1 files changed, 129 insertions, 0 deletions
diff --git a/vendor/github.com/ulikunitz/xz/lzma/lengthcodec.go b/vendor/github.com/ulikunitz/xz/lzma/lengthcodec.go
new file mode 100644
index 000000000..e51773092
--- /dev/null
+++ b/vendor/github.com/ulikunitz/xz/lzma/lengthcodec.go
@@ -0,0 +1,129 @@
+// 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"
+
+// maxPosBits defines the number of bits of the position value that are used to
+// to compute the posState value. The value is used to select the tree codec
+// for length encoding and decoding.
+const maxPosBits = 4
+
+// minMatchLen and maxMatchLen give the minimum and maximum values for
+// encoding and decoding length values. minMatchLen is also used as base
+// for the encoded length values.
+const (
+	minMatchLen = 2
+	maxMatchLen = minMatchLen + 16 + 256 - 1
+)
+
+// lengthCodec support the encoding of the length value.
+type lengthCodec struct {
+	choice [2]prob
+	low    [1 << maxPosBits]treeCodec
+	mid    [1 << maxPosBits]treeCodec
+	high   treeCodec
+}
+
+// deepcopy initializes the lc value as deep copy of the source value.
+func (lc *lengthCodec) deepcopy(src *lengthCodec) {
+	if lc == src {
+		return
+	}
+	lc.choice = src.choice
+	for i := range lc.low {
+		lc.low[i].deepcopy(&src.low[i])
+	}
+	for i := range lc.mid {
+		lc.mid[i].deepcopy(&src.mid[i])
+	}
+	lc.high.deepcopy(&src.high)
+}
+
+// init initializes a new length codec.
+func (lc *lengthCodec) init() {
+	for i := range lc.choice {
+		lc.choice[i] = probInit
+	}
+	for i := range lc.low {
+		lc.low[i] = makeTreeCodec(3)
+	}
+	for i := range lc.mid {
+		lc.mid[i] = makeTreeCodec(3)
+	}
+	lc.high = makeTreeCodec(8)
+}
+
+// lBits gives the number of bits used for the encoding of the l value
+// provided to the range encoder.
+func lBits(l uint32) int {
+	switch {
+	case l < 8:
+		return 4
+	case l < 16:
+		return 5
+	default:
+		return 10
+	}
+}
+
+// Encode encodes the length offset. The length offset l can be compute by
+// subtracting minMatchLen (2) from the actual length.
+//
+//   l = length - minMatchLen
+//
+func (lc *lengthCodec) Encode(e *rangeEncoder, l uint32, posState uint32,
+) (err error) {
+	if l > maxMatchLen-minMatchLen {
+		return errors.New("lengthCodec.Encode: l out of range")
+	}
+	if l < 8 {
+		if err = lc.choice[0].Encode(e, 0); err != nil {
+			return
+		}
+		return lc.low[posState].Encode(e, l)
+	}
+	if err = lc.choice[0].Encode(e, 1); err != nil {
+		return
+	}
+	if l < 16 {
+		if err = lc.choice[1].Encode(e, 0); err != nil {
+			return
+		}
+		return lc.mid[posState].Encode(e, l-8)
+	}
+	if err = lc.choice[1].Encode(e, 1); err != nil {
+		return
+	}
+	if err = lc.high.Encode(e, l-16); err != nil {
+		return
+	}
+	return nil
+}
+
+// Decode reads the length offset. Add minMatchLen to compute the actual length
+// to the length offset l.
+func (lc *lengthCodec) Decode(d *rangeDecoder, posState uint32,
+) (l uint32, err error) {
+	var b uint32
+	if b, err = lc.choice[0].Decode(d); err != nil {
+		return
+	}
+	if b == 0 {
+		l, err = lc.low[posState].Decode(d)
+		return
+	}
+	if b, err = lc.choice[1].Decode(d); err != nil {
+		return
+	}
+	if b == 0 {
+		l, err = lc.mid[posState].Decode(d)
+		l += 8
+		return
+	}
+	l, err = lc.high.Decode(d)
+	l += 16
+	return
+}