mirror of https://go.googlesource.com/go
424 lines
11 KiB
Go
424 lines
11 KiB
Go
// Copyright 2014 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package runtime
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import (
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"internal/abi"
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"internal/cpu"
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"internal/goarch"
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"unsafe"
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)
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const (
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c0 = uintptr((8-goarch.PtrSize)/4*2860486313 + (goarch.PtrSize-4)/4*33054211828000289)
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c1 = uintptr((8-goarch.PtrSize)/4*3267000013 + (goarch.PtrSize-4)/4*23344194077549503)
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)
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func memhash0(p unsafe.Pointer, h uintptr) uintptr {
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return h
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}
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func memhash8(p unsafe.Pointer, h uintptr) uintptr {
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return memhash(p, h, 1)
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}
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func memhash16(p unsafe.Pointer, h uintptr) uintptr {
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return memhash(p, h, 2)
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}
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func memhash128(p unsafe.Pointer, h uintptr) uintptr {
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return memhash(p, h, 16)
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}
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//go:nosplit
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func memhash_varlen(p unsafe.Pointer, h uintptr) uintptr {
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ptr := getclosureptr()
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size := *(*uintptr)(unsafe.Pointer(ptr + unsafe.Sizeof(h)))
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return memhash(p, h, size)
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}
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// runtime variable to check if the processor we're running on
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// actually supports the instructions used by the AES-based
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// hash implementation.
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var useAeshash bool
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// in asm_*.s
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func memhash(p unsafe.Pointer, h, s uintptr) uintptr
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func memhash32(p unsafe.Pointer, h uintptr) uintptr
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func memhash64(p unsafe.Pointer, h uintptr) uintptr
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func strhash(p unsafe.Pointer, h uintptr) uintptr
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func strhashFallback(a unsafe.Pointer, h uintptr) uintptr {
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x := (*stringStruct)(a)
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return memhashFallback(x.str, h, uintptr(x.len))
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}
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// NOTE: Because NaN != NaN, a map can contain any
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// number of (mostly useless) entries keyed with NaNs.
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// To avoid long hash chains, we assign a random number
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// as the hash value for a NaN.
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func f32hash(p unsafe.Pointer, h uintptr) uintptr {
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f := *(*float32)(p)
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switch {
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case f == 0:
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return c1 * (c0 ^ h) // +0, -0
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case f != f:
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return c1 * (c0 ^ h ^ uintptr(rand())) // any kind of NaN
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default:
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return memhash(p, h, 4)
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}
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}
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func f64hash(p unsafe.Pointer, h uintptr) uintptr {
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f := *(*float64)(p)
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switch {
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case f == 0:
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return c1 * (c0 ^ h) // +0, -0
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case f != f:
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return c1 * (c0 ^ h ^ uintptr(rand())) // any kind of NaN
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default:
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return memhash(p, h, 8)
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}
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}
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func c64hash(p unsafe.Pointer, h uintptr) uintptr {
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x := (*[2]float32)(p)
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return f32hash(unsafe.Pointer(&x[1]), f32hash(unsafe.Pointer(&x[0]), h))
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}
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func c128hash(p unsafe.Pointer, h uintptr) uintptr {
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x := (*[2]float64)(p)
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return f64hash(unsafe.Pointer(&x[1]), f64hash(unsafe.Pointer(&x[0]), h))
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}
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func interhash(p unsafe.Pointer, h uintptr) uintptr {
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a := (*iface)(p)
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tab := a.tab
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if tab == nil {
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return h
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}
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t := tab.Type
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if t.Equal == nil {
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// Check hashability here. We could do this check inside
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// typehash, but we want to report the topmost type in
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// the error text (e.g. in a struct with a field of slice type
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// we want to report the struct, not the slice).
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panic(errorString("hash of unhashable type " + toRType(t).string()))
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}
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if isDirectIface(t) {
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return c1 * typehash(t, unsafe.Pointer(&a.data), h^c0)
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} else {
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return c1 * typehash(t, a.data, h^c0)
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}
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}
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func nilinterhash(p unsafe.Pointer, h uintptr) uintptr {
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a := (*eface)(p)
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t := a._type
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if t == nil {
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return h
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}
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if t.Equal == nil {
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// See comment in interhash above.
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panic(errorString("hash of unhashable type " + toRType(t).string()))
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}
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if isDirectIface(t) {
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return c1 * typehash(t, unsafe.Pointer(&a.data), h^c0)
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} else {
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return c1 * typehash(t, a.data, h^c0)
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}
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}
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// typehash computes the hash of the object of type t at address p.
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// h is the seed.
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// This function is seldom used. Most maps use for hashing either
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// fixed functions (e.g. f32hash) or compiler-generated functions
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// (e.g. for a type like struct { x, y string }). This implementation
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// is slower but more general and is used for hashing interface types
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// (called from interhash or nilinterhash, above) or for hashing in
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// maps generated by reflect.MapOf (reflect_typehash, below).
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// Note: this function must match the compiler generated
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// functions exactly. See issue 37716.
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func typehash(t *_type, p unsafe.Pointer, h uintptr) uintptr {
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if t.TFlag&abi.TFlagRegularMemory != 0 {
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// Handle ptr sizes specially, see issue 37086.
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switch t.Size_ {
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case 4:
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return memhash32(p, h)
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case 8:
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return memhash64(p, h)
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default:
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return memhash(p, h, t.Size_)
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}
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}
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switch t.Kind_ & abi.KindMask {
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case abi.Float32:
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return f32hash(p, h)
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case abi.Float64:
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return f64hash(p, h)
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case abi.Complex64:
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return c64hash(p, h)
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case abi.Complex128:
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return c128hash(p, h)
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case abi.String:
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return strhash(p, h)
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case abi.Interface:
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i := (*interfacetype)(unsafe.Pointer(t))
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if len(i.Methods) == 0 {
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return nilinterhash(p, h)
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}
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return interhash(p, h)
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case abi.Array:
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a := (*arraytype)(unsafe.Pointer(t))
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for i := uintptr(0); i < a.Len; i++ {
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h = typehash(a.Elem, add(p, i*a.Elem.Size_), h)
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}
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return h
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case abi.Struct:
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s := (*structtype)(unsafe.Pointer(t))
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for _, f := range s.Fields {
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if f.Name.IsBlank() {
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continue
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}
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h = typehash(f.Typ, add(p, f.Offset), h)
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}
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return h
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default:
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// Should never happen, as typehash should only be called
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// with comparable types.
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panic(errorString("hash of unhashable type " + toRType(t).string()))
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}
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}
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func mapKeyError(t *maptype, p unsafe.Pointer) error {
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if !t.HashMightPanic() {
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return nil
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}
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return mapKeyError2(t.Key, p)
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}
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func mapKeyError2(t *_type, p unsafe.Pointer) error {
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if t.TFlag&abi.TFlagRegularMemory != 0 {
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return nil
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}
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switch t.Kind_ & abi.KindMask {
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case abi.Float32, abi.Float64, abi.Complex64, abi.Complex128, abi.String:
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return nil
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case abi.Interface:
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i := (*interfacetype)(unsafe.Pointer(t))
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var t *_type
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var pdata *unsafe.Pointer
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if len(i.Methods) == 0 {
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a := (*eface)(p)
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t = a._type
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if t == nil {
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return nil
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}
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pdata = &a.data
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} else {
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a := (*iface)(p)
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if a.tab == nil {
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return nil
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}
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t = a.tab.Type
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pdata = &a.data
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}
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if t.Equal == nil {
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return errorString("hash of unhashable type " + toRType(t).string())
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}
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if isDirectIface(t) {
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return mapKeyError2(t, unsafe.Pointer(pdata))
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} else {
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return mapKeyError2(t, *pdata)
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}
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case abi.Array:
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a := (*arraytype)(unsafe.Pointer(t))
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for i := uintptr(0); i < a.Len; i++ {
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if err := mapKeyError2(a.Elem, add(p, i*a.Elem.Size_)); err != nil {
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return err
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}
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}
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return nil
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case abi.Struct:
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s := (*structtype)(unsafe.Pointer(t))
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for _, f := range s.Fields {
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if f.Name.IsBlank() {
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continue
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}
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if err := mapKeyError2(f.Typ, add(p, f.Offset)); err != nil {
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return err
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}
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}
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return nil
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default:
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// Should never happen, keep this case for robustness.
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return errorString("hash of unhashable type " + toRType(t).string())
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}
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}
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//go:linkname reflect_typehash reflect.typehash
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func reflect_typehash(t *_type, p unsafe.Pointer, h uintptr) uintptr {
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return typehash(t, p, h)
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}
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func memequal0(p, q unsafe.Pointer) bool {
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return true
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}
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func memequal8(p, q unsafe.Pointer) bool {
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return *(*int8)(p) == *(*int8)(q)
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}
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func memequal16(p, q unsafe.Pointer) bool {
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return *(*int16)(p) == *(*int16)(q)
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}
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func memequal32(p, q unsafe.Pointer) bool {
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return *(*int32)(p) == *(*int32)(q)
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}
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func memequal64(p, q unsafe.Pointer) bool {
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return *(*int64)(p) == *(*int64)(q)
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}
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func memequal128(p, q unsafe.Pointer) bool {
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return *(*[2]int64)(p) == *(*[2]int64)(q)
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}
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func f32equal(p, q unsafe.Pointer) bool {
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return *(*float32)(p) == *(*float32)(q)
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}
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func f64equal(p, q unsafe.Pointer) bool {
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return *(*float64)(p) == *(*float64)(q)
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}
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func c64equal(p, q unsafe.Pointer) bool {
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return *(*complex64)(p) == *(*complex64)(q)
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}
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func c128equal(p, q unsafe.Pointer) bool {
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return *(*complex128)(p) == *(*complex128)(q)
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}
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func strequal(p, q unsafe.Pointer) bool {
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return *(*string)(p) == *(*string)(q)
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}
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func interequal(p, q unsafe.Pointer) bool {
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x := *(*iface)(p)
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y := *(*iface)(q)
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return x.tab == y.tab && ifaceeq(x.tab, x.data, y.data)
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}
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func nilinterequal(p, q unsafe.Pointer) bool {
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x := *(*eface)(p)
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y := *(*eface)(q)
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return x._type == y._type && efaceeq(x._type, x.data, y.data)
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}
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func efaceeq(t *_type, x, y unsafe.Pointer) bool {
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if t == nil {
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return true
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}
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eq := t.Equal
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if eq == nil {
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panic(errorString("comparing uncomparable type " + toRType(t).string()))
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}
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if isDirectIface(t) {
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// Direct interface types are ptr, chan, map, func, and single-element structs/arrays thereof.
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// Maps and funcs are not comparable, so they can't reach here.
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// Ptrs, chans, and single-element items can be compared directly using ==.
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return x == y
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}
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return eq(x, y)
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}
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func ifaceeq(tab *itab, x, y unsafe.Pointer) bool {
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if tab == nil {
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return true
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}
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t := tab.Type
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eq := t.Equal
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if eq == nil {
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panic(errorString("comparing uncomparable type " + toRType(t).string()))
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}
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if isDirectIface(t) {
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// See comment in efaceeq.
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return x == y
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}
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return eq(x, y)
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}
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// Testing adapters for hash quality tests (see hash_test.go)
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func stringHash(s string, seed uintptr) uintptr {
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return strhash(noescape(unsafe.Pointer(&s)), seed)
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}
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func bytesHash(b []byte, seed uintptr) uintptr {
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s := (*slice)(unsafe.Pointer(&b))
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return memhash(s.array, seed, uintptr(s.len))
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}
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func int32Hash(i uint32, seed uintptr) uintptr {
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return memhash32(noescape(unsafe.Pointer(&i)), seed)
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}
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func int64Hash(i uint64, seed uintptr) uintptr {
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return memhash64(noescape(unsafe.Pointer(&i)), seed)
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}
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func efaceHash(i any, seed uintptr) uintptr {
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return nilinterhash(noescape(unsafe.Pointer(&i)), seed)
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}
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func ifaceHash(i interface {
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F()
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}, seed uintptr) uintptr {
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return interhash(noescape(unsafe.Pointer(&i)), seed)
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}
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const hashRandomBytes = goarch.PtrSize / 4 * 64
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// used in asm_{386,amd64,arm64}.s to seed the hash function
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var aeskeysched [hashRandomBytes]byte
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// used in hash{32,64}.go to seed the hash function
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var hashkey [4]uintptr
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func alginit() {
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// Install AES hash algorithms if the instructions needed are present.
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if (GOARCH == "386" || GOARCH == "amd64") &&
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cpu.X86.HasAES && // AESENC
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cpu.X86.HasSSSE3 && // PSHUFB
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cpu.X86.HasSSE41 { // PINSR{D,Q}
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initAlgAES()
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return
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}
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if GOARCH == "arm64" && cpu.ARM64.HasAES {
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initAlgAES()
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return
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}
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for i := range hashkey {
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hashkey[i] = uintptr(bootstrapRand())
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}
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}
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func initAlgAES() {
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useAeshash = true
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// Initialize with random data so hash collisions will be hard to engineer.
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key := (*[hashRandomBytes / 8]uint64)(unsafe.Pointer(&aeskeysched))
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for i := range key {
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key[i] = bootstrapRand()
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}
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}
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// Note: These routines perform the read with a native endianness.
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func readUnaligned32(p unsafe.Pointer) uint32 {
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q := (*[4]byte)(p)
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if goarch.BigEndian {
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return uint32(q[3]) | uint32(q[2])<<8 | uint32(q[1])<<16 | uint32(q[0])<<24
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}
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return uint32(q[0]) | uint32(q[1])<<8 | uint32(q[2])<<16 | uint32(q[3])<<24
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}
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func readUnaligned64(p unsafe.Pointer) uint64 {
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q := (*[8]byte)(p)
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if goarch.BigEndian {
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return uint64(q[7]) | uint64(q[6])<<8 | uint64(q[5])<<16 | uint64(q[4])<<24 |
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uint64(q[3])<<32 | uint64(q[2])<<40 | uint64(q[1])<<48 | uint64(q[0])<<56
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}
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return uint64(q[0]) | uint64(q[1])<<8 | uint64(q[2])<<16 | uint64(q[3])<<24 | uint64(q[4])<<32 | uint64(q[5])<<40 | uint64(q[6])<<48 | uint64(q[7])<<56
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}
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