diff options
| author | Bruno Haible <bruno@clisp.org> | 2008-04-19 17:26:36 +0200 |
|---|---|---|
| committer | Bruno Haible <bruno@clisp.org> | 2008-04-19 17:26:36 +0200 |
| commit | f797ae74856a21b4471baec28dbbfd82b48fe2dc (patch) | |
| tree | fc1a1a25bd9a89d66437e96c4259e249b3599557 /lib | |
| parent | 2e8956774250d3f5636898fea193c5abaf041d08 (diff) | |
| download | gnulib-f797ae74856a21b4471baec28dbbfd82b48fe2dc.tar.gz | |
Fix rounding when a precision is given.
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/vasnprintf.c | 112 |
1 files changed, 110 insertions, 2 deletions
diff --git a/lib/vasnprintf.c b/lib/vasnprintf.c index 74b30374cb..2ee0c05ce6 100644 --- a/lib/vasnprintf.c +++ b/lib/vasnprintf.c @@ -1404,6 +1404,20 @@ floorlog10 (double x) # endif +/* Tests whether a string of digits consists of exactly PRECISION zeroes and + a single '1' digit. */ +static int +is_borderline (const char *digits, size_t precision) +{ + for (; precision > 0; precision--, digits++) + if (*digits != '0') + return 0; + if (*digits != '1') + return 0; + digits++; + return *digits == '\0'; +} + #endif DCHAR_T * @@ -2853,8 +2867,32 @@ VASNPRINTF (DCHAR_T *resultbuf, size_t *lengthp, exponent += 1; adjusted = 1; } - /* Here ndigits = precision+1. */ + if (is_borderline (digits, precision)) + { + /* Maybe the exponent guess was too high + and a smaller exponent can be reached + by turning a 10...0 into 9...9x. */ + char *digits2 = + scale10_round_decimal_long_double (arg, + (int)precision - exponent + 1); + if (digits2 == NULL) + { + free (digits); + END_LONG_DOUBLE_ROUNDING (); + goto out_of_memory; + } + if (strlen (digits2) == precision + 1) + { + free (digits); + digits = digits2; + exponent -= 1; + } + else + free (digits2); + } + /* Here ndigits = precision+1. */ + *p++ = digits[--ndigits]; if ((flags & FLAG_ALT) || precision > 0) { @@ -2966,6 +3004,30 @@ VASNPRINTF (DCHAR_T *resultbuf, size_t *lengthp, adjusted = 1; } /* Here ndigits = precision. */ + if (is_borderline (digits, precision - 1)) + { + /* Maybe the exponent guess was too high + and a smaller exponent can be reached + by turning a 10...0 into 9...9x. */ + char *digits2 = + scale10_round_decimal_long_double (arg, + (int)(precision - 1) - exponent + 1); + if (digits2 == NULL) + { + free (digits); + END_LONG_DOUBLE_ROUNDING (); + goto out_of_memory; + } + if (strlen (digits2) == precision) + { + free (digits); + digits = digits2; + exponent -= 1; + } + else + free (digits2); + } + /* Here ndigits = precision. */ /* Determine the number of trailing zeroes that have to be dropped. */ @@ -3206,8 +3268,31 @@ VASNPRINTF (DCHAR_T *resultbuf, size_t *lengthp, exponent += 1; adjusted = 1; } - /* Here ndigits = precision+1. */ + if (is_borderline (digits, precision)) + { + /* Maybe the exponent guess was too high + and a smaller exponent can be reached + by turning a 10...0 into 9...9x. */ + char *digits2 = + scale10_round_decimal_double (arg, + (int)precision - exponent + 1); + if (digits2 == NULL) + { + free (digits); + goto out_of_memory; + } + if (strlen (digits2) == precision + 1) + { + free (digits); + digits = digits2; + exponent -= 1; + } + else + free (digits2); + } + /* Here ndigits = precision+1. */ + *p++ = digits[--ndigits]; if ((flags & FLAG_ALT) || precision > 0) { @@ -3332,6 +3417,29 @@ VASNPRINTF (DCHAR_T *resultbuf, size_t *lengthp, adjusted = 1; } /* Here ndigits = precision. */ + if (is_borderline (digits, precision - 1)) + { + /* Maybe the exponent guess was too high + and a smaller exponent can be reached + by turning a 10...0 into 9...9x. */ + char *digits2 = + scale10_round_decimal_double (arg, + (int)(precision - 1) - exponent + 1); + if (digits2 == NULL) + { + free (digits); + goto out_of_memory; + } + if (strlen (digits2) == precision) + { + free (digits); + digits = digits2; + exponent -= 1; + } + else + free (digits2); + } + /* Here ndigits = precision. */ /* Determine the number of trailing zeroes that have to be dropped. */ |