liblzf/lzf_c.c

/*
 * Copyright (c) 2000-2003 Marc Alexander Lehmann <pcg@goof.com>
 * 
 * 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*3) & (HSIZE - 1))
/*
 * IDX works because it is very similar to a multiplicative hash, e.g.
 * (h * 57321 >> (3*8 - HLOG))
 * the next one is also quite good, albeit slow ;)
 * (int)(cos(h & 0xffffff) * 1e6)
 */

#if 0
/* original lzv-like hash function */
# 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;

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

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

              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
              ip += len;
              hval = FRST (ip);
              hval = NEXT (hval, ip);
              htab[IDX (hval)] = ip;
              ip++;
#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:	1.6
Committed:	Tue Apr 20 18:11:58 2004 UTC (20 years ago) by pcg
Content type:	text/plain
Branch:	MAIN
Changes since 1.5:	+10 -0 lines
Log Message:	* empty log message *
#	Content
1	/*
2	* Copyright (c) 2000-2003 Marc Alexander Lehmann <pcg@goof.com>
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)) + h3) & (HSIZE - 1))
52	/*
53	* IDX works because it is very similar to a multiplicative hash, e.g.
54	* (h * 57321 >> (3*8 - HLOG))
55	* the next one is also quite good, albeit slow ;)
56	* (int)(cos(h & 0xffffff) * 1e6)
57	*/
58
59	#if 0
60	/* original lzv-like hash function */
61	# define FRST(p) (p[0] << 5) ^ p[1]
62	# define NEXT(v,p) ((v) << 5) ^ p[2]
63	# define IDX(h) ((h) & (HSIZE - 1))
64	#endif
65
66	#define MAX_LIT (1 << 5)
67	#define MAX_OFF (1 << 13)
68	#define MAX_REF ((1 << 8) + (1 << 3))
69
70	/*
71	* compressed format
72	*
73	* 000LLLLL <L+1> ; literal
74	* LLLOOOOO oooooooo ; backref L
75	* 111OOOOO LLLLLLLL oooooooo ; backref L+7
76	*
77	*/
78
79	unsigned int
80	lzf_compress (const void *const in_data, unsigned int in_len,
81	void *out_data, unsigned int out_len
82	#if LZF_STATE_ARG
83	, LZF_STATE *htab
84	#endif
85	)
86	{
87	#if !LZF_STATE_ARG
88	LZF_STATE htab;
89	#endif
90	const u8 **hslot;
91	const u8 ip = (const u8 )in_data;
92	u8 op = (u8 )out_data;
93	const u8 *in_end = ip + in_len;
94	u8 *out_end = op + out_len;
95	const u8 *ref;
96
97	unsigned int hval = FRST (ip);
98	unsigned long off;
99	int lit = 0;
100
101	#if INIT_HTAB
102	# if USE_MEMCPY
103	memset (htab, 0, sizeof (htab));
104	# else
105	for (hslot = htab; hslot < htab + HSIZE; hslot++)
106	*hslot++ = ip;
107	# endif
108	#endif
109
110	for (;;)
111	{
112	if (ip < in_end - 2)
113	{
114	hval = NEXT (hval, ip);
115	hslot = htab + IDX (hval);
116	ref = hslot; hslot = ip;
117
118	if (1
119	#if INIT_HTAB && !USE_MEMCPY
120	&& ref < ip /* the next test will actually take care of this, but this is faster */
121	#endif
122	&& (off = ip - ref - 1) < MAX_OFF
123	&& ip + 4 < in_end
124	&& ref > (u8 *)in_data
125	#if STRICT_ALIGN
126	&& ref[0] == ip[0]
127	&& ref[1] == ip[1]
128	&& ref[2] == ip[2]
129	#else
130	&& (u16 )ref == (u16 )ip
131	&& ref[2] == ip[2]
132	#endif
133	)
134	{
135	/* match found at ref++ /
136	unsigned int len = 2;
137	unsigned int maxlen = in_end - ip - len;
138	maxlen = maxlen > MAX_REF ? MAX_REF : maxlen;
139
140	do
141	len++;
142	while (len < maxlen && ref[len] == ip[len]);
143
144	if (op + lit + 1 + 3 >= out_end)
145	return 0;
146
147	if (lit)
148	{
149	*op++ = lit - 1;
150	lit = -lit;
151	do
152	*op++ = ip[lit];
153	while (++lit);
154	}
155
156	len -= 2;
157	ip++;
158
159	if (len < 7)
160	{
161	*op++ = (off >> 8) + (len << 5);
162	}
163	else
164	{
165	*op++ = (off >> 8) + ( 7 << 5);
166	*op++ = len - 7;
167	}
168
169	*op++ = off;
170
171	#if ULTRA_FAST
172	ip += len;
173	hval = FRST (ip);
174	hval = NEXT (hval, ip);
175	htab[IDX (hval)] = ip;
176	ip++;
177	#else
178	do
179	{
180	hval = NEXT (hval, ip);
181	htab[IDX (hval)] = ip;
182	ip++;
183	}
184	while (len--);
185	#endif
186	continue;
187	}
188	}
189	else if (ip == in_end)
190	break;
191
192	/* one more literal byte we must copy */
193	lit++;
194	ip++;
195
196	if (lit == MAX_LIT)
197	{
198	if (op + 1 + MAX_LIT >= out_end)
199	return 0;
200
201	*op++ = MAX_LIT - 1;
202	#if USE_MEMCPY
203	memcpy (op, ip - MAX_LIT, MAX_LIT);
204	op += MAX_LIT;
205	lit = 0;
206	#else
207	lit = -lit;
208	do
209	*op++ = ip[lit];
210	while (++lit);
211	#endif
212	}
213	}
214
215	if (lit)
216	{
217	if (op + lit + 1 >= out_end)
218	return 0;
219
220	*op++ = lit - 1;
221	lit = -lit;
222	do
223	*op++ = ip[lit];
224	while (++lit);
225	}
226
227	return op - (u8 *) out_data;
228	}