liblzf/lzf_c.c

/*
 * Copyright (c) 2000-2010 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 HSIZE (1 << (HLOG))

/*
 * don't play with this unless you benchmark!
 * the data format is not dependent on the hash function.
 * the hash function might seem strange, just believe me,
 * it works ;)
 */
#ifndef FRST
# define FRST(p) (((p[0]) << 8) | p[1])
# define NEXT(v,p) (((v) << 8) | p[2])
# if ULTRA_FAST
#  define IDX(h) ((( h             >> (3*8 - HLOG)) - h  ) & (HSIZE - 1))
# elif VERY_FAST
#  define IDX(h) ((( h             >> (3*8 - HLOG)) - h*5) & (HSIZE - 1))
# else
#  define IDX(h) ((((h ^ (h << 5)) >> (3*8 - HLOG)) - h*5) & (HSIZE - 1))
# endif
#endif
/*
 * IDX works because it is very similar to a multiplicative hash, e.g.
 * ((h * 57321 >> (3*8 - HLOG)) & (HSIZE - 1))
 * the latter is also quite fast on newer CPUs, and compresses similarly.
 *
 * the next one is also quite good, albeit slow ;)
 * (int)(cos(h & 0xffffff) * 1e6)
 */

#if 0
/* original lzv-like hash function, much worse and thus slower */
# define FRST(p) (p[0] << 5) ^ p[1]
# define NEXT(v,p) ((v) << 5) ^ p[2]
# define IDX(h) ((h) & (HSIZE - 1))
#endif

#define        MAX_LIT        (1 <<  5)
#define        MAX_OFF        (1 << 13)
#define        MAX_REF        ((1 << 8) + (1 << 3))

#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 (const void *const in_data, unsigned int in_len,
              void *out_data, unsigned int out_len
#if LZF_STATE_ARG
              , LZF_STATE htab
#endif
              )
{
#if !LZF_STATE_ARG
  LZF_STATE htab;
#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;
  const u8 *ref;

  /* off requires a type wide enough to hold a general pointer difference.
   * ISO C doesn't have that (size_t might not be enough and ptrdiff_t only
   * works for differences within a single object). We also assume that no
   * no bit pattern traps. Since the only platform that is both non-POSIX
   * and fails to support both assumptions is windows 64 bit, we make a
   * special workaround for it.
   */
#if defined (WIN32) && defined (_M_X64)
  unsigned _int64 off; /* workaround for missing POSIX compliance */
#else
  unsigned long off;
#endif
  unsigned int hval;
  int lit;

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

#if INIT_HTAB
  memset (htab, 0, sizeof (htab));
#endif

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

  hval = FRST (ip);
  while (ip < in_end - 2)
    {
      LZF_HSLOT *hslot;

      hval = NEXT (hval, ip);
      hslot = htab + IDX (hval);
      ref = *hslot + LZF_HSLOT_BIAS; *hslot = ip - LZF_HSLOT_BIAS;

      if (1
#if INIT_HTAB
          && ref < ip /* the next test will actually take care of this, but this is faster */
#endif
          && (off = ip - ref - 1) < MAX_OFF
          && ref > (u8 *)in_data
          && ref[2] == ip[2]
#if STRICT_ALIGN
          && ((ref[1] << 8) | ref[0]) == ((ip[1] << 8) | ip[0])
#else
          && *(u16 *)ref == *(u16 *)ip
#endif
        )
        {
          /* match found at *ref++ */
          unsigned int len = 2;
          unsigned int maxlen = in_end - ip - len;
          maxlen = maxlen > MAX_REF ? MAX_REF : maxlen;

          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 */

          for (;;)
            {
              if (expect_true (maxlen > 16))
                {
                  len++; if (ref [len] != ip [len]) break;
                  len++; if (ref [len] != ip [len]) break;
                  len++; if (ref [len] != ip [len]) break;
                  len++; if (ref [len] != ip [len]) break;

                  len++; if (ref [len] != ip [len]) break;
                  len++; if (ref [len] != ip [len]) break;
                  len++; if (ref [len] != ip [len]) break;
                  len++; if (ref [len] != ip [len]) break;

                  len++; if (ref [len] != ip [len]) break;
                  len++; if (ref [len] != ip [len]) break;
                  len++; if (ref [len] != ip [len]) break;
                  len++; if (ref [len] != ip [len]) break;

                  len++; if (ref [len] != ip [len]) break;
                  len++; if (ref [len] != ip [len]) break;
                  len++; if (ref [len] != ip [len]) break;
                  len++; if (ref [len] != ip [len]) break;
                }

              do
                len++;
              while (len < maxlen && ref[len] == ip[len]);

              break;
            }

          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;

#if ULTRA_FAST || VERY_FAST
          --ip;
# if VERY_FAST && !ULTRA_FAST
          --ip;
# endif
          hval = FRST (ip);

          hval = NEXT (hval, ip);
          htab[IDX (hval)] = ip - LZF_HSLOT_BIAS;
          ip++;

# if VERY_FAST && !ULTRA_FAST
          hval = NEXT (hval, ip);
          htab[IDX (hval)] = ip - LZF_HSLOT_BIAS;
          ip++;
# endif
#else
          ip -= len + 1;

          do
            {
              hval = NEXT (hval, ip);
              htab[IDX (hval)] = ip - LZF_HSLOT_BIAS;
              ip++;
            }
          while (len--);
#endif
        }
      else
        {
          /* one more literal byte we must copy */
          if (expect_false (op >= out_end))
            return 0;

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

          if (expect_false (lit == 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 == 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;
}

Revision:	1.44
Committed:	Tue Jun 1 09:11:33 2010 UTC (13 years, 11 months ago) by root
Content type:	text/plain
Branch:	MAIN
CVS Tags:	rel-3_6
Changes since 1.43:	+1 -1 lines
Log Message:	* empty log message *
#	Content
1	/*
2	* Copyright (c) 2000-2010 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 HSIZE (1 << (HLOG))
40
41	/*
42	* don't play with this unless you benchmark!
43	* the data format is not dependent on the hash function.
44	* the hash function might seem strange, just believe me,
45	* it works ;)
46	*/
47	#ifndef FRST
48	# define FRST(p) (((p[0]) << 8) \| p[1])
49	# define NEXT(v,p) (((v) << 8) \| p[2])
50	# if ULTRA_FAST
51	# define IDX(h) ((( h >> (3*8 - HLOG)) - h ) & (HSIZE - 1))
52	# elif VERY_FAST
53	# define IDX(h) ((( h >> (38 - HLOG)) - h5) & (HSIZE - 1))
54	# else
55	# define IDX(h) ((((h ^ (h << 5)) >> (38 - HLOG)) - h5) & (HSIZE - 1))
56	# endif
57	#endif
58	/*
59	* IDX works because it is very similar to a multiplicative hash, e.g.
60	* ((h * 57321 >> (3*8 - HLOG)) & (HSIZE - 1))
61	* the latter is also quite fast on newer CPUs, and compresses similarly.
62	*
63	* the next one is also quite good, albeit slow ;)
64	* (int)(cos(h & 0xffffff) * 1e6)
65	*/
66
67	#if 0
68	/* original lzv-like hash function, much worse and thus slower */
69	# define FRST(p) (p[0] << 5) ^ p[1]
70	# define NEXT(v,p) ((v) << 5) ^ p[2]
71	# define IDX(h) ((h) & (HSIZE - 1))
72	#endif
73
74	#define MAX_LIT (1 << 5)
75	#define MAX_OFF (1 << 13)
76	#define MAX_REF ((1 << 8) + (1 << 3))
77
78	#if __GNUC__ >= 3
79	# define expect(expr,value) __builtin_expect ((expr),(value))
80	# define inline inline
81	#else
82	# define expect(expr,value) (expr)
83	# define inline static
84	#endif
85
86	#define expect_false(expr) expect ((expr) != 0, 0)
87	#define expect_true(expr) expect ((expr) != 0, 1)
88
89	/*
90	* compressed format
91	*
92	* 000LLLLL <L+1> ; literal, L+1=1..33 octets
93	* LLLooooo oooooooo ; backref L+1=1..7 octets, o+1=1..4096 offset
94	* 111ooooo LLLLLLLL oooooooo ; backref L+8 octets, o+1=1..4096 offset
95	*
96	*/
97
98	unsigned int
99	lzf_compress (const void *const in_data, unsigned int in_len,
100	void *out_data, unsigned int out_len
101	#if LZF_STATE_ARG
102	, LZF_STATE htab
103	#endif
104	)
105	{
106	#if !LZF_STATE_ARG
107	LZF_STATE htab;
108	#endif
109	const u8 ip = (const u8 )in_data;
110	u8 op = (u8 )out_data;
111	const u8 *in_end = ip + in_len;
112	u8 *out_end = op + out_len;
113	const u8 *ref;
114
115	/* off requires a type wide enough to hold a general pointer difference.
116	* ISO C doesn't have that (size_t might not be enough and ptrdiff_t only
117	* works for differences within a single object). We also assume that no
118	* no bit pattern traps. Since the only platform that is both non-POSIX
119	* and fails to support both assumptions is windows 64 bit, we make a
120	* special workaround for it.
121	*/
122	#if defined (WIN32) && defined (_M_X64)
123	unsigned _int64 off; /* workaround for missing POSIX compliance */
124	#else
125	unsigned long off;
126	#endif
127	unsigned int hval;
128	int lit;
129
130	if (!in_len \|\| !out_len)
131	return 0;
132
133	#if INIT_HTAB
134	memset (htab, 0, sizeof (htab));
135	#endif
136
137	lit = 0; op++; /* start run */
138
139	hval = FRST (ip);
140	while (ip < in_end - 2)
141	{
142	LZF_HSLOT *hslot;
143
144	hval = NEXT (hval, ip);
145	hslot = htab + IDX (hval);
146	ref = hslot + LZF_HSLOT_BIAS; hslot = ip - LZF_HSLOT_BIAS;
147
148	if (1
149	#if INIT_HTAB
150	&& ref < ip /* the next test will actually take care of this, but this is faster */
151	#endif
152	&& (off = ip - ref - 1) < MAX_OFF
153	&& ref > (u8 *)in_data
154	&& ref[2] == ip[2]
155	#if STRICT_ALIGN
156	&& ((ref[1] << 8) \| ref[0]) == ((ip[1] << 8) \| ip[0])
157	#else
158	&& (u16 )ref == (u16 )ip
159	#endif
160	)
161	{
162	/* match found at ref++ /
163	unsigned int len = 2;
164	unsigned int maxlen = in_end - ip - len;
165	maxlen = maxlen > MAX_REF ? MAX_REF : maxlen;
166
167	if (expect_false (op + 3 + 1 >= out_end)) /* first a faster conservative test */
168	if (op - !lit + 3 + 1 >= out_end) /* second the exact but rare test */
169	return 0;
170
171	op [- lit - 1] = lit - 1; /* stop run */
172	op -= !lit; /* undo run if length is zero */
173
174	for (;;)
175	{
176	if (expect_true (maxlen > 16))
177	{
178	len++; if (ref [len] != ip [len]) break;
179	len++; if (ref [len] != ip [len]) break;
180	len++; if (ref [len] != ip [len]) break;
181	len++; if (ref [len] != ip [len]) break;
182
183	len++; if (ref [len] != ip [len]) break;
184	len++; if (ref [len] != ip [len]) break;
185	len++; if (ref [len] != ip [len]) break;
186	len++; if (ref [len] != ip [len]) break;
187
188	len++; if (ref [len] != ip [len]) break;
189	len++; if (ref [len] != ip [len]) break;
190	len++; if (ref [len] != ip [len]) break;
191	len++; if (ref [len] != ip [len]) break;
192
193	len++; if (ref [len] != ip [len]) break;
194	len++; if (ref [len] != ip [len]) break;
195	len++; if (ref [len] != ip [len]) break;
196	len++; if (ref [len] != ip [len]) break;
197	}
198
199	do
200	len++;
201	while (len < maxlen && ref[len] == ip[len]);
202
203	break;
204	}
205
206	len -= 2; /* len is now #octets - 1 */
207	ip++;
208
209	if (len < 7)
210	{
211	*op++ = (off >> 8) + (len << 5);
212	}
213	else
214	{
215	*op++ = (off >> 8) + ( 7 << 5);
216	*op++ = len - 7;
217	}
218
219	*op++ = off;
220
221	lit = 0; op++; /* start run */
222
223	ip += len + 1;
224
225	if (expect_false (ip >= in_end - 2))
226	break;
227
228	#if ULTRA_FAST \|\| VERY_FAST
229	--ip;
230	# if VERY_FAST && !ULTRA_FAST
231	--ip;
232	# endif
233	hval = FRST (ip);
234
235	hval = NEXT (hval, ip);
236	htab[IDX (hval)] = ip - LZF_HSLOT_BIAS;
237	ip++;
238
239	# if VERY_FAST && !ULTRA_FAST
240	hval = NEXT (hval, ip);
241	htab[IDX (hval)] = ip - LZF_HSLOT_BIAS;
242	ip++;
243	# endif
244	#else
245	ip -= len + 1;
246
247	do
248	{
249	hval = NEXT (hval, ip);
250	htab[IDX (hval)] = ip - LZF_HSLOT_BIAS;
251	ip++;
252	}
253	while (len--);
254	#endif
255	}
256	else
257	{
258	/* one more literal byte we must copy */
259	if (expect_false (op >= out_end))
260	return 0;
261
262	lit++; op++ = ip++;
263
264	if (expect_false (lit == MAX_LIT))
265	{
266	op [- lit - 1] = lit - 1; /* stop run */
267	lit = 0; op++; /* start run */
268	}
269	}
270	}
271
272	if (op + 3 > out_end) /* at most 3 bytes can be missing here */
273	return 0;
274
275	while (ip < in_end)
276	{
277	lit++; op++ = ip++;
278
279	if (expect_false (lit == MAX_LIT))
280	{
281	op [- lit - 1] = lit - 1; /* stop run */
282	lit = 0; op++; /* start run */
283	}
284	}
285
286	op [- lit - 1] = lit - 1; /* end run */
287	op -= !lit; /* undo run if length is zero */
288
289	return op - (u8 *)out_data;
290	}
291