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109 lines
3.5 KiB
109 lines
3.5 KiB
12 months ago
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#ifndef INSERT_STRING_H_
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#define INSERT_STRING_H_
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/* insert_string.h -- Private insert_string functions shared with more than
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* one insert string implementation
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*
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* Copyright (C) 1995-2013 Jean-loup Gailly and Mark Adler
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*
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* Copyright (C) 2013 Intel Corporation. All rights reserved.
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* Authors:
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* Wajdi Feghali <wajdi.k.feghali@intel.com>
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* Jim Guilford <james.guilford@intel.com>
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* Vinodh Gopal <vinodh.gopal@intel.com>
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* Erdinc Ozturk <erdinc.ozturk@intel.com>
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* Jim Kukunas <james.t.kukunas@linux.intel.com>
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*
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* Portions are Copyright (C) 2016 12Sided Technology, LLC.
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* Author:
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* Phil Vachon <pvachon@12sidedtech.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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*/
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#ifndef HASH_CALC_OFFSET
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# define HASH_CALC_OFFSET 0
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#endif
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#ifndef HASH_CALC_MASK
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# define HASH_CALC_MASK HASH_MASK
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#endif
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#ifndef HASH_CALC_READ
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# if BYTE_ORDER == LITTLE_ENDIAN
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# define HASH_CALC_READ \
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memcpy(&val, strstart, sizeof(val));
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# else
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# define HASH_CALC_READ \
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val = ((uint32_t)(strstart[0])); \
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val |= ((uint32_t)(strstart[1]) << 8); \
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val |= ((uint32_t)(strstart[2]) << 16); \
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val |= ((uint32_t)(strstart[3]) << 24);
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# endif
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#endif
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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 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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Z_INTERNAL uint32_t UPDATE_HASH(deflate_state *const s, uint32_t h, uint32_t val) {
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(void)s;
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HASH_CALC(s, h, val);
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return h & HASH_CALC_MASK;
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}
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/* ===========================================================================
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* Quick insert string str in the dictionary and set match_head to the previous head
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* of the hash chain (the most recent string with same hash key). Return
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* the previous length of the hash chain.
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*/
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Z_INTERNAL Pos QUICK_INSERT_STRING(deflate_state *const s, uint32_t str) {
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Pos head;
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uint8_t *strstart = s->window + str + HASH_CALC_OFFSET;
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uint32_t val, hm;
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HASH_CALC_VAR_INIT;
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HASH_CALC_READ;
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HASH_CALC(s, HASH_CALC_VAR, val);
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HASH_CALC_VAR &= HASH_CALC_MASK;
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hm = HASH_CALC_VAR;
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head = s->head[hm];
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if (LIKELY(head != str)) {
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s->prev[str & s->w_mask] = head;
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s->head[hm] = (Pos)str;
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}
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return head;
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}
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/* ===========================================================================
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* Insert string str in the dictionary and set match_head to the previous head
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* of the hash chain (the most recent string with same hash key). Return
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* the previous length of the hash chain.
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* IN assertion: all calls to INSERT_STRING are made with consecutive
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* input characters and the first STD_MIN_MATCH bytes of str are valid
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* (except for the last STD_MIN_MATCH-1 bytes of the input file).
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*/
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Z_INTERNAL void INSERT_STRING(deflate_state *const s, uint32_t str, uint32_t count) {
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uint8_t *strstart = s->window + str + HASH_CALC_OFFSET;
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uint8_t *strend = strstart + count;
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for (Pos idx = (Pos)str; strstart < strend; idx++, strstart++) {
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uint32_t val, hm;
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HASH_CALC_VAR_INIT;
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HASH_CALC_READ;
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HASH_CALC(s, HASH_CALC_VAR, val);
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HASH_CALC_VAR &= HASH_CALC_MASK;
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hm = HASH_CALC_VAR;
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Pos head = s->head[hm];
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if (LIKELY(head != idx)) {
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s->prev[idx & s->w_mask] = head;
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s->head[hm] = idx;
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}
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}
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}
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#endif
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