError) Error() string {
+	return "strconv." + e.Func + ": " + "parsing " + Quote(e.Num) + ": " + e.Err.Error()
+}
+
+func syntaxError(fn, str string) *NumError {
+	return &NumError{fn, str, ErrSyntax}
+}
+
+func rangeError(fn, str string) *NumError {
+	return &NumError{fn, str, ErrRange}
+}
+
+const intSize = 32 << (^uint(0) >> 63)
+
+// IntSize is the size in bits of an int or uint value.
+const IntSize = intSize
+
+// Return the first number n such that n*base >= 1<<64.
+func cutoff64(base int) uint64 {
+	if base < 2 {
+		return 0
+	}
+	return (1<<64-1)/uint64(base) + 1
+}
+
+// ParseUint is like ParseInt but for unsigned numbers.
+func ParseUint(s string, base int, bitSize int) (n uint64, err error) {
+	var cutoff, maxVal uint64
+
+	if bitSize == 0 {
+		bitSize = int(IntSize)
+	}
+
+	s0 := s
+	switch {
+	case len(s) < 1:
+		err = ErrSyntax
+		goto Error
+
+	case 2 <= base && base <= 36:
+		// valid base; nothing to do
+
+	case base == 0:
+		// Look for octal, hex prefix.
+		switch {
+		case s[0] == '0' && len(s) > 1 && (s[1] == 'x' || s[1] == 'X'):
+			base = 16
+			s = s[2:]
+			if len(s) < 1 {
+				err = ErrSyntax
+				goto Error
+			}
+		case s[0] == '0':
+			base = 8
+		default:
+			base = 10
+		}
+
+	default:
+		err = errors.New("invalid base " + Itoa(base))
+		goto Error
+	}
+
+	n = 0
+	cutoff = cutoff64(base)
+	maxVal = 1<<uint(bitSize) - 1
+
+	for i := 0; i < len(s); i++ {
+		var v byte
+		d := s[i]
+		switch {
+		case '0' <= d && d <= '9':
+			v = d - '0'
+		case 'a' <= d && d <= 'z':
+			v = d - 'a' + 10
+		case 'A' <= d && d <= 'Z':
+			v = d - 'A' + 10
+		default:
+			n = 0
+			err = ErrSyntax
+			goto Error
+		}
+		if int(v) >= base {
+			n = 0
+			err = ErrSyntax
+			goto Error
+		}
+
+		if n >= cutoff {
+			// n*base overflows
+			n = 1<<64 - 1
+			err = ErrRange
+			goto Error
+		}
+		n *= uint64(base)
+
+		n1 := n + uint64(v)
+		if n1 < n || n1 > maxVal {
+			// n+v overflows
+			n = 1<<64 - 1
+			err = ErrRange
+			goto Error
+		}
+		n = n1
+	}
+
+	return n, nil
+
+Error:
+	return n, &NumError{"ParseUint", s0, err}
+}
+
+// ParseInt interprets a string s in the given base (2 to 36) and
+// returns the corresponding value i.  If base == 0, the base is
+// implied by the string's prefix: base 16 for "0x", base 8 for
+// "0", and base 10 otherwise.
+//
+// The bitSize argument specifies the integer type
+// that the result must fit into.  Bit sizes 0, 8, 16, 32, and 64
+// correspond to int, int8, int16, int32, and int64.
+//
+// The errors that ParseInt returns have concrete type *NumError
+// and include err.Num = s.  If s is empty or contains invalid
+// digits, err.Err = ErrSyntax and the returned value is 0;
+// if the value corresponding to s cannot be represented by a
+// signed integer of the given size, err.Err = ErrRange and the
+// returned value is the maximum magnitude integer of the
+// appropriate bitSize and sign.
+func ParseInt(s string, base int, bitSize int) (i int64, err error) {
+	const fnParseInt = "ParseInt"
+
+	if bitSize == 0 {
+		bitSize = int(IntSize)
+	}
+
+	// Empty string bad.
+	if len(s) == 0 {
+		return 0, syntaxError(fnParseInt, s)
+	}
+
+	// Pick off leading sign.
+	s0 := s
+	neg := false
+	if s[0] == '+' {
+		s = s[1:]
+	} else if s[0] == '-' {
+		neg = true
+		s = s[1:]
+	}
+
+	// Convert unsigned and check range.
+	var un uint64
+	un, err = ParseUint(s, base, bitSize)
+	if err != nil && err.(*NumError).Err != ErrRange {
+		err.(*NumError).Func = fnParseInt
+		err.(*NumError).Num = s0
+		return 0, err
+	}
+	cutoff := uint64(1 << uint(bitSize-1))
+	if !neg && un >= cutoff {
+		return int64(cutoff - 1), rangeError(fnParseInt, s0)
+	}
+	if neg && un > cutoff {
+		return -int64(cutoff), rangeError(fnParseInt, s0)
+	}
+	n := int64(un)
+	if neg {
+		n = -n
+	}
+	return n, nil
+}
+
+// Atoi is shorthand for ParseInt(s, 10, 0).
+func Atoi(s string) (i int, err error) {
+	i64, err := ParseInt(s, 10, 0)
+	return int(i64), err
+}
diff --git a/src/strconv/atoi_test.go b/src/strconv/atoi_test.go
new file mode 100644
index 000000000..940757307
--- /dev/null
+++ b/src/strconv/atoi_test.go
@@ -0,0 +1,326 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package strconv_test
+
+import (
+	"errors"
+	"reflect"
+	. "strconv"
+	"testing"
+)
+
+type atoui64Test struct {
+	in  string
+	out uint64
+	err error
+}
+
+var atoui64tests = []atoui64Test{
+	{"", 0, ErrSyntax},
+	{"0", 0, nil},
+	{"1", 1, nil},
+	{"12345", 12345, nil},
+	{"012345", 12345, nil},
+	{"12345x", 0, ErrSyntax},
+	{"98765432100", 98765432100, nil},
+	{"18446744073709551615", 1<<64 - 1, nil},
+	{"18446744073709551616", 1<<64 - 1, ErrRange},
+	{"18446744073709551620", 1<<64 - 1, ErrRange},
+}
+
+var btoui64tests = []atoui64Test{
+	{"", 0, ErrSyntax},
+	{"0", 0, nil},
+	{"1", 1, nil},
+	{"12345", 12345, nil},
+	{"012345", 012345, nil},
+	{"0x12345", 0x12345, nil},
+	{"0X12345", 0x12345, nil},
+	{"12345x", 0, ErrSyntax},
+	{"98765432100", 98765432100, nil},
+	{"18446744073709551615", 1<<64 - 1, nil},
+	{"18446744073709551616", 1<<64 - 1, ErrRange},
+	{"18446744073709551620", 1<<64 - 1, ErrRange},
+	{"0xFFFFFFFFFFFFFFFF", 1<<64 - 1, nil},
+	{"0x10000000000000000", 1<<64 - 1, ErrRange},
+	{"01777777777777777777777", 1<<64 - 1, nil},
+	{"01777777777777777777778", 0, ErrSyntax},
+	{"02000000000000000000000", 1<<64 - 1, ErrRange},
+	{"0200000000000000000000", 1 << 61, nil},
+}
+
+type atoi64Test struct {
+	in  string
+	out int64
+	err error
+}
+
+var atoi64tests = []atoi64Test{
+	{"", 0, ErrSyntax},
+	{"0", 0, nil},
+	{"-0", 0, nil},
+	{"1", 1, nil},
+	{"-1", -1, nil},
+	{"12345", 12345, nil},
+	{"-12345", -12345, nil},
+	{"012345", 12345, nil},
+	{"-012345", -12345, nil},
+	{"98765432100", 98765432100, nil},
+	{"-98765432100", -98765432100, nil},
+	{"9223372036854775807", 1<<63 - 1, nil},
+	{"-9223372036854775807", -(1<<63 - 1), nil},
+	{"9223372036854775808", 1<<63 - 1, ErrRange},
+	{"-9223372036854775808", -1 << 63, nil},
+	{"9223372036854775809", 1<<63 - 1, ErrRange},
+	{"-9223372036854775809", -1 << 63, ErrRange},
+}
+
+var btoi64tests = []atoi64Test{
+	{"", 0, ErrSyntax},
+	{"0", 0, nil},
+	{"-0", 0, nil},
+	{"1", 1, nil},
+	{"-1", -1, nil},
+	{"12345", 12345, nil},
+	{"-12345", -12345, nil},
+	{"012345", 012345, nil},
+	{"-012345", -012345, nil},
+	{"0x12345", 0x12345, nil},
+	{"-0X12345", -0x12345, nil},
+	{"12345x", 0, ErrSyntax},
+	{"-12345x", 0, ErrSyntax},
+	{"98765432100", 98765432100, nil},
+	{"-98765432100", -98765432100, nil},
+	{"9223372036854775807", 1<<63 - 1, nil},
+	{"-9223372036854775807", -(1<<63 - 1), nil},
+	{"9223372036854775808", 1<<63 - 1, ErrRange},
+	{"-9223372036854775808", -1 << 63, nil},
+	{"9223372036854775809", 1<<63 - 1, ErrRange},
+	{"-9223372036854775809", -1 << 63, ErrRange},
+}
+
+type atoui32Test struct {
+	in  string
+	out uint32
+	err error
+}
+
+var atoui32tests = []atoui32Test{
+	{"", 0, ErrSyntax},
+	{"0", 0, nil},
+	{"1", 1, nil},
+	{"12345", 12345, nil},
+	{"012345", 12345, nil},
+	{"12345x", 0, ErrSyntax},
+	{"987654321", 987654321, nil},
+	{"4294967295", 1<<32 - 1, nil},
+	{"4294967296", 1<<32 - 1, ErrRange},
+}
+
+type atoi32Test struct {
+	in  string
+	out int32
+	err error
+}
+
+var atoi32tests = []atoi32Test{
+	{"", 0, ErrSyntax},
+	{"0", 0, nil},
+	{"-0", 0, nil},
+	{"1", 1, nil},
+	{"-1", -1, nil},
+	{"12345", 12345, nil},
+	{"-12345", -12345, nil},
+	{"012345", 12345, nil},
+	{"-012345", -12345, nil},
+	{"12345x", 0, ErrSyntax},
+	{"-12345x", 0, ErrSyntax},
+	{"987654321", 987654321, nil},
+	{"-987654321", -987654321, nil},
+	{"2147483647", 1<<31 - 1, nil},
+	{"-2147483647", -(1<<31 - 1), nil},
+	{"2147483648", 1<<31 - 1, ErrRange},
+	{"-2147483648", -1 << 31, nil},
+	{"2147483649", 1<<31 - 1, ErrRange},
+	{"-2147483649", -1 << 31, ErrRange},
+}
+
+type numErrorTest struct {
+	num, want string
+}
+
+var numErrorTests = []numErrorTest{
+	{"0", `strconv.ParseFloat: parsing "0": failed`},
+	{"`", "strconv.ParseFloat: parsing \"`\": failed"},
+	{"1\x00.2", `strconv.ParseFloat: parsing "1\x00.2": failed`},
+}
+
+func init() {
+	// The atoi routines return NumErrors wrapping
+	// the error and the string.  Convert the tables above.
+	for i := range atoui64tests {
+		test := &atoui64tests[i]
+		if test.err != nil {
+			test.err = &NumError{"ParseUint", test.in, test.err}
+		}
+	}
+	for i := range btoui64tests {
+		test := &btoui64tests[i]
+		if test.err != nil {
+			test.err = &NumError{"ParseUint", test.in, test.err}
+		}
+	}
+	for i := range atoi64tests {
+		test := &atoi64tests[i]
+		if test.err != nil {
+			test.err = &NumError{"ParseInt", test.in, test.err}
+		}
+	}
+	for i := range btoi64tests {
+		test := &btoi64tests[i]
+		if test.err != nil {
+			test.err = &NumError{"ParseInt", test.in, test.err}
+		}
+	}
+	for i := range atoui32tests {
+		test := &atoui32tests[i]
+		if test.err != nil {
+			test.err = &NumError{"ParseUint", test.in, test.err}
+		}
+	}
+	for i := range atoi32tests {
+		test := &atoi32tests[i]
+		if test.err != nil {
+			test.err = &NumError{"ParseInt", test.in, test.err}
+		}
+	}
+}
+
+func TestParseUint64(t *testing.T) {
+	for i := range atoui64tests {
+		test := &atoui64tests[i]
+		out, err := ParseUint(test.in, 10, 64)
+		if test.out != out || !reflect.DeepEqual(test.err, err) {
+			t.Errorf("Atoui64(%q) = %v, %v want %v, %v",
+				test.in, out, err, test.out, test.err)
+		}
+	}
+}
+
+func TestParseUint64Base(t *testing.T) {
+	for i := range btoui64tests {
+		test := &btoui64tests[i]
+		out, err := ParseUint(test.in, 0, 64)
+		if test.out != out || !reflect.DeepEqual(test.err, err) {
+			t.Errorf("ParseUint(%q) = %v, %v want %v, %v",
+				test.in, out, err, test.out, test.err)
+		}
+	}
+}
+
+func TestParseInt64(t *testing.T) {
+	for i := range atoi64tests {
+		test := &atoi64tests[i]
+		out, err := ParseInt(test.in, 10, 64)
+		if test.out != out || !reflect.DeepEqual(test.err, err) {
+			t.Errorf("Atoi64(%q) = %v, %v want %v, %v",
+				test.in, out, err, test.out, test.err)
+		}
+	}
+}
+
+func TestParseInt64Base(t *testing.T) {
+	for i := range btoi64tests {
+		test := &btoi64tests[i]
+		out, err := ParseInt(test.in, 0, 64)
+		if test.out != out || !reflect.DeepEqual(test.err, err) {
+			t.Errorf("ParseInt(%q) = %v, %v want %v, %v",
+				test.in, out, err, test.out, test.err)
+		}
+	}
+}
+
+func TestParseUint(t *testing.T) {
+	switch IntSize {
+	case 32:
+		for i := range atoui32tests {
+			test := &atoui32tests[i]
+			out, err := ParseUint(test.in, 10, 0)
+			if test.out != uint32(out) || !reflect.DeepEqual(test.err, err) {
+				t.Errorf("Atoui(%q) = %v, %v want %v, %v",
+					test.in, out, err, test.out, test.err)
+			}
+		}
+	case 64:
+		for i := range atoui64tests {
+			test := &atoui64tests[i]
+			out, err := ParseUint(test.in, 10, 0)
+			if test.out != uint64(out) || !reflect.DeepEqual(test.err, err) {
+				t.Errorf("Atoui(%q) = %v, %v want %v, %v",
+					test.in, out, err, test.out, test.err)
+			}
+		}
+	}
+}
+
+func TestParseInt(t *testing.T) {
+	switch IntSize {
+	case 32:
+		for i := range atoi32tests {
+			test := &atoi32tests[i]
+			out, err := ParseInt(test.in, 10, 0)
+			if test.out != int32(out) || !reflect.DeepEqual(test.err, err) {
+				t.Errorf("Atoi(%q) = %v, %v want %v, %v",
+					test.in, out, err, test.out, test.err)
+			}
+		}
+	case 64:
+		for i := range atoi64tests {
+			test := &atoi64tests[i]
+			out, err := ParseInt(test.in, 10, 0)
+			if test.out != int64(out) || !reflect.DeepEqual(test.err, err) {
+				t.Errorf("Atoi(%q) = %v, %v want %v, %v",
+					test.in, out, err, test.out, test.err)
+			}
+		}
+	}
+}
+
+func TestNumError(t *testing.T) {
+	for _, test := range numErrorTests {
+		err := &NumError{
+			Func: "ParseFloat",
+			Num:  test.num,
+			Err:  errors.New("failed"),
+		}
+		if got := err.Error(); got != test.want {
+			t.Errorf(`(&NumError{"ParseFloat", %q, "failed"}).Error() = %v, want %v`, test.num, got, test.want)
+		}
+	}
+}
+
+func BenchmarkAtoi(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		ParseInt("12345678", 10, 0)
+	}
+}
+
+func BenchmarkAtoiNeg(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		ParseInt("-12345678", 10, 0)
+	}
+}
+
+func BenchmarkAtoi64(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		ParseInt("12345678901234", 10, 64)
+	}
+}
+
+func BenchmarkAtoi64Neg(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		ParseInt("-12345678901234", 10, 64)
+	}
+}
diff --git a/src/strconv/decimal.go b/src/strconv/decimal.go
new file mode 100644
index 000000000..42601283d
--- /dev/null
+++ b/src/strconv/decimal.go
@@ -0,0 +1,378 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Multiprecision decimal numbers.
+// For floating-point formatting only; not general purpose.
+// Only operations are assign and (binary) left/right shift.
+// Can do binary floating point in multiprecision decimal precisely
+// because 2 divides 10; cannot do decimal floating point
+// in multiprecision binary precisely.
+
+package strconv
+
+type decimal struct {
+	d     [800]byte // digits
+	nd    int       // number of digits used
+	dp    int       // decimal point
+	neg   bool
+	trunc bool // discarded nonzero digits beyond d[:nd]
+}
+
+func (a *decimal) String() string {
+	n := 10 + a.nd
+	if a.dp > 0 {
+		n += a.dp
+	}
+	if a.dp < 0 {
+		n += -a.dp
+	}
+
+	buf := make([]byte, n)
+	w := 0
+	switch {
+	case a.nd == 0:
+		return "0"
+
+	case a.dp <= 0:
+		// zeros fill space between decimal point and digits
+		buf[w] = '0'
+		w++
+		buf[w] = '.'
+		w++
+		w += digitZero(buf[w : w+-a.dp])
+		w += copy(buf[w:], a.d[0:a.nd])
+
+	case a.dp < a.nd:
+		// decimal point in middle of digits
+		w += copy(buf[w:], a.d[0:a.dp])
+		buf[w] = '.'
+		w++
+		w += copy(buf[w:], a.d[a.dp:a.nd])
+
+	default:
+		// zeros fill space between digits and decimal point
+		w += copy(buf[w:], a.d[0:a.nd])
+		w += digitZero(buf[w : w+a.dp-a.nd])
+	}
+	return string(buf[0:w])
+}
+
+func digitZero(dst []byte) int {
+	for i := range dst {
+		dst[i] = '0'
+	}
+	return len(dst)
+}
+
+// trim trailing zeros from number.
+// (They are meaningless; the decimal point is tracked
+// independent of the number of digits.)
+func trim(a *decimal) {
+	for a.nd > 0 && a.d[a.nd-1] == '0' {
+		a.nd--
+	}
+	if a.nd == 0 {
+		a.dp = 0
+	}
+}
+
+// Assign v to a.
+func (a *decimal) Assign(v uint64) {
+	var buf [24]byte
+
+	// Write reversed decimal in buf.
+	n := 0
+	for v > 0 {
+		v1 := v / 10
+		v -= 10 * v1
+		buf[n] = byte(v + '0')
+		n++
+		v = v1
+	}
+
+	// Reverse again to produce forward decimal in a.d.
+	a.nd = 0
+	for n--; n >= 0; n-- {
+		a.d[a.nd] = buf[n]
+		a.nd++
+	}
+	a.dp = a.nd
+	trim(a)
+}
+
+// Maximum shift that we can do in one pass without overflow.
+// Signed int has 31 bits, and we have to be able to accommodate 9<<k.
+const maxShift = 27
+
+// Binary shift right (* 2) by k bits.  k <= maxShift to avoid overflow.
+func rightShift(a *decimal, k uint) {
+	r := 0 // read pointer
+	w := 0 // write pointer
+
+	// Pick up enough leading digits to cover first shift.
+	n := 0
+	for ; n>>k == 0; r++ {
+		if r >= a.nd {
+			if n == 0 {
+				// a == 0; shouldn't get here, but handle anyway.
+				a.nd = 0
+				return
+			}
+			for n>>k == 0 {
+				n = n * 10
+				r++
+			}
+			break
+		}
+		c := int(a.d[r])
+		n = n*10 + c - '0'
+	}
+	a.dp -= r - 1
+
+	// Pick up a digit, put down a digit.
+	for ; r < a.nd; r++ {
+		c := int(a.d[r])
+		dig := n >> k
+		n -= dig << k
+		a.d[w] = byte(dig + '0')
+		w++
+		n = n*10 + c - '0'
+	}
+
+	// Put down extra digits.
+	for n > 0 {
+		dig := n >> k
+		n -= dig << k
+		if w < len(a.d) {
+			a.d[w] = byte(dig + '0')
+			w++
+		} else if dig > 0 {
+			a.trunc = true
+		}
+		n = n * 10
+	}
+
+	a.nd = w
+	trim(a)
+}
+
+// Cheat sheet for left shift: table indexed by shift count giving
+// number of new digits that will be introduced by that shift.
+//
+// For example, leftcheats[4] = {2, "625"}.  That means that
+// if we are shifting by 4 (multiplying by 16), it will add 2 digits
+// when the string prefix is "625" through "999", and one fewer digit
+// if the string prefix is "000" through "624".
+//
+// Credit for this trick goes to Ken.
+
+type leftCheat struct {
+	delta  int    // number of new digits
+	cutoff string //   minus one digit if original < a.
+}
+
+var leftcheats = []leftCheat{
+	// Leading digits of 1/2^i = 5^i.
+	// 5^23 is not an exact 64-bit floating point number,
+	// so have to use bc for the math.
+	/*
+		seq 27 | sed 's/^/5^/' | bc |
+		awk 'BEGIN{ print "\tleftCheat{ 0, \"\" }," }
+		{
+			log2 = log(2)/log(10)
+			printf("\tleftCheat{ %d, \"%s\" },\t// * %d\n",
+				int(log2*NR+1), $0, 2**NR)
+		}'
+	*/
+	{0, ""},
+	{1, "5"},                   // * 2
+	{1, "25"},                  // * 4
+	{1, "125"},                 // * 8
+	{2, "625"},                 // * 16
+	{2, "3125"},                // * 32
+	{2, "15625"},               // * 64
+	{3, "78125"},               // * 128
+	{3, "390625"},              // * 256
+	{3, "1953125"},             // * 512
+	{4, "9765625"},             // * 1024
+	{4, "48828125"},            // * 2048
+	{4, "244140625"},           // * 4096
+	{4, "1220703125"},          // * 8192
+	{5, "6103515625"},          // * 16384
+	{5, "30517578125"},         // * 32768
+	{5, "152587890625"},        // * 65536
+	{6, "762939453125"},        // * 131072
+	{6, "3814697265625"},       // * 262144
+	{6, "19073486328125"},      // * 524288
+	{7, "95367431640625"},      // * 1048576
+	{7, "476837158203125"},     // * 2097152
+	{7, "2384185791015625"},    // * 4194304
+	{7, "11920928955078125"},   // * 8388608
+	{8, "59604644775390625"},   // * 16777216
+	{8, "298023223876953125"},  // * 33554432
+	{8, "1490116119384765625"}, // * 67108864
+	{9, "7450580596923828125"}, // * 134217728
+}
+
+// Is the leading prefix of b lexicographically less than s?
+func prefixIsLessThan(b []byte, s string) bool {
+	for i := 0; i < len(s); i++ {
+		if i >= len(b) {
+			return true
+		}
+		if b[i] != s[i] {
+			return b[i] < s[i]
+		}
+	}
+	return false
+}
+
+// Binary shift left (/ 2) by k bits.  k <= maxShift to avoid overflow.
+func leftShift(a *decimal, k uint) {
+	delta := leftcheats[k].delta
+	if prefixIsLessThan(a.d[0:a.nd], leftcheats[k].cutoff) {
+		delta--
+	}
+
+	r := a.nd         // read index
+	w := a.nd + delta // write index
+	n := 0
+
+	// Pick up a digit, put down a digit.
+	for r--; r >= 0; r-- {
+		n += (int(a.d[r]) - '0') << k
+		quo := n / 10
+		rem := n - 10*quo
+		w--
+		if w < len(a.d) {
+			a.d[w] = byte(rem + '0')
+		} else if rem != 0 {
+			a.trunc = true
+		}
+		n = quo
+	}
+
+	// Put down extra digits.
+	for n > 0 {
+		quo := n / 10
+		rem := n - 10*quo
+		w--
+		if w < len(a.d) {
+			a.d[w] = byte(rem + '0')
+		} else if rem != 0 {
+			a.trunc = true
+		}
+		n = quo
+	}
+
+	a.nd += delta
+	if a.nd >= len(a.d) {
+		a.nd = len(a.d)
+	}
+	a.dp += delta
+	trim(a)
+}
+
+// Binary shift left (k > 0) or right (k < 0).
+func (a *decimal) Shift(k int) {
+	switch {
+	case a.nd == 0:
+		// nothing to do: a == 0
+	case k > 0:
+		for k > maxShift {
+			leftShift(a, maxShift)
+			k -= maxShift
+		}
+		leftShift(a, uint(k))
+	case k < 0:
+		for k < -maxShift {
+			rightShift(a, maxShift)
+			k += maxShift
+		}
+		rightShift(a, uint(-k))
+	}
+}
+
+// If we chop a at nd digits, should we round up?
+func shouldRoundUp(a *decimal, nd int) bool {
+	if nd < 0 || nd >= a.nd {
+		return false
+	}
+	if a.d[nd] == '5' && nd+1 == a.nd { // exactly halfway - round to even
+		// if we truncated, a little higher than what's recorded - always round up
+		if a.trunc {
+			return true
+		}
+		return nd > 0 && (a.d[nd-1]-'0')%2 != 0
+	}
+	// not halfway - digit tells all
+	return a.d[nd] >= '5'
+}
+
+// Round a to nd digits (or fewer).
+// If nd is zero, it means we're rounding
+// just to the left of the digits, as in
+// 0.09 -> 0.1.
+func (a *decimal) Round(nd int) {
+	if nd < 0 || nd >= a.nd {
+		return
+	}
+	if shouldRoundUp(a, nd) {
+		a.RoundUp(nd)
+	} else {
+		a.RoundDown(nd)
+	}
+}
+
+// Round a down to nd digits (or fewer).
+func (a *decimal) RoundDown(nd int) {
+	if nd < 0 || nd >= a.nd {
+		return
+	}
+	a.nd = nd
+	trim(a)
+}
+
+// Round a up to nd digits (or fewer).
+func (a *decimal) RoundUp(nd int) {
+	if nd < 0 || nd >= a.nd {
+		return
+	}
+
+	// round up
+	for i := nd - 1; i >= 0; i-- {
+		c := a.d[i]
+		if c < '9' { // can stop after this digit
+			a.d[i]++
+			a.nd = i + 1
+			return
+		}
+	}
+
+	// Number is all 9s.
+	// Change to single 1 with adjusted decimal point.
+	a.d[0] = '1'
+	a.nd = 1
+	a.dp++
+}
+
+// Extract integer part, rounded appropriately.
+// No guarantees about overflow.
+func (a *decimal) RoundedInteger() uint64 {
+	if a.dp > 20 {
+		return 0xFFFFFFFFFFFFFFFF
+	}
+	var i int
+	n := uint64(0)
+	for i = 0; i < a.dp && i < a.nd; i++ {
+		n = n*10 + uint64(a.d[i]-'0')
+	}
+	for ; i < a.dp; i++ {
+		n *= 10
+	}
+	if shouldRoundUp(a, a.dp) {
+		n++
+	}
+	return n
+}
diff --git a/src/strconv/decimal_test.go b/src/strconv/decimal_test.go
new file mode 100644
index 000000000..13a127f5b
--- /dev/null
+++ b/src/strconv/decimal_test.go
@@ -0,0 +1,127 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package strconv_test
+
+import (
+	. "strconv"
+	"testing"
+)
+
+type shiftTest struct {
+	i     uint64
+	shift int
+	out   string
+}
+
+var shifttests = []shiftTest{
+	{0, -100, "0"},
+	{0, 100, "0"},
+	{1, 100, "1267650600228229401496703205376"},
+	{1, -100,
+		"0.00000000000000000000000000000078886090522101180541" +
+			"17285652827862296732064351090230047702789306640625",
+	},
+	{12345678, 8, "3160493568"},
+	{12345678, -8, "48225.3046875"},
+	{195312, 9, "99999744"},
+	{1953125, 9, "1000000000"},
+}
+
+func TestDecimalShift(t *testing.T) {
+	for i := 0; i < len(shifttests); i++ {
+		test := &shifttests[i]
+		d := NewDecimal(test.i)
+		d.Shift(test.shift)
+		s := d.String()
+		if s != test.out {
+			t.Errorf("Decimal %v << %v = %v, want %v",
+				test.i, test.shift, s, test.out)
+		}
+	}
+}
+
+type roundTest struct {
+	i               uint64
+	nd              int
+	down, round, up string
+	int             uint64
+}
+
+var roundtests = []roundTest{
+	{0, 4, "0", "0", "0", 0},
+	{12344999, 4, "12340000", "12340000", "12350000", 12340000},
+	{12345000, 4, "12340000", "12340000", "12350000", 12340000},
+	{12345001, 4, "12340000", "12350000", "12350000", 12350000},
+	{23454999, 4, "23450000", "23450000", "23460000", 23450000},
+	{23455000, 4, "23450000", "23460000", "23460000", 23460000},
+	{23455001, 4, "23450000", "23460000", "23460000", 23460000},
+
+	{99994999, 4, "99990000", "99990000", "100000000", 99990000},
+	{99995000, 4, "99990000", "100000000", "100000000", 100000000},
+	{99999999, 4, "99990000", "100000000", "100000000", 100000000},
+
+	{12994999, 4, "12990000", "12990000", "13000000", 12990000},
+	{12995000, 4, "12990000", "13000000", "13000000", 13000000},
+	{12999999, 4, "12990000", "13000000", "13000000", 13000000},
+}
+
+func TestDecimalRound(t *testing.T) {
+	for i := 0; i < len(roundtests); i++ {
+		test := &roundtests[i]
+		d := NewDecimal(test.i)
+		d.RoundDown(test.nd)
+		s := d.String()
+		if s != test.down {
+			t.Errorf("Decimal %v RoundDown %d = %v, want %v",
+				test.i, test.nd, s, test.down)
+		}
+		d = NewDecimal(test.i)
+		d.Round(test.nd)
+		s = d.String()
+		if s != test.round {
+			t.Errorf("Decimal %v Round %d = %v, want %v",
+				test.i, test.nd, s, test.down)
+		}
+		d = NewDecimal(test.i)
+		d.RoundUp(test.nd)
+		s = d.String()
+		if s != test.up {
+			t.Errorf("Decimal %v RoundUp %d = %v, want %v",
+				test.i, test.nd, s, test.up)
+		}
+	}
+}
+
+type roundIntTest struct {
+	i     uint64
+	shift int
+	int   uint64
+}
+
+var roundinttests = []roundIntTest{
+	{0, 100, 0},
+	{512, -8, 2},
+	{513, -8, 2},
+	{640, -8, 2},
+	{641, -8, 3},
+	{384, -8, 2},
+	{385, -8, 2},
+	{383, -8, 1},
+	{1, 100, 1<<64 - 1},
+	{1000, 0, 1000},
+}
+
+func TestDecimalRoundedInteger(t *testing.T) {
+	for i := 0; i < len(roundinttests); i++ {
+		test := roundinttests[i]
+		d := NewDecimal(test.i)
+		d.Shift(test.shift)
+		int := d.RoundedInteger()
+		if int != test.int {
+			t.Errorf("Decimal %v >> %v RoundedInteger = %v, want %v",
+				test.i, test.shift, int, test.int)
+		}
+	}
+}
diff --git a/src/strconv/extfloat.go b/src/strconv/extfloat.go
new file mode 100644
index 000000000..bed8b16bd
--- /dev/null
+++ b/src/strconv/extfloat.go
@@ -0,0 +1,668 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package strconv
+
+// An extFloat represents an extended floating-point number, with more
+// precision than a float64. It does not try to save bits: the
+// number represented by the structure is mant*(2^exp), with a negative
+// sign if neg is true.
+type extFloat struct {
+	mant uint64
+	exp  int
+	neg  bool
+}
+
+// Powers of ten taken from double-conversion library.
+// http://code.google.com/p/double-conversion/
+const (
+	firstPowerOfTen = -348
+	stepPowerOfTen  = 8
+)
+
+var smallPowersOfTen = [...]extFloat{
+	{1 << 63, -63, false},        // 1
+	{0xa << 60, -60, false},      // 1e1
+	{0x64 << 57, -57, false},     // 1e2
+	{0x3e8 << 54, -54, false},    // 1e3
+	{0x2710 << 50, -50, false},   // 1e4
+	{0x186a0 << 47, -47, false},  // 1e5
+	{0xf4240 << 44, -44, false},  // 1e6
+	{0x989680 << 40, -40, false}, // 1e7
+}
+
+var powersOfTen = [...]extFloat{
+	{0xfa8fd5a0081c0288, -1220, false}, // 10^-348
+	{0xbaaee17fa23ebf76, -1193, false}, // 10^-340
+	{0x8b16fb203055ac76, -1166, false}, // 10^-332
+	{0xcf42894a5dce35ea, -1140, false}, // 10^-324
+	{0x9a6bb0aa55653b2d, -1113, false}, // 10^-316
+	{0xe61acf033d1a45df, -1087, false}, // 10^-308
+	{0xab70fe17c79ac6ca, -1060, false}, // 10^-300
+	{0xff77b1fcbebcdc4f, -1034, false}, // 10^-292
+	{0xbe5691ef416bd60c, -1007, false}, // 10^-284
+	{0x8dd01fad907ffc3c, -980, false},  // 10^-276
+	{0xd3515c2831559a83, -954, false},  // 10^-268
+	{0x9d71ac8fada6c9b5, -927, false},  // 10^-260
+	{0xea9c227723ee8bcb, -901, false},  // 10^-252
+	{0xaecc49914078536d, -874, false},  // 10^-244
+	{0x823c12795db6ce57, -847, false},  // 10^-236
+	{0xc21094364dfb5637, -821, false},  // 10^-228
+	{0x9096ea6f3848984f, -794, false},  // 10^-220
+	{0xd77485cb25823ac7, -768, false},  // 10^-212
+	{0xa086cfcd97bf97f4, -741, false},  // 10^-204
+	{0xef340a98172aace5, -715, false},  // 10^-196
+	{0xb23867fb2a35b28e, -688, false},  // 10^-188
+	{0x84c8d4dfd2c63f3b, -661, false},  // 10^-180
+	{0xc5dd44271ad3cdba, -635, false},  // 10^-172
+	{0x936b9fcebb25c996, -608, false},  // 10^-164
+	{0xdbac6c247d62a584, -582, false},  // 10^-156
+	{0xa3ab66580d5fdaf6, -555, false},  // 10^-148
+	{0xf3e2f893dec3f126, -529, false},  // 10^-140
+	{0xb5b5ada8aaff80b8, -502, false},  // 10^-132
+	{0x87625f056c7c4a8b, -475, false},  // 10^-124
+	{0xc9bcff6034c13053, -449, false},  // 10^-116
+	{0x964e858c91ba2655, -422, false},  // 10^-108
+	{0xdff9772470297ebd, -396, false},  // 10^-100
+	{0xa6dfbd9fb8e5b88f, -369, false},  // 10^-92
+	{0xf8a95fcf88747d94, -343, false},  // 10^-84
+	{0xb94470938fa89bcf, -316, false},  // 10^-76
+	{0x8a08f0f8bf0f156b, -289, false},  // 10^-68
+	{0xcdb02555653131b6, -263, false},  // 10^-60
+	{0x993fe2c6d07b7fac, -236, false},  // 10^-52
+	{0xe45c10c42a2b3b06, -210, false},  // 10^-44
+	{0xaa242499697392d3, -183, false},  // 10^-36
+	{0xfd87b5f28300ca0e, -157, false},  // 10^-28
+	{0xbce5086492111aeb, -130, false},  // 10^-20
+	{0x8cbccc096f5088cc, -103, false},  // 10^-12
+	{0xd1b71758e219652c, -77, false},   // 10^-4
+	{0x9c40000000000000, -50, false},   // 10^4
+	{0xe8d4a51000000000, -24, false},   // 10^12
+	{0xad78ebc5ac620000, 3, false},     // 10^20
+	{0x813f3978f8940984, 30, false},    // 10^28
+	{0xc097ce7bc90715b3, 56, false},    // 10^36
+	{0x8f7e32ce7bea5c70, 83, false},    // 10^44
+	{0xd5d238a4abe98068, 109, false},   // 10^52
+	{0x9f4f2726179a2245, 136, false},   // 10^60
+	{0xed63a231d4c4fb27, 162, false},   // 10^68
+	{0xb0de65388cc8ada8, 189, false},   // 10^76
+	{0x83c7088e1aab65db, 216, false},   // 10^84
+	{0xc45d1df942711d9a, 242, false},   // 10^92
+	{0x924d692ca61be758, 269, false},   // 10^100
+	{0xda01ee641a708dea, 295, false},   // 10^108
+	{0xa26da3999aef774a, 322, false},   // 10^116
+	{0xf209787bb47d6b85, 348, false},   // 10^124
+	{0xb454e4a179dd1877, 375, false},   // 10^132
+	{0x865b86925b9bc5c2, 402, false},   // 10^140
+	{0xc83553c5c8965d3d, 428, false},   // 10^148
+	{0x952ab45cfa97a0b3, 455, false},   // 10^156
+	{0xde469fbd99a05fe3, 481, false},   // 10^164
+	{0xa59bc234db398c25, 508, false},   // 10^172
+	{0xf6c69a72a3989f5c, 534, false},   // 10^180
+	{0xb7dcbf5354e9bece, 561, false},   // 10^188
+	{0x88fcf317f22241e2, 588, false},   // 10^196
+	{0xcc20ce9bd35c78a5, 614, false},   // 10^204
+	{0x98165af37b2153df, 641, false},   // 10^212
+	{0xe2a0b5dc971f303a, 667, false},   // 10^220
+	{0xa8d9d1535ce3b396, 694, false},   // 10^228
+	{0xfb9b7cd9a4a7443c, 720, false},   // 10^236
+	{0xbb764c4ca7a44410, 747, false},   // 10^244
+	{0x8bab8eefb6409c1a, 774, false},   // 10^252
+	{0xd01fef10a657842c, 800, false},   // 10^260
+	{0x9b10a4e5e9913129, 827, false},   // 10^268
+	{0xe7109bfba19c0c9d, 853, false},   // 10^276
+	{0xac2820d9623bf429, 880, false},   // 10^284
+	{0x80444b5e7aa7cf85, 907, false},   // 10^292
+	{0xbf21e44003acdd2d, 933, false},   // 10^300
+	{0x8e679c2f5e44ff8f, 960, false},   // 10^308
+	{0xd433179d9c8cb841, 986, false},   // 10^316
+	{0x9e19db92b4e31ba9, 1013, false},  // 10^324
+	{0xeb96bf6ebadf77d9, 1039, false},  // 10^332
+	{0xaf87023b9bf0ee6b, 1066, false},  // 10^340
+}
+
+// floatBits returns the bits of the float64 that best approximates
+// the extFloat passed as receiver. Overflow is set to true if
+// the resulting float64 is ±Inf.
+func (f *extFloat) floatBits(flt *floatInfo) (bits uint64, overflow bool) {
+	f.Normalize()
+
+	exp := f.exp + 63
+
+	// Exponent too small.
+	if exp < flt.bias+1 {
+		n := flt.bias + 1 - exp
+		f.mant >>= uint(n)
+		exp += n
+	}
+
+	// Extract 1+flt.mantbits bits from the 64-bit mantissa.
+	mant := f.mant >> (63 - flt.mantbits)
+	if f.mant&(1<<(62-flt.mantbits)) != 0 {
+		// Round up.
+		mant += 1
+	}
+
+	// Rounding might have added a bit; shift down.
+	if mant == 2<<flt.mantbits {
+		mant >>= 1
+		exp++
+	}
+
+	// Infinities.
+	if exp-flt.bias >= 1<<flt.expbits-1 {
+		// ±Inf
+		mant = 0
+		exp = 1<<flt.expbits - 1 + flt.bias
+		overflow = true
+	} else if mant&(1<<flt.mantbits) == 0 {
+		// Denormalized?
+		exp = flt.bias
+	}
+	// Assemble bits.
+	bits = mant & (uint64(1)<<flt.mantbits - 1)
+	bits |= uint64((exp-flt.bias)&(1<<flt.expbits-1)) << flt.mantbits
+	if f.neg {
+		bits |= 1 << (flt.mantbits + flt.expbits)
+	}
+	return
+}
+
+// AssignComputeBounds sets f to the floating point value
+// defined by mant, exp and precision given by flt. It returns
+// lower, upper such that any number in the closed interval
+// [lower, upper] is converted back to the same floating point number.
+func (f *extFloat) AssignComputeBounds(mant uint64, exp int, neg bool, flt *floatInfo) (lower, upper extFloat) {
+	f.mant = mant
+	f.exp = exp - int(flt.mantbits)
+	f.neg = neg
+	if f.exp <= 0 && mant == (mant>>uint(-f.exp))<<uint(-f.exp) {
+		// An exact integer
+		f.mant >>= uint(-f.exp)
+		f.exp = 0
+		return *f, *f
+	}
+	expBiased := exp - flt.bias
+
+	upper = extFloat{mant: 2*f.mant + 1, exp: f.exp - 1, neg: f.neg}
+	if mant != 1<<flt.mantbits || expBiased == 1 {
+		lower = extFloat{mant: 2*f.mant - 1, exp: f.exp - 1, neg: f.neg}
+	} else {
+		lower = extFloat{mant: 4*f.mant - 1, exp: f.exp - 2, neg: f.neg}
+	}
+	return
+}
+
+// Normalize normalizes f so that the highest bit of the mantissa is
+// set, and returns the number by which the mantissa was left-shifted.
+func (f *extFloat) Normalize() (shift uint) {
+	mant, exp := f.mant, f.exp
+	if mant == 0 {
+		return 0
+	}
+	if mant>>(64-32) == 0 {
+		mant <<= 32
+		exp -= 32
+	}
+	if mant>>(64-16) == 0 {
+		mant <<= 16
+		exp -= 16
+	}
+	if mant>>(64-8) == 0 {
+		mant <<= 8
+		exp -= 8
+	}
+	if mant>>(64-4) == 0 {
+		mant <<= 4
+		exp -= 4
+	}
+	if mant>>(64-2) == 0 {
+		mant <<= 2
+		exp -= 2
+	}
+	if mant>>(64-1) == 0 {
+		mant <<= 1
+		exp -= 1
+	}
+	shift = uint(f.exp - exp)
+	f.mant, f.exp = mant, exp
+	return
+}
+
+// Multiply sets f to the product f*g: the result is correctly rounded,
+// but not normalized.
+func (f *extFloat) Multiply(g extFloat) {
+	fhi, flo := f.mant>>32, uint64(uint32(f.mant))
+	ghi, glo := g.mant>>32, uint64(uint32(g.mant))
+
+	// Cross products.
+	cross1 := fhi * glo
+	cross2 := flo * ghi
+
+	// f.mant*g.mant is fhi*ghi << 64 + (cross1+cross2) << 32 + flo*glo
+	f.mant = fhi*ghi + (cross1 >> 32) + (cross2 >> 32)
+	rem := uint64(uint32(cross1)) + uint64(uint32(cross2)) + ((flo * glo) >> 32)
+	// Round up.
+	rem += (1 << 31)
+
+	f.mant += (rem >> 32)
+	f.exp = f.exp + g.exp + 64
+}
+
+var uint64pow10 = [...]uint64{
+	1, 1e1, 1e2, 1e3, 1e4, 1e5, 1e6, 1e7, 1e8, 1e9,
+	1e10, 1e11, 1e12, 1e13, 1e14, 1e15, 1e16, 1e17, 1e18, 1e19,
+}
+
+// AssignDecimal sets f to an approximate value mantissa*10^exp. It
+// returns true if the value represented by f is guaranteed to be the
+// best approximation of d after being rounded to a float64 or
+// float32 depending on flt.
+func (f *extFloat) AssignDecimal(mantissa uint64, exp10 int, neg bool, trunc bool, flt *floatInfo) (ok bool) {
+	const uint64digits = 19
+	const errorscale = 8
+	errors := 0 // An upper bound for error, computed in errorscale*ulp.
+	if trunc {
+		// the decimal number was truncated.
+		errors += errorscale / 2
+	}
+
+	f.mant = mantissa
+	f.exp = 0
+	f.neg = neg
+
+	// Multiply by powers of ten.
+	i := (exp10 - firstPowerOfTen) / stepPowerOfTen
+	if exp10 < firstPowerOfTen || i >= len(powersOfTen) {
+		return false
+	}
+	adjExp := (exp10 - firstPowerOfTen) % stepPowerOfTen
+
+	// We multiply by exp%step
+	if adjExp < uint64digits && mantissa < uint64pow10[uint64digits-adjExp] {
+		// We can multiply the mantissa exactly.
+		f.mant *= uint64pow10[adjExp]
+		f.Normalize()
+	} else {
+		f.Normalize()
+		f.Multiply(smallPowersOfTen[adjExp])
+		errors += errorscale / 2
+	}
+
+	// We multiply by 10 to the exp - exp%step.
+	f.Multiply(powersOfTen[i])
+	if errors > 0 {
+		errors += 1
+	}
+	errors += errorscale / 2
+
+	// Normalize
+	shift := f.Normalize()
+	errors <<= shift
+
+	// Now f is a good approximation of the decimal.
+	// Check whether the error is too large: that is, if the mantissa
+	// is perturbated by the error, the resulting float64 will change.
+	// The 64 bits mantissa is 1 + 52 bits for float64 + 11 extra bits.
+	//
+	// In many cases the approximation will be good enough.
+	denormalExp := flt.bias - 63
+	var extrabits uint
+	if f.exp <= denormalExp {
+		// f.mant * 2^f.exp is smaller than 2^(flt.bias+1).
+		extrabits = uint(63 - flt.mantbits + 1 + uint(denormalExp-f.exp))
+	} else {
+		extrabits = uint(63 - flt.mantbits)
+	}
+
+	halfway := uint64(1) << (extrabits - 1)
+	mant_extra := f.mant & (1<<extrabits - 1)
+
+	// Do a signed comparison here! If the error estimate could make
+	// the mantissa round differently for the conversion to double,
+	// then we can't give a definite answer.
+	if int64(halfway)-int64(errors) < int64(mant_extra) &&
+		int64(mant_extra) < int64(halfway)+int64(errors) {
+		return false
+	}
+	return true
+}
+
+// Frexp10 is an analogue of math.Frexp for decimal powers. It scales
+// f by an approximate power of ten 10^-exp, and returns exp10, so
+// that f*10^exp10 has the same value as the old f, up to an ulp,
+// as well as the index of 10^-exp in the powersOfTen table.
+func (f *extFloat) frexp10() (exp10, index int) {
+	// The constants expMin and expMax constrain the final value of the
+	// binary exponent of f. We want a small integral part in the result
+	// because finding digits of an integer requires divisions, whereas
+	// digits of the fractional part can be found by repeatedly multiplying
+	// by 10.
+	const expMin = -60
+	const expMax = -32
+	// Find power of ten such that x * 10^n has a binary exponent
+	// between expMin and expMax.
+	approxExp10 := ((expMin+expMax)/2 - f.exp) * 28 / 93 // log(10)/log(2) is close to 93/28.
+	i := (approxExp10 - firstPowerOfTen) / stepPowerOfTen
+Loop:
+	for {
+		exp := f.exp + powersOfTen[i].exp + 64
+		switch {
+		case exp < expMin:
+			i++
+		case exp > expMax:
+			i--
+		default:
+			break Loop
+		}
+	}
+	// Apply the desired decimal shift on f. It will have exponent
+	// in the desired range. This is multiplication by 10^-exp10.
+	f.Multiply(powersOfTen[i])
+
+	return -(firstPowerOfTen + i*stepPowerOfTen), i
+}
+
+// frexp10Many applies a common shift by a power of ten to a, b, c.
+func frexp10Many(a, b, c *extFloat) (exp10 int) {
+	exp10, i := c.frexp10()
+	a.Multiply(powersOfTen[i])
+	b.Multiply(powersOfTen[i])
+	return
+}
+
+// FixedDecimal stores in d the first n significant digits
+// of the decimal representation of f. It returns false
+// if it cannot be sure of the answer.
+func (f *extFloat) FixedDecimal(d *decimalSlice, n int) bool {
+	if f.mant == 0 {
+		d.nd = 0
+		d.dp = 0
+		d.neg = f.neg
+		return true
+	}
+	if n == 0 {
+		panic("strconv: internal error: extFloat.FixedDecimal called with n == 0")
+	}
+	// Multiply by an appropriate power of ten to have a reasonable
+	// number to process.
+	f.Normalize()
+	exp10, _ := f.frexp10()
+
+	shift := uint(-f.exp)
+	integer := uint32(f.mant >> shift)
+	fraction := f.mant - (uint64(integer) << shift)
+	ε := uint64(1) // ε is the uncertainty we have on the mantissa of f.
+
+	// Write exactly n digits to d.
+	needed := n        // how many digits are left to write.
+	integerDigits := 0 // the number of decimal digits of integer.
+	pow10 := uint64(1) // the power of ten by which f was scaled.
+	for i, pow := 0, uint64(1); i < 20; i++ {
+		if pow > uint64(integer) {
+			integerDigits = i
+			break
+		}
+		pow *= 10
+	}
+	rest := integer
+	if integerDigits > needed {
+		// the integral part is already large, trim the last digits.
+		pow10 = uint64pow10[integerDigits-needed]
+		integer /= uint32(pow10)
+		rest -= integer * uint32(pow10)
+	} else {
+		rest = 0
+	}
+
+	// Write the digits of integer: the digits of rest are omitted.
+	var buf [32]byte
+	pos := len(buf)
+	for v := integer; v > 0; {
+		v1 := v / 10
+		v -= 10 * v1
+		pos--
+		buf[pos] = byte(v + '0')
+		v = v1
+	}
+	for i := pos; i < len(buf); i++ {
+		d.d[i-pos] = buf[i]
+	}
+	nd := len(buf) - pos
+	d.nd = nd
+	d.dp = integerDigits + exp10
+	needed -= nd
+
+	if needed > 0 {
+		if rest != 0 || pow10 != 1 {
+			panic("strconv: internal error, rest != 0 but needed > 0")
+		}
+		// Emit digits for the fractional part. Each time, 10*fraction
+		// fits in a uint64 without overflow.
+		for needed > 0 {
+			fraction *= 10
+			ε *= 10 // the uncertainty scales as we multiply by ten.
+			if 2*ε > 1<<shift {
+				// the error is so large it could modify which digit to write, abort.
+				return false
+			}
+			digit := fraction >> shift
+			d.d[nd] = byte(digit + '0')
+			fraction -= digit << shift
+			nd++
+			needed--
+		}
+		d.nd = nd
+	}
+
+	// We have written a truncation of f (a numerator / 10^d.dp). The remaining part
+	// can be interpreted as a small number (< 1) to be added to the last digit of the
+	// numerator.
+	//
+	// If rest > 0, the amount is:
+	//    (rest<<shift | fraction) / (pow10 << shift)
+	//    fraction being known with a ±ε uncertainty.
+	//    The fact that n > 0 guarantees that pow10 << shift does not overflow a uint64.
+	//
+	// If rest = 0, pow10 == 1 and the amount is
+	//    fraction / (1 << shift)
+	//    fraction being known with a ±ε uncertainty.
+	//
+	// We pass this information to the rounding routine for adjustment.
+
+	ok := adjustLastDigitFixed(d, uint64(rest)<<shift|fraction, pow10, shift, ε)
+	if !ok {
+		return false
+	}
+	// Trim trailing zeros.
+	for i := d.nd - 1; i >= 0; i-- {
+		if d.d[i] != '0' {
+			d.nd = i + 1
+			break
+		}
+	}
+	return true
+}
+
+// adjustLastDigitFixed assumes d contains the representation of the integral part
+// of some number, whose fractional part is num / (den << shift). The numerator
+// num is only known up to an uncertainty of size ε, assumed to be less than
+// (den << shift)/2.
+//
+// It will increase the last digit by one to account for correct rounding, typically
+// when the fractional part is greater than 1/2, and will return false if ε is such
+// that no correct answer can be given.
+func adjustLastDigitFixed(d *decimalSlice, num, den uint64, shift uint, ε uint64) bool {
+	if num > den<<shift {
+		panic("strconv: num > den<<shift in adjustLastDigitFixed")
+	}
+	if 2*ε > den<<shift {
+		panic("strconv: ε > (den<<shift)/2")
+	}
+	if 2*(num+ε) < den<<shift {
+		return true
+	}
+	if 2*(num-ε) > den<<shift {
+		// increment d by 1.
+		i := d.nd - 1
+		for ; i >= 0; i-- {
+			if d.d[i] == '9' {
+				d.nd--
+			} else {
+				break
+			}
+		}
+		if i < 0 {
+			d.d[0] = '1'
+			d.nd = 1
+			d.dp++
+		} else {
+			d.d[i]++
+		}
+		return true
+	}
+	return false
+}
+
+// ShortestDecimal stores in d the shortest decimal representation of f
+// which belongs to the open interval (lower, upper), where f is supposed
+// to lie. It returns false whenever the result is unsure. The implementation
+// uses the Grisu3 algorithm.
+func (f *extFloat) ShortestDecimal(d *decimalSlice, lower, upper *extFloat) bool {
+	if f.mant == 0 {
+		d.nd = 0
+		d.dp = 0
+		d.neg = f.neg
+		return true
+	}
+	if f.exp == 0 && *lower == *f && *lower == *upper {
+		// an exact integer.
+		var buf [24]byte
+		n := len(buf) - 1
+		for v := f.mant; v > 0; {
+			v1 := v / 10
+			v -= 10 * v1
+			buf[n] = byte(v + '0')
+			n--
+			v = v1
+		}
+		nd := len(buf) - n - 1
+		for i := 0; i < nd; i++ {
+			d.d[i] = buf[n+1+i]
+		}
+		d.nd, d.dp = nd, nd
+		for d.nd > 0 && d.d[d.nd-1] == '0' {
+			d.nd--
+		}
+		if d.nd == 0 {
+			d.dp = 0
+		}
+		d.neg = f.neg
+		return true
+	}
+	upper.Normalize()
+	// Uniformize exponents.
+	if f.exp > upper.exp {
+		f.mant <<= uint(f.exp - upper.exp)
+		f.exp = upper.exp
+	}
+	if lower.exp > upper.exp {
+		lower.mant <<= uint(lower.exp - upper.exp)
+		lower.exp = upper.exp
+	}
+
+	exp10 := frexp10Many(lower, f, upper)
+	// Take a safety margin due to rounding in frexp10Many, but we lose precision.
+	upper.mant++
+	lower.mant--
+
+	// The shortest representation of f is either rounded up or down, but
+	// in any case, it is a truncation of upper.
+	shift := uint(-upper.exp)
+	integer := uint32(upper.mant >> shift)
+	fraction := upper.mant - (uint64(integer) << shift)
+
+	// How far we can go down from upper until the result is wrong.
+	allowance := upper.mant - lower.mant
+	// How far we should go to get a very precise result.
+	targetDiff := upper.mant - f.mant
+
+	// Count integral digits: there are at most 10.
+	var integerDigits int
+	for i, pow := 0, uint64(1); i < 20; i++ {
+		if pow > uint64(integer) {
+			integerDigits = i
+			break
+		}
+		pow *= 10
+	}
+	for i := 0; i < integerDigits; i++ {
+		pow := uint64pow10[integerDigits-i-1]
+		digit := integer / uint32(pow)
+		d.d[i] = byte(digit + '0')
+		integer -= digit * uint32(pow)
+		// evaluate whether we should stop.
+		if currentDiff := uint64(integer)<<shift + fraction; currentDiff < allowance {
+			d.nd = i + 1
+			d.dp = integerDigits + exp10
+			d.neg = f.neg
+			// Sometimes allowance is so large the last digit might need to be
+			// decremented to get closer to f.
+			return adjustLastDigit(d, currentDiff, targetDiff, allowance, pow<<shift, 2)
+		}
+	}
+	d.nd = integerDigits
+	d.dp = d.nd + exp10
+	d.neg = f.neg
+
+	// Compute digits of the fractional part. At each step fraction does not
+	// overflow. The choice of minExp implies that fraction is less than 2^60.
+	var digit int
+	multiplier := uint64(1)
+	for {
+		fraction *= 10
+		multiplier *= 10
+		digit = int(fraction >> shift)
+		d.d[d.nd] = byte(digit + '0')
+		d.nd++
+		fraction -= uint64(digit) << shift
+		if fraction < allowance*multiplier {
+			// We are in the admissible range. Note that if allowance is about to
+			// overflow, that is, allowance > 2^64/10, the condition is automatically
+			// true due to the limited range of fraction.
+			return adjustLastDigit(d,
+				fraction, targetDiff*multiplier, allowance*multiplier,
+				1<<shift, multiplier*2)
+		}
+	}
+}
+
+// adjustLastDigit modifies d = x-currentDiff*ε, to get closest to
+// d = x-targetDiff*ε, without becoming smaller than x-maxDiff*ε.
+// It assumes that a decimal digit is worth ulpDecimal*ε, and that
+// all data is known with a error estimate of ulpBinary*ε.
+func adjustLastDigit(d *decimalSlice, currentDiff, targetDiff, maxDiff, ulpDecimal, ulpBinary uint64) bool {
+	if ulpDecimal < 2*ulpBinary {
+		// Approximation is too wide.
+		return false
+	}
+	for currentDiff+ulpDecimal/2+ulpBinary < targetDiff {
+		d.d[d.nd-1]--
+		currentDiff += ulpDecimal
+	}
+	if currentDiff+ulpDecimal <= targetDiff+ulpDecimal/2+ulpBinary {
+		// we have two choices, and don't know what to do.
+		return false
+	}
+	if currentDiff < ulpBinary || currentDiff > maxDiff-ulpBinary {
+		// we went too far
+		return false
+	}
+	if d.nd == 1 && d.d[0] == '0' {
+		// the number has actually reached zero.
+		d.nd = 0
+		d.dp = 0
+	}
+	return true
+}
diff --git a/src/strconv/fp_test.go b/src/strconv/fp_test.go
new file mode 100644
index 000000000..6de2f8bc6
--- /dev/null
+++ b/src/strconv/fp_test.go
@@ -0,0 +1,144 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package strconv_test
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"strconv"
+	"strings"
+	"testing"
+)
+
+func pow2(i int) float64 {
+	switch {
+	case i < 0:
+		return 1 / pow2(-i)
+	case i == 0:
+		return 1
+	case i == 1:
+		return 2
+	}
+	return pow2(i/2) * pow2(i-i/2)
+}
+
+// Wrapper around strconv.ParseFloat(x, 64).  Handles dddddp+ddd (binary exponent)
+// itself, passes the rest on to strconv.ParseFloat.
+func myatof64(s string) (f float64, ok bool) {
+	a := strings.SplitN(s, "p", 2)
+	if len(a) == 2 {
+		n, err := strconv.ParseInt(a[0], 10, 64)
+		if err != nil {
+			return 0, false
+		}
+		e, err1 := strconv.Atoi(a[1])
+		if err1 != nil {
+			println("bad e", a[1])
+			return 0, false
+		}
+		v := float64(n)
+		// We expect that v*pow2(e) fits in a float64,
+		// but pow2(e) by itself may not.  Be careful.
+		if e <= -1000 {
+			v *= pow2(-1000)
+			e += 1000
+			for e < 0 {
+				v /= 2
+				e++
+			}
+			return v, true
+		}
+		if e >= 1000 {
+			v *= pow2(1000)
+			e -= 1000
+			for e > 0 {
+				v *= 2
+				e--
+			}
+			return v, true
+		}
+		return v * pow2(e), true
+	}
+	f1, err := strconv.ParseFloat(s, 64)
+	if err != nil {
+		return 0, false
+	}
+	return f1, true
+}
+
+// Wrapper around strconv.ParseFloat(x, 32).  Handles dddddp+ddd (binary exponent)
+// itself, passes the rest on to strconv.ParseFloat.
+func myatof32(s string) (f float32, ok bool) {
+	a := strings.SplitN(s, "p", 2)
+	if len(a) == 2 {
+		n, err := strconv.Atoi(a[0])
+		if err != nil {
+			println("bad n", a[0])
+			return 0, false
+		}
+		e, err1 := strconv.Atoi(a[1])
+		if err1 != nil {
+			println("bad p", a[1])
+			return 0, false
+		}
+		return float32(float64(n) * pow2(e)), true
+	}
+	f64, err1 := strconv.ParseFloat(s, 32)
+	f1 := float32(f64)
+	if err1 != nil {
+		return 0, false
+	}
+	return f1, true
+}
+
+func TestFp(t *testing.T) {
+	f, err := os.Open("testdata/testfp.txt")
+	if err != nil {
+		t.Fatal("testfp: open testdata/testfp.txt:", err)
+	}
+	defer f.Close()
+
+	s := bufio.NewScanner(f)
+
+	for lineno := 1; s.Scan(); lineno++ {
+		line := s.Text()
+		if len(line) == 0 || line[0] == '#' {
+			continue
+		}
+		a := strings.Split(line, " ")
+		if len(a) != 4 {
+			t.Error("testdata/testfp.txt:", lineno, ": wrong field count")
+			continue
+		}
+		var s string
+		var v float64
+		switch a[0] {
+		case "float64":
+			var ok bool
+			v, ok = myatof64(a[2])
+			if !ok {
+				t.Error("testdata/testfp.txt:", lineno, ": cannot atof64 ", a[2])
+				continue
+			}
+			s = fmt.Sprintf(a[1], v)
+		case "float32":
+			v1, ok := myatof32(a[2])
+			if !ok {
+				t.Error("testdata/testfp.txt:", lineno, ": cannot atof32 ", a[2])
+				continue
+			}
+			s = fmt.Sprintf(a[1], v1)
+			v = float64(v1)
+		}
+		if s != a[3] {
+			t.Error("testdata/testfp.txt:", lineno, ": ", a[0], " ", a[1], " ", a[2], " (", v, ") ",
+				"want ", a[3], " got ", s)
+		}
+	}
+	if s.Err() != nil {
+		t.Fatal("testfp: read testdata/testfp.txt: ", s.Err())
+	}
+}
diff --git a/src/strconv/ftoa.go b/src/strconv/ftoa.go
new file mode 100644
index 000000000..1a9c41b85
--- /dev/null
+++ b/src/strconv/ftoa.go
@@ -0,0 +1,475 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Binary to decimal floating point conversion.
+// Algorithm:
+//   1) store mantissa in multiprecision decimal
+//   2) shift decimal by exponent
+//   3) read digits out & format
+
+package strconv
+
+import "math"
+
+// TODO: move elsewhere?
+type floatInfo struct {
+	mantbits uint
+	expbits  uint
+	bias     int
+}
+
+var float32info = floatInfo{23, 8, -127}
+var float64info = floatInfo{52, 11, -1023}
+
+// FormatFloat converts the floating-point number f to a string,
+// according to the format fmt and precision prec.  It rounds the
+// result assuming that the original was obtained from a floating-point
+// value of bitSize bits (32 for float32, 64 for float64).
+//
+// The format fmt is one of
+// 'b' (-ddddp±ddd, a binary exponent),
+// 'e' (-d.dddde±dd, a decimal exponent),
+// 'E' (-d.ddddE±dd, a decimal exponent),
+// 'f' (-ddd.dddd, no exponent),
+// 'g' ('e' for large exponents, 'f' otherwise), or
+// 'G' ('E' for large exponents, 'f' otherwise).
+//
+// The precision prec controls the number of digits
+// (excluding the exponent) printed by the 'e', 'E', 'f', 'g', and 'G' formats.
+// For 'e', 'E', and 'f' it is the number of digits after the decimal point.
+// For 'g' and 'G' it is the total number of digits.
+// The special precision -1 uses the smallest number of digits
+// necessary such that ParseFloat will return f exactly.
+func FormatFloat(f float64, fmt byte, prec, bitSize int) string {
+	return string(genericFtoa(make([]byte, 0, max(prec+4, 24)), f, fmt, prec, bitSize))
+}
+
+// AppendFloat appends the string form of the floating-point number f,
+// as generated by FormatFloat, to dst and returns the extended buffer.
+func AppendFloat(dst []byte, f float64, fmt byte, prec int, bitSize int) []byte {
+	return genericFtoa(dst, f, fmt, prec, bitSize)
+}
+
+func genericFtoa(dst []byte, val float64, fmt byte, prec, bitSize int) []byte {
+	var bits uint64
+	var flt *floatInfo
+	switch bitSize {
+	case 32:
+		bits = uint64(math.Float32bits(float32(val)))
+		flt = &float32info
+	case 64:
+		bits = math.Float64bits(val)
+		flt = &float64info
+	default:
+		panic("strconv: illegal AppendFloat/FormatFloat bitSize")
+	}
+
+	neg := bits>>(flt.expbits+flt.mantbits) != 0
+	exp := int(bits>>flt.mantbits) & (1<<flt.expbits - 1)
+	mant := bits & (uint64(1)<<flt.mantbits - 1)
+
+	switch exp {
+	case 1<<flt.expbits - 1:
+		// Inf, NaN
+		var s string
+		switch {
+		case mant != 0:
+			s = "NaN"
+		case neg:
+			s = "-Inf"
+		default:
+			s = "+Inf"
+		}
+		return append(dst, s...)
+
+	case 0:
+		// denormalized
+		exp++
+
+	default:
+		// add implicit top bit
+		mant |= uint64(1) << flt.mantbits
+	}
+	exp += flt.bias
+
+	// Pick off easy binary format.
+	if fmt == 'b' {
+		return fmtB(dst, neg, mant, exp, flt)
+	}
+
+	if !optimize {
+		return bigFtoa(dst, prec, fmt, neg, mant, exp, flt)
+	}
+
+	var digs decimalSlice
+	ok := false
+	// Negative precision means "only as much as needed to be exact."
+	shortest := prec < 0
+	if shortest {
+		// Try Grisu3 algorithm.
+		f := new(extFloat)
+		lower, upper := f.AssignComputeBounds(mant, exp, neg, flt)
+		var buf [32]byte
+		digs.d = buf[:]
+		ok = f.ShortestDecimal(&digs, &lower, &upper)
+		if !ok {
+			return bigFtoa(dst, prec, fmt, neg, mant, exp, flt)
+		}
+		// Precision for shortest representation mode.
+		switch fmt {
+		case 'e', 'E':
+			prec = digs.nd - 1
+		case 'f':
+			prec = max(digs.nd-digs.dp, 0)
+		case 'g', 'G':
+			prec = digs.nd
+		}
+	} else if fmt != 'f' {
+		// Fixed number of digits.
+		digits := prec
+		switch fmt {
+		case 'e', 'E':
+			digits++
+		case 'g', 'G':
+			if prec == 0 {
+				prec = 1
+			}
+			digits = prec
+		}
+		if digits <= 15 {
+			// try fast algorithm when the number of digits is reasonable.
+			var buf [24]byte
+			digs.d = buf[:]
+			f := extFloat{mant, exp - int(flt.mantbits), neg}
+			ok = f.FixedDecimal(&digs, digits)
+		}
+	}
+	if !ok {
+		return bigFtoa(dst, prec, fmt, neg, mant, exp, flt)
+	}
+	return formatDigits(dst, shortest, neg, digs, prec, fmt)
+}
+
+// bigFtoa uses multiprecision computations to format a float.
+func bigFtoa(dst []byte, prec int, fmt byte, neg bool, mant uint64, exp int, flt *floatInfo) []byte {
+	d := new(decimal)
+	d.Assign(mant)
+	d.Shift(exp - int(flt.mantbits))
+	var digs decimalSlice
+	shortest := prec < 0
+	if shortest {
+		roundShortest(d, mant, exp, flt)
+		digs = decimalSlice{d: d.d[:], nd: d.nd, dp: d.dp}
+		// Precision for shortest representation mode.
+		switch fmt {
+		case 'e', 'E':
+			prec = digs.nd - 1
+		case 'f':
+			prec = max(digs.nd-digs.dp, 0)
+		case 'g', 'G':
+			prec = digs.nd
+		}
+	} else {
+		// Round appropriately.
+		switch fmt {
+		case 'e', 'E':
+			d.Round(prec + 1)
+		case 'f':
+			d.Round(d.dp + prec)
+		case 'g', 'G':
+			if prec == 0 {
+				prec = 1
+			}
+			d.Round(prec)
+		}
+		digs = decimalSlice{d: d.d[:], nd: d.nd, dp: d.dp}
+	}
+	return formatDigits(dst, shortest, neg, digs, prec, fmt)
+}
+
+func formatDigits(dst []byte, shortest bool, neg bool, digs decimalSlice, prec int, fmt byte) []byte {
+	switch fmt {
+	case 'e', 'E':
+		return fmtE(dst, neg, digs, prec, fmt)
+	case 'f':
+		return fmtF(dst, neg, digs, prec)
+	case 'g', 'G':
+		// trailing fractional zeros in 'e' form will be trimmed.
+		eprec := prec
+		if eprec > digs.nd && digs.nd >= digs.dp {
+			eprec = digs.nd
+		}
+		// %e is used if the exponent from the conversion
+		// is less than -4 or greater than or equal to the precision.
+		// if precision was the shortest possible, use precision 6 for this decision.
+		if shortest {
+			eprec = 6
+		}
+		exp := digs.dp - 1
+		if exp < -4 || exp >= eprec {
+			if prec > digs.nd {
+				prec = digs.nd
+			}
+			return fmtE(dst, neg, digs, prec-1, fmt+'e'-'g')
+		}
+		if prec > digs.dp {
+			prec = digs.nd
+		}
+		return fmtF(dst, neg, digs, max(prec-digs.dp, 0))
+	}
+
+	// unknown format
+	return append(dst, '%', fmt)
+}
+
+// Round d (= mant * 2^exp) to the shortest number of digits
+// that will let the original floating point value be precisely
+// reconstructed.  Size is original floating point size (64 or 32).
+func roundShortest(d *decimal, mant uint64, exp int, flt *floatInfo) {
+	// If mantissa is zero, the number is zero; stop now.
+	if mant == 0 {
+		d.nd = 0
+		return
+	}
+
+	// Compute upper and lower such that any decimal number
+	// between upper and lower (possibly inclusive)
+	// will round to the original floating point number.
+
+	// We may see at once that the number is already shortest.
+	//
+	// Suppose d is not denormal, so that 2^exp <= d < 10^dp.
+	// The closest shorter number is at least 10^(dp-nd) away.
+	// The lower/upper bounds computed below are at distance
+	// at most 2^(exp-mantbits).
+	//
+	// So the number is already shortest if 10^(dp-nd) > 2^(exp-mantbits),
+	// or equivalently log2(10)*(dp-nd) > exp-mantbits.
+	// It is true if 332/100*(dp-nd) >= exp-mantbits (log2(10) > 3.32).
+	minexp := flt.bias + 1 // minimum possible exponent
+	if exp > minexp && 332*(d.dp-d.nd) >= 100*(exp-int(flt.mantbits)) {
+		// The number is already shortest.
+		return
+	}
+
+	// d = mant << (exp - mantbits)
+	// Next highest floating point number is mant+1 << exp-mantbits.
+	// Our upper bound is halfway between, mant*2+1 << exp-mantbits-1.
+	upper := new(decimal)
+	upper.Assign(mant*2 + 1)
+	upper.Shift(exp - int(flt.mantbits) - 1)
+
+	// d = mant << (exp - mantbits)
+	// Next lowest floating point number is mant-1 << exp-mantbits,
+	// unless mant-1 drops the significant bit and exp is not the minimum exp,
+	// in which case the next lowest is mant*2-1 << exp-mantbits-1.
+	// Either way, call it mantlo << explo-mantbits.
+	// Our lower bound is halfway between, mantlo*2+1 << explo-mantbits-1.
+	var mantlo uint64
+	var explo int
+	if mant > 1<<flt.mantbits || exp == minexp {
+		mantlo = mant - 1
+		explo = exp
+	} else {
+		mantlo = mant*2 - 1
+		explo = exp - 1
+	}
+	lower := new(decimal)
+	lower.Assign(mantlo*2 + 1)
+	lower.Shift(explo - int(flt.mantbits) - 1)
+
+	// The upper and lower bounds are possible outputs only if
+	// the original mantissa is even, so that IEEE round-to-even
+	// would round to the original mantissa and not the neighbors.
+	inclusive := mant%2 == 0
+
+	// Now we can figure out the minimum number of digits required.
+	// Walk along until d has distinguished itself from upper and lower.
+	for i := 0; i < d.nd; i++ {
+		var l, m, u byte // lower, middle, upper digits
+		if i < lower.nd {
+			l = lower.d[i]
+		} else {
+			l = '0'
+		}
+		m = d.d[i]
+		if i < upper.nd {
+			u = upper.d[i]
+		} else {
+			u = '0'
+		}
+
+		// Okay to round down (truncate) if lower has a different digit
+		// or if lower is inclusive and is exactly the result of rounding down.
+		okdown := l != m || (inclusive && l == m && i+1 == lower.nd)
+
+		// Okay to round up if upper has a different digit and
+		// either upper is inclusive or upper is bigger than the result of rounding up.
+		okup := m != u && (inclusive || m+1 < u || i+1 < upper.nd)
+
+		// If it's okay to do either, then round to the nearest one.
+		// If it's okay to do only one, do it.
+		switch {
+		case okdown && okup:
+			d.Round(i + 1)
+			return
+		case okdown:
+			d.RoundDown(i + 1)
+			return
+		case okup:
+			d.RoundUp(i + 1)
+			return
+		}
+	}
+}
+
+type decimalSlice struct {
+	d      []byte
+	nd, dp int
+	neg    bool
+}
+
+// %e: -d.ddddde±dd
+func fmtE(dst []byte, neg bool, d decimalSlice, prec int, fmt byte) []byte {
+	// sign
+	if neg {
+		dst = append(dst, '-')
+	}
+
+	// first digit
+	ch := byte('0')
+	if d.nd != 0 {
+		ch = d.d[0]
+	}
+	dst = append(dst, ch)
+
+	// .moredigits
+	if prec > 0 {
+		dst = append(dst, '.')
+		i := 1
+		m := d.nd + prec + 1 - max(d.nd, prec+1)
+		for i < m {
+			dst = append(dst, d.d[i])
+			i++
+		}
+		for i <= prec {
+			dst = append(dst, '0')
+			i++
+		}
+	}
+
+	// e±
+	dst = append(dst, fmt)
+	exp := d.dp - 1
+	if d.nd == 0 { // special case: 0 has exponent 0
+		exp = 0
+	}
+	if exp < 0 {
+		ch = '-'
+		exp = -exp
+	} else {
+		ch = '+'
+	}
+	dst = append(dst, ch)
+
+	// dddd
+	var buf [3]byte
+	i := len(buf)
+	for exp >= 10 {
+		i--
+		buf[i] = byte(exp%10 + '0')
+		exp /= 10
+	}
+	// exp < 10
+	i--
+	buf[i] = byte(exp + '0')
+
+	switch i {
+	case 0:
+		dst = append(dst, buf[0], buf[1], buf[2])
+	case 1:
+		dst = append(dst, buf[1], buf[2])
+	case 2:
+		// leading zeroes
+		dst = append(dst, '0', buf[2])
+	}
+	return dst
+}
+
+// %f: -ddddddd.ddddd
+func fmtF(dst []byte, neg bool, d decimalSlice, prec int) []byte {
+	// sign
+	if neg {
+		dst = append(dst, '-')
+	}
+
+	// integer, padded with zeros as needed.
+	if d.dp > 0 {
+		var i int
+		for i = 0; i < d.dp && i < d.nd; i++ {
+			dst = append(dst, d.d[i])
+		}
+		for ; i < d.dp; i++ {
+			dst = append(dst, '0')
+		}
+	} else {
+		dst = append(dst, '0')
+	}
+
+	// fraction
+	if prec > 0 {
+		dst = append(dst, '.')
+		for i := 0; i < prec; i++ {
+			ch := byte('0')
+			if j := d.dp + i; 0 <= j && j < d.nd {
+				ch = d.d[j]
+			}
+			dst = append(dst, ch)
+		}
+	}
+
+	return dst
+}
+
+// %b: -ddddddddp+ddd
+func fmtB(dst []byte, neg bool, mant uint64, exp int, flt *floatInfo) []byte {
+	var buf [50]byte
+	w := len(buf)
+	exp -= int(flt.mantbits)
+	esign := byte('+')
+	if exp < 0 {
+		esign = '-'
+		exp = -exp
+	}
+	n := 0
+	for exp > 0 || n < 1 {
+		n++
+		w--
+		buf[w] = byte(exp%10 + '0')
+		exp /= 10
+	}
+	w--
+	buf[w] = esign
+	w--
+	buf[w] = 'p'
+	n = 0
+	for mant > 0 || n < 1 {
+		n++
+		w--
+		buf[w] = byte(mant%10 + '0')
+		mant /= 10
+	}
+	if neg {
+		w--
+		buf[w] = '-'
+	}
+	return append(dst, buf[w:]...)
+}
+
+func max(a, b int) int {
+	if a > b {
+		return a
+	}
+	return b
+}
diff --git a/src/strconv/ftoa_test.go b/src/strconv/ftoa_test.go
new file mode 100644
index 000000000..39b861547
--- /dev/null
+++ b/src/strconv/ftoa_test.go
@@ -0,0 +1,240 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package strconv_test
+
+import (
+	"math"
+	"math/rand"
+	. "strconv"
+	"testing"
+)
+
+type ftoaTest struct {
+	f    float64
+	fmt  byte
+	prec int
+	s    string
+}
+
+func fdiv(a, b float64) float64 { return a / b } // keep compiler in the dark
+
+const (
+	below1e23 = 99999999999999974834176
+	above1e23 = 100000000000000008388608
+)
+
+var ftoatests = []ftoaTest{
+	{1, 'e', 5, "1.00000e+00"},
+	{1, 'f', 5, "1.00000"},
+	{1, 'g', 5, "1"},
+	{1, 'g', -1, "1"},
+	{20, 'g', -1, "20"},
+	{1234567.8, 'g', -1, "1.2345678e+06"},
+	{200000, 'g', -1, "200000"},
+	{2000000, 'g', -1, "2e+06"},
+
+	// g conversion and zero suppression
+	{400, 'g', 2, "4e+02"},
+	{40, 'g', 2, "40"},
+	{4, 'g', 2, "4"},
+	{.4, 'g', 2, "0.4"},
+	{.04, 'g', 2, "0.04"},
+	{.004, 'g', 2, "0.004"},
+	{.0004, 'g', 2, "0.0004"},
+	{.00004, 'g', 2, "4e-05"},
+	{.000004, 'g', 2, "4e-06"},
+
+	{0, 'e', 5, "0.00000e+00"},
+	{0, 'f', 5, "0.00000"},
+	{0, 'g', 5, "0"},
+	{0, 'g', -1, "0"},
+
+	{-1, 'e', 5, "-1.00000e+00"},
+	{-1, 'f', 5, "-1.00000"},
+	{-1, 'g', 5, "-1"},
+	{-1, 'g', -1, "-1"},
+
+	{12, 'e', 5, "1.20000e+01"},
+	{12, 'f', 5, "12.00000"},
+	{12, 'g', 5, "12"},
+	{12, 'g', -1, "12"},
+
+	{123456700, 'e', 5, "1.23457e+08"},
+	{123456700, 'f', 5, "123456700.00000"},
+	{123456700, 'g', 5, "1.2346e+08"},
+	{123456700, 'g', -1, "1.234567e+08"},
+
+	{1.2345e6, 'e', 5, "1.23450e+06"},
+	{1.2345e6, 'f', 5, "1234500.00000"},
+	{1.2345e6, 'g', 5, "1.2345e+06"},
+
+	{1e23, 'e', 17, "9.99999999999999916e+22"},
+	{1e23, 'f', 17, "99999999999999991611392.00000000000000000"},
+	{1e23, 'g', 17, "9.9999999999999992e+22"},
+
+	{1e23, 'e', -1, "1e+23"},
+	{1e23, 'f', -1, "100000000000000000000000"},
+	{1e23, 'g', -1, "1e+23"},
+
+	{below1e23, 'e', 17, "9.99999999999999748e+22"},
+	{below1e23, 'f', 17, "99999999999999974834176.00000000000000000"},
+	{below1e23, 'g', 17, "9.9999999999999975e+22"},
+
+	{below1e23, 'e', -1, "9.999999999999997e+22"},
+	{below1e23, 'f', -1, "99999999999999970000000"},
+	{below1e23, 'g', -1, "9.999999999999997e+22"},
+
+	{above1e23, 'e', 17, "1.00000000000000008e+23"},
+	{above1e23, 'f', 17, "100000000000000008388608.00000000000000000"},
+	{above1e23, 'g', 17, "1.0000000000000001e+23"},
+
+	{above1e23, 'e', -1, "1.0000000000000001e+23"},
+	{above1e23, 'f', -1, "100000000000000010000000"},
+	{above1e23, 'g', -1, "1.0000000000000001e+23"},
+
+	{fdiv(5e-304, 1e20), 'g', -1, "5e-324"},
+	{fdiv(-5e-304, 1e20), 'g', -1, "-5e-324"},
+
+	{32, 'g', -1, "32"},
+	{32, 'g', 0, "3e+01"},
+
+	{100, 'x', -1, "%x"},
+
+	{math.NaN(), 'g', -1, "NaN"},
+	{-math.NaN(), 'g', -1, "NaN"},
+	{math.Inf(0), 'g', -1, "+Inf"},
+	{math.Inf(-1), 'g', -1, "-Inf"},
+	{-math.Inf(0), 'g', -1, "-Inf"},
+
+	{-1, 'b', -1, "-4503599627370496p-52"},
+
+	// fixed bugs
+	{0.9, 'f', 1, "0.9"},
+	{0.09, 'f', 1, "0.1"},
+	{0.0999, 'f', 1, "0.1"},
+	{0.05, 'f', 1, "0.1"},
+	{0.05, 'f', 0, "0"},
+	{0.5, 'f', 1, "0.5"},
+	{0.5, 'f', 0, "0"},
+	{1.5, 'f', 0, "2"},
+
+	// http://www.exploringbinary.com/java-hangs-when-converting-2-2250738585072012e-308/
+	{2.2250738585072012e-308, 'g', -1, "2.2250738585072014e-308"},
+	// http://www.exploringbinary.com/php-hangs-on-numeric-value-2-2250738585072011e-308/
+	{2.2250738585072011e-308, 'g', -1, "2.225073858507201e-308"},
+
+	// Issue 2625.
+	{383260575764816448, 'f', 0, "383260575764816448"},
+	{383260575764816448, 'g', -1, "3.8326057576481645e+17"},
+}
+
+func TestFtoa(t *testing.T) {
+	for i := 0; i < len(ftoatests); i++ {
+		test := &ftoatests[i]
+		s := FormatFloat(test.f, test.fmt, test.prec, 64)
+		if s != test.s {
+			t.Error("testN=64", test.f, string(test.fmt), test.prec, "want", test.s, "got", s)
+		}
+		x := AppendFloat([]byte("abc"), test.f, test.fmt, test.prec, 64)
+		if string(x) != "abc"+test.s {
+			t.Error("AppendFloat testN=64", test.f, string(test.fmt), test.prec, "want", "abc"+test.s, "got", string(x))
+		}
+		if float64(float32(test.f)) == test.f && test.fmt != 'b' {
+			s := FormatFloat(test.f, test.fmt, test.prec, 32)
+			if s != test.s {
+				t.Error("testN=32", test.f, string(test.fmt), test.prec, "want", test.s, "got", s)
+			}
+			x := AppendFloat([]byte("abc"), test.f, test.fmt, test.prec, 32)
+			if string(x) != "abc"+test.s {
+				t.Error("AppendFloat testN=32", test.f, string(test.fmt), test.prec, "want", "abc"+test.s, "got", string(x))
+			}
+		}
+	}
+}
+
+func TestFtoaRandom(t *testing.T) {
+	N := int(1e4)
+	if testing.Short() {
+		N = 100
+	}
+	t.Logf("testing %d random numbers with fast and slow FormatFloat", N)
+	for i := 0; i < N; i++ {
+		bits := uint64(rand.Uint32())<<32 | uint64(rand.Uint32())
+		x := math.Float64frombits(bits)
+
+		shortFast := FormatFloat(x, 'g', -1, 64)
+		SetOptimize(false)
+		shortSlow := FormatFloat(x, 'g', -1, 64)
+		SetOptimize(true)
+		if shortSlow != shortFast {
+			t.Errorf("%b printed as %s, want %s", x, shortFast, shortSlow)
+		}
+
+		prec := rand.Intn(12) + 5
+		shortFast = FormatFloat(x, 'e', prec, 64)
+		SetOptimize(false)
+		shortSlow = FormatFloat(x, 'e', prec, 64)
+		SetOptimize(true)
+		if shortSlow != shortFast {
+			t.Errorf("%b printed as %s, want %s", x, shortFast, shortSlow)
+		}
+	}
+}
+
+func BenchmarkFormatFloatDecimal(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		FormatFloat(33909, 'g', -1, 64)
+	}
+}
+
+func BenchmarkFormatFloat(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		FormatFloat(339.7784, 'g', -1, 64)
+	}
+}
+
+func BenchmarkFormatFloatExp(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		FormatFloat(-5.09e75, 'g', -1, 64)
+	}
+}
+
+func BenchmarkFormatFloatNegExp(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		FormatFloat(-5.11e-95, 'g', -1, 64)
+	}
+}
+
+func BenchmarkFormatFloatBig(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		FormatFloat(123456789123456789123456789, 'g', -1, 64)
+	}
+}
+
+func benchmarkAppendFloat(b *testing.B, f float64, fmt byte, prec, bitSize int) {
+	dst := make([]byte, 30)
+	for i := 0; i < b.N; i++ {
+		AppendFloat(dst[:0], f, fmt, prec, bitSize)
+	}
+}
+
+func BenchmarkAppendFloatDecimal(b *testing.B) { benchmarkAppendFloat(b, 33909, 'g', -1, 64) }
+func BenchmarkAppendFloat(b *testing.B)        { benchmarkAppendFloat(b, 339.7784, 'g', -1, 64) }
+func BenchmarkAppendFloatExp(b *testing.B)     { benchmarkAppendFloat(b, -5.09e75, 'g', -1, 64) }
+func BenchmarkAppendFloatNegExp(b *testing.B)  { benchmarkAppendFloat(b, -5.11e-95, 'g', -1, 64) }
+func BenchmarkAppendFloatBig(b *testing.B) {
+	benchmarkAppendFloat(b, 123456789123456789123456789, 'g', -1, 64)
+}
+
+func BenchmarkAppendFloat32Integer(b *testing.B)       { benchmarkAppendFloat(b, 33909, 'g', -1, 32) }
+func BenchmarkAppendFloat32ExactFraction(b *testing.B) { benchmarkAppendFloat(b, 3.375, 'g', -1, 32) }
+func BenchmarkAppendFloat32Point(b *testing.B)         { benchmarkAppendFloat(b, 339.7784, 'g', -1, 32) }
+func BenchmarkAppendFloat32Exp(b *testing.B)           { benchmarkAppendFloat(b, -5.09e25, 'g', -1, 32) }
+func BenchmarkAppendFloat32NegExp(b *testing.B)        { benchmarkAppendFloat(b, -5.11e-25, 'g', -1, 32) }
+
+func BenchmarkAppendFloat64Fixed1(b *testing.B) { benchmarkAppendFloat(b, 123456, 'e', 3, 64) }
+func BenchmarkAppendFloat64Fixed2(b *testing.B) { benchmarkAppendFloat(b, 123.456, 'e', 3, 64) }
+func BenchmarkAppendFloat64Fixed3(b *testing.B) { benchmarkAppendFloat(b, 1.23456e+78, 'e', 3, 64) }
+func BenchmarkAppendFloat64Fixed4(b *testing.B) { benchmarkAppendFloat(b, 1.23456e-78, 'e', 3, 64) }
diff --git a/src/strconv/internal_test.go b/src/strconv/internal_test.go
new file mode 100644
index 000000000..d0fa80edf
--- /dev/null
+++ b/src/strconv/internal_test.go
@@ -0,0 +1,19 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// export access to strconv internals for tests
+
+package strconv
+
+func NewDecimal(i uint64) *decimal {
+	d := new(decimal)
+	d.Assign(i)
+	return d
+}
+
+func SetOptimize(b bool) bool {
+	old := optimize
+	optimize = b
+	return old
+}
diff --git a/src/strconv/isprint.go b/src/strconv/isprint.go
new file mode 100644
index 000000000..80738ed71
--- /dev/null
+++ b/src/strconv/isprint.go
@@ -0,0 +1,624 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// DO NOT EDIT.  GENERATED BY
+//     go run makeisprint.go -output isprint.go
+
+package strconv
+
+// (468+138+67)*2 + (326)*4 = 2650 bytes
+
+var isPrint16 = []uint16{
+	0x0020, 0x007e,
+	0x00a1, 0x0377,
+	0x037a, 0x037f,
+	0x0384, 0x0556,
+	0x0559, 0x058a,
+	0x058d, 0x05c7,
+	0x05d0, 0x05ea,
+	0x05f0, 0x05f4,
+	0x0606, 0x061b,
+	0x061e, 0x070d,
+	0x0710, 0x074a,
+	0x074d, 0x07b1,
+	0x07c0, 0x07fa,
+	0x0800, 0x082d,
+	0x0830, 0x085b,
+	0x085e, 0x085e,
+	0x08a0, 0x08b2,
+	0x08e4, 0x098c,
+	0x098f, 0x0990,
+	0x0993, 0x09b2,
+	0x09b6, 0x09b9,
+	0x09bc, 0x09c4,
+	0x09c7, 0x09c8,
+	0x09cb, 0x09ce,
+	0x09d7, 0x09d7,
+	0x09dc, 0x09e3,
+	0x09e6, 0x09fb,
+	0x0a01, 0x0a0a,
+	0x0a0f, 0x0a10,
+	0x0a13, 0x0a39,
+	0x0a3c, 0x0a42,
+	0x0a47, 0x0a48,
+	0x0a4b, 0x0a4d,
+	0x0a51, 0x0a51,
+	0x0a59, 0x0a5e,
+	0x0a66, 0x0a75,
+	0x0a81, 0x0ab9,
+	0x0abc, 0x0acd,
+	0x0ad0, 0x0ad0,
+	0x0ae0, 0x0ae3,
+	0x0ae6, 0x0af1,
+	0x0b01, 0x0b0c,
+	0x0b0f, 0x0b10,
+	0x0b13, 0x0b39,
+	0x0b3c, 0x0b44,
+	0x0b47, 0x0b48,
+	0x0b4b, 0x0b4d,
+	0x0b56, 0x0b57,
+	0x0b5c, 0x0b63,
+	0x0b66, 0x0b77,
+	0x0b82, 0x0b8a,
+	0x0b8e, 0x0b95,
+	0x0b99, 0x0b9f,
+	0x0ba3, 0x0ba4,
+	0x0ba8, 0x0baa,
+	0x0bae, 0x0bb9,
+	0x0bbe, 0x0bc2,
+	0x0bc6, 0x0bcd,
+	0x0bd0, 0x0bd0,
+	0x0bd7, 0x0bd7,
+	0x0be6, 0x0bfa,
+	0x0c00, 0x0c39,
+	0x0c3d, 0x0c4d,
+	0x0c55, 0x0c59,
+	0x0c60, 0x0c63,
+	0x0c66, 0x0c6f,
+	0x0c78, 0x0cb9,
+	0x0cbc, 0x0ccd,
+	0x0cd5, 0x0cd6,
+	0x0cde, 0x0ce3,
+	0x0ce6, 0x0cf2,
+	0x0d01, 0x0d3a,
+	0x0d3d, 0x0d4e,
+	0x0d57, 0x0d57,
+	0x0d60, 0x0d63,
+	0x0d66, 0x0d75,
+	0x0d79, 0x0d7f,
+	0x0d82, 0x0d96,
+	0x0d9a, 0x0dbd,
+	0x0dc0, 0x0dc6,
+	0x0dca, 0x0dca,
+	0x0dcf, 0x0ddf,
+	0x0de6, 0x0def,
+	0x0df2, 0x0df4,
+	0x0e01, 0x0e3a,
+	0x0e3f, 0x0e5b,
+	0x0e81, 0x0e84,
+	0x0e87, 0x0e8a,
+	0x0e8d, 0x0e8d,
+	0x0e94, 0x0ea7,
+	0x0eaa, 0x0ebd,
+	0x0ec0, 0x0ecd,
+	0x0ed0, 0x0ed9,
+	0x0edc, 0x0edf,
+	0x0f00, 0x0f6c,
+	0x0f71, 0x0fda,
+	0x1000, 0x10c7,
+	0x10cd, 0x10cd,
+	0x10d0, 0x124d,
+	0x1250, 0x125d,
+	0x1260, 0x128d,
+	0x1290, 0x12b5,
+	0x12b8, 0x12c5,
+	0x12c8, 0x1315,
+	0x1318, 0x135a,
+	0x135d, 0x137c,
+	0x1380, 0x1399,
+	0x13a0, 0x13f4,
+	0x1400, 0x169c,
+	0x16a0, 0x16f8,
+	0x1700, 0x1714,
+	0x1720, 0x1736,
+	0x1740, 0x1753,
+	0x1760, 0x1773,
+	0x1780, 0x17dd,
+	0x17e0, 0x17e9,
+	0x17f0, 0x17f9,
+	0x1800, 0x180d,
+	0x1810, 0x1819,
+	0x1820, 0x1877,
+	0x1880, 0x18aa,
+	0x18b0, 0x18f5,
+	0x1900, 0x192b,
+	0x1930, 0x193b,
+	0x1940, 0x1940,
+	0x1944, 0x196d,
+	0x1970, 0x1974,
+	0x1980, 0x19ab,
+	0x19b0, 0x19c9,
+	0x19d0, 0x19da,
+	0x19de, 0x1a1b,
+	0x1a1e, 0x1a7c,
+	0x1a7f, 0x1a89,
+	0x1a90, 0x1a99,
+	0x1aa0, 0x1aad,
+	0x1ab0, 0x1abe,
+	0x1b00, 0x1b4b,
+	0x1b50, 0x1b7c,
+	0x1b80, 0x1bf3,
+	0x1bfc, 0x1c37,
+	0x1c3b, 0x1c49,
+	0x1c4d, 0x1c7f,
+	0x1cc0, 0x1cc7,
+	0x1cd0, 0x1cf9,
+	0x1d00, 0x1df5,
+	0x1dfc, 0x1f15,
+	0x1f18, 0x1f1d,
+	0x1f20, 0x1f45,
+	0x1f48, 0x1f4d,
+	0x1f50, 0x1f7d,
+	0x1f80, 0x1fd3,
+	0x1fd6, 0x1fef,
+	0x1ff2, 0x1ffe,
+	0x2010, 0x2027,
+	0x2030, 0x205e,
+	0x2070, 0x2071,
+	0x2074, 0x209c,
+	0x20a0, 0x20bd,
+	0x20d0, 0x20f0,
+	0x2100, 0x2189,
+	0x2190, 0x23fa,
+	0x2400, 0x2426,
+	0x2440, 0x244a,
+	0x2460, 0x2b73,
+	0x2b76, 0x2b95,
+	0x2b98, 0x2bb9,
+	0x2bbd, 0x2bd1,
+	0x2c00, 0x2cf3,
+	0x2cf9, 0x2d27,
+	0x2d2d, 0x2d2d,
+	0x2d30, 0x2d67,
+	0x2d6f, 0x2d70,
+	0x2d7f, 0x2d96,
+	0x2da0, 0x2e42,
+	0x2e80, 0x2ef3,
+	0x2f00, 0x2fd5,
+	0x2ff0, 0x2ffb,
+	0x3001, 0x3096,
+	0x3099, 0x30ff,
+	0x3105, 0x312d,
+	0x3131, 0x31ba,
+	0x31c0, 0x31e3,
+	0x31f0, 0x4db5,
+	0x4dc0, 0x9fcc,
+	0xa000, 0xa48c,
+	0xa490, 0xa4c6,
+	0xa4d0, 0xa62b,
+	0xa640, 0xa6f7,
+	0xa700, 0xa7ad,
+	0xa7b0, 0xa7b1,
+	0xa7f7, 0xa82b,
+	0xa830, 0xa839,
+	0xa840, 0xa877,
+	0xa880, 0xa8c4,
+	0xa8ce, 0xa8d9,
+	0xa8e0, 0xa8fb,
+	0xa900, 0xa953,
+	0xa95f, 0xa97c,
+	0xa980, 0xa9d9,
+	0xa9de, 0xaa36,
+	0xaa40, 0xaa4d,
+	0xaa50, 0xaa59,
+	0xaa5c, 0xaac2,
+	0xaadb, 0xaaf6,
+	0xab01, 0xab06,
+	0xab09, 0xab0e,
+	0xab11, 0xab16,
+	0xab20, 0xab5f,
+	0xab64, 0xab65,
+	0xabc0, 0xabed,
+	0xabf0, 0xabf9,
+	0xac00, 0xd7a3,
+	0xd7b0, 0xd7c6,
+	0xd7cb, 0xd7fb,
+	0xf900, 0xfa6d,
+	0xfa70, 0xfad9,
+	0xfb00, 0xfb06,
+	0xfb13, 0xfb17,
+	0xfb1d, 0xfbc1,
+	0xfbd3, 0xfd3f,
+	0xfd50, 0xfd8f,
+	0xfd92, 0xfdc7,
+	0xfdf0, 0xfdfd,
+	0xfe00, 0xfe19,
+	0xfe20, 0xfe2d,
+	0xfe30, 0xfe6b,
+	0xfe70, 0xfefc,
+	0xff01, 0xffbe,
+	0xffc2, 0xffc7,
+	0xffca, 0xffcf,
+	0xffd2, 0xffd7,
+	0xffda, 0xffdc,
+	0xffe0, 0xffee,
+	0xfffc, 0xfffd,
+}
+
+var isNotPrint16 = []uint16{
+	0x00ad,
+	0x038b,
+	0x038d,
+	0x03a2,
+	0x0530,
+	0x0560,
+	0x0588,
+	0x0590,
+	0x06dd,
+	0x083f,
+	0x0984,
+	0x09a9,
+	0x09b1,
+	0x09de,
+	0x0a04,
+	0x0a29,
+	0x0a31,
+	0x0a34,
+	0x0a37,
+	0x0a3d,
+	0x0a5d,
+	0x0a84,
+	0x0a8e,
+	0x0a92,
+	0x0aa9,
+	0x0ab1,
+	0x0ab4,
+	0x0ac6,
+	0x0aca,
+	0x0b04,
+	0x0b29,
+	0x0b31,
+	0x0b34,
+	0x0b5e,
+	0x0b84,
+	0x0b91,
+	0x0b9b,
+	0x0b9d,
+	0x0bc9,
+	0x0c04,
+	0x0c0d,
+	0x0c11,
+	0x0c29,
+	0x0c45,
+	0x0c49,
+	0x0c57,
+	0x0c80,
+	0x0c84,
+	0x0c8d,
+	0x0c91,
+	0x0ca9,
+	0x0cb4,
+	0x0cc5,
+	0x0cc9,
+	0x0cdf,
+	0x0cf0,
+	0x0d04,
+	0x0d0d,
+	0x0d11,
+	0x0d45,
+	0x0d49,
+	0x0d84,
+	0x0db2,
+	0x0dbc,
+	0x0dd5,
+	0x0dd7,
+	0x0e83,
+	0x0e89,
+	0x0e98,
+	0x0ea0,
+	0x0ea4,
+	0x0ea6,
+	0x0eac,
+	0x0eba,
+	0x0ec5,
+	0x0ec7,
+	0x0f48,
+	0x0f98,
+	0x0fbd,
+	0x0fcd,
+	0x10c6,
+	0x1249,
+	0x1257,
+	0x1259,
+	0x1289,
+	0x12b1,
+	0x12bf,
+	0x12c1,
+	0x12d7,
+	0x1311,
+	0x1680,
+	0x170d,
+	0x176d,
+	0x1771,
+	0x191f,
+	0x1a5f,
+	0x1cf7,
+	0x1f58,
+	0x1f5a,
+	0x1f5c,
+	0x1f5e,
+	0x1fb5,
+	0x1fc5,
+	0x1fdc,
+	0x1ff5,
+	0x208f,
+	0x2bc9,
+	0x2c2f,
+	0x2c5f,
+	0x2d26,
+	0x2da7,
+	0x2daf,
+	0x2db7,
+	0x2dbf,
+	0x2dc7,
+	0x2dcf,
+	0x2dd7,
+	0x2ddf,
+	0x2e9a,
+	0x3040,
+	0x318f,
+	0x321f,
+	0x32ff,
+	0xa69e,
+	0xa78f,
+	0xa9ce,
+	0xa9ff,
+	0xab27,
+	0xab2f,
+	0xfb37,
+	0xfb3d,
+	0xfb3f,
+	0xfb42,
+	0xfb45,
+	0xfe53,
+	0xfe67,
+	0xfe75,
+	0xffe7,
+}
+
+var isPrint32 = []uint32{
+	0x010000, 0x01004d,
+	0x010050, 0x01005d,
+	0x010080, 0x0100fa,
+	0x010100, 0x010102,
+	0x010107, 0x010133,
+	0x010137, 0x01018c,
+	0x010190, 0x01019b,
+	0x0101a0, 0x0101a0,
+	0x0101d0, 0x0101fd,
+	0x010280, 0x01029c,
+	0x0102a0, 0x0102d0,
+	0x0102e0, 0x0102fb,
+	0x010300, 0x010323,
+	0x010330, 0x01034a,
+	0x010350, 0x01037a,
+	0x010380, 0x0103c3,
+	0x0103c8, 0x0103d5,
+	0x010400, 0x01049d,
+	0x0104a0, 0x0104a9,
+	0x010500, 0x010527,
+	0x010530, 0x010563,
+	0x01056f, 0x01056f,
+	0x010600, 0x010736,
+	0x010740, 0x010755,
+	0x010760, 0x010767,
+	0x010800, 0x010805,
+	0x010808, 0x010838,
+	0x01083c, 0x01083c,
+	0x01083f, 0x01089e,
+	0x0108a7, 0x0108af,
+	0x010900, 0x01091b,
+	0x01091f, 0x010939,
+	0x01093f, 0x01093f,
+	0x010980, 0x0109b7,
+	0x0109be, 0x0109bf,
+	0x010a00, 0x010a06,
+	0x010a0c, 0x010a33,
+	0x010a38, 0x010a3a,
+	0x010a3f, 0x010a47,
+	0x010a50, 0x010a58,
+	0x010a60, 0x010a9f,
+	0x010ac0, 0x010ae6,
+	0x010aeb, 0x010af6,
+	0x010b00, 0x010b35,
+	0x010b39, 0x010b55,
+	0x010b58, 0x010b72,
+	0x010b78, 0x010b91,
+	0x010b99, 0x010b9c,
+	0x010ba9, 0x010baf,
+	0x010c00, 0x010c48,
+	0x010e60, 0x010e7e,
+	0x011000, 0x01104d,
+	0x011052, 0x01106f,
+	0x01107f, 0x0110c1,
+	0x0110d0, 0x0110e8,
+	0x0110f0, 0x0110f9,
+	0x011100, 0x011143,
+	0x011150, 0x011176,
+	0x011180, 0x0111c8,
+	0x0111cd, 0x0111cd,
+	0x0111d0, 0x0111da,
+	0x0111e1, 0x0111f4,
+	0x011200, 0x01123d,
+	0x0112b0, 0x0112ea,
+	0x0112f0, 0x0112f9,
+	0x011301, 0x01130c,
+	0x01130f, 0x011310,
+	0x011313, 0x011339,
+	0x01133c, 0x011344,
+	0x011347, 0x011348,
+	0x01134b, 0x01134d,
+	0x011357, 0x011357,
+	0x01135d, 0x011363,
+	0x011366, 0x01136c,
+	0x011370, 0x011374,
+	0x011480, 0x0114c7,
+	0x0114d0, 0x0114d9,
+	0x011580, 0x0115b5,
+	0x0115b8, 0x0115c9,
+	0x011600, 0x011644,
+	0x011650, 0x011659,
+	0x011680, 0x0116b7,
+	0x0116c0, 0x0116c9,
+	0x0118a0, 0x0118f2,
+	0x0118ff, 0x0118ff,
+	0x011ac0, 0x011af8,
+	0x012000, 0x012398,
+	0x012400, 0x012474,
+	0x013000, 0x01342e,
+	0x016800, 0x016a38,
+	0x016a40, 0x016a69,
+	0x016a6e, 0x016a6f,
+	0x016ad0, 0x016aed,
+	0x016af0, 0x016af5,
+	0x016b00, 0x016b45,
+	0x016b50, 0x016b77,
+	0x016b7d, 0x016b8f,
+	0x016f00, 0x016f44,
+	0x016f50, 0x016f7e,
+	0x016f8f, 0x016f9f,
+	0x01b000, 0x01b001,
+	0x01bc00, 0x01bc6a,
+	0x01bc70, 0x01bc7c,
+	0x01bc80, 0x01bc88,
+	0x01bc90, 0x01bc99,
+	0x01bc9c, 0x01bc9f,
+	0x01d000, 0x01d0f5,
+	0x01d100, 0x01d126,
+	0x01d129, 0x01d172,
+	0x01d17b, 0x01d1dd,
+	0x01d200, 0x01d245,
+	0x01d300, 0x01d356,
+	0x01d360, 0x01d371,
+	0x01d400, 0x01d49f,
+	0x01d4a2, 0x01d4a2,
+	0x01d4a5, 0x01d4a6,
+	0x01d4a9, 0x01d50a,
+	0x01d50d, 0x01d546,
+	0x01d54a, 0x01d6a5,
+	0x01d6a8, 0x01d7cb,
+	0x01d7ce, 0x01d7ff,
+	0x01e800, 0x01e8c4,
+	0x01e8c7, 0x01e8d6,
+	0x01ee00, 0x01ee24,
+	0x01ee27, 0x01ee3b,
+	0x01ee42, 0x01ee42,
+	0x01ee47, 0x01ee54,
+	0x01ee57, 0x01ee64,
+	0x01ee67, 0x01ee9b,
+	0x01eea1, 0x01eebb,
+	0x01eef0, 0x01eef1,
+	0x01f000, 0x01f02b,
+	0x01f030, 0x01f093,
+	0x01f0a0, 0x01f0ae,
+	0x01f0b1, 0x01f0f5,
+	0x01f100, 0x01f10c,
+	0x01f110, 0x01f16b,
+	0x01f170, 0x01f19a,
+	0x01f1e6, 0x01f202,
+	0x01f210, 0x01f23a,
+	0x01f240, 0x01f248,
+	0x01f250, 0x01f251,
+	0x01f300, 0x01f32c,
+	0x01f330, 0x01f37d,
+	0x01f380, 0x01f3ce,
+	0x01f3d4, 0x01f3f7,
+	0x01f400, 0x01f54a,
+	0x01f550, 0x01f642,
+	0x01f645, 0x01f6cf,
+	0x01f6e0, 0x01f6ec,
+	0x01f6f0, 0x01f6f3,
+	0x01f700, 0x01f773,
+	0x01f780, 0x01f7d4,
+	0x01f800, 0x01f80b,
+	0x01f810, 0x01f847,
+	0x01f850, 0x01f859,
+	0x01f860, 0x01f887,
+	0x01f890, 0x01f8ad,
+	0x020000, 0x02a6d6,
+	0x02a700, 0x02b734,
+	0x02b740, 0x02b81d,
+	0x02f800, 0x02fa1d,
+	0x0e0100, 0x0e01ef,
+}
+
+var isNotPrint32 = []uint16{ // add 0x10000 to each entry
+	0x000c,
+	0x0027,
+	0x003b,
+	0x003e,
+	0x039e,
+	0x0809,
+	0x0836,
+	0x0856,
+	0x0a04,
+	0x0a14,
+	0x0a18,
+	0x10bd,
+	0x1135,
+	0x1212,
+	0x1304,
+	0x1329,
+	0x1331,
+	0x1334,
+	0x246f,
+	0x6a5f,
+	0x6b5a,
+	0x6b62,
+	0xd455,
+	0xd49d,
+	0xd4ad,
+	0xd4ba,
+	0xd4bc,
+	0xd4c4,
+	0xd506,
+	0xd515,
+	0xd51d,
+	0xd53a,
+	0xd53f,
+	0xd545,
+	0xd551,
+	0xee04,
+	0xee20,
+	0xee23,
+	0xee28,
+	0xee33,
+	0xee38,
+	0xee3a,
+	0xee48,
+	0xee4a,
+	0xee4c,
+	0xee50,
+	0xee53,
+	0xee58,
+	0xee5a,
+	0xee5c,
+	0xee5e,
+	0xee60,
+	0xee63,
+	0xee6b,
+	0xee73,
+	0xee78,
+	0xee7d,
+	0xee7f,
+	0xee8a,
+	0xeea4,
+	0xeeaa,
+	0xf0c0,
+	0xf0d0,
+	0xf12f,
+	0xf4ff,
+	0xf57a,
+	0xf5a4,
+}
diff --git a/src/strconv/itoa.go b/src/strconv/itoa.go
new file mode 100644
index 000000000..67f17d866
--- /dev/null
+++ b/src/strconv/itoa.go
@@ -0,0 +1,131 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package strconv
+
+// FormatUint returns the string representation of i in the given base,
+// for 2 <= base <= 36. The result uses the lower-case letters 'a' to 'z'
+// for digit values >= 10.
+func FormatUint(i uint64, base int) string {
+	_, s := formatBits(nil, i, base, false, false)
+	return s
+}
+
+// FormatInt returns the string representation of i in the given base,
+// for 2 <= base <= 36. The result uses the lower-case letters 'a' to 'z'
+// for digit values >= 10.
+func FormatInt(i int64, base int) string {
+	_, s := formatBits(nil, uint64(i), base, i < 0, false)
+	return s
+}
+
+// Itoa is shorthand for FormatInt(i, 10).
+func Itoa(i int) string {
+	return FormatInt(int64(i), 10)
+}
+
+// AppendInt appends the string form of the integer i,
+// as generated by FormatInt, to dst and returns the extended buffer.
+func AppendInt(dst []byte, i int64, base int) []byte {
+	dst, _ = formatBits(dst, uint64(i), base, i < 0, true)
+	return dst
+}
+
+// AppendUint appends the string form of the unsigned integer i,
+// as generated by FormatUint, to dst and returns the extended buffer.
+func AppendUint(dst []byte, i uint64, base int) []byte {
+	dst, _ = formatBits(dst, i, base, false, true)
+	return dst
+}
+
+const (
+	digits   = "0123456789abcdefghijklmnopqrstuvwxyz"
+	digits01 = "0123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789"
+	digits10 = "0000000000111111111122222222223333333333444444444455555555556666666666777777777788888888889999999999"
+)
+
+var shifts = [len(digits) + 1]uint{
+	1 << 1: 1,
+	1 << 2: 2,
+	1 << 3: 3,
+	1 << 4: 4,
+	1 << 5: 5,
+}
+
+// formatBits computes the string representation of u in the given base.
+// If neg is set, u is treated as negative int64 value. If append_ is
+// set, the string is appended to dst and the resulting byte slice is
+// returned as the first result value; otherwise the string is returned
+// as the second result value.
+//
+func formatBits(dst []byte, u uint64, base int, neg, append_ bool) (d []byte, s string) {
+	if base < 2 || base > len(digits) {
+		panic("strconv: illegal AppendInt/FormatInt base")
+	}
+	// 2 <= base && base <= len(digits)
+
+	var a [64 + 1]byte // +1 for sign of 64bit value in base 2
+	i := len(a)
+
+	if neg {
+		u = -u
+	}
+
+	// convert bits
+	if base == 10 {
+		// common case: use constants for / and % because
+		// the compiler can optimize it into a multiply+shift,
+		// and unroll loop
+		for u >= 100 {
+			i -= 2
+			q := u / 100
+			j := uintptr(u - q*100)
+			a[i+1] = digits01[j]
+			a[i+0] = digits10[j]
+			u = q
+		}
+		if u >= 10 {
+			i--
+			q := u / 10
+			a[i] = digits[uintptr(u-q*10)]
+			u = q
+		}
+
+	} else if s := shifts[base]; s > 0 {
+		// base is power of 2: use shifts and masks instead of / and %
+		b := uint64(base)
+		m := uintptr(b) - 1 // == 1<<s - 1
+		for u >= b {
+			i--
+			a[i] = digits[uintptr(u)&m]
+			u >>= s
+		}
+
+	} else {
+		// general case
+		b := uint64(base)
+		for u >= b {
+			i--
+			a[i] = digits[uintptr(u%b)]
+			u /= b
+		}
+	}
+
+	// u < base
+	i--
+	a[i] = digits[uintptr(u)]
+
+	// add sign, if any
+	if neg {
+		i--
+		a[i] = '-'
+	}
+
+	if append_ {
+		d = append(dst, a[i:]...)
+		return
+	}
+	s = string(a[i:])
+	return
+}
diff --git a/src/strconv/itoa_test.go b/src/strconv/itoa_test.go
new file mode 100644
index 000000000..e0213ae9a
--- /dev/null
+++ b/src/strconv/itoa_test.go
@@ -0,0 +1,160 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package strconv_test
+
+import (
+	. "strconv"
+	"testing"
+)
+
+type itob64Test struct {
+	in   int64
+	base int
+	out  string
+}
+
+var itob64tests = []itob64Test{
+	{0, 10, "0"},
+	{1, 10, "1"},
+	{-1, 10, "-1"},
+	{12345678, 10, "12345678"},
+	{-987654321, 10, "-987654321"},
+	{1<<31 - 1, 10, "2147483647"},
+	{-1<<31 + 1, 10, "-2147483647"},
+	{1 << 31, 10, "2147483648"},
+	{-1 << 31, 10, "-2147483648"},
+	{1<<31 + 1, 10, "2147483649"},
+	{-1<<31 - 1, 10, "-2147483649"},
+	{1<<32 - 1, 10, "4294967295"},
+	{-1<<32 + 1, 10, "-4294967295"},
+	{1 << 32, 10, "4294967296"},
+	{-1 << 32, 10, "-4294967296"},
+	{1<<32 + 1, 10, "4294967297"},
+	{-1<<32 - 1, 10, "-4294967297"},
+	{1 << 50, 10, "1125899906842624"},
+	{1<<63 - 1, 10, "9223372036854775807"},
+	{-1<<63 + 1, 10, "-9223372036854775807"},
+	{-1 << 63, 10, "-9223372036854775808"},
+
+	{0, 2, "0"},
+	{10, 2, "1010"},
+	{-1, 2, "-1"},
+	{1 << 15, 2, "1000000000000000"},
+
+	{-8, 8, "-10"},
+	{057635436545, 8, "57635436545"},
+	{1 << 24, 8, "100000000"},
+
+	{16, 16, "10"},
+	{-0x123456789abcdef, 16, "-123456789abcdef"},
+	{1<<63 - 1, 16, "7fffffffffffffff"},
+	{1<<63 - 1, 2, "111111111111111111111111111111111111111111111111111111111111111"},
+
+	{16, 17, "g"},
+	{25, 25, "10"},
+	{(((((17*35+24)*35+21)*35+34)*35+12)*35+24)*35 + 32, 35, "holycow"},
+	{(((((17*36+24)*36+21)*36+34)*36+12)*36+24)*36 + 32, 36, "holycow"},
+}
+
+func TestItoa(t *testing.T) {
+	for _, test := range itob64tests {
+		s := FormatInt(test.in, test.base)
+		if s != test.out {
+			t.Errorf("FormatInt(%v, %v) = %v want %v",
+				test.in, test.base, s, test.out)
+		}
+		x := AppendInt([]byte("abc"), test.in, test.base)
+		if string(x) != "abc"+test.out {
+			t.Errorf("AppendInt(%q, %v, %v) = %q want %v",
+				"abc", test.in, test.base, x, test.out)
+		}
+
+		if test.in >= 0 {
+			s := FormatUint(uint64(test.in), test.base)
+			if s != test.out {
+				t.Errorf("FormatUint(%v, %v) = %v want %v",
+					test.in, test.base, s, test.out)
+			}
+			x := AppendUint(nil, uint64(test.in), test.base)
+			if string(x) != test.out {
+				t.Errorf("AppendUint(%q, %v, %v) = %q want %v",
+					"abc", uint64(test.in), test.base, x, test.out)
+			}
+		}
+
+		if test.base == 10 && int64(int(test.in)) == test.in {
+			s := Itoa(int(test.in))
+			if s != test.out {
+				t.Errorf("Itoa(%v) = %v want %v",
+					test.in, s, test.out)
+			}
+		}
+	}
+}
+
+type uitob64Test struct {
+	in   uint64
+	base int
+	out  string
+}
+
+var uitob64tests = []uitob64Test{
+	{1<<63 - 1, 10, "9223372036854775807"},
+	{1 << 63, 10, "9223372036854775808"},
+	{1<<63 + 1, 10, "9223372036854775809"},
+	{1<<64 - 2, 10, "18446744073709551614"},
+	{1<<64 - 1, 10, "18446744073709551615"},
+	{1<<64 - 1, 2, "1111111111111111111111111111111111111111111111111111111111111111"},
+}
+
+func TestUitoa(t *testing.T) {
+	for _, test := range uitob64tests {
+		s := FormatUint(test.in, test.base)
+		if s != test.out {
+			t.Errorf("FormatUint(%v, %v) = %v want %v",
+				test.in, test.base, s, test.out)
+		}
+		x := AppendUint([]byte("abc"), test.in, test.base)
+		if string(x) != "abc"+test.out {
+			t.Errorf("AppendUint(%q, %v, %v) = %q want %v",
+				"abc", test.in, test.base, x, test.out)
+		}
+
+	}
+}
+
+func BenchmarkFormatInt(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		for _, test := range itob64tests {
+			FormatInt(test.in, test.base)
+		}
+	}
+}
+
+func BenchmarkAppendInt(b *testing.B) {
+	dst := make([]byte, 0, 30)
+	for i := 0; i < b.N; i++ {
+		for _, test := range itob64tests {
+			AppendInt(dst, test.in, test.base)
+		}
+	}
+}
+
+func BenchmarkFormatUint(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		for _, test := range uitob64tests {
+			FormatUint(test.in, test.base)
+		}
+	}
+}
+
+func BenchmarkAppendUint(b *testing.B) {
+	dst := make([]byte, 0, 30)
+	for i := 0; i < b.N; i++ {
+		for _, test := range uitob64tests {
+			AppendUint(dst, test.in, test.base)
+		}
+	}
+}
diff --git a/src/strconv/makeisprint.go b/src/strconv/makeisprint.go
new file mode 100644
index 000000000..588d0a00b
--- /dev/null
+++ b/src/strconv/makeisprint.go
@@ -0,0 +1,187 @@
+// Copyright 2012 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build ignore
+
+//
+// usage:
+//
+// go run makeisprint.go -output isprint.go
+//
+
+package main
+
+import (
+	"bytes"
+	"flag"
+	"fmt"
+	"go/format"
+	"io/ioutil"
+	"log"
+	"unicode"
+)
+
+var filename = flag.String("output", "isprint.go", "output file name")
+
+var (
+	range16  []uint16
+	except16 []uint16
+	range32  []uint32
+	except32 []uint32
+)
+
+// bsearch16 returns the smallest i such that a[i] >= x.
+// If there is no such i, bsearch16 returns len(a).
+func bsearch16(a []uint16, x uint16) int {
+	i, j := 0, len(a)
+	for i < j {
+		h := i + (j-i)/2
+		if a[h] < x {
+			i = h + 1
+		} else {
+			j = h
+		}
+	}
+	return i
+}
+
+// bsearch32 returns the smallest i such that a[i] >= x.
+// If there is no such i, bsearch32 returns len(a).
+func bsearch32(a []uint32, x uint32) int {
+	i, j := 0, len(a)
+	for i < j {
+		h := i + (j-i)/2
+		if a[h] < x {
+			i = h + 1
+		} else {
+			j = h
+		}
+	}
+	return i
+}
+
+func isPrint(r rune) bool {
+	// Same algorithm, either on uint16 or uint32 value.
+	// First, find first i such that rang[i] >= x.
+	// This is the index of either the start or end of a pair that might span x.
+	// The start is even (rang[i&^1]) and the end is odd (rang[i|1]).
+	// If we find x in a range, make sure x is not in exception list.
+
+	if 0 <= r && r < 1<<16 {
+		rr, rang, except := uint16(r), range16, except16
+		i := bsearch16(rang, rr)
+		if i >= len(rang) || rr < rang[i&^1] || rang[i|1] < rr {
+			return false
+		}
+		j := bsearch16(except, rr)
+		return j >= len(except) || except[j] != rr
+	}
+
+	rr, rang, except := uint32(r), range32, except32
+	i := bsearch32(rang, rr)
+	if i >= len(rang) || rr < rang[i&^1] || rang[i|1] < rr {
+		return false
+	}
+	j := bsearch32(except, rr)
+	return j >= len(except) || except[j] != rr
+}
+
+func scan(min, max rune) (rang, except []uint32) {
+	lo := rune(-1)
+	for i := min; ; i++ {
+		if (i > max || !unicode.IsPrint(i)) && lo >= 0 {
+			// End range, but avoid flip flop.
+			if i+1 <= max && unicode.IsPrint(i+1) {
+				except = append(except, uint32(i))
+				continue
+			}
+			rang = append(rang, uint32(lo), uint32(i-1))
+			lo = -1
+		}
+		if i > max {
+			break
+		}
+		if lo < 0 && unicode.IsPrint(i) {
+			lo = i
+		}
+	}
+	return
+}
+
+func to16(x []uint32) []uint16 {
+	var y []uint16
+	for _, v := range x {
+		if uint32(uint16(v)) != v {
+			panic("bad 32->16 conversion")
+		}
+		y = append(y, uint16(v))
+	}
+	return y
+}
+
+func main() {
+	flag.Parse()
+
+	rang, except := scan(0, 0xFFFF)
+	range16 = to16(rang)
+	except16 = to16(except)
+	range32, except32 = scan(0x10000, unicode.MaxRune)
+
+	for i := rune(0); i <= unicode.MaxRune; i++ {
+		if isPrint(i) != unicode.IsPrint(i) {
+			log.Fatalf("%U: isPrint=%v, want %v\n", i, isPrint(i), unicode.IsPrint(i))
+		}
+	}
+
+	var buf bytes.Buffer
+
+	fmt.Fprintf(&buf, `// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.`+"\n\n")
+	fmt.Fprintf(&buf, "// DO NOT EDIT.  GENERATED BY\n")
+	fmt.Fprintf(&buf, "//     go run makeisprint.go -output isprint.go\n\n")
+	fmt.Fprintf(&buf, "package strconv\n\n")
+
+	fmt.Fprintf(&buf, "// (%d+%d+%d)*2 + (%d)*4 = %d bytes\n\n",
+		len(range16), len(except16), len(except32),
+		len(range32),
+		(len(range16)+len(except16)+len(except32))*2+
+			(len(range32))*4)
+
+	fmt.Fprintf(&buf, "var isPrint16 = []uint16{\n")
+	for i := 0; i < len(range16); i += 2 {
+		fmt.Fprintf(&buf, "\t%#04x, %#04x,\n", range16[i], range16[i+1])
+	}
+	fmt.Fprintf(&buf, "}\n\n")
+
+	fmt.Fprintf(&buf, "var isNotPrint16 = []uint16{\n")
+	for _, r := range except16 {
+		fmt.Fprintf(&buf, "\t%#04x,\n", r)
+	}
+	fmt.Fprintf(&buf, "}\n\n")
+
+	fmt.Fprintf(&buf, "var isPrint32 = []uint32{\n")
+	for i := 0; i < len(range32); i += 2 {
+		fmt.Fprintf(&buf, "\t%#06x, %#06x,\n", range32[i], range32[i+1])
+	}
+	fmt.Fprintf(&buf, "}\n\n")
+
+	fmt.Fprintf(&buf, "var isNotPrint32 = []uint16{ // add 0x10000 to each entry\n")
+	for _, r := range except32 {
+		if r >= 0x20000 {
+			log.Fatalf("%U too big for isNotPrint32\n", r)
+		}
+		fmt.Fprintf(&buf, "\t%#04x,\n", r-0x10000)
+	}
+	fmt.Fprintf(&buf, "}\n")
+
+	data, err := format.Source(buf.Bytes())
+	if err != nil {
+		log.Fatal(err)
+	}
+	err = ioutil.WriteFile(*filename, data, 0644)
+	if err != nil {
+		log.Fatal(err)
+	}
+}
diff --git a/src/strconv/quote.go b/src/strconv/quote.go
new file mode 100644
index 000000000..4469c688b
--- /dev/null
+++ b/src/strconv/quote.go
@@ -0,0 +1,455 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:generate go run makeisprint.go -output isprint.go
+
+package strconv
+
+import (
+	"unicode/utf8"
+)
+
+const lowerhex = "0123456789abcdef"
+
+func quoteWith(s string, quote byte, ASCIIonly bool) string {
+	var runeTmp [utf8.UTFMax]byte
+	buf := make([]byte, 0, 3*len(s)/2) // Try to avoid more allocations.
+	buf = append(buf, quote)
+	for width := 0; len(s) > 0; s = s[width:] {
+		r := rune(s[0])
+		width = 1
+		if r >= utf8.RuneSelf {
+			r, width = utf8.DecodeRuneInString(s)
+		}
+		if width == 1 && r == utf8.RuneError {
+			buf = append(buf, `\x`...)
+			buf = append(buf, lowerhex[s[0]>>4])
+			buf = append(buf, lowerhex[s[0]&0xF])
+			continue
+		}
+		if r == rune(quote) || r == '\\' { // always backslashed
+			buf = append(buf, '\\')
+			buf = append(buf, byte(r))
+			continue
+		}
+		if ASCIIonly {
+			if r < utf8.RuneSelf && IsPrint(r) {
+				buf = append(buf, byte(r))
+				continue
+			}
+		} else if IsPrint(r) {
+			n := utf8.EncodeRune(runeTmp[:], r)
+			buf = append(buf, runeTmp[:n]...)
+			continue
+		}
+		switch r {
+		case '\a':
+			buf = append(buf, `\a`...)
+		case '\b':
+			buf = append(buf, `\b`...)
+		case '\f':
+			buf = append(buf, `\f`...)
+		case '\n':
+			buf = append(buf, `\n`...)
+		case '\r':
+			buf = append(buf, `\r`...)
+		case '\t':
+			buf = append(buf, `\t`...)
+		case '\v':
+			buf = append(buf, `\v`...)
+		default:
+			switch {
+			case r < ' ':
+				buf = append(buf, `\x`...)
+				buf = append(buf, lowerhex[s[0]>>4])
+				buf = append(buf, lowerhex[s[0]&0xF])
+			case r > utf8.MaxRune:
+				r = 0xFFFD
+				fallthrough
+			case r < 0x10000:
+				buf = append(buf, `\u`...)
+				for s := 12; s >= 0; s -= 4 {
+					buf = append(buf, lowerhex[r>>uint(s)&0xF])
+				}
+			default:
+				buf = append(buf, `\U`...)
+				for s := 28; s >= 0; s -= 4 {
+					buf = append(buf, lowerhex[r>>uint(s)&0xF])
+				}
+			}
+		}
+	}
+	buf = append(buf, quote)
+	return string(buf)
+
+}
+
+// Quote returns a double-quoted Go string literal representing s.  The
+// returned string uses Go escape sequences (\t, \n, \xFF, \u0100) for
+// control characters and non-printable characters as defined by
+// IsPrint.
+func Quote(s string) string {
+	return quoteWith(s, '"', false)
+}
+
+// AppendQuote appends a double-quoted Go string literal representing s,
+// as generated by Quote, to dst and returns the extended buffer.
+func AppendQuote(dst []byte, s string) []byte {
+	return append(dst, Quote(s)...)
+}
+
+// QuoteToASCII returns a double-quoted Go string literal representing s.
+// The returned string uses Go escape sequences (\t, \n, \xFF, \u0100) for
+// non-ASCII characters and non-printable characters as defined by IsPrint.
+func QuoteToASCII(s string) string {
+	return quoteWith(s, '"', true)
+}
+
+// AppendQuoteToASCII appends a double-quoted Go string literal representing s,
+// as generated by QuoteToASCII, to dst and returns the extended buffer.
+func AppendQuoteToASCII(dst []byte, s string) []byte {
+	return append(dst, QuoteToASCII(s)...)
+}
+
+// QuoteRune returns a single-quoted Go character literal representing the
+// rune.  The returned string uses Go escape sequences (\t, \n, \xFF, \u0100)
+// for control characters and non-printable characters as defined by IsPrint.
+func QuoteRune(r rune) string {
+	// TODO: avoid the allocation here.
+	return quoteWith(string(r), '\'', false)
+}
+
+// AppendQuoteRune appends a single-quoted Go character literal representing the rune,
+// as generated by QuoteRune, to dst and returns the extended buffer.
+func AppendQuoteRune(dst []byte, r rune) []byte {
+	return append(dst, QuoteRune(r)...)
+}
+
+// QuoteRuneToASCII returns a single-quoted Go character literal representing
+// the rune.  The returned string uses Go escape sequences (\t, \n, \xFF,
+// \u0100) for non-ASCII characters and non-printable characters as defined
+// by IsPrint.
+func QuoteRuneToASCII(r rune) string {
+	// TODO: avoid the allocation here.
+	return quoteWith(string(r), '\'', true)
+}
+
+// AppendQuoteRuneToASCII appends a single-quoted Go character literal representing the rune,
+// as generated by QuoteRuneToASCII, to dst and returns the extended buffer.
+func AppendQuoteRuneToASCII(dst []byte, r rune) []byte {
+	return append(dst, QuoteRuneToASCII(r)...)
+}
+
+// CanBackquote reports whether the string s can be represented
+// unchanged as a single-line backquoted string without control
+// characters other than space and tab.
+func CanBackquote(s string) bool {
+	for len(s) > 0 {
+		r, wid := utf8.DecodeRuneInString(s)
+		s = s[wid:]
+		if wid > 1 {
+			if r == '\ufeff' {
+				return false // BOMs are invisible and should not be quoted.
+			}
+			continue // All other multibyte runes are correctly encoded and assumed printable.
+		}
+		if r == utf8.RuneError {
+			return false
+		}
+		if (r < ' ' && r != '\t') || r == '`' || r == '\u007F' {
+			return false
+		}
+	}
+	return true
+}
+
+func unhex(b byte) (v rune, ok bool) {
+	c := rune(b)
+	switch {
+	case '0' <= c && c <= '9':
+		return c - '0', true
+	case 'a' <= c && c <= 'f':
+		return c - 'a' + 10, true
+	case 'A' <= c && c <= 'F':
+		return c - 'A' + 10, true
+	}
+	return
+}
+
+// UnquoteChar decodes the first character or byte in the escaped string
+// or character literal represented by the string s.
+// It returns four values:
+//
+//	1) value, the decoded Unicode code point or byte value;
+//	2) multibyte, a boolean indicating whether the decoded character requires a multibyte UTF-8 representation;
+//	3) tail, the remainder of the string after the character; and
+//	4) an error that will be nil if the character is syntactically valid.
+//
+// The second argument, quote, specifies the type of literal being parsed
+// and therefore which escaped quote character is permitted.
+// If set to a single quote, it permits the sequence \' and disallows unescaped '.
+// If set to a double quote, it permits \" and disallows unescaped ".
+// If set to zero, it does not permit either escape and allows both quote characters to appear unescaped.
+func UnquoteChar(s string, quote byte) (value rune, multibyte bool, tail string, err error) {
+	// easy cases
+	switch c := s[0]; {
+	case c == quote && (quote == '\'' || quote == '"'):
+		err = ErrSyntax
+		return
+	case c >= utf8.RuneSelf:
+		r, size := utf8.DecodeRuneInString(s)
+		return r, true, s[size:], nil
+	case c != '\\':
+		return rune(s[0]), false, s[1:], nil
+	}
+
+	// hard case: c is backslash
+	if len(s) <= 1 {
+		err = ErrSyntax
+		return
+	}
+	c := s[1]
+	s = s[2:]
+
+	switch c {
+	case 'a':
+		value = '\a'
+	case 'b':
+		value = '\b'
+	case 'f':
+		value = '\f'
+	case 'n':
+		value = '\n'
+	case 'r':
+		value = '\r'
+	case 't':
+		value = '\t'
+	case 'v':
+		value = '\v'
+	case 'x', 'u', 'U':
+		n := 0
+		switch c {
+		case 'x':
+			n = 2
+		case 'u':
+			n = 4
+		case 'U':
+			n = 8
+		}
+		var v rune
+		if len(s) < n {
+			err = ErrSyntax
+			return
+		}
+		for j := 0; j < n; j++ {
+			x, ok := unhex(s[j])
+			if !ok {
+				err = ErrSyntax
+				return
+			}
+			v = v<<4 | x
+		}
+		s = s[n:]
+		if c == 'x' {
+			// single-byte string, possibly not UTF-8
+			value = v
+			break
+		}
+		if v > utf8.MaxRune {
+			err = ErrSyntax
+			return
+		}
+		value = v
+		multibyte = true
+	case '0', '1', '2', '3', '4', '5', '6', '7':
+		v := rune(c) - '0'
+		if len(s) < 2 {
+			err = ErrSyntax
+			return
+		}
+		for j := 0; j < 2; j++ { // one digit already; two more
+			x := rune(s[j]) - '0'
+			if x < 0 || x > 7 {
+				err = ErrSyntax
+				return
+			}
+			v = (v << 3) | x
+		}
+		s = s[2:]
+		if v > 255 {
+			err = ErrSyntax
+			return
+		}
+		value = v
+	case '\\':
+		value = '\\'
+	case '\'', '"':
+		if c != quote {
+			err = ErrSyntax
+			return
+		}
+		value = rune(c)
+	default:
+		err = ErrSyntax
+		return
+	}
+	tail = s
+	return
+}
+
+// Unquote interprets s as a single-quoted, double-quoted,
+// or backquoted Go string literal, returning the string value
+// that s quotes.  (If s is single-quoted, it would be a Go
+// character literal; Unquote returns the corresponding
+// one-character string.)
+func Unquote(s string) (t string, err error) {
+	n := len(s)
+	if n < 2 {
+		return "", ErrSyntax
+	}
+	quote := s[0]
+	if quote != s[n-1] {
+		return "", ErrSyntax
+	}
+	s = s[1 : n-1]
+
+	if quote == '`' {
+		if contains(s, '`') {
+			return "", ErrSyntax
+		}
+		return s, nil
+	}
+	if quote != '"' && quote != '\'' {
+		return "", ErrSyntax
+	}
+	if contains(s, '\n') {
+		return "", ErrSyntax
+	}
+
+	// Is it trivial?  Avoid allocation.
+	if !contains(s, '\\') && !contains(s, quote) {
+		switch quote {
+		case '"':
+			return s, nil
+		case '\'':
+			r, size := utf8.DecodeRuneInString(s)
+			if size == len(s) && (r != utf8.RuneError || size != 1) {
+				return s, nil
+			}
+		}
+	}
+
+	var runeTmp [utf8.UTFMax]byte
+	buf := make([]byte, 0, 3*len(s)/2) // Try to avoid more allocations.
+	for len(s) > 0 {
+		c, multibyte, ss, err := UnquoteChar(s, quote)
+		if err != nil {
+			return "", err
+		}
+		s = ss
+		if c < utf8.RuneSelf || !multibyte {
+			buf = append(buf, byte(c))
+		} else {
+			n := utf8.EncodeRune(runeTmp[:], c)
+			buf = append(buf, runeTmp[:n]...)
+		}
+		if quote == '\'' && len(s) != 0 {
+			// single-quoted must be single character
+			return "", ErrSyntax
+		}
+	}
+	return string(buf), nil
+}
+
+// contains reports whether the string contains the byte c.
+func contains(s string, c byte) bool {
+	for i := 0; i < len(s); i++ {
+		if s[i] == c {
+			return true
+		}
+	}
+	return false
+}
+
+// bsearch16 returns the smallest i such that a[i] >= x.
+// If there is no such i, bsearch16 returns len(a).
+func bsearch16(a []uint16, x uint16) int {
+	i, j := 0, len(a)
+	for i < j {
+		h := i + (j-i)/2
+		if a[h] < x {
+			i = h + 1
+		} else {
+			j = h
+		}
+	}
+	return i
+}
+
+// bsearch32 returns the smallest i such that a[i] >= x.
+// If there is no such i, bsearch32 returns len(a).
+func bsearch32(a []uint32, x uint32) int {
+	i, j := 0, len(a)
+	for i < j {
+		h := i + (j-i)/2
+		if a[h] < x {
+			i = h + 1
+		} else {
+			j = h
+		}
+	}
+	return i
+}
+
+// TODO: IsPrint is a local implementation of unicode.IsPrint, verified by the tests
+// to give the same answer. It allows this package not to depend on unicode,
+// and therefore not pull in all the Unicode tables. If the linker were better
+// at tossing unused tables, we could get rid of this implementation.
+// That would be nice.
+
+// IsPrint reports whether the rune is defined as printable by Go, with
+// the same definition as unicode.IsPrint: letters, numbers, punctuation,
+// symbols and ASCII space.
+func IsPrint(r rune) bool {
+	// Fast check for Latin-1
+	if r <= 0xFF {
+		if 0x20 <= r && r <= 0x7E {
+			// All the ASCII is printable from space through DEL-1.
+			return true
+		}
+		if 0xA1 <= r && r <= 0xFF {
+			// Similarly for ¡ through ÿ...
+			return r != 0xAD // ...except for the bizarre soft hyphen.
+		}
+		return false
+	}
+
+	// Same algorithm, either on uint16 or uint32 value.
+	// First, find first i such that isPrint[i] >= x.
+	// This is the index of either the start or end of a pair that might span x.
+	// The start is even (isPrint[i&^1]) and the end is odd (isPrint[i|1]).
+	// If we find x in a range, make sure x is not in isNotPrint list.
+
+	if 0 <= r && r < 1<<16 {
+		rr, isPrint, isNotPrint := uint16(r), isPrint16, isNotPrint16
+		i := bsearch16(isPrint, rr)
+		if i >= len(isPrint) || rr < isPrint[i&^1] || isPrint[i|1] < rr {
+			return false
+		}
+		j := bsearch16(isNotPrint, rr)
+		return j >= len(isNotPrint) || isNotPrint[j] != rr
+	}
+
+	rr, isPrint, isNotPrint := uint32(r), isPrint32, isNotPrint32
+	i := bsearch32(isPrint, rr)
+	if i >= len(isPrint) || rr < isPrint[i&^1] || isPrint[i|1] < rr {
+		return false
+	}
+	if r >= 0x20000 {
+		return true
+	}
+	r -= 0x10000
+	j := bsearch16(isNotPrint, uint16(r))
+	return j >= len(isNotPrint) || isNotPrint[j] != uint16(r)
+}
diff --git a/src/strconv/quote_example_test.go b/src/strconv/quote_example_test.go
new file mode 100644
index 000000000..405a57eb5
--- /dev/null
+++ b/src/strconv/quote_example_test.go
@@ -0,0 +1,35 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package strconv_test
+
+import (
+	"fmt"
+	"strconv"
+)
+
+func ExampleUnquote() {
+	test := func(s string) {
+		t, err := strconv.Unquote(s)
+		if err != nil {
+			fmt.Printf("Unquote(%#v): %v\n", s, err)
+		} else {
+			fmt.Printf("Unquote(%#v) = %v\n", s, t)
+		}
+	}
+
+	s := `cafe\u0301`
+	// If the string doesn't have quotes, it can't be unquoted.
+	test(s) // invalid syntax
+	test("`" + s + "`")
+	test(`"` + s + `"`)
+
+	test(`'\u00e9'`)
+
+	// Output:
+	// Unquote("cafe\\u0301"): invalid syntax
+	// Unquote("`cafe\\u0301`") = cafe\u0301
+	// Unquote("\"cafe\\u0301\"") = café
+	// Unquote("'\\u00e9'") = é
+}
diff --git a/src/strconv/quote_test.go b/src/strconv/quote_test.go
new file mode 100644
index 000000000..3bf162f98
--- /dev/null
+++ b/src/strconv/quote_test.go
@@ -0,0 +1,266 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package strconv_test
+
+import (
+	. "strconv"
+	"testing"
+	"unicode"
+)
+
+// Verify that our isPrint agrees with unicode.IsPrint
+func TestIsPrint(t *testing.T) {
+	n := 0
+	for r := rune(0); r <= unicode.MaxRune; r++ {
+		if IsPrint(r) != unicode.IsPrint(r) {
+			t.Errorf("IsPrint(%U)=%t incorrect", r, IsPrint(r))
+			n++
+			if n > 10 {
+				return
+			}
+		}
+	}
+}
+
+type quoteTest struct {
+	in    string
+	out   string
+	ascii string
+}
+
+var quotetests = []quoteTest{
+	{"\a\b\f\r\n\t\v", `"\a\b\f\r\n\t\v"`, `"\a\b\f\r\n\t\v"`},
+	{"\\", `"\\"`, `"\\"`},
+	{"abc\xffdef", `"abc\xffdef"`, `"abc\xffdef"`},
+	{"\u263a", `"☺"`, `"\u263a"`},
+	{"\U0010ffff", `"\U0010ffff"`, `"\U0010ffff"`},
+	{"\x04", `"\x04"`, `"\x04"`},
+}
+
+func TestQuote(t *testing.T) {
+	for _, tt := range quotetests {
+		if out := Quote(tt.in); out != tt.out {
+			t.Errorf("Quote(%s) = %s, want %s", tt.in, out, tt.out)
+		}
+		if out := AppendQuote([]byte("abc"), tt.in); string(out) != "abc"+tt.out {
+			t.Errorf("AppendQuote(%q, %s) = %s, want %s", "abc", tt.in, out, "abc"+tt.out)
+		}
+	}
+}
+
+func TestQuoteToASCII(t *testing.T) {
+	for _, tt := range quotetests {
+		if out := QuoteToASCII(tt.in); out != tt.ascii {
+			t.Errorf("QuoteToASCII(%s) = %s, want %s", tt.in, out, tt.ascii)
+		}
+		if out := AppendQuoteToASCII([]byte("abc"), tt.in); string(out) != "abc"+tt.ascii {
+			t.Errorf("AppendQuoteToASCII(%q, %s) = %s, want %s", "abc", tt.in, out, "abc"+tt.ascii)
+		}
+	}
+}
+
+type quoteRuneTest struct {
+	in    rune
+	out   string
+	ascii string
+}
+
+var quoterunetests = []quoteRuneTest{
+	{'a', `'a'`, `'a'`},
+	{'\a', `'\a'`, `'\a'`},
+	{'\\', `'\\'`, `'\\'`},
+	{0xFF, `'ÿ'`, `'\u00ff'`},
+	{0x263a, `'☺'`, `'\u263a'`},
+	{0xfffd, `'�'`, `'\ufffd'`},
+	{0x0010ffff, `'\U0010ffff'`, `'\U0010ffff'`},
+	{0x0010ffff + 1, `'�'`, `'\ufffd'`},
+	{0x04, `'\x04'`, `'\x04'`},
+}
+
+func TestQuoteRune(t *testing.T) {
+	for _, tt := range quoterunetests {
+		if out := QuoteRune(tt.in); out != tt.out {
+			t.Errorf("QuoteRune(%U) = %s, want %s", tt.in, out, tt.out)
+		}
+		if out := AppendQuoteRune([]byte("abc"), tt.in); string(out) != "abc"+tt.out {
+			t.Errorf("AppendQuoteRune(%q, %U) = %s, want %s", "abc", tt.in, out, "abc"+tt.out)
+		}
+	}
+}
+
+func TestQuoteRuneToASCII(t *testing.T) {
+	for _, tt := range quoterunetests {
+		if out := QuoteRuneToASCII(tt.in); out != tt.ascii {
+			t.Errorf("QuoteRuneToASCII(%U) = %s, want %s", tt.in, out, tt.ascii)
+		}
+		if out := AppendQuoteRuneToASCII([]byte("abc"), tt.in); string(out) != "abc"+tt.ascii {
+			t.Errorf("AppendQuoteRuneToASCII(%q, %U) = %s, want %s", "abc", tt.in, out, "abc"+tt.ascii)
+		}
+	}
+}
+
+type canBackquoteTest struct {
+	in  string
+	out bool
+}
+
+var canbackquotetests = []canBackquoteTest{
+	{"`", false},
+	{string(0), false},
+	{string(1), false},
+	{string(2), false},
+	{string(3), false},
+	{string(4), false},
+	{string(5), false},
+	{string(6), false},
+	{string(7), false},
+	{string(8), false},
+	{string(9), true}, // \t
+	{string(10), false},
+	{string(11), false},
+	{string(12), false},
+	{string(13), false},
+	{string(14), false},
+	{string(15), false},
+	{string(16), false},
+	{string(17), false},
+	{string(18), false},
+	{string(19), false},
+	{string(20), false},
+	{string(21), false},
+	{string(22), false},
+	{string(23), false},
+	{string(24), false},
+	{string(25), false},
+	{string(26), false},
+	{string(27), false},
+	{string(28), false},
+	{string(29), false},
+	{string(30), false},
+	{string(31), false},
+	{string(0x7F), false},
+	{`' !"#$%&'()*+,-./:;<=>?@[\]^_{|}~`, true},
+	{`0123456789`, true},
+	{`ABCDEFGHIJKLMNOPQRSTUVWXYZ`, true},
+	{`abcdefghijklmnopqrstuvwxyz`, true},
+	{`☺`, true},
+	{"\x80", false},
+	{"a\xe0\xa0z", false},
+	{"\ufeffabc", false},
+	{"a\ufeffz", false},
+}
+
+func TestCanBackquote(t *testing.T) {
+	for _, tt := range canbackquotetests {
+		if out := CanBackquote(tt.in); out != tt.out {
+			t.Errorf("CanBackquote(%q) = %v, want %v", tt.in, out, tt.out)
+		}
+	}
+}
+
+type unQuoteTest struct {
+	in  string
+	out string
+}
+
+var unquotetests = []unQuoteTest{
+	{`""`, ""},
+	{`"a"`, "a"},
+	{`"abc"`, "abc"},
+	{`"☺"`, "☺"},
+	{`"hello world"`, "hello world"},
+	{`"\xFF"`, "\xFF"},
+	{`"\377"`, "\377"},
+	{`"\u1234"`, "\u1234"},
+	{`"\U00010111"`, "\U00010111"},
+	{`"\U0001011111"`, "\U0001011111"},
+	{`"\a\b\f\n\r\t\v\\\""`, "\a\b\f\n\r\t\v\\\""},
+	{`"'"`, "'"},
+
+	{`'a'`, "a"},
+	{`'☹'`, "☹"},
+	{`'\a'`, "\a"},
+	{`'\x10'`, "\x10"},
+	{`'\377'`, "\377"},
+	{`'\u1234'`, "\u1234"},
+	{`'\U00010111'`, "\U00010111"},
+	{`'\t'`, "\t"},
+	{`' '`, " "},
+	{`'\''`, "'"},
+	{`'"'`, "\""},
+
+	{"``", ``},
+	{"`a`", `a`},
+	{"`abc`", `abc`},
+	{"`☺`", `☺`},
+	{"`hello world`", `hello world`},
+	{"`\\xFF`", `\xFF`},
+	{"`\\377`", `\377`},
+	{"`\\`", `\`},
+	{"`\n`", "\n"},
+	{"`	`", `	`},
+	{"` `", ` `},
+}
+
+var misquoted = []string{
+	``,
+	`"`,
+	`"a`,
+	`"'`,
+	`b"`,
+	`"\"`,
+	`"\9"`,
+	`"\19"`,
+	`"\129"`,
+	`'\'`,
+	`'\9'`,
+	`'\19'`,
+	`'\129'`,
+	`'ab'`,
+	`"\x1!"`,
+	`"\U12345678"`,
+	`"\z"`,
+	"`",
+	"`xxx",
+	"`\"",
+	`"\'"`,
+	`'\"'`,
+	"\"\n\"",
+	"\"\\n\n\"",
+	"'\n'",
+}
+
+func TestUnquote(t *testing.T) {
+	for _, tt := range unquotetests {
+		if out, err := Unquote(tt.in); err != nil && out != tt.out {
+			t.Errorf("Unquote(%#q) = %q, %v want %q, nil", tt.in, out, err, tt.out)
+		}
+	}
+
+	// run the quote tests too, backward
+	for _, tt := range quotetests {
+		if in, err := Unquote(tt.out); in != tt.in {
+			t.Errorf("Unquote(%#q) = %q, %v, want %q, nil", tt.out, in, err, tt.in)
+		}
+	}
+
+	for _, s := range misquoted {
+		if out, err := Unquote(s); out != "" || err != ErrSyntax {
+			t.Errorf("Unquote(%#q) = %q, %v want %q, %v", s, out, err, "", ErrSyntax)
+		}
+	}
+}
+
+func BenchmarkUnquoteEasy(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		Unquote(`"Give me a rock, paper and scissors and I will move the world."`)
+	}
+}
+
+func BenchmarkUnquoteHard(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		Unquote(`"\x47ive me a \x72ock, \x70aper and \x73cissors and \x49 will move the world."`)
+	}
+}
diff --git a/src/strconv/strconv_test.go b/src/strconv/strconv_test.go
new file mode 100644
index 000000000..9a007dde4
--- /dev/null
+++ b/src/strconv/strconv_test.go
@@ -0,0 +1,57 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package strconv_test
+
+import (
+	"runtime"
+	. "strconv"
+	"strings"
+	"testing"
+)
+
+var (
+	globalBuf [64]byte
+	nextToOne = "1.00000000000000011102230246251565404236316680908203125" + strings.Repeat("0", 10000) + "1"
+
+	mallocTest = []struct {
+		count int
+		desc  string
+		fn    func()
+	}{
+		{0, `AppendInt(localBuf[:0], 123, 10)`, func() {
+			var localBuf [64]byte
+			AppendInt(localBuf[:0], 123, 10)
+		}},
+		{0, `AppendInt(globalBuf[:0], 123, 10)`, func() { AppendInt(globalBuf[:0], 123, 10) }},
+		{0, `AppendFloat(localBuf[:0], 1.23, 'g', 5, 64)`, func() {
+			var localBuf [64]byte
+			AppendFloat(localBuf[:0], 1.23, 'g', 5, 64)
+		}},
+		{0, `AppendFloat(globalBuf[:0], 1.23, 'g', 5, 64)`, func() { AppendFloat(globalBuf[:0], 1.23, 'g', 5, 64) }},
+		{0, `ParseFloat("123.45", 64)`, func() { ParseFloat("123.45", 64) }},
+		{0, `ParseFloat("123.456789123456789", 64)`, func() { ParseFloat("123.456789123456789", 64) }},
+		{0, `ParseFloat("1.000000000000000111022302462515654042363166809082031251", 64)`, func() {
+			ParseFloat("1.000000000000000111022302462515654042363166809082031251", 64)
+		}},
+		{0, `ParseFloat("1.0000000000000001110223024625156540423631668090820312500...001", 64)`, func() {
+			ParseFloat(nextToOne, 64)
+		}},
+	}
+)
+
+func TestCountMallocs(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skipping malloc count in short mode")
+	}
+	if runtime.GOMAXPROCS(0) > 1 {
+		t.Skip("skipping; GOMAXPROCS>1")
+	}
+	for _, mt := range mallocTest {
+		allocs := testing.AllocsPerRun(100, mt.fn)
+		if max := float64(mt.count); allocs > max {
+			t.Errorf("%s: %v allocs, want <=%v", mt.desc, allocs, max)
+		}
+	}
+}
diff --git a/src/strconv/testdata/testfp.txt b/src/strconv/testdata/testfp.txt
new file mode 100644
index 000000000..08d3c4ef0
--- /dev/null
+++ b/src/strconv/testdata/testfp.txt
@@ -0,0 +1,181 @@
+# Floating-point conversion test cases.
+# Empty lines and lines beginning with # are ignored.
+# The rest have four fields per line: type, format, input, and output.
+# The input is given either in decimal or binary scientific notation.
+# The output is the string that should be produced by formatting the
+# input with the given format.
+#
+# The formats are as in C's printf, except that %b means print
+# binary scientific notation: NpE = N x 2^E.
+
+# TODO:
+#	Powers of 10.
+#	Powers of 2.
+#	%.20g versions.
+#	random sources
+#	random targets
+#	random targets ± half a ULP
+
+# Difficult boundary cases, derived from tables given in
+#	Vern Paxson, A Program for Testing IEEE Decimal-Binary Conversion
+#	ftp://ftp.ee.lbl.gov/testbase-report.ps.Z
+
+# Table 1: Stress Inputs for Conversion to 53-bit Binary, < 1/2 ULP
+float64 %b 5e+125 6653062250012735p+365
+float64 %b 69e+267 4705683757438170p+841
+float64 %b 999e-026 6798841691080350p-129
+float64 %b 7861e-034 8975675289889240p-153
+float64 %b 75569e-254 6091718967192243p-880
+float64 %b 928609e-261 7849264900213743p-900
+float64 %b 9210917e+080 8341110837370930p+236
+float64 %b 84863171e+114 4625202867375927p+353
+float64 %b 653777767e+273 5068902999763073p+884
+float64 %b 5232604057e-298 5741343011915040p-1010
+float64 %b 27235667517e-109 6707124626673586p-380
+float64 %b 653532977297e-123 7078246407265384p-422
+float64 %b 3142213164987e-294 8219991337640559p-988
+float64 %b 46202199371337e-072 5224462102115359p-246
+float64 %b 231010996856685e-073 5224462102115359p-247
+float64 %b 9324754620109615e+212 5539753864394442p+705
+float64 %b 78459735791271921e+049 8388176519442766p+166
+float64 %b 272104041512242479e+200 5554409530847367p+670
+float64 %b 6802601037806061975e+198 5554409530847367p+668
+float64 %b 20505426358836677347e-221 4524032052079546p-722
+float64 %b 836168422905420598437e-234 5070963299887562p-760
+float64 %b 4891559871276714924261e+222 6452687840519111p+757
+
+# Table 2: Stress Inputs for Conversion to 53-bit Binary, > 1/2 ULP
+float64 %b 9e-265 8168427841980010p-930
+float64 %b 85e-037 6360455125664090p-169
+float64 %b 623e+100 6263531988747231p+289
+float64 %b 3571e+263 6234526311072170p+833
+float64 %b 81661e+153 6696636728760206p+472
+float64 %b 920657e-023 5975405561110124p-109
+float64 %b 4603285e-024 5975405561110124p-110
+float64 %b 87575437e-309 8452160731874668p-1053
+float64 %b 245540327e+122 4985336549131723p+381
+float64 %b 6138508175e+120 4985336549131723p+379
+float64 %b 83356057653e+193 5986732817132056p+625
+float64 %b 619534293513e+124 4798406992060657p+399
+float64 %b 2335141086879e+218 5419088166961646p+713
+float64 %b 36167929443327e-159 8135819834632444p-536
+float64 %b 609610927149051e-255 4576664294594737p-850
+float64 %b 3743626360493413e-165 6898586531774201p-549
+float64 %b 94080055902682397e-242 6273271706052298p-800
+float64 %b 899810892172646163e+283 7563892574477827p+947
+float64 %b 7120190517612959703e+120 5385467232557565p+409
+float64 %b 25188282901709339043e-252 5635662608542340p-825
+float64 %b 308984926168550152811e-052 5644774693823803p-157
+float64 %b 6372891218502368041059e+064 4616868614322430p+233
+
+# Table 3: Stress Inputs for Converting 53-bit Binary to Decimal, < 1/2 ULP
+float64 %.0e 8511030020275656p-342 9e-88
+float64 %.1e 5201988407066741p-824 4.6e-233
+float64 %.2e 6406892948269899p+237 1.41e+87
+float64 %.3e 8431154198732492p+72 3.981e+37
+float64 %.4e 6475049196144587p+99 4.1040e+45
+float64 %.5e 8274307542972842p+726 2.92084e+234
+float64 %.6e 5381065484265332p-456 2.891946e-122
+float64 %.7e 6761728585499734p-1057 4.3787718e-303
+float64 %.8e 7976538478610756p+376 1.22770163e+129
+float64 %.9e 5982403858958067p+377 1.841552452e+129
+float64 %.10e 5536995190630837p+93 5.4835744350e+43
+float64 %.11e 7225450889282194p+710 3.89190181146e+229
+float64 %.12e 7225450889282194p+709 1.945950905732e+229
+float64 %.13e 8703372741147379p+117 1.4460958381605e+51
+float64 %.14e 8944262675275217p-1001 4.17367747458531e-286
+float64 %.15e 7459803696087692p-707 1.107950772878888e-197
+float64 %.16e 6080469016670379p-381 1.2345501366327440e-99
+float64 %.17e 8385515147034757p+721 9.25031711960365024e+232
+float64 %.18e 7514216811389786p-828 4.198047150284889840e-234
+float64 %.19e 8397297803260511p-345 1.1716315319786511046e-88
+float64 %.20e 6733459239310543p+202 4.32810072844612493629e+76
+float64 %.21e 8091450587292794p-473 3.317710118160031081518e-127
+
+# Table 4: Stress Inputs for Converting 53-bit Binary to Decimal, > 1/2 ULP
+float64 %.0e 6567258882077402p+952 3e+302
+float64 %.1e 6712731423444934p+535 7.6e+176
+float64 %.2e 6712731423444934p+534 3.78e+176
+float64 %.3e 5298405411573037p-957 4.350e-273
+float64 %.4e 5137311167659507p-144 2.3037e-28
+float64 %.5e 6722280709661868p+363 1.26301e+125
+float64 %.6e 5344436398034927p-169 7.142211e-36
+float64 %.7e 8369123604277281p-853 1.3934574e-241
+float64 %.8e 8995822108487663p-780 1.41463449e-219
+float64 %.9e 8942832835564782p-383 4.539277920e-100
+float64 %.10e 8942832835564782p-384 2.2696389598e-100
+float64 %.11e 8942832835564782p-385 1.13481947988e-100
+float64 %.12e 6965949469487146p-249 7.700366561890e-60
+float64 %.13e 6965949469487146p-250 3.8501832809448e-60
+float64 %.14e 6965949469487146p-251 1.92509164047238e-60
+float64 %.15e 7487252720986826p+548 6.898586531774201e+180
+float64 %.16e 5592117679628511p+164 1.3076622631878654e+65
+float64 %.17e 8887055249355788p+665 1.36052020756121240e+216
+float64 %.18e 6994187472632449p+690 3.592810217475959676e+223
+float64 %.19e 8797576579012143p+588 8.9125197712484551899e+192
+float64 %.20e 7363326733505337p+272 5.58769757362301140950e+97
+float64 %.21e 8549497411294502p-448 1.176257830728540379990e-119
+
+# Table 14: Stress Inputs for Conversion to 24-bit Binary, <1/2 ULP
+# NOTE: The lines with exponent p-149 have been changed from the
+# paper.  Those entries originally read p-150 and had a mantissa
+# twice as large (and even), but IEEE single-precision has no p-150:
+# that's the start of the denormals.
+float32 %b 5e-20 15474250p-88
+float32 %b 67e+14 12479722p+29
+float32 %b 985e+15 14333636p+36
+# float32 %b 7693e-42 10979816p-150
+float32 %b 7693e-42 5489908p-149
+float32 %b 55895e-16 12888509p-61
+# float32 %b 996622e-44 14224264p-150
+float32 %b 996622e-44 7112132p-149
+float32 %b 7038531e-32 11420669p-107
+# float32 %b 60419369e-46 8623340p-150
+float32 %b 60419369e-46 4311670p-149
+float32 %b 702990899e-20 16209866p-61
+# float32 %b 6930161142e-48 9891056p-150
+float32 %b 6930161142e-48 4945528p-149
+float32 %b 25933168707e+13 14395800p+54
+float32 %b 596428896559e+20 12333860p+82
+
+# Table 15: Stress Inputs for Conversion to 24-bit Binary, >1/2 ULP
+float32 %b 3e-23 9507380p-98
+float32 %b 57e+18 12960300p+42
+float32 %b 789e-35 10739312p-130
+float32 %b 2539e-18 11990089p-72
+float32 %b 76173e+28 9845130p+86
+float32 %b 887745e-11 9760860p-40
+float32 %b 5382571e-37 11447463p-124
+float32 %b 82381273e-35 8554961p-113
+float32 %b 750486563e-38 9975678p-120
+float32 %b 3752432815e-39 9975678p-121
+float32 %b 75224575729e-45 13105970p-137
+float32 %b 459926601011e+15 12466336p+65
+
+# Table 16: Stress Inputs for Converting 24-bit Binary to Decimal, < 1/2 ULP
+float32 %.0e 12676506p-102 2e-24
+float32 %.1e 12676506p-103 1.2e-24
+float32 %.2e 15445013p+86 1.19e+33
+float32 %.3e 13734123p-138 3.941e-35
+float32 %.4e 12428269p-130 9.1308e-33
+float32 %.5e 15334037p-146 1.71900e-37
+float32 %.6e 11518287p-41 5.237910e-06
+float32 %.7e 12584953p-145 2.8216440e-37
+float32 %.8e 15961084p-125 3.75243281e-31
+float32 %.9e 14915817p-146 1.672120916e-37
+float32 %.10e 10845484p-102 2.1388945814e-24
+float32 %.11e 16431059p-61 7.12583594561e-12
+
+# Table 17: Stress Inputs for Converting 24-bit Binary to Decimal, > 1/2 ULP
+float32 %.0e 16093626p+69 1e+28
+float32 %.1e 9983778p+25 3.4e+14
+float32 %.2e 12745034p+104 2.59e+38
+float32 %.3e 12706553p+72 6.001e+28
+float32 %.4e 11005028p+45 3.8721e+20
+float32 %.5e 15059547p+71 3.55584e+28
+float32 %.6e 16015691p-99 2.526831e-23
+float32 %.7e 8667859p+56 6.2458507e+23
+float32 %.8e 14855922p-82 3.07213267e-18
+float32 %.9e 14855922p-83 1.536066333e-18
+float32 %.10e 10144164p-110 7.8147796834e-27
+float32 %.11e 13248074p+95 5.24810279937e+35