1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
|
// Copyright 2023 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.
//go:build !purego
package maphash
import (
"unsafe"
)
//go:linkname runtime_fastrand64 runtime.fastrand64
func runtime_fastrand64() uint64
//go:linkname runtime_memhash runtime.memhash
//go:noescape
func runtime_memhash(p unsafe.Pointer, seed, s uintptr) uintptr
func rthash(buf []byte, seed uint64) uint64 {
if len(buf) == 0 {
return seed
}
len := len(buf)
// The runtime hasher only works on uintptr. For 64-bit
// architectures, we use the hasher directly. Otherwise,
// we use two parallel hashers on the lower and upper 32 bits.
if unsafe.Sizeof(uintptr(0)) == 8 {
return uint64(runtime_memhash(unsafe.Pointer(&buf[0]), uintptr(seed), uintptr(len)))
}
lo := runtime_memhash(unsafe.Pointer(&buf[0]), uintptr(seed), uintptr(len))
hi := runtime_memhash(unsafe.Pointer(&buf[0]), uintptr(seed>>32), uintptr(len))
return uint64(hi)<<32 | uint64(lo)
}
func rthashString(s string, state uint64) uint64 {
buf := unsafe.Slice(unsafe.StringData(s), len(s))
return rthash(buf, state)
}
func randUint64() uint64 {
return runtime_fastrand64()
}
|
