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// 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 runtime
import (
"unsafe"
)
type sliceStruct struct {
array unsafe.Pointer
len int
cap int
}
// TODO: take uintptrs instead of int64s?
func makeslice(t *slicetype, len64 int64, cap64 int64) sliceStruct {
// NOTE: The len > MaxMem/elemsize check here is not strictly necessary,
// but it produces a 'len out of range' error instead of a 'cap out of range' error
// when someone does make([]T, bignumber). 'cap out of range' is true too,
// but since the cap is only being supplied implicitly, saying len is clearer.
// See issue 4085.
len := int(len64)
if len64 < 0 || int64(len) != len64 || t.elem.size > 0 && uintptr(len) > maxmem/uintptr(t.elem.size) {
panic(errorString("makeslice: len out of range"))
}
cap := int(cap64)
if cap < len || int64(cap) != cap64 || t.elem.size > 0 && uintptr(cap) > maxmem/uintptr(t.elem.size) {
panic(errorString("makeslice: cap out of range"))
}
p := newarray(t.elem, uintptr(cap))
return sliceStruct{p, len, cap}
}
// TODO: take uintptr instead of int64?
func growslice(t *slicetype, old sliceStruct, n int64) sliceStruct {
if n < 1 {
panic(errorString("growslice: invalid n"))
}
cap64 := int64(old.cap) + n
cap := int(cap64)
if int64(cap) != cap64 || cap < old.cap || t.elem.size > 0 && uintptr(cap) > maxmem/uintptr(t.elem.size) {
panic(errorString("growslice: cap out of range"))
}
if raceenabled {
callerpc := getcallerpc(unsafe.Pointer(&t))
racereadrangepc(old.array, uintptr(old.len*int(t.elem.size)), callerpc, funcPC(growslice))
}
et := t.elem
if et.size == 0 {
return sliceStruct{old.array, old.len, cap}
}
newcap := old.cap
if newcap+newcap < cap {
newcap = cap
} else {
for {
if old.len < 1024 {
newcap += newcap
} else {
newcap += newcap / 4
}
if newcap >= cap {
break
}
}
}
if uintptr(newcap) >= maxmem/uintptr(et.size) {
panic(errorString("growslice: cap out of range"))
}
lenmem := uintptr(old.len) * uintptr(et.size)
capmem := goroundupsize(uintptr(newcap) * uintptr(et.size))
newcap = int(capmem / uintptr(et.size))
var p unsafe.Pointer
if et.kind&kindNoPointers != 0 {
p = rawmem(capmem)
memclr(add(p, lenmem), capmem-lenmem)
} else {
// Note: can't use rawmem (which avoids zeroing of memory), because then GC can scan unitialized memory
p = newarray(et, uintptr(newcap))
}
memmove(p, old.array, lenmem)
return sliceStruct{p, old.len, newcap}
}
func slicecopy(to sliceStruct, fm sliceStruct, width uintptr) int {
if fm.len == 0 || to.len == 0 || width == 0 {
return 0
}
n := fm.len
if to.len < n {
n = to.len
}
if raceenabled {
callerpc := getcallerpc(unsafe.Pointer(&to))
pc := funcPC(slicecopy)
racewriterangepc(to.array, uintptr(n*int(width)), callerpc, pc)
racereadrangepc(fm.array, uintptr(n*int(width)), callerpc, pc)
}
size := uintptr(n) * width
if size == 1 { // common case worth about 2x to do here
// TODO: is this still worth it with new memmove impl?
*(*byte)(to.array) = *(*byte)(fm.array) // known to be a byte pointer
} else {
memmove(to.array, fm.array, size)
}
return int(n)
}
func slicestringcopy(to []byte, fm string) int {
if len(fm) == 0 || len(to) == 0 {
return 0
}
n := len(fm)
if len(to) < n {
n = len(to)
}
if raceenabled {
callerpc := getcallerpc(unsafe.Pointer(&to))
pc := funcPC(slicestringcopy)
racewriterangepc(unsafe.Pointer(&to[0]), uintptr(n), callerpc, pc)
}
memmove(unsafe.Pointer(&to[0]), unsafe.Pointer((*stringStruct)(unsafe.Pointer(&fm)).str), uintptr(n))
return n
}
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