12345678910111213141516171819202122232425262728293031323334353637383940414243444546 |
- // +build !appengine
- // This file encapsulates usage of unsafe.
- // xxhash_safe.go contains the safe implementations.
- package xxhash
- import (
- "reflect"
- "unsafe"
- )
- // Notes:
- //
- // See https://groups.google.com/d/msg/golang-nuts/dcjzJy-bSpw/tcZYBzQqAQAJ
- // for some discussion about these unsafe conversions.
- //
- // In the future it's possible that compiler optimizations will make these
- // unsafe operations unnecessary: https://golang.org/issue/2205.
- //
- // Both of these wrapper functions still incur function call overhead since they
- // will not be inlined. We could write Go/asm copies of Sum64 and Digest.Write
- // for strings to squeeze out a bit more speed. Mid-stack inlining should
- // eventually fix this.
- // Sum64String computes the 64-bit xxHash digest of s.
- // It may be faster than Sum64([]byte(s)) by avoiding a copy.
- func Sum64String(s string) uint64 {
- var b []byte
- bh := (*reflect.SliceHeader)(unsafe.Pointer(&b))
- bh.Data = (*reflect.StringHeader)(unsafe.Pointer(&s)).Data
- bh.Len = len(s)
- bh.Cap = len(s)
- return Sum64(b)
- }
- // WriteString adds more data to d. It always returns len(s), nil.
- // It may be faster than Write([]byte(s)) by avoiding a copy.
- func (d *Digest) WriteString(s string) (n int, err error) {
- var b []byte
- bh := (*reflect.SliceHeader)(unsafe.Pointer(&b))
- bh.Data = (*reflect.StringHeader)(unsafe.Pointer(&s)).Data
- bh.Len = len(s)
- bh.Cap = len(s)
- return d.Write(b)
- }
|