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comparison mupdf-source/thirdparty/brotli/c/enc/find_match_length.h @ 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 2010 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 /* Function to find maximal matching prefixes of strings. */
8
9 #ifndef BROTLI_ENC_FIND_MATCH_LENGTH_H_
10 #define BROTLI_ENC_FIND_MATCH_LENGTH_H_
11
12 #include <brotli/types.h>
13
14 #include "../common/platform.h"
15
16 #if defined(__cplusplus) || defined(c_plusplus)
17 extern "C" {
18 #endif
19
20 /* Separate implementation for little-endian 64-bit targets, for speed. */
21 #if defined(BROTLI_TZCNT64) && BROTLI_64_BITS && BROTLI_LITTLE_ENDIAN
22 static BROTLI_INLINE size_t FindMatchLengthWithLimit(const uint8_t* s1,
23 const uint8_t* s2,
24 size_t limit) {
25 const uint8_t *s1_orig = s1;
26 for (; limit >= 8; limit -= 8) {
27 uint64_t x = BROTLI_UNALIGNED_LOAD64LE(s2) ^
28 BROTLI_UNALIGNED_LOAD64LE(s1);
29 s2 += 8;
30 if (x != 0) {
31 size_t matching_bits = (size_t)BROTLI_TZCNT64(x);
32 return (size_t)(s1 - s1_orig) + (matching_bits >> 3);
33 }
34 s1 += 8;
35 }
36 while (limit && *s1 == *s2) {
37 limit--;
38 ++s2;
39 ++s1;
40 }
41 return (size_t)(s1 - s1_orig);
42 }
43 #else
44 static BROTLI_INLINE size_t FindMatchLengthWithLimit(const uint8_t* s1,
45 const uint8_t* s2,
46 size_t limit) {
47 size_t matched = 0;
48 const uint8_t* s2_limit = s2 + limit;
49 const uint8_t* s2_ptr = s2;
50 /* Find out how long the match is. We loop over the data 32 bits at a
51 time until we find a 32-bit block that doesn't match; then we find
52 the first non-matching bit and use that to calculate the total
53 length of the match. */
54 while (s2_ptr <= s2_limit - 4 &&
55 BrotliUnalignedRead32(s2_ptr) ==
56 BrotliUnalignedRead32(s1 + matched)) {
57 s2_ptr += 4;
58 matched += 4;
59 }
60 while ((s2_ptr < s2_limit) && (s1[matched] == *s2_ptr)) {
61 ++s2_ptr;
62 ++matched;
63 }
64 return matched;
65 }
66 #endif
67
68 #if defined(__cplusplus) || defined(c_plusplus)
69 } /* extern "C" */
70 #endif
71
72 #endif /* BROTLI_ENC_FIND_MATCH_LENGTH_H_ */