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int.go
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int.go
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package encoding
import (
"encoding/binary"
"fmt"
"sync"
)
// MarshalUint16 appends marshaled v to dst and returns the result.
func MarshalUint16(dst []byte, u uint16) []byte {
return append(dst, byte(u>>8), byte(u))
}
// UnmarshalUint16 returns unmarshaled uint32 from src.
func UnmarshalUint16(src []byte) uint16 {
// This is faster than the manual conversion.
return binary.BigEndian.Uint16(src[:2])
}
// MarshalUint32 appends marshaled v to dst and returns the result.
func MarshalUint32(dst []byte, u uint32) []byte {
return append(dst, byte(u>>24), byte(u>>16), byte(u>>8), byte(u))
}
// UnmarshalUint32 returns unmarshaled uint32 from src.
func UnmarshalUint32(src []byte) uint32 {
// This is faster than the manual conversion.
return binary.BigEndian.Uint32(src[:4])
}
// MarshalUint64 appends marshaled v to dst and returns the result.
func MarshalUint64(dst []byte, u uint64) []byte {
return append(dst, byte(u>>56), byte(u>>48), byte(u>>40), byte(u>>32), byte(u>>24), byte(u>>16), byte(u>>8), byte(u))
}
// UnmarshalUint64 returns unmarshaled uint64 from src.
func UnmarshalUint64(src []byte) uint64 {
// This is faster than the manual conversion.
return binary.BigEndian.Uint64(src[:8])
}
// MarshalInt16 appends marshaled v to dst and returns the result.
func MarshalInt16(dst []byte, v int16) []byte {
// Such encoding for negative v must improve compression.
v = (v << 1) ^ (v >> 15) // zig-zag encoding without branching.
u := uint16(v)
return append(dst, byte(u>>8), byte(u))
}
// UnmarshalInt16 returns unmarshaled int16 from src.
func UnmarshalInt16(src []byte) int16 {
// This is faster than the manual conversion.
u := binary.BigEndian.Uint16(src[:2])
v := int16(u>>1) ^ (int16(u<<15) >> 15) // zig-zag decoding without branching.
return v
}
// MarshalInt64 appends marshaled v to dst and returns the result.
func MarshalInt64(dst []byte, v int64) []byte {
// Such encoding for negative v must improve compression.
v = (v << 1) ^ (v >> 63) // zig-zag encoding without branching.
u := uint64(v)
return append(dst, byte(u>>56), byte(u>>48), byte(u>>40), byte(u>>32), byte(u>>24), byte(u>>16), byte(u>>8), byte(u))
}
// UnmarshalInt64 returns unmarshaled int64 from src.
func UnmarshalInt64(src []byte) int64 {
// This is faster than the manual conversion.
u := binary.BigEndian.Uint64(src[:8])
v := int64(u>>1) ^ (int64(u<<63) >> 63) // zig-zag decoding without branching.
return v
}
// MarshalVarInt64 appends marshalsed v to dst and returns the result.
func MarshalVarInt64(dst []byte, v int64) []byte {
var tmp [1]int64
tmp[0] = v
return MarshalVarInt64s(dst, tmp[:])
}
// MarshalVarInt64s appends marshaled vs to dst and returns the result.
func MarshalVarInt64s(dst []byte, vs []int64) []byte {
for _, v := range vs {
if v < 0x40 && v > -0x40 {
// Fast path
c := int8(v)
v := (c << 1) ^ (c >> 7) // zig-zag encoding without branching.
dst = append(dst, byte(v))
continue
}
v = (v << 1) ^ (v >> 63) // zig-zag encoding without branching.
u := uint64(v)
for u > 0x7f {
dst = append(dst, 0x80|byte(u))
u >>= 7
}
dst = append(dst, byte(u))
}
return dst
}
// UnmarshalVarInt64 returns unmarshaled int64 from src and returns
// the remaining tail from src.
func UnmarshalVarInt64(src []byte) ([]byte, int64, error) {
var tmp [1]int64
tail, err := UnmarshalVarInt64s(tmp[:], src)
return tail, tmp[0], err
}
// UnmarshalVarInt64s unmarshals len(dst) int64 values from src to dst
// and returns the remaining tail from src.
func UnmarshalVarInt64s(dst []int64, src []byte) ([]byte, error) {
idx := uint(0)
for i := range dst {
if idx >= uint(len(src)) {
return nil, fmt.Errorf("cannot unmarshal varint from empty data")
}
c := src[idx]
idx++
if c < 0x80 {
// Fast path
v := int8(c>>1) ^ (int8(c<<7) >> 7) // zig-zag decoding without branching.
dst[i] = int64(v)
continue
}
// Slow path
u := uint64(c & 0x7f)
startIdx := idx - 1
shift := uint8(0)
for c >= 0x80 {
if idx >= uint(len(src)) {
return nil, fmt.Errorf("unexpected end of encoded varint at byte %d; src=%x", idx-startIdx, src[startIdx:])
}
if idx-startIdx > 9 {
return src[idx:], fmt.Errorf("too long encoded varint; the maximum allowed length is 10 bytes; got %d bytes; src=%x",
(idx-startIdx)+1, src[startIdx:])
}
c = src[idx]
idx++
shift += 7
u |= uint64(c&0x7f) << shift
}
v := int64(u>>1) ^ (int64(u<<63) >> 63) // zig-zag decoding without branching.
dst[i] = v
}
return src[idx:], nil
}
// MarshalVarUint64 appends marshaled u to dst and returns the result.
func MarshalVarUint64(dst []byte, u uint64) []byte {
var tmp [1]uint64
tmp[0] = u
return MarshalVarUint64s(dst, tmp[:])
}
// MarshalVarUint64s appends marshaled us to dst and returns the result.
func MarshalVarUint64s(dst []byte, us []uint64) []byte {
for _, u := range us {
if u < 0x80 {
// Fast path
dst = append(dst, byte(u))
continue
}
for u > 0x7f {
dst = append(dst, 0x80|byte(u))
u >>= 7
}
dst = append(dst, byte(u))
}
return dst
}
// UnmarshalVarUint64 returns unmarshaled uint64 from src and returns
// the remaining tail from src.
func UnmarshalVarUint64(src []byte) ([]byte, uint64, error) {
var tmp [1]uint64
tail, err := UnmarshalVarUint64s(tmp[:], src)
return tail, tmp[0], err
}
// UnmarshalVarUint64s unmarshals len(dst) uint64 values from src to dst
// and returns the remaining tail from src.
func UnmarshalVarUint64s(dst []uint64, src []byte) ([]byte, error) {
idx := uint(0)
for i := range dst {
if idx >= uint(len(src)) {
return nil, fmt.Errorf("cannot unmarshal varuint from empty data")
}
c := src[idx]
idx++
if c < 0x80 {
// Fast path
dst[i] = uint64(c)
continue
}
// Slow path
u := uint64(c & 0x7f)
startIdx := idx - 1
shift := uint8(0)
for c >= 0x80 {
if idx >= uint(len(src)) {
return nil, fmt.Errorf("unexpected end of encoded varint at byte %d; src=%x", idx-startIdx, src[startIdx:])
}
if idx-startIdx > 9 {
return src[idx:], fmt.Errorf("too long encoded varint; the maximum allowed length is 10 bytes; got %d bytes; src=%x",
(idx-startIdx)+1, src[startIdx:])
}
c = src[idx]
idx++
shift += 7
u |= uint64(c&0x7f) << shift
}
dst[i] = u
}
return src[idx:], nil
}
// MarshalBytes appends marshaled b to dst and returns the result.
func MarshalBytes(dst, b []byte) []byte {
dst = MarshalVarUint64(dst, uint64(len(b)))
dst = append(dst, b...)
return dst
}
// UnmarshalBytes returns unmarshaled bytes from src.
func UnmarshalBytes(src []byte) ([]byte, []byte, error) {
tail, n, err := UnmarshalVarUint64(src)
if err != nil {
return nil, nil, fmt.Errorf("cannot unmarshal string size: %w", err)
}
src = tail
if uint64(len(src)) < n {
return nil, nil, fmt.Errorf("src is too short for reading string with size %d; len(src)=%d", n, len(src))
}
return src[n:], src[:n], nil
}
// GetInt64s returns an int64 slice with the given size.
// The slice contents isn't initialized - it may contain garbage.
func GetInt64s(size int) *Int64s {
v := int64sPool.Get()
if v == nil {
return &Int64s{
A: make([]int64, size),
}
}
is := v.(*Int64s)
if n := size - cap(is.A); n > 0 {
is.A = append(is.A[:cap(is.A)], make([]int64, n)...)
}
is.A = is.A[:size]
return is
}
// PutInt64s returns is to the pool.
func PutInt64s(is *Int64s) {
int64sPool.Put(is)
}
// Int64s holds an int64 slice
type Int64s struct {
A []int64
}
var int64sPool sync.Pool
// GetUint64s returns an uint64 slice with the given size.
// The slice contents isn't initialized - it may contain garbage.
func GetUint64s(size int) *Uint64s {
v := uint64sPool.Get()
if v == nil {
return &Uint64s{
A: make([]uint64, size),
}
}
is := v.(*Uint64s)
if n := size - cap(is.A); n > 0 {
is.A = append(is.A[:cap(is.A)], make([]uint64, n)...)
}
is.A = is.A[:size]
return is
}
// PutUint64s returns is to the pool.
func PutUint64s(is *Uint64s) {
uint64sPool.Put(is)
}
// Uint64s holds an uint64 slice
type Uint64s struct {
A []uint64
}
var uint64sPool sync.Pool