liblzf/lzf_c.c

/*
 * Copyright (c) 2000-2007 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!
 * decompression is not dependent on the hash function
 * the hashing 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])
# define IDX(h) ((((h ^ (h << 5)) >> (3*8 - HLOG)) - h*5) & (HSIZE - 1))
/*# define IDX(h) ((ip[0] * 121 ^ ip[1] * 33 ^ ip[2] * 1) & (HSIZE-1))*/
#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 (__i386 || __amd64) && __GNUC__ >= 3
# define lzf_movsb(dst, src, len)                \
   asm ("rep movsb"                              \
        : "=D" (dst), "=S" (src), "=c" (len)     \
        :  "0" (dst),  "1" (src),  "2" (len));
#endif

/*
 * 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
  memset (htab, 0, sizeof (htab));
# if 0
  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;

#ifdef lzf_movsb
          ip -= lit;
          lzf_movsb (op, ip, lit);
#else
          lit = -lit;
          do
            *op++ = ip[lit];
          while (++lit);
#endif
        }
    }

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

      *op++ = lit - 1;
#ifdef lzf_movsb
      ip -= lit;
      lzf_movsb (op, ip, lit);
#else
      lit = -lit;
      do
        *op++ = ip[lit];
      while (++lit);
#endif
    }

  return op - (u8 *) out_data;
}

Revision:	1.16
Committed:	Mon Nov 5 23:28:40 2007 UTC (16 years, 6 months ago) by root
Content type:	text/plain
Branch:	MAIN
Changes since 1.15:	+9 -8 lines
Log Message:	* empty log message *
#	Content
1	/*
2	* Copyright (c) 2000-2007 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	* decompression is not dependent on the hash function
44	* the hashing 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	# define IDX(h) ((((h ^ (h << 5)) >> (38 - HLOG)) - h5) & (HSIZE - 1))
51	/# define IDX(h) ((ip[0] 121 ^ ip[1] * 33 ^ ip[2] * 1) & (HSIZE-1))*/
52	#endif
53	/*
54	* IDX works because it is very similar to a multiplicative hash, e.g.
55	* ((h * 57321 >> (3*8 - HLOG)) & (HSIZE - 1))
56	* the latter is also quite fast on newer CPUs, and compresses similarly.
57	*
58	* the next one is also quite good, albeit slow ;)
59	* (int)(cos(h & 0xffffff) * 1e6)
60	*/
61
62	#if 0
63	/* original lzv-like hash function, much worse and thus slower */
64	# define FRST(p) (p[0] << 5) ^ p[1]
65	# define NEXT(v,p) ((v) << 5) ^ p[2]
66	# define IDX(h) ((h) & (HSIZE - 1))
67	#endif
68
69	#define MAX_LIT (1 << 5)
70	#define MAX_OFF (1 << 13)
71	#define MAX_REF ((1 << 8) + (1 << 3))
72
73	#if (__i386 \|\| __amd64) && __GNUC__ >= 3
74	# define lzf_movsb(dst, src, len) \
75	asm ("rep movsb" \
76	: "=D" (dst), "=S" (src), "=c" (len) \
77	: "0" (dst), "1" (src), "2" (len));
78	#endif
79
80	/*
81	* compressed format
82	*
83	* 000LLLLL <L+1> ; literal
84	* LLLooooo oooooooo ; backref L
85	* 111ooooo LLLLLLLL oooooooo ; backref L+7
86	*
87	*/
88
89	unsigned int
90	lzf_compress (const void *const in_data, unsigned int in_len,
91	void *out_data, unsigned int out_len
92	#if LZF_STATE_ARG
93	, LZF_STATE htab
94	#endif
95	)
96	{
97	#if !LZF_STATE_ARG
98	LZF_STATE htab;
99	#endif
100	const u8 **hslot;
101	const u8 ip = (const u8 )in_data;
102	u8 op = (u8 )out_data;
103	const u8 *in_end = ip + in_len;
104	u8 *out_end = op + out_len;
105	const u8 *ref;
106
107	unsigned int hval = FRST (ip);
108	unsigned long off;
109	int lit = 0;
110
111	#if INIT_HTAB
112	memset (htab, 0, sizeof (htab));
113	# if 0
114	for (hslot = htab; hslot < htab + HSIZE; hslot++)
115	*hslot++ = ip;
116	# endif
117	#endif
118
119	for (;;)
120	{
121	if (ip < in_end - 2)
122	{
123	hval = NEXT (hval, ip);
124	hslot = htab + IDX (hval);
125	ref = hslot; hslot = ip;
126
127	if (1
128	#if INIT_HTAB && !USE_MEMCPY
129	&& ref < ip /* the next test will actually take care of this, but this is faster */
130	#endif
131	&& (off = ip - ref - 1) < MAX_OFF
132	&& ip + 4 < in_end
133	&& ref > (u8 *)in_data
134	#if STRICT_ALIGN
135	&& ref[0] == ip[0]
136	&& ref[1] == ip[1]
137	&& ref[2] == ip[2]
138	#else
139	&& (u16 )ref == (u16 )ip
140	&& ref[2] == ip[2]
141	#endif
142	)
143	{
144	/* match found at ref++ /
145	unsigned int len = 2;
146	unsigned int maxlen = in_end - ip - len;
147	maxlen = maxlen > MAX_REF ? MAX_REF : maxlen;
148
149	if (op + lit + 1 + 3 >= out_end)
150	return 0;
151
152	do
153	len++;
154	while (len < maxlen && ref[len] == ip[len]);
155
156	if (lit)
157	{
158	*op++ = lit - 1;
159	lit = -lit;
160	do
161	*op++ = ip[lit];
162	while (++lit);
163	}
164
165	len -= 2;
166	ip++;
167
168	if (len < 7)
169	{
170	*op++ = (off >> 8) + (len << 5);
171	}
172	else
173	{
174	*op++ = (off >> 8) + ( 7 << 5);
175	*op++ = len - 7;
176	}
177
178	*op++ = off;
179
180	#if ULTRA_FAST \|\| VERY_FAST
181	ip += len;
182	#if VERY_FAST && !ULTRA_FAST
183	--ip;
184	#endif
185	hval = FRST (ip);
186
187	hval = NEXT (hval, ip);
188	htab[IDX (hval)] = ip;
189	ip++;
190
191	#if VERY_FAST && !ULTRA_FAST
192	hval = NEXT (hval, ip);
193	htab[IDX (hval)] = ip;
194	ip++;
195	#endif
196	#else
197	do
198	{
199	hval = NEXT (hval, ip);
200	htab[IDX (hval)] = ip;
201	ip++;
202	}
203	while (len--);
204	#endif
205	continue;
206	}
207	}
208	else if (ip == in_end)
209	break;
210
211	/* one more literal byte we must copy */
212	lit++;
213	ip++;
214
215	if (lit == MAX_LIT)
216	{
217	if (op + 1 + MAX_LIT >= out_end)
218	return 0;
219
220	*op++ = MAX_LIT - 1;
221
222	#ifdef lzf_movsb
223	ip -= lit;
224	lzf_movsb (op, ip, lit);
225	#else
226	lit = -lit;
227	do
228	*op++ = ip[lit];
229	while (++lit);
230	#endif
231	}
232	}
233
234	if (lit)
235	{
236	if (op + lit + 1 >= out_end)
237	return 0;
238
239	*op++ = lit - 1;
240	#ifdef lzf_movsb
241	ip -= lit;
242	lzf_movsb (op, ip, lit);
243	#else
244	lit = -lit;
245	do
246	*op++ = ip[lit];
247	while (++lit);
248	#endif
249	}
250
251	return op - (u8 *) out_data;
252	}
253