Golang程序
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340行
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8.37 KB
// Copyright 2014 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"
const (
c0 = uintptr((8-ptrSize)/4*2860486313 + (ptrSize-4)/4*33054211828000289)
c1 = uintptr((8-ptrSize)/4*3267000013 + (ptrSize-4)/4*23344194077549503)
)
// type algorithms - known to compiler
const (
alg_MEM = iota
alg_MEM0
alg_MEM8
alg_MEM16
alg_MEM32
alg_MEM64
alg_MEM128
alg_NOEQ
alg_NOEQ0
alg_NOEQ8
alg_NOEQ16
alg_NOEQ32
alg_NOEQ64
alg_NOEQ128
alg_STRING
alg_INTER
alg_NILINTER
alg_SLICE
alg_FLOAT32
alg_FLOAT64
alg_CPLX64
alg_CPLX128
alg_max
)
// typeAlg is also copied/used in reflect/type.go.
// keep them in sync.
type typeAlg struct {
// function for hashing objects of this type
// (ptr to object, seed) -> hash
hash func(unsafe.Pointer, uintptr) uintptr
// function for comparing objects of this type
// (ptr to object A, ptr to object B) -> ==?
equal func(unsafe.Pointer, unsafe.Pointer) bool
}
func memhash0(p unsafe.Pointer, h uintptr) uintptr {
return h
}
func memhash8(p unsafe.Pointer, h uintptr) uintptr {
return memhash(p, h, 1)
}
func memhash16(p unsafe.Pointer, h uintptr) uintptr {
return memhash(p, h, 2)
}
func memhash32(p unsafe.Pointer, h uintptr) uintptr {
return memhash(p, h, 4)
}
func memhash64(p unsafe.Pointer, h uintptr) uintptr {
return memhash(p, h, 8)
}
func memhash128(p unsafe.Pointer, h uintptr) uintptr {
return memhash(p, h, 16)
}
// memhash_varlen is defined in assembly because it needs access
// to the closure. It appears here to provide an argument
// signature for the assembly routine.
func memhash_varlen(p unsafe.Pointer, h uintptr) uintptr
var algarray = [alg_max]typeAlg{
alg_MEM: {nil, nil}, // not used
alg_MEM0: {memhash0, memequal0},
alg_MEM8: {memhash8, memequal8},
alg_MEM16: {memhash16, memequal16},
alg_MEM32: {memhash32, memequal32},
alg_MEM64: {memhash64, memequal64},
alg_MEM128: {memhash128, memequal128},
alg_NOEQ: {nil, nil},
alg_NOEQ0: {nil, nil},
alg_NOEQ8: {nil, nil},
alg_NOEQ16: {nil, nil},
alg_NOEQ32: {nil, nil},
alg_NOEQ64: {nil, nil},
alg_NOEQ128: {nil, nil},
alg_STRING: {strhash, strequal},
alg_INTER: {interhash, interequal},
alg_NILINTER: {nilinterhash, nilinterequal},
alg_SLICE: {nil, nil},
alg_FLOAT32: {f32hash, f32equal},
alg_FLOAT64: {f64hash, f64equal},
alg_CPLX64: {c64hash, c64equal},
alg_CPLX128: {c128hash, c128equal},
}
var useAeshash bool
// in asm_*.s
func aeshash(p unsafe.Pointer, h, s uintptr) uintptr
func aeshash32(p unsafe.Pointer, h uintptr) uintptr
func aeshash64(p unsafe.Pointer, h uintptr) uintptr
func aeshashstr(p unsafe.Pointer, h uintptr) uintptr
func strhash(a unsafe.Pointer, h uintptr) uintptr {
x := (*stringStruct)(a)
return memhash(x.str, h, uintptr(x.len))
}
// NOTE: Because NaN != NaN, a map can contain any
// number of (mostly useless) entries keyed with NaNs.
// To avoid long hash chains, we assign a random number
// as the hash value for a NaN.
func f32hash(p unsafe.Pointer, h uintptr) uintptr {
f := *(*float32)(p)
switch {
case f == 0:
return c1 * (c0 ^ h) // +0, -0
case f != f:
return c1 * (c0 ^ h ^ uintptr(fastrand1())) // any kind of NaN
default:
return memhash(p, h, 4)
}
}
func f64hash(p unsafe.Pointer, h uintptr) uintptr {
f := *(*float64)(p)
switch {
case f == 0:
return c1 * (c0 ^ h) // +0, -0
case f != f:
return c1 * (c0 ^ h ^ uintptr(fastrand1())) // any kind of NaN
default:
return memhash(p, h, 8)
}
}
func c64hash(p unsafe.Pointer, h uintptr) uintptr {
x := (*[2]float32)(p)
return f32hash(unsafe.Pointer(&x[1]), f32hash(unsafe.Pointer(&x[0]), h))
}
func c128hash(p unsafe.Pointer, h uintptr) uintptr {
x := (*[2]float64)(p)
return f64hash(unsafe.Pointer(&x[1]), f64hash(unsafe.Pointer(&x[0]), h))
}
func interhash(p unsafe.Pointer, h uintptr) uintptr {
a := (*iface)(p)
tab := a.tab
if tab == nil {
return h
}
t := tab._type
fn := t.alg.hash
if fn == nil {
panic(errorString("hash of unhashable type " + *t._string))
}
if isDirectIface(t) {
return c1 * fn(unsafe.Pointer(&a.data), h^c0)
} else {
return c1 * fn(a.data, h^c0)
}
}
func nilinterhash(p unsafe.Pointer, h uintptr) uintptr {
a := (*eface)(p)
t := a._type
if t == nil {
return h
}
fn := t.alg.hash
if fn == nil {
panic(errorString("hash of unhashable type " + *t._string))
}
if isDirectIface(t) {
return c1 * fn(unsafe.Pointer(&a.data), h^c0)
} else {
return c1 * fn(a.data, h^c0)
}
}
func memequal(p, q unsafe.Pointer, size uintptr) bool {
if p == q {
return true
}
return memeq(p, q, size)
}
func memequal0(p, q unsafe.Pointer) bool {
return true
}
func memequal8(p, q unsafe.Pointer) bool {
return *(*int8)(p) == *(*int8)(q)
}
func memequal16(p, q unsafe.Pointer) bool {
return *(*int16)(p) == *(*int16)(q)
}
func memequal32(p, q unsafe.Pointer) bool {
return *(*int32)(p) == *(*int32)(q)
}
func memequal64(p, q unsafe.Pointer) bool {
return *(*int64)(p) == *(*int64)(q)
}
func memequal128(p, q unsafe.Pointer) bool {
return *(*[2]int64)(p) == *(*[2]int64)(q)
}
func f32equal(p, q unsafe.Pointer) bool {
return *(*float32)(p) == *(*float32)(q)
}
func f64equal(p, q unsafe.Pointer) bool {
return *(*float64)(p) == *(*float64)(q)
}
func c64equal(p, q unsafe.Pointer) bool {
return *(*complex64)(p) == *(*complex64)(q)
}
func c128equal(p, q unsafe.Pointer) bool {
return *(*complex128)(p) == *(*complex128)(q)
}
func strequal(p, q unsafe.Pointer) bool {
return *(*string)(p) == *(*string)(q)
}
func interequal(p, q unsafe.Pointer) bool {
return ifaceeq(*(*interface {
f()
})(p), *(*interface {
f()
})(q))
}
func nilinterequal(p, q unsafe.Pointer) bool {
return efaceeq(*(*interface{})(p), *(*interface{})(q))
}
func efaceeq(p, q interface{}) bool {
x := (*eface)(unsafe.Pointer(&p))
y := (*eface)(unsafe.Pointer(&q))
t := x._type
if t != y._type {
return false
}
if t == nil {
return true
}
eq := t.alg.equal
if eq == nil {
panic(errorString("comparing uncomparable type " + *t._string))
}
if isDirectIface(t) {
return eq(noescape(unsafe.Pointer(&x.data)), noescape(unsafe.Pointer(&y.data)))
}
return eq(x.data, y.data)
}
func ifaceeq(p, q interface {
f()
}) bool {
x := (*iface)(unsafe.Pointer(&p))
y := (*iface)(unsafe.Pointer(&q))
xtab := x.tab
if xtab != y.tab {
return false
}
if xtab == nil {
return true
}
t := xtab._type
eq := t.alg.equal
if eq == nil {
panic(errorString("comparing uncomparable type " + *t._string))
}
if isDirectIface(t) {
return eq(noescape(unsafe.Pointer(&x.data)), noescape(unsafe.Pointer(&y.data)))
}
return eq(x.data, y.data)
}
// Testing adapters for hash quality tests (see hash_test.go)
func stringHash(s string, seed uintptr) uintptr {
return algarray[alg_STRING].hash(noescape(unsafe.Pointer(&s)), seed)
}
func bytesHash(b []byte, seed uintptr) uintptr {
s := (*slice)(unsafe.Pointer(&b))
return memhash(s.array, seed, uintptr(s.len))
}
func int32Hash(i uint32, seed uintptr) uintptr {
return algarray[alg_MEM32].hash(noescape(unsafe.Pointer(&i)), seed)
}
func int64Hash(i uint64, seed uintptr) uintptr {
return algarray[alg_MEM64].hash(noescape(unsafe.Pointer(&i)), seed)
}
func efaceHash(i interface{}, seed uintptr) uintptr {
return algarray[alg_NILINTER].hash(noescape(unsafe.Pointer(&i)), seed)
}
func ifaceHash(i interface {
F()
}, seed uintptr) uintptr {
return algarray[alg_INTER].hash(noescape(unsafe.Pointer(&i)), seed)
}
// Testing adapter for memclr
func memclrBytes(b []byte) {
s := (*slice)(unsafe.Pointer(&b))
memclr(s.array, uintptr(s.len))
}
const hashRandomBytes = ptrSize / 4 * 64
// used in asm_{386,amd64}.s to seed the hash function
var aeskeysched [hashRandomBytes]byte
// used in hash{32,64}.go to seed the hash function
var hashkey [4]uintptr
func init() {
// Install aes hash algorithm if we have the instructions we need
if (GOARCH == "386" || GOARCH == "amd64") &&
GOOS != "nacl" &&
cpuid_ecx&(1<<25) != 0 && // aes (aesenc)
cpuid_ecx&(1<<9) != 0 && // sse3 (pshufb)
cpuid_ecx&(1<<19) != 0 { // sse4.1 (pinsr{d,q})
useAeshash = true
algarray[alg_MEM32].hash = aeshash32
algarray[alg_MEM64].hash = aeshash64
algarray[alg_STRING].hash = aeshashstr
// Initialize with random data so hash collisions will be hard to engineer.
getRandomData(aeskeysched[:])
return
}
getRandomData((*[len(hashkey) * ptrSize]byte)(unsafe.Pointer(&hashkey))[:])
hashkey[0] |= 1 // make sure this number is odd
}