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 **hslot;
  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));
# if 0
  for (hslot = htab; hslot < htab + HSIZE; hslot++)
    *hslot++ = ip;
# endif
#endif

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

  hval = FRST (ip);
  while (ip < in_end - 2)
    {
      hval = NEXT (hval, ip);
      hslot = htab + IDX (hval);
      ref = *hslot; *hslot = ip;

      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
          && ip + 4 < in_end
          && 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;
          ip++;

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

          do
            {
              hval = NEXT (hval, ip);
              htab[IDX (hval)] = ip;
              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:	1.41
Committed:	Tue Jun 1 02:30:06 2010 UTC (13 years, 11 months ago) by root
Content type:	text/plain
Branch:	MAIN
Changes since 1.40:	+2 -2 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 **hslot;
110	const u8 ip = (const u8 )in_data;
111	u8 op = (u8 )out_data;
112	const u8 *in_end = ip + in_len;
113	u8 *out_end = op + out_len;
114	const u8 *ref;
115
116	/* off requires a type wide enough to hold a general pointer difference.
117	* ISO C doesn't have that (size_t might not be enough and ptrdiff_t only
118	* works for differences within a single object). We also assume that no
119	* no bit pattern traps. Since the only platform that is both non-POSIX
120	* and fails to support both assumptions is windows 64 bit, we make a
121	* special workaround for it.
122	*/
123	#if defined (WIN32) && defined (_M_X64)
124	unsigned _int64 off; /* workaround for missing POSIX compliance */
125	#else
126	unsigned long off;
127	#endif
128	unsigned int hval;
129	int lit;
130
131	if (!in_len \|\| !out_len)
132	return 0;
133
134	#if INIT_HTAB
135	memset (htab, 0, sizeof (htab));
136	# if 0
137	for (hslot = htab; hslot < htab + HSIZE; hslot++)
138	*hslot++ = ip;
139	# endif
140	#endif
141
142	lit = 0; op++; /* start run */
143
144	hval = FRST (ip);
145	while (ip < in_end - 2)
146	{
147	hval = NEXT (hval, ip);
148	hslot = htab + IDX (hval);
149	ref = hslot; hslot = ip;
150
151	if (1
152	#if INIT_HTAB
153	&& ref < ip /* the next test will actually take care of this, but this is faster */
154	#endif
155	&& (off = ip - ref - 1) < MAX_OFF
156	&& ip + 4 < in_end
157	&& ref > (u8 *)in_data
158	&& ref[2] == ip[2]
159	#if STRICT_ALIGN
160	&& (ref[1] << 8) \| ref[0] == (ip[1] << 8) \| ip[0]
161	#else
162	&& (u16 )ref == (u16 )ip
163	#endif
164	)
165	{
166	/* match found at ref++ /
167	unsigned int len = 2;
168	unsigned int maxlen = in_end - ip - len;
169	maxlen = maxlen > MAX_REF ? MAX_REF : maxlen;
170
171	if (expect_false (op + 3 + 1 >= out_end)) /* first a faster conservative test */
172	if (op - !lit + 3 + 1 >= out_end) /* second the exact but rare test */
173	return 0;
174
175	op [- lit - 1] = lit - 1; /* stop run */
176	op -= !lit; /* undo run if length is zero */
177
178	for (;;)
179	{
180	if (expect_true (maxlen > 16))
181	{
182	len++; if (ref [len] != ip [len]) break;
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
187	len++; if (ref [len] != ip [len]) break;
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
192	len++; if (ref [len] != ip [len]) break;
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
197	len++; if (ref [len] != ip [len]) break;
198	len++; if (ref [len] != ip [len]) break;
199	len++; if (ref [len] != ip [len]) break;
200	len++; if (ref [len] != ip [len]) break;
201	}
202
203	do
204	len++;
205	while (len < maxlen && ref[len] == ip[len]);
206
207	break;
208	}
209
210	len -= 2; /* len is now #octets - 1 */
211	ip++;
212
213	if (len < 7)
214	{
215	*op++ = (off >> 8) + (len << 5);
216	}
217	else
218	{
219	*op++ = (off >> 8) + ( 7 << 5);
220	*op++ = len - 7;
221	}
222
223	*op++ = off;
224	lit = 0; op++; /* start run */
225
226	ip += len + 1;
227
228	if (expect_false (ip >= in_end - 2))
229	break;
230
231	#if ULTRA_FAST \|\| VERY_FAST
232	--ip;
233	# if VERY_FAST && !ULTRA_FAST
234	--ip;
235	# endif
236	hval = FRST (ip);
237
238	hval = NEXT (hval, ip);
239	htab[IDX (hval)] = ip;
240	ip++;
241
242	# if VERY_FAST && !ULTRA_FAST
243	hval = NEXT (hval, ip);
244	htab[IDX (hval)] = ip;
245	ip++;
246	# endif
247	#else
248	ip -= len + 1;
249
250	do
251	{
252	hval = NEXT (hval, ip);
253	htab[IDX (hval)] = ip;
254	ip++;
255	}
256	while (len--);
257	#endif
258	}
259	else
260	{
261	/* one more literal byte we must copy */
262	if (expect_false (op >= out_end))
263	return 0;
264
265	lit++; op++ = ip++;
266
267	if (expect_false (lit == MAX_LIT))
268	{
269	op [- lit - 1] = lit - 1; /* stop run */
270	lit = 0; op++; /* start run */
271	}
272	}
273	}
274
275	if (op + 3 > out_end) /* at most 3 bytes can be missing here */
276	return 0;
277
278	while (ip < in_end)
279	{
280	lit++; op++ = ip++;
281
282	if (expect_false (lit == MAX_LIT))
283	{
284	op [- lit - 1] = lit - 1; /* stop run */
285	lit = 0; op++; /* start run */
286	}
287	}
288
289	op [- lit - 1] = lit - 1; /* end run */
290	op -= !lit; /* undo run if length is zero */
291
292	return op - (u8 *)out_data;
293	}
294