liblzf/lzf_c.c

/*
 * Copyright (c) 2000-2005 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.
 * 
 *   3.  The name of the author may not be used to endorse or promote products
 *       derived from this software without specific prior written permission.
 * 
 * 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 version 2 (the "GPL"), 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!
 * decompression is not dependent on the hash function
 * the hashing function might seem strange, just believe me
 * it works ;)
 */
#define FRST(p) (((p[0]) << 8) | p[1])
#define NEXT(v,p) (((v) << 8) | p[2])
#define IDX(h) ((((h ^ (h << 5)) >> (3*8 - HLOG)) - h*5) & (HSIZE - 1))
/*
 * 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 sligthly better
 *
 * 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))

/*
 * compressed format
 *
 * 000LLLLL <L+1>    ; literal
 * LLLOOOOO oooooooo ; backref L
 * 111OOOOO LLLLLLLL oooooooo ; backref L+7
 *
 */

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;

  unsigned int hval = FRST (ip);
  unsigned long off;
           int lit = 0;

#if INIT_HTAB
# if USE_MEMCPY
    memset (htab, 0, sizeof (htab));
# else
    for (hslot = htab; hslot < htab + HSIZE; hslot++)
      *hslot++ = ip;
# endif
#endif

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

          if (1
#if INIT_HTAB && !USE_MEMCPY
              && 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
#if STRICT_ALIGN
              && ref[0] == ip[0]
              && ref[1] == ip[1]
              && ref[2] == ip[2]
#else
              && *(u16 *)ref == *(u16 *)ip
              && ref[2] == ip[2]
#endif
            )
            {
              /* match found at *ref++ */
              unsigned int len = 2;
              unsigned int maxlen = in_end - ip - len;
              maxlen = maxlen > MAX_REF ? MAX_REF : maxlen;

              if (op + lit + 1 + 3 >= out_end)
                return 0;

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

              if (lit)
                {
                  *op++ = lit - 1;
                  lit = -lit;
                  do
                    *op++ = ip[lit];
                  while (++lit);
                }

              len -= 2;
              ip++;

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

              *op++ = off;

#if ULTRA_FAST || VERY_FAST
              ip += len;
#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
              do
                {
                  hval = NEXT (hval, ip);
                  htab[IDX (hval)] = ip;
                  ip++;
                }
              while (len--);
#endif
              continue;
            }
        }
      else if (ip == in_end)
        break;

      /* one more literal byte we must copy */
      lit++;
      ip++;

      if (lit == MAX_LIT)
        {
          if (op + 1 + MAX_LIT >= out_end)
            return 0;

          *op++ = MAX_LIT - 1;
#if USE_MEMCPY
          memcpy (op, ip - MAX_LIT, MAX_LIT);
          op += MAX_LIT;
          lit = 0;
#else
          lit = -lit;
          do
            *op++ = ip[lit];
          while (++lit);
#endif
        }
    }

  if (lit)
    {
      if (op + lit + 1 >= out_end)
        return 0;

      *op++ = lit - 1;
      lit = -lit;
      do
        *op++ = ip[lit];
      while (++lit);
    }

  return op - (u8 *) out_data;
}
Revision:	1.9
Committed:	Tue Mar 8 19:59:52 2005 UTC (19 years, 2 months ago) by root
Content type:	text/plain
Branch:	MAIN
CVS Tags:	rel-1_5
Changes since 1.8:	+16 -6 lines
Log Message:	* empty log message *
#	Content
1	/*
2	* Copyright (c) 2000-2005 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	* 3. The name of the author may not be used to endorse or promote products
15	* derived from this software without specific prior written permission.
16	*
17	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
18	* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MER-
19	* CHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
20	* EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPE-
21	* CIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
22	* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
23	* OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
24	* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTH-
25	* ERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
26	* OF THE POSSIBILITY OF SUCH DAMAGE.
27	*
28	* Alternatively, the contents of this file may be used under the terms of
29	* the GNU General Public License version 2 (the "GPL"), in which case the
30	* provisions of the GPL are applicable instead of the above. If you wish to
31	* allow the use of your version of this file only under the terms of the
32	* GPL and not to allow others to use your version of this file under the
33	* BSD license, indicate your decision by deleting the provisions above and
34	* replace them with the notice and other provisions required by the GPL. If
35	* you do not delete the provisions above, a recipient may use your version
36	* of this file under either the BSD or the GPL.
37	*/
38
39	#include "lzfP.h"
40
41	#define HSIZE (1 << (HLOG))
42
43	/*
44	* don't play with this unless you benchmark!
45	* decompression is not dependent on the hash function
46	* the hashing function might seem strange, just believe me
47	* it works ;)
48	*/
49	#define FRST(p) (((p[0]) << 8) \| p[1])
50	#define NEXT(v,p) (((v) << 8) \| p[2])
51	#define IDX(h) ((((h ^ (h << 5)) >> (38 - HLOG)) - h5) & (HSIZE - 1))
52	/*
53	* IDX works because it is very similar to a multiplicative hash, e.g.
54	* ((h * 57321 >> (3*8 - HLOG)) & (HSIZE - 1))
55	* the latter is also quite fast on newer CPUs, and sligthly better
56	*
57	* the next one is also quite good, albeit slow ;)
58	* (int)(cos(h & 0xffffff) * 1e6)
59	*/
60
61	#if 0
62	/* original lzv-like hash function, much worse and thus slower */
63	# define FRST(p) (p[0] << 5) ^ p[1]
64	# define NEXT(v,p) ((v) << 5) ^ p[2]
65	# define IDX(h) ((h) & (HSIZE - 1))
66	#endif
67
68	#define MAX_LIT (1 << 5)
69	#define MAX_OFF (1 << 13)
70	#define MAX_REF ((1 << 8) + (1 << 3))
71
72	/*
73	* compressed format
74	*
75	* 000LLLLL <L+1> ; literal
76	* LLLOOOOO oooooooo ; backref L
77	* 111OOOOO LLLLLLLL oooooooo ; backref L+7
78	*
79	*/
80
81	unsigned int
82	lzf_compress (const void *const in_data, unsigned int in_len,
83	void *out_data, unsigned int out_len
84	#if LZF_STATE_ARG
85	, LZF_STATE *htab
86	#endif
87	)
88	{
89	#if !LZF_STATE_ARG
90	LZF_STATE htab;
91	#endif
92	const u8 **hslot;
93	const u8 ip = (const u8 )in_data;
94	u8 op = (u8 )out_data;
95	const u8 *in_end = ip + in_len;
96	u8 *out_end = op + out_len;
97	const u8 *ref;
98
99	unsigned int hval = FRST (ip);
100	unsigned long off;
101	int lit = 0;
102
103	#if INIT_HTAB
104	# if USE_MEMCPY
105	memset (htab, 0, sizeof (htab));
106	# else
107	for (hslot = htab; hslot < htab + HSIZE; hslot++)
108	*hslot++ = ip;
109	# endif
110	#endif
111
112	for (;;)
113	{
114	if (ip < in_end - 2)
115	{
116	hval = NEXT (hval, ip);
117	hslot = htab + IDX (hval);
118	ref = hslot; hslot = ip;
119
120	if (1
121	#if INIT_HTAB && !USE_MEMCPY
122	&& ref < ip /* the next test will actually take care of this, but this is faster */
123	#endif
124	&& (off = ip - ref - 1) < MAX_OFF
125	&& ip + 4 < in_end
126	&& ref > (u8 *)in_data
127	#if STRICT_ALIGN
128	&& ref[0] == ip[0]
129	&& ref[1] == ip[1]
130	&& ref[2] == ip[2]
131	#else
132	&& (u16 )ref == (u16 )ip
133	&& ref[2] == ip[2]
134	#endif
135	)
136	{
137	/* match found at ref++ /
138	unsigned int len = 2;
139	unsigned int maxlen = in_end - ip - len;
140	maxlen = maxlen > MAX_REF ? MAX_REF : maxlen;
141
142	if (op + lit + 1 + 3 >= out_end)
143	return 0;
144
145	do
146	len++;
147	while (len < maxlen && ref[len] == ip[len]);
148
149	if (lit)
150	{
151	*op++ = lit - 1;
152	lit = -lit;
153	do
154	*op++ = ip[lit];
155	while (++lit);
156	}
157
158	len -= 2;
159	ip++;
160
161	if (len < 7)
162	{
163	*op++ = (off >> 8) + (len << 5);
164	}
165	else
166	{
167	*op++ = (off >> 8) + ( 7 << 5);
168	*op++ = len - 7;
169	}
170
171	*op++ = off;
172
173	#if ULTRA_FAST \|\| VERY_FAST
174	ip += len;
175	#if VERY_FAST && !ULTRA_FAST
176	--ip;
177	#endif
178	hval = FRST (ip);
179
180	hval = NEXT (hval, ip);
181	htab[IDX (hval)] = ip;
182	ip++;
183
184	#if VERY_FAST && !ULTRA_FAST
185	hval = NEXT (hval, ip);
186	htab[IDX (hval)] = ip;
187	ip++;
188	#endif
189	#else
190	do
191	{
192	hval = NEXT (hval, ip);
193	htab[IDX (hval)] = ip;
194	ip++;
195	}
196	while (len--);
197	#endif
198	continue;
199	}
200	}
201	else if (ip == in_end)
202	break;
203
204	/* one more literal byte we must copy */
205	lit++;
206	ip++;
207
208	if (lit == MAX_LIT)
209	{
210	if (op + 1 + MAX_LIT >= out_end)
211	return 0;
212
213	*op++ = MAX_LIT - 1;
214	#if USE_MEMCPY
215	memcpy (op, ip - MAX_LIT, MAX_LIT);
216	op += MAX_LIT;
217	lit = 0;
218	#else
219	lit = -lit;
220	do
221	*op++ = ip[lit];
222	while (++lit);
223	#endif
224	}
225	}
226
227	if (lit)
228	{
229	if (op + lit + 1 >= out_end)
230	return 0;
231
232	*op++ = lit - 1;
233	lit = -lit;
234	do
235	*op++ = ip[lit];
236	while (++lit);
237	}
238
239	return op - (u8 *) out_data;
240	}