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utils.go
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utils.go
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package threefish
import (
"math/bits"
"encoding/binary"
)
// Endianness option
const littleEndian bool = true
func GETU64(ptr []byte) uint64 {
if littleEndian {
return binary.LittleEndian.Uint64(ptr)
} else {
return binary.BigEndian.Uint64(ptr)
}
}
func PUTU64(ptr []byte, a uint64) {
if littleEndian {
binary.LittleEndian.PutUint64(ptr, a)
} else {
binary.BigEndian.PutUint64(ptr, a)
}
}
func bytesToUint64s(b []byte) []uint64 {
size := len(b) / 8
dst := make([]uint64, size)
for i := 0; i < size; i++ {
j := i * 8
if littleEndian {
dst[i] = binary.LittleEndian.Uint64(b[j:])
} else {
dst[i] = binary.BigEndian.Uint64(b[j:])
}
}
return dst
}
func uint64sToBytes(w []uint64) []byte {
size := len(w) * 8
dst := make([]byte, size)
for i := 0; i < len(w); i++ {
j := i * 8
if littleEndian {
binary.LittleEndian.PutUint64(dst[j:], w[i])
} else {
binary.BigEndian.PutUint64(dst[j:], w[i])
}
}
return dst
}
func rotl64(x uint64, n int) uint64 {
return bits.RotateLeft64(x, n)
}
func rotr64(x uint64, n int) uint64 {
return rotl64(x, 64 - n)
}
// calculateTweak loads a tweak value from src and extends it into dst.
func calculateTweak(dst *[(tweakSize / 8) + 1]uint64, src []byte) error {
if len(src) != tweakSize {
return new(TweakSizeError)
}
dst[0] = GETU64(src[0:])
dst[1] = GETU64(src[8:])
dst[2] = dst[0] ^ dst[1]
return nil
}