gitea/vendor/github.com/pingcap/tidb/util/codec/number.go

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