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0de26fd78e
Zlib-ng is zlib replacement with optimizations for "next generation" systems. Its optimization may benifits image library decode and encode speed such as libpng. In our tests, if using zlib-ng and libpng combination on a x86_64 machine with AVX2, the time of `imdecode` amd `imencode` will drop 20% approximately. This patch enables zlib-ng's optimization if `CV_DISABLE_OPTIMIZATION` is OFF. Since Zlib-ng can dispatch intrinsics on the fly, port work is much easier. Related discussion: https://github.com/opencv/opencv/issues/22573
53 lines
1.8 KiB
C
53 lines
1.8 KiB
C
/* slide_hash.c -- slide hash table C implementation
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*
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* Copyright (C) 1995-2013 Jean-loup Gailly and Mark Adler
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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 "zbuild.h"
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#include "deflate.h"
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/* ===========================================================================
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* Slide the hash table when sliding the window down (could be avoided with 32
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* bit values at the expense of memory usage). We slide even when level == 0 to
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* keep the hash table consistent if we switch back to level > 0 later.
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*/
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static inline void slide_hash_c_chain(Pos *table, uint32_t entries, uint16_t wsize) {
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#ifdef NOT_TWEAK_COMPILER
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table += entries;
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do {
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unsigned m;
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m = *--table;
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*table = (Pos)(m >= wsize ? m-wsize : 0);
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/* If entries is not on any hash chain, prev[entries] is garbage but
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* its value will never be used.
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*/
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} while (--entries);
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#else
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{
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/* As of I make this change, gcc (4.8.*) isn't able to vectorize
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* this hot loop using saturated-subtraction on x86-64 architecture.
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* To avoid this defect, we can change the loop such that
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* o. the pointer advance forward, and
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* o. demote the variable 'm' to be local to the loop, and
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* choose type "Pos" (instead of 'unsigned int') for the
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* variable to avoid unnecessary zero-extension.
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*/
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unsigned int i;
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Pos *q = table;
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for (i = 0; i < entries; i++) {
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Pos m = *q;
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Pos t = (Pos)wsize;
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*q++ = (Pos)(m >= t ? m-t: 0);
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}
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}
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#endif /* NOT_TWEAK_COMPILER */
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}
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Z_INTERNAL void slide_hash_c(deflate_state *s) {
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uint16_t wsize = (uint16_t)s->w_size;
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slide_hash_c_chain(s->head, HASH_SIZE, wsize);
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slide_hash_c_chain(s->prev, wsize, wsize);
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}
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