989489096e
This commit implements a massive refactor of the repository, and moves the build system over to use Mage (magefile.org) which should allow seamless building across multiple platforms.
70 lines
1.8 KiB
Go
70 lines
1.8 KiB
Go
// Copyright 2014-2017 Ulrich Kunitz. All rights reserved.
|
|
// Use of this source code is governed by a BSD-style
|
|
// license that can be found in the LICENSE file.
|
|
|
|
package lzma
|
|
|
|
import (
|
|
"errors"
|
|
"fmt"
|
|
)
|
|
|
|
// maximum and minimum values for the LZMA properties.
|
|
const (
|
|
minPB = 0
|
|
maxPB = 4
|
|
)
|
|
|
|
// maxPropertyCode is the possible maximum of a properties code byte.
|
|
const maxPropertyCode = (maxPB+1)*(maxLP+1)*(maxLC+1) - 1
|
|
|
|
// Properties contains the parameters LC, LP and PB. The parameter LC
|
|
// defines the number of literal context bits; parameter LP the number
|
|
// of literal position bits and PB the number of position bits.
|
|
type Properties struct {
|
|
LC int
|
|
LP int
|
|
PB int
|
|
}
|
|
|
|
// String returns the properties in a string representation.
|
|
func (p *Properties) String() string {
|
|
return fmt.Sprintf("LC %d LP %d PB %d", p.LC, p.LP, p.PB)
|
|
}
|
|
|
|
// PropertiesForCode converts a properties code byte into a Properties value.
|
|
func PropertiesForCode(code byte) (p Properties, err error) {
|
|
if code > maxPropertyCode {
|
|
return p, errors.New("lzma: invalid properties code")
|
|
}
|
|
p.LC = int(code % 9)
|
|
code /= 9
|
|
p.LP = int(code % 5)
|
|
code /= 5
|
|
p.PB = int(code % 5)
|
|
return p, err
|
|
}
|
|
|
|
// verify checks the properties for correctness.
|
|
func (p *Properties) verify() error {
|
|
if p == nil {
|
|
return errors.New("lzma: properties are nil")
|
|
}
|
|
if !(minLC <= p.LC && p.LC <= maxLC) {
|
|
return errors.New("lzma: lc out of range")
|
|
}
|
|
if !(minLP <= p.LP && p.LP <= maxLP) {
|
|
return errors.New("lzma: lp out of range")
|
|
}
|
|
if !(minPB <= p.PB && p.PB <= maxPB) {
|
|
return errors.New("lzma: pb out of range")
|
|
}
|
|
return nil
|
|
}
|
|
|
|
// Code converts the properties to a byte. The function assumes that
|
|
// the properties components are all in range.
|
|
func (p Properties) Code() byte {
|
|
return byte((p.PB*5+p.LP)*9 + p.LC)
|
|
}
|