1// +build !appengine
2
3// This file encapsulates usage of unsafe.
4// xxhash_safe.go contains the safe implementations.
5
6package xxhash
7
8import (
9	"reflect"
10	"unsafe"
11)
12
13// Sum64String computes the 64-bit xxHash digest of s.
14// It may be faster than Sum64([]byte(s)) by avoiding a copy.
15//
16// TODO(caleb): Consider removing this if an optimization is ever added to make
17// it unnecessary: https://golang.org/issue/2205.
18//
19// TODO(caleb): We still have a function call; we could instead write Go/asm
20// copies of Sum64 for strings to squeeze out a bit more speed.
21func Sum64String(s string) uint64 {
22	// See https://groups.google.com/d/msg/golang-nuts/dcjzJy-bSpw/tcZYBzQqAQAJ
23	// for some discussion about this unsafe conversion.
24	var b []byte
25	bh := (*reflect.SliceHeader)(unsafe.Pointer(&b))
26	bh.Data = (*reflect.StringHeader)(unsafe.Pointer(&s)).Data
27	bh.Len = len(s)
28	bh.Cap = len(s)
29	return Sum64(b)
30}
31