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171 lines
4.9 KiB
Go
171 lines
4.9 KiB
Go
// Copyright 2015 PingCAP, Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package codec
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import (
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"encoding/binary"
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"github.com/juju/errors"
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)
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const signMask uint64 = 0x8000000000000000
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func encodeIntToCmpUint(v int64) uint64 {
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u := uint64(v)
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if u&signMask > 0 {
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u &= ^signMask
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} else {
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u |= signMask
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}
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return u
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}
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func decodeCmpUintToInt(u uint64) int64 {
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if u&signMask > 0 {
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u &= ^signMask
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} else {
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u |= signMask
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}
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return int64(u)
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}
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// EncodeInt appends the encoded value to slice b and returns the appended slice.
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// EncodeInt guarantees that the encoded value is in ascending order for comparison.
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func EncodeInt(b []byte, v int64) []byte {
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var data [8]byte
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u := encodeIntToCmpUint(v)
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binary.BigEndian.PutUint64(data[:], u)
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return append(b, data[:]...)
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}
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// EncodeIntDesc appends the encoded value to slice b and returns the appended slice.
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// EncodeIntDesc guarantees that the encoded value is in descending order for comparison.
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func EncodeIntDesc(b []byte, v int64) []byte {
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var data [8]byte
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u := encodeIntToCmpUint(v)
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binary.BigEndian.PutUint64(data[:], ^u)
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return append(b, data[:]...)
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}
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// DecodeInt decodes value encoded by EncodeInt before.
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// It returns the leftover un-decoded slice, decoded value if no error.
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func DecodeInt(b []byte) ([]byte, int64, error) {
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if len(b) < 8 {
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return nil, 0, errors.New("insufficient bytes to decode value")
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}
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u := binary.BigEndian.Uint64(b[:8])
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v := decodeCmpUintToInt(u)
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b = b[8:]
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return b, v, nil
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}
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// DecodeIntDesc decodes value encoded by EncodeInt before.
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// It returns the leftover un-decoded slice, decoded value if no error.
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func DecodeIntDesc(b []byte) ([]byte, int64, error) {
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if len(b) < 8 {
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return nil, 0, errors.New("insufficient bytes to decode value")
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}
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u := binary.BigEndian.Uint64(b[:8])
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v := decodeCmpUintToInt(^u)
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b = b[8:]
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return b, v, nil
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}
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// EncodeUint appends the encoded value to slice b and returns the appended slice.
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// EncodeUint guarantees that the encoded value is in ascending order for comparison.
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func EncodeUint(b []byte, v uint64) []byte {
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var data [8]byte
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binary.BigEndian.PutUint64(data[:], v)
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return append(b, data[:]...)
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}
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// EncodeUintDesc appends the encoded value to slice b and returns the appended slice.
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// EncodeUintDesc guarantees that the encoded value is in descending order for comparison.
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func EncodeUintDesc(b []byte, v uint64) []byte {
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var data [8]byte
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binary.BigEndian.PutUint64(data[:], ^v)
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return append(b, data[:]...)
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}
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// DecodeUint decodes value encoded by EncodeUint before.
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// It returns the leftover un-decoded slice, decoded value if no error.
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func DecodeUint(b []byte) ([]byte, uint64, error) {
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if len(b) < 8 {
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return nil, 0, errors.New("insufficient bytes to decode value")
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}
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v := binary.BigEndian.Uint64(b[:8])
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b = b[8:]
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return b, v, nil
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}
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// DecodeUintDesc decodes value encoded by EncodeInt before.
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// It returns the leftover un-decoded slice, decoded value if no error.
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func DecodeUintDesc(b []byte) ([]byte, uint64, error) {
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if len(b) < 8 {
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return nil, 0, errors.New("insufficient bytes to decode value")
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}
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data := b[:8]
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v := binary.BigEndian.Uint64(data)
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b = b[8:]
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return b, ^v, nil
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}
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// EncodeVarint appends the encoded value to slice b and returns the appended slice.
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// Note that the encoded result is not memcomparable.
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func EncodeVarint(b []byte, v int64) []byte {
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var data [binary.MaxVarintLen64]byte
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n := binary.PutVarint(data[:], v)
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return append(b, data[:n]...)
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}
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// DecodeVarint decodes value encoded by EncodeVarint before.
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// It returns the leftover un-decoded slice, decoded value if no error.
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func DecodeVarint(b []byte) ([]byte, int64, error) {
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v, n := binary.Varint(b)
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if n > 0 {
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return b[n:], v, nil
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}
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if n < 0 {
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return nil, 0, errors.New("value larger than 64 bits")
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}
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return nil, 0, errors.New("insufficient bytes to decode value")
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}
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// EncodeUvarint appends the encoded value to slice b and returns the appended slice.
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// Note that the encoded result is not memcomparable.
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func EncodeUvarint(b []byte, v uint64) []byte {
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var data [binary.MaxVarintLen64]byte
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n := binary.PutUvarint(data[:], v)
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return append(b, data[:n]...)
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}
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// DecodeUvarint decodes value encoded by EncodeUvarint before.
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// It returns the leftover un-decoded slice, decoded value if no error.
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func DecodeUvarint(b []byte) ([]byte, uint64, error) {
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v, n := binary.Uvarint(b)
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if n > 0 {
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return b[n:], v, nil
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}
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if n < 0 {
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return nil, 0, errors.New("value larger than 64 bits")
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}
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return nil, 0, errors.New("insufficient bytes to decode value")
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}
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