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comparison mupdf-source/thirdparty/brotli/c/dec/bit_reader.c @ 2:b50eed0cc0ef upstream

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ADD: MuPDF v1.26.7: the MuPDF source as downloaded by a default build of PyMuPDF 1.26.4. The directory name has changed: no version number in the expanded directory now.
author Franz Glasner <fzglas.hg@dom66.de>
date Mon, 15 Sep 2025 11:43:07 +0200
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1:1d09e1dec1d9 2:b50eed0cc0ef
1 /* Copyright 2013 Google Inc. All Rights Reserved.
2
3 Distributed under MIT license.
4 See file LICENSE for detail or copy at https://opensource.org/licenses/MIT
5 */
6
7 /* Bit reading helpers */
8
9 #include "bit_reader.h"
10
11 #include <brotli/types.h>
12
13 #include "../common/platform.h"
14
15 #if defined(__cplusplus) || defined(c_plusplus)
16 extern "C" {
17 #endif
18
19 const brotli_reg_t kBrotliBitMask[33] = { 0x00000000,
20 0x00000001, 0x00000003, 0x00000007, 0x0000000F,
21 0x0000001F, 0x0000003F, 0x0000007F, 0x000000FF,
22 0x000001FF, 0x000003FF, 0x000007FF, 0x00000FFF,
23 0x00001FFF, 0x00003FFF, 0x00007FFF, 0x0000FFFF,
24 0x0001FFFF, 0x0003FFFF, 0x0007FFFF, 0x000FFFFF,
25 0x001FFFFF, 0x003FFFFF, 0x007FFFFF, 0x00FFFFFF,
26 0x01FFFFFF, 0x03FFFFFF, 0x07FFFFFF, 0x0FFFFFFF,
27 0x1FFFFFFF, 0x3FFFFFFF, 0x7FFFFFFF, 0xFFFFFFFF
28 };
29
30 void BrotliInitBitReader(BrotliBitReader* const br) {
31 br->val_ = 0;
32 br->bit_pos_ = 0;
33 }
34
35 BROTLI_BOOL BrotliWarmupBitReader(BrotliBitReader* const br) {
36 size_t aligned_read_mask = (sizeof(br->val_) >> 1) - 1;
37 /* Fixing alignment after unaligned BrotliFillWindow would result accumulator
38 overflow. If unalignment is caused by BrotliSafeReadBits, then there is
39 enough space in accumulator to fix alignment. */
40 if (BROTLI_UNALIGNED_READ_FAST) {
41 aligned_read_mask = 0;
42 }
43 if (BrotliGetAvailableBits(br) == 0) {
44 br->val_ = 0;
45 if (!BrotliPullByte(br)) {
46 return BROTLI_FALSE;
47 }
48 }
49
50 while ((((size_t)br->next_in) & aligned_read_mask) != 0) {
51 if (!BrotliPullByte(br)) {
52 /* If we consumed all the input, we don't care about the alignment. */
53 return BROTLI_TRUE;
54 }
55 }
56 return BROTLI_TRUE;
57 }
58
59 BROTLI_BOOL BrotliSafeReadBits32Slow(BrotliBitReader* const br,
60 brotli_reg_t n_bits, brotli_reg_t* val) {
61 brotli_reg_t low_val;
62 brotli_reg_t high_val;
63 BrotliBitReaderState memento;
64 BROTLI_DCHECK(n_bits <= 32);
65 BROTLI_DCHECK(n_bits > 24);
66 BrotliBitReaderSaveState(br, &memento);
67 if (!BrotliSafeReadBits(br, 16, &low_val) ||
68 !BrotliSafeReadBits(br, n_bits - 16, &high_val)) {
69 BrotliBitReaderRestoreState(br, &memento);
70 return BROTLI_FALSE;
71 }
72 *val = low_val | (high_val << 16);
73 return BROTLI_TRUE;
74 }
75
76 #if defined(__cplusplus) || defined(c_plusplus)
77 } /* extern "C" */
78 #endif