nmdc-telegramfrontend/vendor/github.com/cxmcc/tiger/compress.go

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2018-06-03 03:28:05 +00:00
package tiger
import (
"encoding/binary"
"unsafe"
)
var littleEndian bool
func init() {
x := uint32(0x04030201)
y := [4]byte{0x1, 0x2, 0x3, 0x4}
littleEndian = *(*[4]byte)(unsafe.Pointer(&x)) == y
}
func pass(a, b, c uint64, x []uint64, mul uint64) (uint64, uint64, uint64) {
a, b, c = round(a, b, c, x[0], mul)
b, c, a = round(b, c, a, x[1], mul)
c, a, b = round(c, a, b, x[2], mul)
a, b, c = round(a, b, c, x[3], mul)
b, c, a = round(b, c, a, x[4], mul)
c, a, b = round(c, a, b, x[5], mul)
a, b, c = round(a, b, c, x[6], mul)
b, c, a = round(b, c, a, x[7], mul)
return a, b, c
}
func round(a, b, c, x, mul uint64) (uint64, uint64, uint64) {
c ^= x
a -= t1[c&0xff] ^ t2[(c>>16)&0xff] ^ t3[(c>>32)&0xff] ^ t4[(c>>48)&0xff]
b += t4[(c>>8)&0xff] ^ t3[(c>>24)&0xff] ^ t2[(c>>40)&0xff] ^ t1[(c>>56)&0xff]
b *= mul
return a, b, c
}
func keySchedule(x []uint64) {
x[0] -= x[7] ^ 0xa5a5a5a5a5a5a5a5
x[1] ^= x[0]
x[2] += x[1]
x[3] -= x[2] ^ ((^x[1]) << 19)
x[4] ^= x[3]
x[5] += x[4]
x[6] -= x[5] ^ ((^x[4]) >> 23)
x[7] ^= x[6]
x[0] += x[7]
x[1] -= x[0] ^ ((^x[7]) << 19)
x[2] ^= x[1]
x[3] += x[2]
x[4] -= x[3] ^ ((^x[2]) >> 23)
x[5] ^= x[4]
x[6] += x[5]
x[7] -= x[6] ^ 0x0123456789abcdef
}
func (d *digest) compress(data []byte) {
// save_abc
a := d.a
b := d.b
c := d.c
var x []uint64
if littleEndian {
x = []uint64{
binary.LittleEndian.Uint64(data[0:8]),
binary.LittleEndian.Uint64(data[8:16]),
binary.LittleEndian.Uint64(data[16:24]),
binary.LittleEndian.Uint64(data[24:32]),
binary.LittleEndian.Uint64(data[32:40]),
binary.LittleEndian.Uint64(data[40:48]),
binary.LittleEndian.Uint64(data[48:56]),
binary.LittleEndian.Uint64(data[56:64]),
}
} else {
x = []uint64{
binary.BigEndian.Uint64(data[0:8]),
binary.BigEndian.Uint64(data[8:16]),
binary.BigEndian.Uint64(data[16:24]),
binary.BigEndian.Uint64(data[24:32]),
binary.BigEndian.Uint64(data[32:40]),
binary.BigEndian.Uint64(data[40:48]),
binary.BigEndian.Uint64(data[48:56]),
binary.BigEndian.Uint64(data[56:64]),
}
}
d.a, d.b, d.c = pass(d.a, d.b, d.c, x, 5)
keySchedule(x)
d.c, d.a, d.b = pass(d.c, d.a, d.b, x, 7)
keySchedule(x)
d.b, d.c, d.a = pass(d.b, d.c, d.a, x, 9)
// feedforward
d.a ^= a
d.b -= b
d.c += c
}