/src/c-blosc2/internal-complibs/zlib-ng-2.0.7/deflate_medium.c

Source
/* deflate_medium.c -- The deflate_medium deflate strategy
 *
 * Copyright (C) 2013 Intel Corporation. All rights reserved.
 * Authors:
 *  Arjan van de Ven    <arjan@linux.intel.com>
 *
 * For conditions of distribution and use, see copyright notice in zlib.h
 */
#ifndef NO_MEDIUM_STRATEGY
#include <stdint.h>
#include "zbuild.h"
#include "deflate.h"
#include "deflate_p.h"
#include "functable.h"

struct match {
    uint16_t match_start;
    uint16_t match_length;
    uint16_t strstart;
    uint16_t orgstart;
};

static int emit_match(deflate_state *s, struct match match) {
    int bflush = 0;

    /* matches that are not long enough we need to emit as literals */
    if (match.match_length < MIN_MATCH) {
        while (match.match_length) {
            bflush += zng_tr_tally_lit(s, s->window[match.strstart]);
            s->lookahead--;
            match.strstart++;
            match.match_length--;
        }
        return bflush;
    }

    check_match(s, match.strstart, match.match_start, match.match_length);

    bflush += zng_tr_tally_dist(s, match.strstart - match.match_start, match.match_length - MIN_MATCH);

    s->lookahead -= match.match_length;
    return bflush;
}

static void insert_match(deflate_state *s, struct match match) {
    if (UNLIKELY(s->lookahead <= (unsigned int)(match.match_length + MIN_MATCH)))
        return;

    /* matches that are not long enough we need to emit as literals */
    if (LIKELY(match.match_length < MIN_MATCH)) {
        match.strstart++;
        match.match_length--;
        if (UNLIKELY(match.match_length > 0)) {
            if (match.strstart >= match.orgstart) {
                if (match.strstart + match.match_length - 1 >= match.orgstart) {
                    functable.insert_string(s, match.strstart, match.match_length);
                } else {
                    functable.insert_string(s, match.strstart, match.orgstart - match.strstart + 1);
                }
                match.strstart += match.match_length;
                match.match_length = 0;
            }
        }
        return;
    }

    /* Insert new strings in the hash table only if the match length
     * is not too large. This saves time but degrades compression.
     */
    if (match.match_length <= 16* s->max_insert_length && s->lookahead >= MIN_MATCH) {
        match.match_length--; /* string at strstart already in table */
        match.strstart++;

        if (LIKELY(match.strstart >= match.orgstart)) {
            if (LIKELY(match.strstart + match.match_length - 1 >= match.orgstart)) {
                functable.insert_string(s, match.strstart, match.match_length);
            } else {
                functable.insert_string(s, match.strstart, match.orgstart - match.strstart + 1);
            }
        } else if (match.orgstart < match.strstart + match.match_length) {
            functable.insert_string(s, match.orgstart, match.strstart + match.match_length - match.orgstart);
        }
        match.strstart += match.match_length;
        match.match_length = 0;
    } else {
        match.strstart += match.match_length;
        match.match_length = 0;
        if (match.strstart >= (MIN_MATCH - 2))
#if MIN_MATCH != 3
            functable.insert_string(s, match.strstart + 2 - MIN_MATCH, MIN_MATCH - 2);
#else
            functable.quick_insert_string(s, match.strstart + 2 - MIN_MATCH);
#endif
        /* If lookahead < MIN_MATCH, ins_h is garbage, but it does not
         * matter since it will be recomputed at next deflate call.
         */
    }
}

static void fizzle_matches(deflate_state *s, struct match *current, struct match *next) {
    Pos limit;
    unsigned char *match, *orig;
    int changed = 0;
    struct match c, n;
    /* step zero: sanity checks */

    if (current->match_length <= 1)
        return;

    if (UNLIKELY(current->match_length > 1 + next->match_start))
        return;

    if (UNLIKELY(current->match_length > 1 + next->strstart))
        return;

    match = s->window - current->match_length + 1 + next->match_start;
    orig  = s->window - current->match_length + 1 + next->strstart;

    /* quick exit check.. if this fails then don't bother with anything else */
    if (LIKELY(*match != *orig))
        return;

    c = *current;
    n = *next;

    /* step one: try to move the "next" match to the left as much as possible */
    limit = next->strstart > MAX_DIST(s) ? next->strstart - (Pos)MAX_DIST(s) : 0;

    match = s->window + n.match_start - 1;
    orig = s->window + n.strstart - 1;

    while (*match == *orig) {
        if (UNLIKELY(c.match_length < 1))
            break;
        if (UNLIKELY(n.strstart <= limit))
            break;
        if (UNLIKELY(n.match_length >= 256))
            break;
        if (UNLIKELY(n.match_start <= 1))
            break;

        n.strstart--;
        n.match_start--;
        n.match_length++;
        c.match_length--;
        match--;
        orig--;
        changed++;
    }

    if (!changed)
        return;

    if (c.match_length <= 1 && n.match_length != 2) {
        n.orgstart++;
        *current = c;
        *next = n;
    } else {
        return;
    }
}

Z_INTERNAL block_state deflate_medium(deflate_state *s, int flush) {
    /* Align the first struct to start on a new cacheline, this allows us to fit both structs in one cacheline */
    ALIGNED_(16) struct match current_match;
                 struct match next_match;

    memset(&current_match, 0, sizeof(struct match));
    memset(&next_match, 0, sizeof(struct match));

    for (;;) {
        Pos hash_head = 0;    /* head of the hash chain */
        int bflush = 0;       /* set if current block must be flushed */
        int64_t dist;

        /* Make sure that we always have enough lookahead, except
         * at the end of the input file. We need MAX_MATCH bytes
         * for the next match, plus MIN_MATCH bytes to insert the
         * string following the next current_match.
         */
        if (s->lookahead < MIN_LOOKAHEAD) {
            fill_window(s);
            if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
                return need_more;
            }
            if (UNLIKELY(s->lookahead == 0))
                break; /* flush the current block */
            next_match.match_length = 0;
        }

        /* Insert the string window[strstart .. strstart+2] in the
         * dictionary, and set hash_head to the head of the hash chain:
         */

        /* If we already have a future match from a previous round, just use that */
        if (next_match.match_length > 0) {
            current_match = next_match;
            next_match.match_length = 0;
        } else {
            hash_head = 0;
            if (s->lookahead >= MIN_MATCH) {
                hash_head = functable.quick_insert_string(s, s->strstart);
            }

            current_match.strstart = (uint16_t)s->strstart;
            current_match.orgstart = current_match.strstart;

            /* Find the longest match, discarding those <= prev_length.
             * At this point we have always match_length < MIN_MATCH
             */

            dist = (int64_t)s->strstart - hash_head;
            if (dist <= MAX_DIST(s) && dist > 0 && hash_head != 0) {
                /* To simplify the code, we prevent matches with the string
                 * of window index 0 (in particular we have to avoid a match
                 * of the string with itself at the start of the input file).
                 */
                current_match.match_length = (uint16_t)functable.longest_match(s, hash_head);
                current_match.match_start = (uint16_t)s->match_start;
                if (UNLIKELY(current_match.match_length < MIN_MATCH))
                    current_match.match_length = 1;
                if (UNLIKELY(current_match.match_start >= current_match.strstart)) {
                    /* this can happen due to some restarts */
                    current_match.match_length = 1;
                }
            } else {
                /* Set up the match to be a 1 byte literal */
                current_match.match_start = 0;
                current_match.match_length = 1;
            }
        }

        insert_match(s, current_match);

        /* now, look ahead one */
        if (LIKELY(s->lookahead > MIN_LOOKAHEAD && (uint32_t)(current_match.strstart + current_match.match_length) < (s->window_size - MIN_LOOKAHEAD))) {
            s->strstart = current_match.strstart + current_match.match_length;
            hash_head = functable.quick_insert_string(s, s->strstart);

            next_match.strstart = (uint16_t)s->strstart;
            next_match.orgstart = next_match.strstart;

            /* Find the longest match, discarding those <= prev_length.
             * At this point we have always match_length < MIN_MATCH
             */

            dist = (int64_t)s->strstart - hash_head;
            if (dist <= MAX_DIST(s) && dist > 0 && hash_head != 0) {
                /* To simplify the code, we prevent matches with the string
                 * of window index 0 (in particular we have to avoid a match
                 * of the string with itself at the start of the input file).
                 */
                next_match.match_length = (uint16_t)functable.longest_match(s, hash_head);
                next_match.match_start = (uint16_t)s->match_start;
                if (UNLIKELY(next_match.match_start >= next_match.strstart)) {
                    /* this can happen due to some restarts */
                    next_match.match_length = 1;
                }
                if (next_match.match_length < MIN_MATCH)
                    next_match.match_length = 1;
                else
                    fizzle_matches(s, &current_match, &next_match);
            } else {
                /* Set up the match to be a 1 byte literal */
                next_match.match_start = 0;
                next_match.match_length = 1;
            }

            s->strstart = current_match.strstart;
        } else {
            next_match.match_length = 0;
        }

        /* now emit the current match */
        bflush = emit_match(s, current_match);

        /* move the "cursor" forward */
        s->strstart += current_match.match_length;

        if (UNLIKELY(bflush))
            FLUSH_BLOCK(s, 0);
    }
    s->insert = s->strstart < MIN_MATCH-1 ? s->strstart : MIN_MATCH-1;
    if (flush == Z_FINISH) {
        FLUSH_BLOCK(s, 1);
        return finish_done;
    }
    if (UNLIKELY(s->sym_next))
        FLUSH_BLOCK(s, 0);

    return block_done;
}
#endif

Coverage Report

Created: 2025-12-14 06:06

Line	Count	Source
1		/* deflate_medium.c -- The deflate_medium deflate strategy
2		*
3		* Copyright (C) 2013 Intel Corporation. All rights reserved.
4		* Authors:
5		* Arjan van de Ven <arjan@linux.intel.com>
6		*
7		* For conditions of distribution and use, see copyright notice in zlib.h
8		*/
9		#ifndef NO_MEDIUM_STRATEGY
10		#include <stdint.h>
11		#include "zbuild.h"
12		#include "deflate.h"
13		#include "deflate_p.h"
14		#include "functable.h"
15
16		struct match {
17		uint16_t match_start;
18		uint16_t match_length;
19		uint16_t strstart;
20		uint16_t orgstart;
21		};
22
23	12.7M	static int emit_match(deflate_state *s, struct match match) {
24	12.7M	int bflush = 0;
25
26		/* matches that are not long enough we need to emit as literals */
27	12.7M	if (match.match_length < MIN_MATCH) {
28	24.3M	while (match.match_length) {
29	12.1M	bflush += zng_tr_tally_lit(s, s->window[match.strstart]);
30	12.1M	s->lookahead--;
31	12.1M	match.strstart++;
32	12.1M	match.match_length--;
33	12.1M	}
34	12.1M	return bflush;
35	12.1M	}
36
37	570k	check_match(s, match.strstart, match.match_start, match.match_length);
38
39	570k	bflush += zng_tr_tally_dist(s, match.strstart - match.match_start, match.match_length - MIN_MATCH);
40
41	570k	s->lookahead -= match.match_length;
42	570k	return bflush;
43	12.7M	}
44
45	12.7M	static void insert_match(deflate_state *s, struct match match) {
46	12.7M	if (UNLIKELY(s->lookahead <= (unsigned int)(match.match_length + MIN_MATCH)))
47	18.1k	return;
48
49		/* matches that are not long enough we need to emit as literals */
50	12.7M	if (LIKELY(match.match_length < MIN_MATCH)) {
51	12.1M	match.strstart++;
52	12.1M	match.match_length--;
53	12.1M	if (UNLIKELY(match.match_length > 0)) {
54	0	if (match.strstart >= match.orgstart) {
55	0	if (match.strstart + match.match_length - 1 >= match.orgstart) {
56	0	functable.insert_string(s, match.strstart, match.match_length);
57	0	} else {
58	0	functable.insert_string(s, match.strstart, match.orgstart - match.strstart + 1);
59	0	}
60	0	match.strstart += match.match_length;
61	0	match.match_length = 0;
62	0	}
63	0	}
64	12.1M	return;
65	12.1M	}
66
67		/* Insert new strings in the hash table only if the match length
68		* is not too large. This saves time but degrades compression.
69		*/
70	599k	if (match.match_length <= 16* s->max_insert_length && s->lookahead >= MIN_MATCH) {
71	538k	match.match_length--; /* string at strstart already in table */
72	538k	match.strstart++;
73
74	538k	if (LIKELY(match.strstart >= match.orgstart)) {
75	504k	if (LIKELY(match.strstart + match.match_length - 1 >= match.orgstart)) {
76	504k	functable.insert_string(s, match.strstart, match.match_length);
77	504k	} else {
78	0	functable.insert_string(s, match.strstart, match.orgstart - match.strstart + 1);
79	0	}
80	504k	} else if (match.orgstart < match.strstart + match.match_length) {
81	33.7k	functable.insert_string(s, match.orgstart, match.strstart + match.match_length - match.orgstart);
82	33.7k	}
83	538k	match.strstart += match.match_length;
84	538k	match.match_length = 0;
85	538k	} else {
86	61.3k	match.strstart += match.match_length;
87	61.3k	match.match_length = 0;
88	61.3k	if (match.strstart >= (MIN_MATCH - 2))
89		#if MIN_MATCH != 3
90		functable.insert_string(s, match.strstart + 2 - MIN_MATCH, MIN_MATCH - 2);
91		#else
92	61.3k	functable.quick_insert_string(s, match.strstart + 2 - MIN_MATCH);
93	61.3k	#endif
94		/* If lookahead < MIN_MATCH, ins_h is garbage, but it does not
95		* matter since it will be recomputed at next deflate call.
96		*/
97	61.3k	}
98	599k	}
99
100	574k	static void fizzle_matches(deflate_state s, struct match current, struct match *next) {
101	574k	Pos limit;
102	574k	unsigned char match, orig;
103	574k	int changed = 0;
104	574k	struct match c, n;
105		/* step zero: sanity checks */
106
107	574k	if (current->match_length <= 1)
108	259k	return;
109
110	315k	if (UNLIKELY(current->match_length > 1 + next->match_start))
111	15.9k	return;
112
113	299k	if (UNLIKELY(current->match_length > 1 + next->strstart))
114	0	return;
115
116	299k	match = s->window - current->match_length + 1 + next->match_start;
117	299k	orig = s->window - current->match_length + 1 + next->strstart;
118
119		/* quick exit check.. if this fails then don't bother with anything else */
120	299k	if (LIKELY(match != orig))
121	145k	return;
122
123	153k	c = *current;
124	153k	n = *next;
125
126		/* step one: try to move the "next" match to the left as much as possible */
127	153k	limit = next->strstart > MAX_DIST(s) ? next->strstart - (Pos)MAX_DIST(s) : 0;
128
129	153k	match = s->window + n.match_start - 1;
130	153k	orig = s->window + n.strstart - 1;
131
132	2.49M	while (match == orig) {
133	2.39M	if (UNLIKELY(c.match_length < 1))
134	9.10k	break;
135	2.38M	if (UNLIKELY(n.strstart <= limit))
136	0	break;
137	2.38M	if (UNLIKELY(n.match_length >= 256))
138	43.2k	break;
139	2.34M	if (UNLIKELY(n.match_start <= 1))
140	474	break;
141
142	2.33M	n.strstart--;
143	2.33M	n.match_start--;
144	2.33M	n.match_length++;
145	2.33M	c.match_length--;
146	2.33M	match--;
147	2.33M	orig--;
148	2.33M	changed++;
149	2.33M	}
150
151	153k	if (!changed)
152	58.8k	return;
153
154	95.1k	if (c.match_length <= 1 && n.match_length != 2) {
155	36.4k	n.orgstart++;
156	36.4k	*current = c;
157	36.4k	*next = n;
158	58.6k	} else {
159	58.6k	return;
160	58.6k	}
161	95.1k	}
162
163	9.94k	Z_INTERNAL block_state deflate_medium(deflate_state *s, int flush) {
164		/* Align the first struct to start on a new cacheline, this allows us to fit both structs in one cacheline */
165	9.94k	ALIGNED_(16) struct match current_match;
166	9.94k	struct match next_match;
167
168	9.94k	memset(&current_match, 0, sizeof(struct match));
169	9.94k	memset(&next_match, 0, sizeof(struct match));
170
171	12.7M	for (;;) {
172	12.7M	Pos hash_head = 0; /* head of the hash chain */
173	12.7M	int bflush = 0; /* set if current block must be flushed */
174	12.7M	int64_t dist;
175
176		/* Make sure that we always have enough lookahead, except
177		* at the end of the input file. We need MAX_MATCH bytes
178		* for the next match, plus MIN_MATCH bytes to insert the
179		* string following the next current_match.
180		*/
181	12.7M	if (s->lookahead < MIN_LOOKAHEAD) {
182	715k	fill_window(s);
183	715k	if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
184	0	return need_more;
185	0	}
186	715k	if (UNLIKELY(s->lookahead == 0))
187	9.94k	break; /* flush the current block */
188	705k	next_match.match_length = 0;
189	705k	}
190
191		/* Insert the string window[strstart .. strstart+2] in the
192		* dictionary, and set hash_head to the head of the hash chain:
193		*/
194
195		/* If we already have a future match from a previous round, just use that */
196	12.7M	if (next_match.match_length > 0) {
197	12.0M	current_match = next_match;
198	12.0M	next_match.match_length = 0;
199	12.0M	} else {
200	705k	hash_head = 0;
201	705k	if (s->lookahead >= MIN_MATCH) {
202	699k	hash_head = functable.quick_insert_string(s, s->strstart);
203	699k	}
204
205	705k	current_match.strstart = (uint16_t)s->strstart;
206	705k	current_match.orgstart = current_match.strstart;
207
208		/* Find the longest match, discarding those <= prev_length.
209		* At this point we have always match_length < MIN_MATCH
210		*/
211
212	705k	dist = (int64_t)s->strstart - hash_head;
213	705k	if (dist <= MAX_DIST(s) && dist > 0 && hash_head != 0) {
214		/* To simplify the code, we prevent matches with the string
215		* of window index 0 (in particular we have to avoid a match
216		* of the string with itself at the start of the input file).
217		*/
218	70.0k	current_match.match_length = (uint16_t)functable.longest_match(s, hash_head);
219	70.0k	current_match.match_start = (uint16_t)s->match_start;
220	70.0k	if (UNLIKELY(current_match.match_length < MIN_MATCH))
221	30.9k	current_match.match_length = 1;
222	70.0k	if (UNLIKELY(current_match.match_start >= current_match.strstart)) {
223		/* this can happen due to some restarts */
224	0	current_match.match_length = 1;
225	0	}
226	635k	} else {
227		/* Set up the match to be a 1 byte literal */
228	635k	current_match.match_start = 0;
229	635k	current_match.match_length = 1;
230	635k	}
231	705k	}
232
233	12.7M	insert_match(s, current_match);
234
235		/* now, look ahead one */
236	12.7M	if (LIKELY(s->lookahead > MIN_LOOKAHEAD && (uint32_t)(current_match.strstart + current_match.match_length) < (s->window_size - MIN_LOOKAHEAD))) {
237	12.0M	s->strstart = current_match.strstart + current_match.match_length;
238	12.0M	hash_head = functable.quick_insert_string(s, s->strstart);
239
240	12.0M	next_match.strstart = (uint16_t)s->strstart;
241	12.0M	next_match.orgstart = next_match.strstart;
242
243		/* Find the longest match, discarding those <= prev_length.
244		* At this point we have always match_length < MIN_MATCH
245		*/
246
247	12.0M	dist = (int64_t)s->strstart - hash_head;
248	12.0M	if (dist <= MAX_DIST(s) && dist > 0 && hash_head != 0) {
249		/* To simplify the code, we prevent matches with the string
250		* of window index 0 (in particular we have to avoid a match
251		* of the string with itself at the start of the input file).
252		*/
253	837k	next_match.match_length = (uint16_t)functable.longest_match(s, hash_head);
254	837k	next_match.match_start = (uint16_t)s->match_start;
255	837k	if (UNLIKELY(next_match.match_start >= next_match.strstart)) {
256		/* this can happen due to some restarts */
257	0	next_match.match_length = 1;
258	0	}
259	837k	if (next_match.match_length < MIN_MATCH)
260	263k	next_match.match_length = 1;
261	574k	else
262	574k	fizzle_matches(s, &current_match, &next_match);
263	11.1M	} else {
264		/* Set up the match to be a 1 byte literal */
265	11.1M	next_match.match_start = 0;
266	11.1M	next_match.match_length = 1;
267	11.1M	}
268
269	12.0M	s->strstart = current_match.strstart;
270	12.0M	} else {
271	698k	next_match.match_length = 0;
272	698k	}
273
274		/* now emit the current match */
275	12.7M	bflush = emit_match(s, current_match);
276
277		/* move the "cursor" forward */
278	12.7M	s->strstart += current_match.match_length;
279
280	12.7M	if (UNLIKELY(bflush))
281	12.7M	FLUSH_BLOCK(s, 0);
282	12.7M	}
283	9.94k	s->insert = s->strstart < MIN_MATCH-1 ? s->strstart : MIN_MATCH-1;
284	9.94k	if (flush == Z_FINISH) {
285	9.94k	FLUSH_BLOCK(s, 1);
286	9.05k	return finish_done;
287	9.94k	}
288	0	if (UNLIKELY(s->sym_next))
289	0	FLUSH_BLOCK(s, 0);
290
291	0	return block_done;
292	0	}
293		#endif