liblzf/lzf_c.c

/*
 * Copyright (c) 2000-2010,2012 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 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 MULTIPLICATION_IS_SLOW
#  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
# else
/* this one was developed with sesse,
 * and is very similar to the one in snappy.
 * it does need a modern enough cpu with a fast multiplication.
 */
#  define IDX(h) (((h * 0x1e35a7bdU) >> (32 - HLOG - 8)) & (HSIZE - 1))
# endif
#endif

#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 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)
  /* workaround for missing POSIX compliance */
  #if __GNUC__
    unsigned long long off;
  #else
    unsigned __int64 off;
  #endif
#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:	1.49
Committed:	Fri Nov 16 22:48:52 2012 UTC (11 years, 6 months ago) by root
Content type:	text/plain
Branch:	MAIN
Changes since 1.48:	+4 -4 lines
Log Message:	* empty log message *
#	User	Rev	Content
1	root	1.1	/*
2	root	1.47	* Copyright (c) 2000-2010,2012 Marc Alexander Lehmann <schmorp@schmorp.de>
3	root	1.49	*
4	root	1.1	* Redistribution and use in source and binary forms, with or without modifica-
5			* tion, are permitted provided that the following conditions are met:
6	root	1.49	*
7	root	1.1	* 1. Redistributions of source code must retain the above copyright notice,
8			* this list of conditions and the following disclaimer.
9	root	1.49	*
10	root	1.1	* 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	root	1.49	*
14	root	1.1	* 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	pcg	1.6	*
25			* Alternatively, the contents of this file may be used under the terms of
26	root	1.16	* 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	root	1.1	*/
36
37			#include "lzfP.h"
38
39			#define HSIZE (1 << (HLOG))
40
41			/*
42			* don't play with this unless you benchmark!
43	root	1.41	* the data format is not dependent on the hash function.
44			* the hash function might seem strange, just believe me,
45	root	1.1	* it works ;)
46			*/
47	root	1.10	#ifndef FRST
48			# define FRST(p) (((p[0]) << 8) \| p[1])
49			# define NEXT(v,p) (((v) << 8) \| p[2])
50	root	1.45	# if MULTIPLICATION_IS_SLOW
51			# if ULTRA_FAST
52			# define IDX(h) ((( h >> (3*8 - HLOG)) - h ) & (HSIZE - 1))
53			# elif VERY_FAST
54			# define IDX(h) ((( h >> (38 - HLOG)) - h5) & (HSIZE - 1))
55			# else
56			# define IDX(h) ((((h ^ (h << 5)) >> (38 - HLOG)) - h5) & (HSIZE - 1))
57			# endif
58	root	1.22	# else
59	root	1.45	/* this one was developed with sesse,
60			* and is very similar to the one in snappy.
61			* it does need a modern enough cpu with a fast multiplication.
62			*/
63			# define IDX(h) (((h * 0x1e35a7bdU) >> (32 - HLOG - 8)) & (HSIZE - 1))
64	root	1.22	# endif
65	root	1.10	#endif
66	root	1.1
67			#if 0
68	root	1.7	/* original lzv-like hash function, much worse and thus slower */
69	root	1.1	# define FRST(p) (p[0] << 5) ^ p[1]
70	root	1.2	# define NEXT(v,p) ((v) << 5) ^ p[2]
71			# define IDX(h) ((h) & (HSIZE - 1))
72	root	1.1	#endif
73
74			#define MAX_LIT (1 << 5)
75			#define MAX_OFF (1 << 13)
76	root	1.12	#define MAX_REF ((1 << 8) + (1 << 3))
77	root	1.1
78	root	1.17	#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	root	1.1	/*
90			* compressed format
91			*
92	root	1.38	* 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	root	1.1	*
96			*/
97
98			unsigned int
99			lzf_compress (const void *const in_data, unsigned int in_len,
100	pcg	1.4	void *out_data, unsigned int out_len
101	pcg	1.5	#if LZF_STATE_ARG
102	root	1.11	, LZF_STATE htab
103	pcg	1.4	#endif
104			)
105	root	1.1	{
106	pcg	1.5	#if !LZF_STATE_ARG
107	pcg	1.4	LZF_STATE htab;
108			#endif
109			const u8 ip = (const u8 )in_data;
110			u8 op = (u8 )out_data;
111	root	1.1	const u8 *in_end = ip + in_len;
112			u8 *out_end = op + out_len;
113			const u8 *ref;
114
115	root	1.32	/* 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	root	1.46	* works for differences within a single object). We also assume that
118	root	1.32	* 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	root	1.47	#if defined (_WIN32) && defined (_M_X64)
123			/* workaround for missing POSIX compliance */
124	root	1.48	#if __GNUC__
125	root	1.47	unsigned long long off;
126			#else
127			unsigned __int64 off;
128			#endif
129	root	1.31	#else
130	root	1.1	unsigned long off;
131	root	1.31	#endif
132	root	1.32	unsigned int hval;
133	root	1.22	int lit;
134
135			if (!in_len \|\| !out_len)
136			return 0;
137	root	1.1
138			#if INIT_HTAB
139	root	1.14	memset (htab, 0, sizeof (htab));
140	root	1.1	#endif
141
142	root	1.22	lit = 0; op++; /* start run */
143
144			hval = FRST (ip);
145			while (ip < in_end - 2)
146	root	1.1	{
147	root	1.42	LZF_HSLOT *hslot;
148
149	root	1.22	hval = NEXT (hval, ip);
150			hslot = htab + IDX (hval);
151	root	1.42	ref = hslot + LZF_HSLOT_BIAS; hslot = ip - LZF_HSLOT_BIAS;
152	root	1.1
153	root	1.22	if (1
154	ayin	1.27	#if INIT_HTAB
155	root	1.22	&& ref < ip /* the next test will actually take care of this, but this is faster */
156	root	1.1	#endif
157	root	1.22	&& (off = ip - ref - 1) < MAX_OFF
158			&& ref > (u8 *)in_data
159	root	1.40	&& ref[2] == ip[2]
160	root	1.1	#if STRICT_ALIGN
161	root	1.43	&& ((ref[1] << 8) \| ref[0]) == ((ip[1] << 8) \| ip[0])
162	root	1.1	#else
163	root	1.22	&& (u16 )ref == (u16 )ip
164	root	1.1	#endif
165	root	1.22	)
166			{
167			/* match found at ref++ /
168			unsigned int len = 2;
169			unsigned int maxlen = in_end - ip - len;
170			maxlen = maxlen > MAX_REF ? MAX_REF : maxlen;
171
172	root	1.36	if (expect_false (op + 3 + 1 >= out_end)) /* first a faster conservative test */
173			if (op - !lit + 3 + 1 >= out_end) /* second the exact but rare test */
174			return 0;
175
176	root	1.22	op [- lit - 1] = lit - 1; /* stop run */
177			op -= !lit; /* undo run if length is zero */
178	root	1.9
179	root	1.22	for (;;)
180			{
181			if (expect_true (maxlen > 16))
182	pcg	1.5	{
183	root	1.22	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			len++; if (ref [len] != ip [len]) break;
199			len++; if (ref [len] != ip [len]) break;
200			len++; if (ref [len] != ip [len]) break;
201			len++; if (ref [len] != ip [len]) break;
202	pcg	1.5	}
203
204	root	1.22	do
205			len++;
206			while (len < maxlen && ref[len] == ip[len]);
207	root	1.18
208	root	1.22	break;
209			}
210	root	1.18
211	root	1.33	len -= 2; /* len is now #octets - 1 */
212	root	1.22	ip++;
213	pcg	1.5
214	root	1.22	if (len < 7)
215			{
216			*op++ = (off >> 8) + (len << 5);
217			}
218			else
219			{
220			*op++ = (off >> 8) + ( 7 << 5);
221			*op++ = len - 7;
222			}
223	root	1.1
224	root	1.22	*op++ = off;
225	root	1.44
226	root	1.34	lit = 0; op++; /* start run */
227
228			ip += len + 1;
229
230	root	1.35	if (expect_false (ip >= in_end - 2))
231	root	1.34	break;
232	root	1.1
233	root	1.9	#if ULTRA_FAST \|\| VERY_FAST
234	root	1.34	--ip;
235	root	1.33	# if VERY_FAST && !ULTRA_FAST
236	root	1.34	--ip;
237	root	1.33	# endif
238	root	1.34	hval = FRST (ip);
239	root	1.9
240	root	1.34	hval = NEXT (hval, ip);
241	root	1.42	htab[IDX (hval)] = ip - LZF_HSLOT_BIAS;
242	root	1.34	ip++;
243	root	1.9
244	root	1.33	# if VERY_FAST && !ULTRA_FAST
245	root	1.34	hval = NEXT (hval, ip);
246	root	1.42	htab[IDX (hval)] = ip - LZF_HSLOT_BIAS;
247	root	1.34	ip++;
248			# endif
249			#else
250			ip -= len + 1;
251
252			do
253			{
254	pcg	1.5	hval = NEXT (hval, ip);
255	root	1.42	htab[IDX (hval)] = ip - LZF_HSLOT_BIAS;
256	pcg	1.5	ip++;
257	root	1.34	}
258			while (len--);
259	root	1.33	#endif
260	pcg	1.5	}
261	root	1.26	else
262	pcg	1.5	{
263	root	1.26	/* one more literal byte we must copy */
264			if (expect_false (op >= out_end))
265			return 0;
266
267			lit++; op++ = ip++;
268
269			if (expect_false (lit == MAX_LIT))
270			{
271			op [- lit - 1] = lit - 1; /* stop run */
272			lit = 0; op++; /* start run */
273			}
274	pcg	1.5	}
275	root	1.1	}
276
277	root	1.29	if (op + 3 > out_end) /* at most 3 bytes can be missing here */
278	root	1.22	return 0;
279
280			while (ip < in_end)
281	root	1.1	{
282	root	1.26	lit++; op++ = ip++;
283	root	1.28
284			if (expect_false (lit == MAX_LIT))
285			{
286			op [- lit - 1] = lit - 1; /* stop run */
287			lit = 0; op++; /* start run */
288			}
289	root	1.22	}
290	root	1.1
291	root	1.24	op [- lit - 1] = lit - 1; /* end run */
292			op -= !lit; /* undo run if length is zero */
293	root	1.1
294	root	1.22	return op - (u8 *)out_data;
295	root	1.1	}
296	root	1.14