blob: abade2d605279b6a57d475d73d63b5033230676c [file] [log] [blame]
Scott Bakered4efab2020-01-13 19:12:25 -08001// 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 fse
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
Scott Bakered4efab2020-01-13 19:12:25 -080028// Uint32 returns a little endian uint32 starting at current offset.
29func (b byteReader) Uint32() uint32 {
David K. Bainbridgebd6b2882021-08-26 13:31:02 +000030 b2 := b.b[b.off:]
31 b2 = b2[:4]
Scott Bakered4efab2020-01-13 19:12:25 -080032 v3 := uint32(b2[3])
33 v2 := uint32(b2[2])
34 v1 := uint32(b2[1])
35 v0 := uint32(b2[0])
36 return v0 | (v1 << 8) | (v2 << 16) | (v3 << 24)
37}
38
39// unread returns the unread portion of the input.
40func (b byteReader) unread() []byte {
41 return b.b[b.off:]
42}
43
44// remain will return the number of bytes remaining.
45func (b byteReader) remain() int {
46 return len(b.b) - b.off
47}