blob: 50bcdf6ea99ce456802f645b08d4489b364349c8 [file] [log] [blame]
khenaidoo7d3c5582021-08-11 18:09:44 -04001// Copyright 2018 Klaus Post. All rights reserved.
2// Use of this source code is governed by a BSD-style
3// license that can be found in the LICENSE file.
4// Based on work Copyright (c) 2013, Yann Collet, released under BSD License.
5
6package huff0
7
8// byteReader provides a byte reader that reads
9// little endian values from a byte stream.
10// The input stream is manually advanced.
11// The reader performs no bounds checks.
12type byteReader struct {
13 b []byte
14 off int
15}
16
17// init will initialize the reader and set the input.
18func (b *byteReader) init(in []byte) {
19 b.b = in
20 b.off = 0
21}
22
23// advance the stream b n bytes.
24func (b *byteReader) advance(n uint) {
25 b.off += int(n)
26}
27
28// Int32 returns a little endian int32 starting at current offset.
29func (b byteReader) Int32() int32 {
30 v3 := int32(b.b[b.off+3])
31 v2 := int32(b.b[b.off+2])
32 v1 := int32(b.b[b.off+1])
33 v0 := int32(b.b[b.off])
34 return (v3 << 24) | (v2 << 16) | (v1 << 8) | v0
35}
36
37// Uint32 returns a little endian uint32 starting at current offset.
38func (b byteReader) Uint32() uint32 {
39 v3 := uint32(b.b[b.off+3])
40 v2 := uint32(b.b[b.off+2])
41 v1 := uint32(b.b[b.off+1])
42 v0 := uint32(b.b[b.off])
43 return (v3 << 24) | (v2 << 16) | (v1 << 8) | v0
44}
45
46// unread returns the unread portion of the input.
47func (b byteReader) unread() []byte {
48 return b.b[b.off:]
49}
50
51// remain will return the number of bytes remaining.
52func (b byteReader) remain() int {
53 return len(b.b) - b.off
54}