178 строки
6.3 KiB
C
178 строки
6.3 KiB
C
#ifndef ARCH_ARM
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/*
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* Fill Window with SSE2-optimized hash shifting
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*
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* Copyright (C) 2013 Intel Corporation
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* Authors:
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* Arjan van de Ven <arjan@linux.intel.com>
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* Jim Kukunas <james.t.kukunas@linux.intel.com>
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*
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* For conditions of distribution and use, see copyright notice in zlib.h
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*/
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#include <immintrin.h>
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#include "deflate.h"
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#define UPDATE_HASH(s,h,i) \
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{\
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if (s->level < 6) { \
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h = (3483 * (s->window[i]) +\
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23081* (s->window[i+1]) +\
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6954 * (s->window[i+2]) +\
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20947* (s->window[i+3])) & s->hash_mask;\
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} else {\
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h = (25881* (s->window[i]) +\
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24674* (s->window[i+1]) +\
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25811* (s->window[i+2])) & s->hash_mask;\
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}\
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}\
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extern int read_buf OF((z_streamp strm, Bytef *buf, unsigned size));
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void fill_window_sse(deflate_state *s)
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{
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const __m128i xmm_wsize = _mm_set1_epi16(s->w_size);
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register unsigned n;
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register Posf *p;
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unsigned more; /* Amount of free space at the end of the window. */
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uInt wsize = s->w_size;
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Assert(s->lookahead < MIN_LOOKAHEAD, "already enough lookahead");
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do {
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more = (unsigned)(s->window_size -(ulg)s->lookahead -(ulg)s->strstart);
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/* Deal with !@#$% 64K limit: */
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if (sizeof(int) <= 2) {
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if (more == 0 && s->strstart == 0 && s->lookahead == 0) {
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more = wsize;
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} else if (more == (unsigned)(-1)) {
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/* Very unlikely, but possible on 16 bit machine if
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* strstart == 0 && lookahead == 1 (input done a byte at time)
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*/
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more--;
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}
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}
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/* If the window is almost full and there is insufficient lookahead,
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* move the upper half to the lower one to make room in the upper half.
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*/
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if (s->strstart >= wsize+MAX_DIST(s)) {
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zmemcpy(s->window, s->window+wsize, (unsigned)wsize);
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s->match_start -= wsize;
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s->strstart -= wsize; /* we now have strstart >= MAX_DIST */
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s->block_start -= (long) wsize;
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/* Slide the hash table (could be avoided with 32 bit values
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at the expense of memory usage). We slide even when level == 0
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to keep the hash table consistent if we switch back to level > 0
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later. (Using level 0 permanently is not an optimal usage of
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zlib, so we don't care about this pathological case.)
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*/
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n = s->hash_size;
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p = &s->head[n];
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p -= 8;
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do {
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__m128i value, result;
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value = _mm_loadu_si128((__m128i *)p);
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result = _mm_subs_epu16(value, xmm_wsize);
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_mm_storeu_si128((__m128i *)p, result);
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p -= 8;
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n -= 8;
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} while (n > 0);
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n = wsize;
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#ifndef FASTEST
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p = &s->prev[n];
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p -= 8;
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do {
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__m128i value, result;
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value = _mm_loadu_si128((__m128i *)p);
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result = _mm_subs_epu16(value, xmm_wsize);
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_mm_storeu_si128((__m128i *)p, result);
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p -= 8;
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n -= 8;
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} while (n > 0);
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#endif
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more += wsize;
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}
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if (s->strm->avail_in == 0) break;
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/* If there was no sliding:
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* strstart <= WSIZE+MAX_DIST-1 && lookahead <= MIN_LOOKAHEAD - 1 &&
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* more == window_size - lookahead - strstart
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* => more >= window_size - (MIN_LOOKAHEAD-1 + WSIZE + MAX_DIST-1)
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* => more >= window_size - 2*WSIZE + 2
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* In the BIG_MEM or MMAP case (not yet supported),
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* window_size == input_size + MIN_LOOKAHEAD &&
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* strstart + s->lookahead <= input_size => more >= MIN_LOOKAHEAD.
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* Otherwise, window_size == 2*WSIZE so more >= 2.
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* If there was sliding, more >= WSIZE. So in all cases, more >= 2.
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*/
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Assert(more >= 2, "more < 2");
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n = read_buf(s->strm, s->window + s->strstart + s->lookahead, more);
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s->lookahead += n;
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/* Initialize the hash value now that we have some input: */
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if (s->lookahead >= MIN_MATCH) {
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uInt str = s->strstart;
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s->ins_h = s->window[str];
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if (str >= 1)
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UPDATE_HASH(s, s->ins_h, str + 1 - (MIN_MATCH-1));
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#if MIN_MATCH != 3
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Call UPDATE_HASH() MIN_MATCH-3 more times
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#endif
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}
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/* If the whole input has less than MIN_MATCH bytes, ins_h is garbage,
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* but this is not important since only literal bytes will be emitted.
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*/
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} while (s->lookahead < MIN_LOOKAHEAD && s->strm->avail_in != 0);
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/* If the WIN_INIT bytes after the end of the current data have never been
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* written, then zero those bytes in order to avoid memory check reports of
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* the use of uninitialized (or uninitialised as Julian writes) bytes by
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* the longest match routines. Update the high water mark for the next
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* time through here. WIN_INIT is set to MAX_MATCH since the longest match
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* routines allow scanning to strstart + MAX_MATCH, ignoring lookahead.
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*/
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if (s->high_water < s->window_size) {
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ulg curr = s->strstart + (ulg)(s->lookahead);
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ulg init;
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if (s->high_water < curr) {
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/* Previous high water mark below current data -- zero WIN_INIT
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* bytes or up to end of window, whichever is less.
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*/
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init = s->window_size - curr;
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if (init > WIN_INIT)
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init = WIN_INIT;
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zmemzero(s->window + curr, (unsigned)init);
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s->high_water = curr + init;
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}
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else if (s->high_water < (ulg)curr + WIN_INIT) {
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/* High water mark at or above current data, but below current data
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* plus WIN_INIT -- zero out to current data plus WIN_INIT, or up
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* to end of window, whichever is less.
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*/
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init = (ulg)curr + WIN_INIT - s->high_water;
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if (init > s->window_size - s->high_water)
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init = s->window_size - s->high_water;
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zmemzero(s->window + s->high_water, (unsigned)init);
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s->high_water += init;
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}
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}
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Assert((ulg)s->strstart <= s->window_size - MIN_LOOKAHEAD,
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"not enough room for search");
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}
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#endif
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