30 lines
906 B
Go
30 lines
906 B
Go
// +build !appengine
|
|
|
|
// This file encapsulates usage of unsafe.
|
|
// xxhash_safe.go contains the safe implementations.
|
|
|
|
package xxhash
|
|
|
|
import (
|
|
"reflect"
|
|
"unsafe"
|
|
)
|
|
|
|
// Sum64String computes the 64-bit xxHash digest of s.
|
|
// It may be faster than Sum64([]byte(s)) by avoiding a copy.
|
|
//
|
|
// TODO(caleb): Consider removing this if an optimization is ever added to make
|
|
// it unnecessary: https://golang.org/issue/2205.
|
|
//
|
|
// TODO(caleb): We still have a function call; we could instead write Go/asm
|
|
// copies of Sum64 for strings to squeeze out a bit more speed.
|
|
func Sum64String(s string) uint64 {
|
|
// See https://groups.google.com/d/msg/golang-nuts/dcjzJy-bSpw/tcZYBzQqAQAJ
|
|
// for some discussion about this unsafe conversion.
|
|
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)
|
|
}
|