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Side by Side Diff: third_party/brotli/enc/find_match_length.h

Issue 2537133002: Update brotli to v1.0.0-snapshot. (Closed)
Patch Set: Fixed typo Created 4 years ago
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1 /* Copyright 2010 Google Inc. All Rights Reserved. 1 /* Copyright 2010 Google Inc. All Rights Reserved.
2 2
3 Distributed under MIT license. 3 Distributed under MIT license.
4 See file LICENSE for detail or copy at https://opensource.org/licenses/MIT 4 See file LICENSE for detail or copy at https://opensource.org/licenses/MIT
5 */ 5 */
6 6
7 // Function to find maximal matching prefixes of strings. 7 /* Function to find maximal matching prefixes of strings. */
8 8
9 #ifndef BROTLI_ENC_FIND_MATCH_LENGTH_H_ 9 #ifndef BROTLI_ENC_FIND_MATCH_LENGTH_H_
10 #define BROTLI_ENC_FIND_MATCH_LENGTH_H_ 10 #define BROTLI_ENC_FIND_MATCH_LENGTH_H_
11 11
12 #include <brotli/types.h>
13 #include "./port.h"
12 14
13 #include "./port.h" 15 #if defined(__cplusplus) || defined(c_plusplus)
14 #include "./types.h" 16 extern "C" {
17 #endif
15 18
16 namespace brotli { 19 /* Separate implementation for little-endian 64-bit targets, for speed. */
17
18 // Separate implementation for little-endian 64-bit targets, for speed.
19 #if defined(__GNUC__) && defined(_LP64) && defined(IS_LITTLE_ENDIAN) 20 #if defined(__GNUC__) && defined(_LP64) && defined(IS_LITTLE_ENDIAN)
20 21
21 static inline size_t FindMatchLengthWithLimit(const uint8_t* s1, 22 static BROTLI_INLINE size_t FindMatchLengthWithLimit(const uint8_t* s1,
22 const uint8_t* s2, 23 const uint8_t* s2,
23 size_t limit) { 24 size_t limit) {
24 size_t matched = 0; 25 size_t matched = 0;
25 size_t limit2 = (limit >> 3) + 1; // + 1 is for pre-decrement in while 26 size_t limit2 = (limit >> 3) + 1; /* + 1 is for pre-decrement in while */
26 while (PREDICT_TRUE(--limit2)) { 27 while (BROTLI_PREDICT_TRUE(--limit2)) {
27 if (PREDICT_FALSE(BROTLI_UNALIGNED_LOAD64(s2) == 28 if (BROTLI_PREDICT_FALSE(BROTLI_UNALIGNED_LOAD64(s2) ==
28 BROTLI_UNALIGNED_LOAD64(s1 + matched))) { 29 BROTLI_UNALIGNED_LOAD64(s1 + matched))) {
29 s2 += 8; 30 s2 += 8;
30 matched += 8; 31 matched += 8;
31 } else { 32 } else {
32 uint64_t x = 33 uint64_t x =
33 BROTLI_UNALIGNED_LOAD64(s2) ^ BROTLI_UNALIGNED_LOAD64(s1 + matched); 34 BROTLI_UNALIGNED_LOAD64(s2) ^ BROTLI_UNALIGNED_LOAD64(s1 + matched);
34 size_t matching_bits = static_cast<size_t>(__builtin_ctzll(x)); 35 size_t matching_bits = (size_t)__builtin_ctzll(x);
35 matched += matching_bits >> 3; 36 matched += matching_bits >> 3;
36 return matched; 37 return matched;
37 } 38 }
38 } 39 }
39 limit = (limit & 7) + 1; // + 1 is for pre-decrement in while 40 limit = (limit & 7) + 1; /* + 1 is for pre-decrement in while */
40 while (--limit) { 41 while (--limit) {
41 if (PREDICT_TRUE(s1[matched] == *s2)) { 42 if (BROTLI_PREDICT_TRUE(s1[matched] == *s2)) {
42 ++s2; 43 ++s2;
43 ++matched; 44 ++matched;
44 } else { 45 } else {
45 return matched; 46 return matched;
46 } 47 }
47 } 48 }
48 return matched; 49 return matched;
49 } 50 }
50 #else 51 #else
51 static inline size_t FindMatchLengthWithLimit(const uint8_t* s1, 52 static BROTLI_INLINE size_t FindMatchLengthWithLimit(const uint8_t* s1,
52 const uint8_t* s2, 53 const uint8_t* s2,
53 size_t limit) { 54 size_t limit) {
54 size_t matched = 0; 55 size_t matched = 0;
55 const uint8_t* s2_limit = s2 + limit; 56 const uint8_t* s2_limit = s2 + limit;
56 const uint8_t* s2_ptr = s2; 57 const uint8_t* s2_ptr = s2;
57 // Find out how long the match is. We loop over the data 32 bits at a 58 /* Find out how long the match is. We loop over the data 32 bits at a
58 // time until we find a 32-bit block that doesn't match; then we find 59 time until we find a 32-bit block that doesn't match; then we find
59 // the first non-matching bit and use that to calculate the total 60 the first non-matching bit and use that to calculate the total
60 // length of the match. 61 length of the match. */
61 while (s2_ptr <= s2_limit - 4 && 62 while (s2_ptr <= s2_limit - 4 &&
62 BROTLI_UNALIGNED_LOAD32(s2_ptr) == 63 BROTLI_UNALIGNED_LOAD32(s2_ptr) ==
63 BROTLI_UNALIGNED_LOAD32(s1 + matched)) { 64 BROTLI_UNALIGNED_LOAD32(s1 + matched)) {
64 s2_ptr += 4; 65 s2_ptr += 4;
65 matched += 4; 66 matched += 4;
66 } 67 }
67 while ((s2_ptr < s2_limit) && (s1[matched] == *s2_ptr)) { 68 while ((s2_ptr < s2_limit) && (s1[matched] == *s2_ptr)) {
68 ++s2_ptr; 69 ++s2_ptr;
69 ++matched; 70 ++matched;
70 } 71 }
71 return matched; 72 return matched;
72 } 73 }
73 #endif 74 #endif
74 75
75 } // namespace brotli 76 #if defined(__cplusplus) || defined(c_plusplus)
77 } /* extern "C" */
78 #endif
76 79
77 #endif // BROTLI_ENC_FIND_MATCH_LENGTH_H_ 80 #endif /* BROTLI_ENC_FIND_MATCH_LENGTH_H_ */
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