mirror of https://github.com/octoleo/restic.git
410 lines
7.4 KiB
Go
410 lines
7.4 KiB
Go
/*
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* Minio Cloud Storage, (C) 2016 Minio, Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package sha256
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import (
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"crypto/sha256"
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"encoding/binary"
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"hash"
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"runtime"
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)
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// Size - The size of a SHA256 checksum in bytes.
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const Size = 32
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// BlockSize - The blocksize of SHA256 in bytes.
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const BlockSize = 64
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const (
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chunk = BlockSize
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init0 = 0x6A09E667
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init1 = 0xBB67AE85
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init2 = 0x3C6EF372
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init3 = 0xA54FF53A
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init4 = 0x510E527F
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init5 = 0x9B05688C
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init6 = 0x1F83D9AB
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init7 = 0x5BE0CD19
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)
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// digest represents the partial evaluation of a checksum.
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type digest struct {
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h [8]uint32
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x [chunk]byte
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nx int
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len uint64
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}
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// Reset digest back to default
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func (d *digest) Reset() {
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d.h[0] = init0
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d.h[1] = init1
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d.h[2] = init2
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d.h[3] = init3
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d.h[4] = init4
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d.h[5] = init5
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d.h[6] = init6
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d.h[7] = init7
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d.nx = 0
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d.len = 0
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}
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type blockfuncType int
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const (
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blockfuncGeneric blockfuncType = iota
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blockfuncAvx512 blockfuncType = iota
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blockfuncAvx2 blockfuncType = iota
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blockfuncAvx blockfuncType = iota
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blockfuncSsse blockfuncType = iota
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blockfuncSha blockfuncType = iota
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blockfuncArm blockfuncType = iota
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)
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var blockfunc blockfuncType
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func init() {
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is386bit := runtime.GOARCH == "386"
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isARM := runtime.GOARCH == "arm"
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switch {
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case is386bit || isARM:
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blockfunc = blockfuncGeneric
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case sha && ssse3 && sse41:
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blockfunc = blockfuncSha
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case avx2:
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blockfunc = blockfuncAvx2
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case avx:
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blockfunc = blockfuncAvx
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case ssse3:
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blockfunc = blockfuncSsse
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case armSha:
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blockfunc = blockfuncArm
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default:
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blockfunc = blockfuncGeneric
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}
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}
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// New returns a new hash.Hash computing the SHA256 checksum.
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func New() hash.Hash {
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if blockfunc != blockfuncGeneric {
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d := new(digest)
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d.Reset()
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return d
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}
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// Fallback to the standard golang implementation
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// if no features were found.
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return sha256.New()
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}
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// Sum256 - single caller sha256 helper
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func Sum256(data []byte) (result [Size]byte) {
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var d digest
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d.Reset()
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d.Write(data)
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result = d.checkSum()
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return
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}
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// Return size of checksum
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func (d *digest) Size() int { return Size }
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// Return blocksize of checksum
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func (d *digest) BlockSize() int { return BlockSize }
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// Write to digest
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func (d *digest) Write(p []byte) (nn int, err error) {
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nn = len(p)
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d.len += uint64(nn)
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if d.nx > 0 {
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n := copy(d.x[d.nx:], p)
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d.nx += n
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if d.nx == chunk {
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block(d, d.x[:])
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d.nx = 0
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}
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p = p[n:]
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}
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if len(p) >= chunk {
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n := len(p) &^ (chunk - 1)
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block(d, p[:n])
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p = p[n:]
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}
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if len(p) > 0 {
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d.nx = copy(d.x[:], p)
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}
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return
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}
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// Return sha256 sum in bytes
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func (d *digest) Sum(in []byte) []byte {
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// Make a copy of d0 so that caller can keep writing and summing.
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d0 := *d
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hash := d0.checkSum()
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return append(in, hash[:]...)
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}
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// Intermediate checksum function
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func (d *digest) checkSum() (digest [Size]byte) {
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n := d.nx
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var k [64]byte
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copy(k[:], d.x[:n])
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k[n] = 0x80
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if n >= 56 {
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block(d, k[:])
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// clear block buffer - go compiles this to optimal 1x xorps + 4x movups
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// unfortunately expressing this more succinctly results in much worse code
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k[0] = 0
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k[1] = 0
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k[2] = 0
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k[3] = 0
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k[4] = 0
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k[5] = 0
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k[6] = 0
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k[7] = 0
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k[8] = 0
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k[9] = 0
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k[10] = 0
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k[11] = 0
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k[12] = 0
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k[13] = 0
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k[14] = 0
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k[15] = 0
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k[16] = 0
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k[17] = 0
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k[18] = 0
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k[19] = 0
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k[20] = 0
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k[21] = 0
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k[22] = 0
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k[23] = 0
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k[24] = 0
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k[25] = 0
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k[26] = 0
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k[27] = 0
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k[28] = 0
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k[29] = 0
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k[30] = 0
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k[31] = 0
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k[32] = 0
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k[33] = 0
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k[34] = 0
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k[35] = 0
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k[36] = 0
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k[37] = 0
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k[38] = 0
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k[39] = 0
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k[40] = 0
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k[41] = 0
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k[42] = 0
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k[43] = 0
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k[44] = 0
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k[45] = 0
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k[46] = 0
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k[47] = 0
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k[48] = 0
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k[49] = 0
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k[50] = 0
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k[51] = 0
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k[52] = 0
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k[53] = 0
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k[54] = 0
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k[55] = 0
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k[56] = 0
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k[57] = 0
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k[58] = 0
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k[59] = 0
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k[60] = 0
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k[61] = 0
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k[62] = 0
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k[63] = 0
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}
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binary.BigEndian.PutUint64(k[56:64], uint64(d.len)<<3)
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block(d, k[:])
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{
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const i = 0
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binary.BigEndian.PutUint32(digest[i*4:i*4+4], d.h[i])
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}
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{
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const i = 1
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binary.BigEndian.PutUint32(digest[i*4:i*4+4], d.h[i])
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}
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{
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const i = 2
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binary.BigEndian.PutUint32(digest[i*4:i*4+4], d.h[i])
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}
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{
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const i = 3
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binary.BigEndian.PutUint32(digest[i*4:i*4+4], d.h[i])
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}
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{
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const i = 4
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binary.BigEndian.PutUint32(digest[i*4:i*4+4], d.h[i])
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}
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{
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const i = 5
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binary.BigEndian.PutUint32(digest[i*4:i*4+4], d.h[i])
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}
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{
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const i = 6
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binary.BigEndian.PutUint32(digest[i*4:i*4+4], d.h[i])
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}
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{
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const i = 7
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binary.BigEndian.PutUint32(digest[i*4:i*4+4], d.h[i])
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}
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return
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}
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func block(dig *digest, p []byte) {
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if blockfunc == blockfuncSha {
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blockShaGo(dig, p)
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} else if blockfunc == blockfuncAvx2 {
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blockAvx2Go(dig, p)
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} else if blockfunc == blockfuncAvx {
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blockAvxGo(dig, p)
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} else if blockfunc == blockfuncSsse {
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blockSsseGo(dig, p)
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} else if blockfunc == blockfuncArm {
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blockArmGo(dig, p)
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} else if blockfunc == blockfuncGeneric {
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blockGeneric(dig, p)
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}
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}
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func blockGeneric(dig *digest, p []byte) {
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var w [64]uint32
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h0, h1, h2, h3, h4, h5, h6, h7 := dig.h[0], dig.h[1], dig.h[2], dig.h[3], dig.h[4], dig.h[5], dig.h[6], dig.h[7]
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for len(p) >= chunk {
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// Can interlace the computation of w with the
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// rounds below if needed for speed.
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for i := 0; i < 16; i++ {
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j := i * 4
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w[i] = uint32(p[j])<<24 | uint32(p[j+1])<<16 | uint32(p[j+2])<<8 | uint32(p[j+3])
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}
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for i := 16; i < 64; i++ {
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v1 := w[i-2]
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t1 := (v1>>17 | v1<<(32-17)) ^ (v1>>19 | v1<<(32-19)) ^ (v1 >> 10)
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v2 := w[i-15]
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t2 := (v2>>7 | v2<<(32-7)) ^ (v2>>18 | v2<<(32-18)) ^ (v2 >> 3)
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w[i] = t1 + w[i-7] + t2 + w[i-16]
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}
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a, b, c, d, e, f, g, h := h0, h1, h2, h3, h4, h5, h6, h7
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for i := 0; i < 64; i++ {
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t1 := h + ((e>>6 | e<<(32-6)) ^ (e>>11 | e<<(32-11)) ^ (e>>25 | e<<(32-25))) + ((e & f) ^ (^e & g)) + _K[i] + w[i]
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t2 := ((a>>2 | a<<(32-2)) ^ (a>>13 | a<<(32-13)) ^ (a>>22 | a<<(32-22))) + ((a & b) ^ (a & c) ^ (b & c))
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h = g
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g = f
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f = e
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e = d + t1
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d = c
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c = b
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b = a
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a = t1 + t2
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}
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h0 += a
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h1 += b
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h2 += c
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h3 += d
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h4 += e
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h5 += f
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h6 += g
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h7 += h
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p = p[chunk:]
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}
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dig.h[0], dig.h[1], dig.h[2], dig.h[3], dig.h[4], dig.h[5], dig.h[6], dig.h[7] = h0, h1, h2, h3, h4, h5, h6, h7
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}
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var _K = []uint32{
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0x428a2f98,
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0x71374491,
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0xb5c0fbcf,
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0xe9b5dba5,
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0x3956c25b,
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0x59f111f1,
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0x923f82a4,
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0xab1c5ed5,
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0xd807aa98,
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0x12835b01,
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0x243185be,
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0x550c7dc3,
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0x72be5d74,
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0x80deb1fe,
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0x9bdc06a7,
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0xc19bf174,
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0xe49b69c1,
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0xefbe4786,
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0x0fc19dc6,
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0x240ca1cc,
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0x2de92c6f,
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0x4a7484aa,
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0x5cb0a9dc,
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0x76f988da,
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0x983e5152,
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0xa831c66d,
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0xb00327c8,
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0xbf597fc7,
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0xc6e00bf3,
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0xd5a79147,
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0x06ca6351,
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0x14292967,
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0x27b70a85,
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0x2e1b2138,
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0x4d2c6dfc,
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0x53380d13,
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0x650a7354,
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0x766a0abb,
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0x81c2c92e,
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0x92722c85,
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0xa2bfe8a1,
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0xa81a664b,
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0xc24b8b70,
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0xc76c51a3,
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0xd192e819,
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0xd6990624,
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0xf40e3585,
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0x106aa070,
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0x19a4c116,
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0x1e376c08,
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0x2748774c,
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0x34b0bcb5,
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0x391c0cb3,
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0x4ed8aa4a,
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0x5b9cca4f,
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0x682e6ff3,
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0x748f82ee,
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0x78a5636f,
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0x84c87814,
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0x8cc70208,
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0x90befffa,
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0xa4506ceb,
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0xbef9a3f7,
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0xc67178f2,
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}
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