vendor

vendor/github.com/ulikunitz/xz/lzma/properties.go

@@ -0,0 +1,69 @@
+// 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)
+}