liblzf/lzf_c_best.c

/*
 * Copyright (c) 2000-2012 Marc Alexander Lehmann <schmorp@schmorp.de>
 *
 * Redistribution and use in source and binary forms, with or without modifica-
 * tion, are permitted provided that the following conditions are met:
 *
 *   1.  Redistributions of source code must retain the above copyright notice,
 *       this list of conditions and the following disclaimer.
 *
 *   2.  Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MER-
 * CHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO
 * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPE-
 * CIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTH-
 * ERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * Alternatively, the contents of this file may be used under the terms of
 * the GNU General Public License ("GPL") version 2 or any later version,
 * in which case the provisions of the GPL are applicable instead of
 * the above. If you wish to allow the use of your version of this file
 * only under the terms of the GPL and not to allow others to use your
 * version of this file under the BSD license, indicate your decision
 * by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL. If you do not delete the
 * provisions above, a recipient may use your version of this file under
 * either the BSD or the GPL.
 */

#include "lzfP.h"

#define HASH(p) (p[0] << 6) ^ (p[1] << 3) ^ p[2]

#if __GNUC__ >= 3
# define expect(expr,value)         __builtin_expect ((expr),(value))
# define inline                     inline
#else
# define expect(expr,value)         (expr)
# define inline                     static
#endif

#define expect_false(expr) expect ((expr) != 0, 0)
#define expect_true(expr)  expect ((expr) != 0, 1)

/*
 * compressed format
 *
 * 000LLLLL <L+1>    ; literal, L+1=1..33 octets
 * LLLooooo oooooooo ; backref L+1=1..7 octets, o+1=1..4096 offset
 * 111ooooo LLLLLLLL oooooooo ; backref L+8 octets, o+1=1..4096 offset
 *
 */

unsigned int
lzf_compress_best (const void *const in_data, unsigned int in_len,
                   void *out_data, unsigned int out_len
#if LZF_STATE_ARG
              , LZF_STATE_BEST state
#endif
              )
{
  const u8 *ip = (const u8 *)in_data;
        u8 *op = (u8 *)out_data;
  const u8 *in_end  = ip + in_len;
        u8 *out_end = op + out_len;

#if !LZF_STATE_ARG
  LZF_STATE_BEST state;
#endif
#define STATE state[0]

  int lit;

  if (!in_len || !out_len)
    return 0;

  lit = 0; op++; /* start run */

  lit++; *op++ = *ip++;

  &state; /* avoid undefined behaviour by forcing non-register class, 6.3.2.1p2 */

  while (ip < in_end - 2)
    {
      int best_l = 0;
      const u8 *best_p;
      int e = (in_end - ip < LZF_MAX_REF ? in_end - ip : LZF_MAX_REF) - 1;
      unsigned int res = ((unsigned long)ip) & (LZF_MAX_OFF - 1);
      u16 hash = HASH (ip);
      u16 diff;
      const u8 *b = ip < (u8 *)in_data + LZF_MAX_OFF ? in_data : ip - LZF_MAX_OFF;
      const u8 *p = STATE.first [hash];
      STATE.prev [res] = ip - p; /* update ptr to previous hash match */
      STATE.first [hash] = ip; /* first hash match is here */

      if (p < ip)
        while (p >= b)
          {
            if (p[2] == ip[2]) /* first two bytes almost always match */
              if (p[best_l] == ip[best_l]) /* new match must be longer than the old one to qualify */
                if (p[1] == ip[1] && p[0] == ip[0]) /* just to be sure */
                  {
                    int l = 3;

                    while (p[l] == ip[l] && l < e)
                      ++l;

                    if (l >= best_l)
                      {
                        best_p = p;
                        best_l = l;
                      }
                  }

            diff = STATE.prev [((unsigned long)p) & (LZF_MAX_OFF - 1)];
            p = diff ? p - diff : 0;
          }

      if (best_l)
        {
          int len = best_l;
          int off = ip - best_p - 1;

          if (expect_false (op + 3 + 1 >= out_end)) /* first a faster conservative test */
            if (op - !lit + 3 + 1 >= out_end) /* second the exact but rare test */
              return 0;

          op [- lit - 1] = lit - 1; /* stop run */
          op -= !lit; /* undo run if length is zero */

          len -= 2; /* len is now #octets - 1 */
          ip++;

          if (len < 7)
            {
              *op++ = (off >> 8) + (len << 5);
            }
          else
            {
              *op++ = (off >> 8) + (  7 << 5);
              *op++ = len - 7;
            }

          *op++ = off;

          lit = 0; op++; /* start run */

          ip += len + 1;

          if (expect_false (ip >= in_end - 2))
            break;

          ip -= len + 1;

          //printf (" fill %p for %d\n", ip, len);//D
          do
            {
              u16 hash = HASH (ip);
              res = ((unsigned long)ip) & (LZF_MAX_OFF - 1);

              p = STATE.first [hash];
              STATE.prev [res] = ip - p; /* update ptr to previous hash match */
              STATE.first [hash] = ip; /* first hash match is here */

              ip++;
            }
          while (len--);
        }
      else
        {
          /* one more literal byte we must copy */
          if (expect_false (op >= out_end))
            return 0;

          lit++; *op++ = *ip++;

          if (expect_false (lit == LZF_MAX_LIT))
            {
              op [- lit - 1] = lit - 1; /* stop run */
              lit = 0; op++; /* start run */
            }
        }
    }

  if (op + 3 > out_end) /* at most 3 bytes can be missing here */
    return 0;

  while (ip < in_end)
    {
      lit++; *op++ = *ip++;

      if (expect_false (lit == LZF_MAX_LIT))
        {
          op [- lit - 1] = lit - 1; /* stop run */
          lit = 0; op++; /* start run */
        }
    }

  op [- lit - 1] = lit - 1; /* end run */
  op -= !lit; /* undo run if length is zero */

  return op - (u8 *)out_data;

#undef STATE
}


Revision:	1.6
Committed:	Sun Oct 11 22:26:07 2015 UTC (10 years, 4 months ago) by root
Content type:	text/plain
Branch:	MAIN
CVS Tags:	HEAD
Changes since 1.5:	+2 -0 lines
Log Message:	* empty log message *
#	Content
1	/*
2	* Copyright (c) 2000-2012 Marc Alexander Lehmann <schmorp@schmorp.de>
3	*
4	* Redistribution and use in source and binary forms, with or without modifica-
5	* tion, are permitted provided that the following conditions are met:
6	*
7	* 1. Redistributions of source code must retain the above copyright notice,
8	* this list of conditions and the following disclaimer.
9	*
10	* 2. Redistributions in binary form must reproduce the above copyright
11	* notice, this list of conditions and the following disclaimer in the
12	* documentation and/or other materials provided with the distribution.
13	*
14	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
15	* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MER-
16	* CHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
17	* EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPE-
18	* CIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
19	* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
20	* OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
21	* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTH-
22	* ERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
23	* OF THE POSSIBILITY OF SUCH DAMAGE.
24	*
25	* Alternatively, the contents of this file may be used under the terms of
26	* the GNU General Public License ("GPL") version 2 or any later version,
27	* in which case the provisions of the GPL are applicable instead of
28	* the above. If you wish to allow the use of your version of this file
29	* only under the terms of the GPL and not to allow others to use your
30	* version of this file under the BSD license, indicate your decision
31	* by deleting the provisions above and replace them with the notice
32	* and other provisions required by the GPL. If you do not delete the
33	* provisions above, a recipient may use your version of this file under
34	* either the BSD or the GPL.
35	*/
36
37	#include "lzfP.h"
38
39	#define HASH(p) (p[0] << 6) ^ (p[1] << 3) ^ p[2]
40
41	#if __GNUC__ >= 3
42	# define expect(expr,value) __builtin_expect ((expr),(value))
43	# define inline inline
44	#else
45	# define expect(expr,value) (expr)
46	# define inline static
47	#endif
48
49	#define expect_false(expr) expect ((expr) != 0, 0)
50	#define expect_true(expr) expect ((expr) != 0, 1)
51
52	/*
53	* compressed format
54	*
55	* 000LLLLL <L+1> ; literal, L+1=1..33 octets
56	* LLLooooo oooooooo ; backref L+1=1..7 octets, o+1=1..4096 offset
57	* 111ooooo LLLLLLLL oooooooo ; backref L+8 octets, o+1=1..4096 offset
58	*
59	*/
60
61	unsigned int
62	lzf_compress_best (const void *const in_data, unsigned int in_len,
63	void *out_data, unsigned int out_len
64	#if LZF_STATE_ARG
65	, LZF_STATE_BEST state
66	#endif
67	)
68	{
69	const u8 ip = (const u8 )in_data;
70	u8 op = (u8 )out_data;
71	const u8 *in_end = ip + in_len;
72	u8 *out_end = op + out_len;
73
74	#if !LZF_STATE_ARG
75	LZF_STATE_BEST state;
76	#endif
77	#define STATE state[0]
78
79	int lit;
80
81	if (!in_len \|\| !out_len)
82	return 0;
83
84	lit = 0; op++; /* start run */
85
86	lit++; op++ = ip++;
87
88	&state; /* avoid undefined behaviour by forcing non-register class, 6.3.2.1p2 */
89
90	while (ip < in_end - 2)
91	{
92	int best_l = 0;
93	const u8 *best_p;
94	int e = (in_end - ip < LZF_MAX_REF ? in_end - ip : LZF_MAX_REF) - 1;
95	unsigned int res = ((unsigned long)ip) & (LZF_MAX_OFF - 1);
96	u16 hash = HASH (ip);
97	u16 diff;
98	const u8 b = ip < (u8 )in_data + LZF_MAX_OFF ? in_data : ip - LZF_MAX_OFF;
99	const u8 *p = STATE.first [hash];
100	STATE.prev [res] = ip - p; /* update ptr to previous hash match */
101	STATE.first [hash] = ip; /* first hash match is here */
102
103	if (p < ip)
104	while (p >= b)
105	{
106	if (p[2] == ip[2]) /* first two bytes almost always match */
107	if (p[best_l] == ip[best_l]) /* new match must be longer than the old one to qualify */
108	if (p[1] == ip[1] && p[0] == ip[0]) /* just to be sure */
109	{
110	int l = 3;
111
112	while (p[l] == ip[l] && l < e)
113	++l;
114
115	if (l >= best_l)
116	{
117	best_p = p;
118	best_l = l;
119	}
120	}
121
122	diff = STATE.prev [((unsigned long)p) & (LZF_MAX_OFF - 1)];
123	p = diff ? p - diff : 0;
124	}
125
126	if (best_l)
127	{
128	int len = best_l;
129	int off = ip - best_p - 1;
130
131	if (expect_false (op + 3 + 1 >= out_end)) /* first a faster conservative test */
132	if (op - !lit + 3 + 1 >= out_end) /* second the exact but rare test */
133	return 0;
134
135	op [- lit - 1] = lit - 1; /* stop run */
136	op -= !lit; /* undo run if length is zero */
137
138	len -= 2; /* len is now #octets - 1 */
139	ip++;
140
141	if (len < 7)
142	{
143	*op++ = (off >> 8) + (len << 5);
144	}
145	else
146	{
147	*op++ = (off >> 8) + ( 7 << 5);
148	*op++ = len - 7;
149	}
150
151	*op++ = off;
152
153	lit = 0; op++; /* start run */
154
155	ip += len + 1;
156
157	if (expect_false (ip >= in_end - 2))
158	break;
159
160	ip -= len + 1;
161
162	//printf (" fill %p for %d\n", ip, len);//D
163	do
164	{
165	u16 hash = HASH (ip);
166	res = ((unsigned long)ip) & (LZF_MAX_OFF - 1);
167
168	p = STATE.first [hash];
169	STATE.prev [res] = ip - p; /* update ptr to previous hash match */
170	STATE.first [hash] = ip; /* first hash match is here */
171
172	ip++;
173	}
174	while (len--);
175	}
176	else
177	{
178	/* one more literal byte we must copy */
179	if (expect_false (op >= out_end))
180	return 0;
181
182	lit++; op++ = ip++;
183
184	if (expect_false (lit == LZF_MAX_LIT))
185	{
186	op [- lit - 1] = lit - 1; /* stop run */
187	lit = 0; op++; /* start run */
188	}
189	}
190	}
191
192	if (op + 3 > out_end) /* at most 3 bytes can be missing here */
193	return 0;
194
195	while (ip < in_end)
196	{
197	lit++; op++ = ip++;
198
199	if (expect_false (lit == LZF_MAX_LIT))
200	{
201	op [- lit - 1] = lit - 1; /* stop run */
202	lit = 0; op++; /* start run */
203	}
204	}
205
206	op [- lit - 1] = lit - 1; /* end run */
207	op -= !lit; /* undo run if length is zero */
208
209	return op - (u8 *)out_data;
210
211	#undef STATE
212	}
213
214