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https://github.com/GerbilSoft/zlib-ng.git
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0129e88cee
From commit d306c75d3b:
.. we hash 4 bytes, instead of 3, for certain levels. This shortens the hash chains, and also improves the quality
of each hash entry.
33 lines
1.1 KiB
C
33 lines
1.1 KiB
C
/* insert_string_c -- insert_string variant for c
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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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*/
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#include "zbuild.h"
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#include "deflate.h"
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/* ===========================================================================
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* Update a hash value with the given input byte
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* IN assertion: all calls to to UPDATE_HASH are made with consecutive
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* input characters, so that a running hash key can be computed from the
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* previous key instead of complete recalculation each time.
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*/
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#if defined(__x86_64__) || defined(_M_X64) || defined(__i386) || defined(_M_IX86)
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# define UPDATE_HASH(s, h, val) \
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h = (3483 * ((val) & 0xff) +\
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23081 * (((val) >> 8) & 0xff) +\
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6954 * (((val) >> 16) & 0xff) +\
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20947 * (((val) >> 24) & 0xff));
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#else
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# define UPDATE_HASH(s, h, val)\
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h = (s->ins_h = ((s->ins_h << s->hash_shift) ^ ((val) >> ((MIN_MATCH - 1) * 8))) & s->hash_mask)
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#endif
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#define INSERT_STRING insert_string_c
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#define QUICK_INSERT_STRING quick_insert_string_c
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#include "insert_string_tpl.h"
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