xor.go

     1  // Copyright 2015 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package sha3
     6  
     7  import (
     8  	"crypto/subtle"
     9  	"encoding/binary"
    10  	"unsafe"
    11  
    12  	"golang.org/x/sys/cpu"
    13  )
    14  
    15  // xorIn xors the bytes in buf into the state.
    16  func xorIn(d *state, buf []byte) {
    17  	if cpu.IsBigEndian {
    18  		for i := 0; len(buf) >= 8; i++ {
    19  			a := binary.LittleEndian.Uint64(buf)
    20  			d.a[i] ^= a
    21  			buf = buf[8:]
    22  		}
    23  	} else {
    24  		ab := (*[25 * 64 / 8]byte)(unsafe.Pointer(&d.a))
    25  		subtle.XORBytes(ab[:], ab[:], buf)
    26  	}
    27  }
    28  
    29  // copyOut copies uint64s to a byte buffer.
    30  func copyOut(d *state, b []byte) {
    31  	if cpu.IsBigEndian {
    32  		for i := 0; len(b) >= 8; i++ {
    33  			binary.LittleEndian.PutUint64(b, d.a[i])
    34  			b = b[8:]
    35  		}
    36  	} else {
    37  		ab := (*[25 * 64 / 8]byte)(unsafe.Pointer(&d.a))
    38  		copy(b, ab[:])
    39  	}
    40  }
    41
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