mirror of
https://github.com/superseriousbusiness/gotosocial.git
synced 2024-12-05 10:02:47 +00:00
244 lines
5.5 KiB
Go
244 lines
5.5 KiB
Go
// Package xxhash implements the 64-bit variant of xxHash (XXH64) as described
|
|
// at http://cyan4973.github.io/xxHash/.
|
|
package xxhash
|
|
|
|
import (
|
|
"encoding/binary"
|
|
"errors"
|
|
"math/bits"
|
|
)
|
|
|
|
const (
|
|
prime1 uint64 = 11400714785074694791
|
|
prime2 uint64 = 14029467366897019727
|
|
prime3 uint64 = 1609587929392839161
|
|
prime4 uint64 = 9650029242287828579
|
|
prime5 uint64 = 2870177450012600261
|
|
)
|
|
|
|
// Store the primes in an array as well.
|
|
//
|
|
// The consts are used when possible in Go code to avoid MOVs but we need a
|
|
// contiguous array for the assembly code.
|
|
var primes = [...]uint64{prime1, prime2, prime3, prime4, prime5}
|
|
|
|
// Digest implements hash.Hash64.
|
|
//
|
|
// Note that a zero-valued Digest is not ready to receive writes.
|
|
// Call Reset or create a Digest using New before calling other methods.
|
|
type Digest struct {
|
|
v1 uint64
|
|
v2 uint64
|
|
v3 uint64
|
|
v4 uint64
|
|
total uint64
|
|
mem [32]byte
|
|
n int // how much of mem is used
|
|
}
|
|
|
|
// New creates a new Digest with a zero seed.
|
|
func New() *Digest {
|
|
return NewWithSeed(0)
|
|
}
|
|
|
|
// NewWithSeed creates a new Digest with the given seed.
|
|
func NewWithSeed(seed uint64) *Digest {
|
|
var d Digest
|
|
d.ResetWithSeed(seed)
|
|
return &d
|
|
}
|
|
|
|
// Reset clears the Digest's state so that it can be reused.
|
|
// It uses a seed value of zero.
|
|
func (d *Digest) Reset() {
|
|
d.ResetWithSeed(0)
|
|
}
|
|
|
|
// ResetWithSeed clears the Digest's state so that it can be reused.
|
|
// It uses the given seed to initialize the state.
|
|
func (d *Digest) ResetWithSeed(seed uint64) {
|
|
d.v1 = seed + prime1 + prime2
|
|
d.v2 = seed + prime2
|
|
d.v3 = seed
|
|
d.v4 = seed - prime1
|
|
d.total = 0
|
|
d.n = 0
|
|
}
|
|
|
|
// Size always returns 8 bytes.
|
|
func (d *Digest) Size() int { return 8 }
|
|
|
|
// BlockSize always returns 32 bytes.
|
|
func (d *Digest) BlockSize() int { return 32 }
|
|
|
|
// Write adds more data to d. It always returns len(b), nil.
|
|
func (d *Digest) Write(b []byte) (n int, err error) {
|
|
n = len(b)
|
|
d.total += uint64(n)
|
|
|
|
memleft := d.mem[d.n&(len(d.mem)-1):]
|
|
|
|
if d.n+n < 32 {
|
|
// This new data doesn't even fill the current block.
|
|
copy(memleft, b)
|
|
d.n += n
|
|
return
|
|
}
|
|
|
|
if d.n > 0 {
|
|
// Finish off the partial block.
|
|
c := copy(memleft, b)
|
|
d.v1 = round(d.v1, u64(d.mem[0:8]))
|
|
d.v2 = round(d.v2, u64(d.mem[8:16]))
|
|
d.v3 = round(d.v3, u64(d.mem[16:24]))
|
|
d.v4 = round(d.v4, u64(d.mem[24:32]))
|
|
b = b[c:]
|
|
d.n = 0
|
|
}
|
|
|
|
if len(b) >= 32 {
|
|
// One or more full blocks left.
|
|
nw := writeBlocks(d, b)
|
|
b = b[nw:]
|
|
}
|
|
|
|
// Store any remaining partial block.
|
|
copy(d.mem[:], b)
|
|
d.n = len(b)
|
|
|
|
return
|
|
}
|
|
|
|
// Sum appends the current hash to b and returns the resulting slice.
|
|
func (d *Digest) Sum(b []byte) []byte {
|
|
s := d.Sum64()
|
|
return append(
|
|
b,
|
|
byte(s>>56),
|
|
byte(s>>48),
|
|
byte(s>>40),
|
|
byte(s>>32),
|
|
byte(s>>24),
|
|
byte(s>>16),
|
|
byte(s>>8),
|
|
byte(s),
|
|
)
|
|
}
|
|
|
|
// Sum64 returns the current hash.
|
|
func (d *Digest) Sum64() uint64 {
|
|
var h uint64
|
|
|
|
if d.total >= 32 {
|
|
v1, v2, v3, v4 := d.v1, d.v2, d.v3, d.v4
|
|
h = rol1(v1) + rol7(v2) + rol12(v3) + rol18(v4)
|
|
h = mergeRound(h, v1)
|
|
h = mergeRound(h, v2)
|
|
h = mergeRound(h, v3)
|
|
h = mergeRound(h, v4)
|
|
} else {
|
|
h = d.v3 + prime5
|
|
}
|
|
|
|
h += d.total
|
|
|
|
b := d.mem[:d.n&(len(d.mem)-1)]
|
|
for ; len(b) >= 8; b = b[8:] {
|
|
k1 := round(0, u64(b[:8]))
|
|
h ^= k1
|
|
h = rol27(h)*prime1 + prime4
|
|
}
|
|
if len(b) >= 4 {
|
|
h ^= uint64(u32(b[:4])) * prime1
|
|
h = rol23(h)*prime2 + prime3
|
|
b = b[4:]
|
|
}
|
|
for ; len(b) > 0; b = b[1:] {
|
|
h ^= uint64(b[0]) * prime5
|
|
h = rol11(h) * prime1
|
|
}
|
|
|
|
h ^= h >> 33
|
|
h *= prime2
|
|
h ^= h >> 29
|
|
h *= prime3
|
|
h ^= h >> 32
|
|
|
|
return h
|
|
}
|
|
|
|
const (
|
|
magic = "xxh\x06"
|
|
marshaledSize = len(magic) + 8*5 + 32
|
|
)
|
|
|
|
// MarshalBinary implements the encoding.BinaryMarshaler interface.
|
|
func (d *Digest) MarshalBinary() ([]byte, error) {
|
|
b := make([]byte, 0, marshaledSize)
|
|
b = append(b, magic...)
|
|
b = appendUint64(b, d.v1)
|
|
b = appendUint64(b, d.v2)
|
|
b = appendUint64(b, d.v3)
|
|
b = appendUint64(b, d.v4)
|
|
b = appendUint64(b, d.total)
|
|
b = append(b, d.mem[:d.n]...)
|
|
b = b[:len(b)+len(d.mem)-d.n]
|
|
return b, nil
|
|
}
|
|
|
|
// UnmarshalBinary implements the encoding.BinaryUnmarshaler interface.
|
|
func (d *Digest) UnmarshalBinary(b []byte) error {
|
|
if len(b) < len(magic) || string(b[:len(magic)]) != magic {
|
|
return errors.New("xxhash: invalid hash state identifier")
|
|
}
|
|
if len(b) != marshaledSize {
|
|
return errors.New("xxhash: invalid hash state size")
|
|
}
|
|
b = b[len(magic):]
|
|
b, d.v1 = consumeUint64(b)
|
|
b, d.v2 = consumeUint64(b)
|
|
b, d.v3 = consumeUint64(b)
|
|
b, d.v4 = consumeUint64(b)
|
|
b, d.total = consumeUint64(b)
|
|
copy(d.mem[:], b)
|
|
d.n = int(d.total % uint64(len(d.mem)))
|
|
return nil
|
|
}
|
|
|
|
func appendUint64(b []byte, x uint64) []byte {
|
|
var a [8]byte
|
|
binary.LittleEndian.PutUint64(a[:], x)
|
|
return append(b, a[:]...)
|
|
}
|
|
|
|
func consumeUint64(b []byte) ([]byte, uint64) {
|
|
x := u64(b)
|
|
return b[8:], x
|
|
}
|
|
|
|
func u64(b []byte) uint64 { return binary.LittleEndian.Uint64(b) }
|
|
func u32(b []byte) uint32 { return binary.LittleEndian.Uint32(b) }
|
|
|
|
func round(acc, input uint64) uint64 {
|
|
acc += input * prime2
|
|
acc = rol31(acc)
|
|
acc *= prime1
|
|
return acc
|
|
}
|
|
|
|
func mergeRound(acc, val uint64) uint64 {
|
|
val = round(0, val)
|
|
acc ^= val
|
|
acc = acc*prime1 + prime4
|
|
return acc
|
|
}
|
|
|
|
func rol1(x uint64) uint64 { return bits.RotateLeft64(x, 1) }
|
|
func rol7(x uint64) uint64 { return bits.RotateLeft64(x, 7) }
|
|
func rol11(x uint64) uint64 { return bits.RotateLeft64(x, 11) }
|
|
func rol12(x uint64) uint64 { return bits.RotateLeft64(x, 12) }
|
|
func rol18(x uint64) uint64 { return bits.RotateLeft64(x, 18) }
|
|
func rol23(x uint64) uint64 { return bits.RotateLeft64(x, 23) }
|
|
func rol27(x uint64) uint64 { return bits.RotateLeft64(x, 27) }
|
|
func rol31(x uint64) uint64 { return bits.RotateLeft64(x, 31) }
|