66 lines
1.9 KiB
Go
66 lines
1.9 KiB
Go
|
// 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 (
|
||
|
|
"math"
|
||
|
|
|
||
|
|
"github.com/juju/errors"
|
||
|
|
)
|
||
|
|
|
||
|
|
func encodeFloatToCmpUint64(f float64) uint64 {
|
||
|
|
u := math.Float64bits(f)
|
||
|
|
if f >= 0 {
|
||
|
|
u |= signMask
|
||
|
|
} else {
|
||
|
|
u = ^u
|
||
|
|
}
|
||
|
|
return u
|
||
|
|
}
|
||
|
|
|
||
|
|
func decodeCmpUintToFloat(u uint64) float64 {
|
||
|
|
if u&signMask > 0 {
|
||
|
|
u &= ^signMask
|
||
|
|
} else {
|
||
|
|
u = ^u
|
||
|
|
}
|
||
|
|
return math.Float64frombits(u)
|
||
|
|
}
|
||
|
|
|
||
|
|
// EncodeFloat encodes a float v into a byte slice which can be sorted lexicographically later.
|
||
|
|
// EncodeFloat guarantees that the encoded value is in ascending order for comparison.
|
||
|
|
func EncodeFloat(b []byte, v float64) []byte {
|
||
|
|
u := encodeFloatToCmpUint64(v)
|
||
|
|
return EncodeUint(b, u)
|
||
|
|
}
|
||
|
|
|
||
|
|
// DecodeFloat decodes a float from a byte slice generated with EncodeFloat before.
|
||
|
|
func DecodeFloat(b []byte) ([]byte, float64, error) {
|
||
|
|
b, u, err := DecodeUint(b)
|
||
|
|
return b, decodeCmpUintToFloat(u), errors.Trace(err)
|
||
|
|
}
|
||
|
|
|
||
|
|
// EncodeFloatDesc encodes a float v into a byte slice which can be sorted lexicographically later.
|
||
|
|
// EncodeFloatDesc guarantees that the encoded value is in descending order for comparison.
|
||
|
|
func EncodeFloatDesc(b []byte, v float64) []byte {
|
||
|
|
u := encodeFloatToCmpUint64(v)
|
||
|
|
return EncodeUintDesc(b, u)
|
||
|
|
}
|
||
|
|
|
||
|
|
// DecodeFloatDesc decodes a float from a byte slice generated with EncodeFloatDesc before.
|
||
|
|
func DecodeFloatDesc(b []byte) ([]byte, float64, error) {
|
||
|
|
b, u, err := DecodeUintDesc(b)
|
||
|
|
return b, decodeCmpUintToFloat(u), errors.Trace(err)
|
||
|
|
}
|