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| 1 /* | |
| 2 * Fill Window with SSE2-optimized hash shifting | |
| 3 * | |
| 4 * Copyright (C) 2013 Intel Corporation | |
| 5 * Authors: | |
| 6 * Arjan van de Ven <arjan@linux.intel.com> | |
| 7 * Jim Kukunas <james.t.kukunas@linux.intel.com> | |
| 8 * | |
| 9 * For conditions of distribution and use, see copyright notice in zlib.h | |
| 10 */ | |
| 11 | |
| 12 #include <immintrin.h> | |
| 13 #include "deflate.h" | |
| 14 | |
| 15 #define UPDATE_HASH(s,h,i) \ | |
| 16 {\ | |
| 17 if (s->level < 6) { \ | |
| 18 h = (3483 * (s->window[i]) +\ | |
| 19 23081* (s->window[i+1]) +\ | |
| 20 6954 * (s->window[i+2]) +\ | |
| 21 20947* (s->window[i+3])) & s->hash_mask;\ | |
| 22 } else {\ | |
| 23 h = (25881* (s->window[i]) +\ | |
| 24 24674* (s->window[i+1]) +\ | |
| 25 25811* (s->window[i+2])) & s->hash_mask;\ | |
| 26 }\ | |
| 27 }\ | |
| 28 | |
| 29 extern int read_buf OF((z_streamp strm, Bytef *buf, unsigned size)); | |
| 30 | |
| 31 void fill_window_sse(deflate_state *s) | |
| 32 { | |
| 33 const __m128i xmm_wsize = _mm_set1_epi16(s->w_size); | |
| 34 | |
| 35 register unsigned n; | |
| 36 register Posf *p; | |
| 37 unsigned more; /* Amount of free space at the end of the window. */ | |
| 38 uInt wsize = s->w_size; | |
| 39 | |
| 40 Assert(s->lookahead < MIN_LOOKAHEAD, "already enough lookahead"); | |
| 41 | |
| 42 do { | |
| 43 more = (unsigned)(s->window_size -(ulg)s->lookahead -(ulg)s->strstart); | |
| 44 | |
| 45 /* Deal with !@#$% 64K limit: */ | |
| 46 if (sizeof(int) <= 2) { | |
| 47 if (more == 0 && s->strstart == 0 && s->lookahead == 0) { | |
| 48 more = wsize; | |
| 49 | |
| 50 } else if (more == (unsigned)(-1)) { | |
| 51 /* Very unlikely, but possible on 16 bit machine if | |
| 52 * strstart == 0 && lookahead == 1 (input done a byte at time) | |
| 53 */ | |
| 54 more--; | |
| 55 } | |
| 56 } | |
| 57 | |
| 58 /* If the window is almost full and there is insufficient lookahead, | |
| 59 * move the upper half to the lower one to make room in the upper half. | |
| 60 */ | |
| 61 if (s->strstart >= wsize+MAX_DIST(s)) { | |
| 62 | |
| 63 zmemcpy(s->window, s->window+wsize, (unsigned)wsize); | |
| 64 s->match_start -= wsize; | |
| 65 s->strstart -= wsize; /* we now have strstart >= MAX_DIST */ | |
| 66 s->block_start -= (long) wsize; | |
| 67 | |
| 68 /* Slide the hash table (could be avoided with 32 bit values | |
| 69 at the expense of memory usage). We slide even when level == 0 | |
| 70 to keep the hash table consistent if we switch back to level > 0 | |
| 71 later. (Using level 0 permanently is not an optimal usage of | |
| 72 zlib, so we don't care about this pathological case.) | |
| 73 */ | |
| 74 n = s->hash_size; | |
| 75 p = &s->head[n]; | |
| 76 p -= 8; | |
| 77 do { | |
| 78 __m128i value, result; | |
| 79 | |
| 80 value = _mm_loadu_si128((__m128i *)p); | |
| 81 result = _mm_subs_epu16(value, xmm_wsize); | |
| 82 _mm_storeu_si128((__m128i *)p, result); | |
| 83 | |
| 84 p -= 8; | |
| 85 n -= 8; | |
| 86 } while (n > 0); | |
| 87 | |
| 88 n = wsize; | |
| 89 #ifndef FASTEST | |
| 90 p = &s->prev[n]; | |
| 91 p -= 8; | |
| 92 do { | |
| 93 __m128i value, result; | |
| 94 | |
| 95 value = _mm_loadu_si128((__m128i *)p); | |
| 96 result = _mm_subs_epu16(value, xmm_wsize); | |
| 97 _mm_storeu_si128((__m128i *)p, result); | |
| 98 | |
| 99 p -= 8; | |
| 100 n -= 8; | |
| 101 } while (n > 0); | |
| 102 #endif | |
| 103 more += wsize; | |
| 104 } | |
| 105 if (s->strm->avail_in == 0) break; | |
| 106 | |
| 107 /* If there was no sliding: | |
| 108 * strstart <= WSIZE+MAX_DIST-1 && lookahead <= MIN_LOOKAHEAD - 1 && | |
| 109 * more == window_size - lookahead - strstart | |
| 110 * => more >= window_size - (MIN_LOOKAHEAD-1 + WSIZE + MAX_DIST-1) | |
| 111 * => more >= window_size - 2*WSIZE + 2 | |
| 112 * In the BIG_MEM or MMAP case (not yet supported), | |
| 113 * window_size == input_size + MIN_LOOKAHEAD && | |
| 114 * strstart + s->lookahead <= input_size => more >= MIN_LOOKAHEAD. | |
| 115 * Otherwise, window_size == 2*WSIZE so more >= 2. | |
| 116 * If there was sliding, more >= WSIZE. So in all cases, more >= 2. | |
| 117 */ | |
| 118 Assert(more >= 2, "more < 2"); | |
| 119 | |
| 120 n = read_buf(s->strm, s->window + s->strstart + s->lookahead, more); | |
| 121 s->lookahead += n; | |
| 122 | |
| 123 /* Initialize the hash value now that we have some input: */ | |
| 124 if (s->lookahead >= MIN_MATCH) { | |
| 125 uInt str = s->strstart; | |
| 126 s->ins_h = s->window[str]; | |
| 127 if (str >= 1) | |
| 128 UPDATE_HASH(s, s->ins_h, str + 1 - (MIN_MATCH-1)); | |
| 129 #if MIN_MATCH != 3 | |
| 130 Call UPDATE_HASH() MIN_MATCH-3 more times | |
| 131 #endif | |
| 132 } | |
| 133 /* If the whole input has less than MIN_MATCH bytes, ins_h is garbage, | |
| 134 * but this is not important since only literal bytes will be emitted. | |
| 135 */ | |
| 136 | |
| 137 } while (s->lookahead < MIN_LOOKAHEAD && s->strm->avail_in != 0); | |
| 138 | |
| 139 /* If the WIN_INIT bytes after the end of the current data have never been | |
| 140 * written, then zero those bytes in order to avoid memory check reports of | |
| 141 * the use of uninitialized (or uninitialised as Julian writes) bytes by | |
| 142 * the longest match routines. Update the high water mark for the next | |
| 143 * time through here. WIN_INIT is set to MAX_MATCH since the longest match | |
| 144 * routines allow scanning to strstart + MAX_MATCH, ignoring lookahead. | |
| 145 */ | |
| 146 if (s->high_water < s->window_size) { | |
| 147 ulg curr = s->strstart + (ulg)(s->lookahead); | |
| 148 ulg init; | |
| 149 | |
| 150 if (s->high_water < curr) { | |
| 151 /* Previous high water mark below current data -- zero WIN_INIT | |
| 152 * bytes or up to end of window, whichever is less. | |
| 153 */ | |
| 154 init = s->window_size - curr; | |
| 155 if (init > WIN_INIT) | |
| 156 init = WIN_INIT; | |
| 157 zmemzero(s->window + curr, (unsigned)init); | |
| 158 s->high_water = curr + init; | |
| 159 } | |
| 160 else if (s->high_water < (ulg)curr + WIN_INIT) { | |
| 161 /* High water mark at or above current data, but below current data | |
| 162 * plus WIN_INIT -- zero out to current data plus WIN_INIT, or up | |
| 163 * to end of window, whichever is less. | |
| 164 */ | |
| 165 init = (ulg)curr + WIN_INIT - s->high_water; | |
| 166 if (init > s->window_size - s->high_water) | |
| 167 init = s->window_size - s->high_water; | |
| 168 zmemzero(s->window + s->high_water, (unsigned)init); | |
| 169 s->high_water += init; | |
| 170 } | |
| 171 } | |
| 172 | |
| 173 Assert((ulg)s->strstart <= s->window_size - MIN_LOOKAHEAD, | |
| 174 "not enough room for search"); | |
| 175 } | |
| OLD | NEW |
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Chromium Code Reviews
Issue 665203006:
Revert of Reland "Integrate SIMD optimisations for zlib" (Closed)
Base URL: https://chromium.googlesource.com/chromium/src.git@master