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comparison mupdf-source/thirdparty/zxing-cpp/core/src/BitSource.cpp @ 3:2c135c81b16c

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MERGE: upstream PyMuPDF 1.26.4 with MuPDF 1.26.7
author Franz Glasner <fzglas.hg@dom66.de>
date Mon, 15 Sep 2025 11:44:09 +0200
parents b50eed0cc0ef
children
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0:6015a75abc2d 3:2c135c81b16c
1 /*
2 * Copyright 2016 Nu-book Inc.
3 * Copyright 2016 ZXing authors
4 */
5 // SPDX-License-Identifier: Apache-2.0
6
7 #include "BitSource.h"
8
9 #include "ByteArray.h"
10 #include "ZXAlgorithms.h"
11
12 #include <stdexcept>
13
14 namespace ZXing {
15
16 int
17 BitSource::available() const
18 {
19 return 8 * (Size(_bytes) - _byteOffset) - _bitOffset;
20 }
21
22 static int ReadBitsImpl(int numBits, const ByteArray& _bytes, int available, int& _byteOffset, int& _bitOffset)
23 {
24 if (numBits < 1 || numBits > 32 || numBits > available) {
25 throw std::out_of_range("BitSource::readBits: out of range");
26 }
27
28 int result = 0;
29
30 // First, read remainder from current byte
31 if (_bitOffset > 0) {
32 int bitsLeft = 8 - _bitOffset;
33 int toRead = numBits < bitsLeft ? numBits : bitsLeft;
34 int bitsToNotRead = bitsLeft - toRead;
35 int mask = (0xFF >> (8 - toRead)) << bitsToNotRead;
36 result = (_bytes[_byteOffset] & mask) >> bitsToNotRead;
37 numBits -= toRead;
38 _bitOffset += toRead;
39 if (_bitOffset == 8) {
40 _bitOffset = 0;
41 _byteOffset++;
42 }
43 }
44
45 // Next read whole bytes
46 if (numBits > 0) {
47 while (numBits >= 8) {
48 result = (result << 8) | _bytes[_byteOffset];
49 _byteOffset++;
50 numBits -= 8;
51 }
52
53 // Finally read a partial byte
54 if (numBits > 0) {
55 int bitsToNotRead = 8 - numBits;
56 int mask = (0xFF >> bitsToNotRead) << bitsToNotRead;
57 result = (result << numBits) | ((_bytes[_byteOffset] & mask) >> bitsToNotRead);
58 _bitOffset += numBits;
59 }
60 }
61
62 return result;
63 }
64
65 int BitSource::readBits(int numBits)
66 {
67 return ReadBitsImpl(numBits, _bytes, available(), _byteOffset, _bitOffset);
68 }
69
70 int BitSource::peakBits(int numBits) const
71 {
72 int bitOffset = _bitOffset;
73 int byteOffset = _byteOffset;
74 return ReadBitsImpl(numBits, _bytes, available(), byteOffset, bitOffset);
75 }
76
77 } // ZXing