vendor

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

@@ -0,0 +1,49 @@
+// 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 "fmt"
+
+// directCodec allows the encoding and decoding of values with a fixed number
+// of bits. The number of bits must be in the range [1,32].
+type directCodec byte
+
+// makeDirectCodec creates a directCodec. The function panics if the number of
+// bits is not in the range [1,32].
+func makeDirectCodec(bits int) directCodec {
+	if !(1 <= bits && bits <= 32) {
+		panic(fmt.Errorf("bits=%d out of range", bits))
+	}
+	return directCodec(bits)
+}
+
+// Bits returns the number of bits supported by this codec.
+func (dc directCodec) Bits() int {
+	return int(dc)
+}
+
+// Encode uses the range encoder to encode a value with the fixed number of
+// bits. The most-significant bit is encoded first.
+func (dc directCodec) Encode(e *rangeEncoder, v uint32) error {
+	for i := int(dc) - 1; i >= 0; i-- {
+		if err := e.DirectEncodeBit(v >> uint(i)); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// Decode uses the range decoder to decode a value with the given number of
+// given bits. The most-significant bit is decoded first.
+func (dc directCodec) Decode(d *rangeDecoder) (v uint32, err error) {
+	for i := int(dc) - 1; i >= 0; i-- {
+		x, err := d.DirectDecodeBit()
+		if err != nil {
+			return 0, err
+		}
+		v = (v << 1) | x
+	}
+	return v, nil
+}