mirror of https://github.com/acidanthera/audk.git
81 lines
2.5 KiB
C
81 lines
2.5 KiB
C
|
/* Copyright 2010 Google Inc. All Rights Reserved.
|
||
|
|
|
||
|
|
Distributed under MIT license.
|
||
|
|
See file LICENSE for detail or copy at https://opensource.org/licenses/MIT
|
||
|
|
*/
|
||
|
|
|
||
|
|
/* Function to find maximal matching prefixes of strings. */
|
||
|
|
|
||
|
|
#ifndef BROTLI_ENC_FIND_MATCH_LENGTH_H_
|
||
|
|
#define BROTLI_ENC_FIND_MATCH_LENGTH_H_
|
||
|
|
|
||
|
|
#include "../common/types.h"
|
||
|
|
#include "./port.h"
|
||
|
|
|
||
|
|
#if defined(__cplusplus) || defined(c_plusplus)
|
||
|
|
extern "C" {
|
||
|
|
#endif
|
||
|
|
|
||
|
|
/* Separate implementation for little-endian 64-bit targets, for speed. */
|
||
|
|
#if defined(__GNUC__) && defined(_LP64) && defined(IS_LITTLE_ENDIAN)
|
||
|
|
|
||
|
|
static BROTLI_INLINE size_t FindMatchLengthWithLimit(const uint8_t* s1,
|
||
|
|
const uint8_t* s2,
|
||
|
|
size_t limit) {
|
||
|
|
size_t matched = 0;
|
||
|
|
size_t limit2 = (limit >> 3) + 1; /* + 1 is for pre-decrement in while */
|
||
|
|
while (PREDICT_TRUE(--limit2)) {
|
||
|
|
if (PREDICT_FALSE(BROTLI_UNALIGNED_LOAD64(s2) ==
|
||
|
|
BROTLI_UNALIGNED_LOAD64(s1 + matched))) {
|
||
|
|
s2 += 8;
|
||
|
|
matched += 8;
|
||
|
|
} else {
|
||
|
|
uint64_t x =
|
||
|
|
BROTLI_UNALIGNED_LOAD64(s2) ^ BROTLI_UNALIGNED_LOAD64(s1 + matched);
|
||
|
|
size_t matching_bits = (size_t)__builtin_ctzll(x);
|
||
|
|
matched += matching_bits >> 3;
|
||
|
|
return matched;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
limit = (limit & 7) + 1; /* + 1 is for pre-decrement in while */
|
||
|
|
while (--limit) {
|
||
|
|
if (PREDICT_TRUE(s1[matched] == *s2)) {
|
||
|
|
++s2;
|
||
|
|
++matched;
|
||
|
|
} else {
|
||
|
|
return matched;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
return matched;
|
||
|
|
}
|
||
|
|
#else
|
||
|
|
static BROTLI_INLINE size_t FindMatchLengthWithLimit(const uint8_t* s1,
|
||
|
|
const uint8_t* s2,
|
||
|
|
size_t limit) {
|
||
|
|
size_t matched = 0;
|
||
|
|
const uint8_t* s2_limit = s2 + limit;
|
||
|
|
const uint8_t* s2_ptr = s2;
|
||
|
|
/* Find out how long the match is. We loop over the data 32 bits at a
|
||
|
|
time until we find a 32-bit block that doesn't match; then we find
|
||
|
|
the first non-matching bit and use that to calculate the total
|
||
|
|
length of the match. */
|
||
|
|
while (s2_ptr <= s2_limit - 4 &&
|
||
|
|
BROTLI_UNALIGNED_LOAD32(s2_ptr) ==
|
||
|
|
BROTLI_UNALIGNED_LOAD32(s1 + matched)) {
|
||
|
|
s2_ptr += 4;
|
||
|
|
matched += 4;
|
||
|
|
}
|
||
|
|
while ((s2_ptr < s2_limit) && (s1[matched] == *s2_ptr)) {
|
||
|
|
++s2_ptr;
|
||
|
|
++matched;
|
||
|
|
}
|
||
|
|
return matched;
|
||
|
|
}
|
||
|
|
#endif
|
||
|
|
|
||
|
|
#if defined(__cplusplus) || defined(c_plusplus)
|
||
|
|
} /* extern "C" */
|
||
|
|
#endif
|
||
|
|
|
||
|
|
#endif /* BROTLI_ENC_FIND_MATCH_LENGTH_H_ */
|