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 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 ;)
 */
#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:	1.15
Committed:	Fri Nov 2 12:39:20 2007 UTC (16 years, 6 months ago) by root
Content type:	text/plain
Branch:	MAIN
CVS Tags:	rel-2_1
Changes since 1.14:	+1 -4 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 version 2 (the "GPL"), in which case the
27	* provisions of the GPL are applicable instead of the above. If you wish to
28	* allow the use of your version of this file only under the terms of the
29	* GPL and not to allow others to use your version of this file under the
30	* BSD license, indicate your decision by deleting the provisions above and
31	* replace them with the notice and other provisions required by the GPL. If
32	* you do not delete the provisions above, a recipient may use your version
33	* of this file under either the BSD or the GPL.
34	*/
35
36	#include "lzfP.h"
37
38	#define HSIZE (1 << (HLOG))
39
40	/*
41	* don't play with this unless you benchmark!
42	* decompression is not dependent on the hash function
43	* the hashing function might seem strange, just believe me
44	* it works ;)
45	*/
46	#ifndef FRST
47	# define FRST(p) (((p[0]) << 8) \| p[1])
48	# define NEXT(v,p) (((v) << 8) \| p[2])
49	# define IDX(h) ((((h ^ (h << 5)) >> (38 - HLOG)) - h5) & (HSIZE - 1))
50	/# define IDX(h) ((ip[0] 121 ^ ip[1] * 33 ^ ip[2] * 1) & (HSIZE-1))*/
51	#endif
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 compresses similarly.
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	#if (__i386 \|\| __amd64) && __GNUC__ >= 3
73	# define lzf_movsb(dst, src, len) \
74	asm ("rep movsb" \
75	: "=D" (dst), "=S" (src), "=c" (len) \
76	: "0" (dst), "1" (src), "2" (len));
77	#endif
78
79	/*
80	* compressed format
81	*
82	* 000LLLLL <L+1> ; literal
83	* LLLooooo oooooooo ; backref L
84	* 111ooooo LLLLLLLL oooooooo ; backref L+7
85	*
86	*/
87
88	unsigned int
89	lzf_compress (const void *const in_data, unsigned int in_len,
90	void *out_data, unsigned int out_len
91	#if LZF_STATE_ARG
92	, LZF_STATE htab
93	#endif
94	)
95	{
96	#if !LZF_STATE_ARG
97	LZF_STATE htab;
98	#endif
99	const u8 **hslot;
100	const u8 ip = (const u8 )in_data;
101	u8 op = (u8 )out_data;
102	const u8 *in_end = ip + in_len;
103	u8 *out_end = op + out_len;
104	const u8 *ref;
105
106	unsigned int hval = FRST (ip);
107	unsigned long off;
108	int lit = 0;
109
110	#if INIT_HTAB
111	memset (htab, 0, sizeof (htab));
112	# if 0
113	for (hslot = htab; hslot < htab + HSIZE; hslot++)
114	*hslot++ = ip;
115	# endif
116	#endif
117
118	for (;;)
119	{
120	if (ip < in_end - 2)
121	{
122	hval = NEXT (hval, ip);
123	hslot = htab + IDX (hval);
124	ref = hslot; hslot = ip;
125
126	if (1
127	#if INIT_HTAB && !USE_MEMCPY
128	&& ref < ip /* the next test will actually take care of this, but this is faster */
129	#endif
130	&& (off = ip - ref - 1) < MAX_OFF
131	&& ip + 4 < in_end
132	&& ref > (u8 *)in_data
133	#if STRICT_ALIGN
134	&& ref[0] == ip[0]
135	&& ref[1] == ip[1]
136	&& ref[2] == ip[2]
137	#else
138	&& (u16 )ref == (u16 )ip
139	&& ref[2] == ip[2]
140	#endif
141	)
142	{
143	/* match found at ref++ /
144	unsigned int len = 2;
145	unsigned int maxlen = in_end - ip - len;
146	maxlen = maxlen > MAX_REF ? MAX_REF : maxlen;
147
148	if (op + lit + 1 + 3 >= out_end)
149	return 0;
150
151	do
152	len++;
153	while (len < maxlen && ref[len] == ip[len]);
154
155	if (lit)
156	{
157	*op++ = lit - 1;
158	lit = -lit;
159	do
160	*op++ = ip[lit];
161	while (++lit);
162	}
163
164	len -= 2;
165	ip++;
166
167	if (len < 7)
168	{
169	*op++ = (off >> 8) + (len << 5);
170	}
171	else
172	{
173	*op++ = (off >> 8) + ( 7 << 5);
174	*op++ = len - 7;
175	}
176
177	*op++ = off;
178
179	#if ULTRA_FAST \|\| VERY_FAST
180	ip += len;
181	#if VERY_FAST && !ULTRA_FAST
182	--ip;
183	#endif
184	hval = FRST (ip);
185
186	hval = NEXT (hval, ip);
187	htab[IDX (hval)] = ip;
188	ip++;
189
190	#if VERY_FAST && !ULTRA_FAST
191	hval = NEXT (hval, ip);
192	htab[IDX (hval)] = ip;
193	ip++;
194	#endif
195	#else
196	do
197	{
198	hval = NEXT (hval, ip);
199	htab[IDX (hval)] = ip;
200	ip++;
201	}
202	while (len--);
203	#endif
204	continue;
205	}
206	}
207	else if (ip == in_end)
208	break;
209
210	/* one more literal byte we must copy */
211	lit++;
212	ip++;
213
214	if (lit == MAX_LIT)
215	{
216	if (op + 1 + MAX_LIT >= out_end)
217	return 0;
218
219	*op++ = MAX_LIT - 1;
220
221	#ifdef lzf_movsb
222	ip -= lit;
223	lzf_movsb (op, ip, lit);
224	#else
225	lit = -lit;
226	do
227	*op++ = ip[lit];
228	while (++lit);
229	#endif
230	}
231	}
232
233	if (lit)
234	{
235	if (op + lit + 1 >= out_end)
236	return 0;
237
238	*op++ = lit - 1;
239	#ifdef lzf_movsb
240	ip -= lit;
241	lzf_movsb (op, ip, lit);
242	#else
243	lit = -lit;
244	do
245	*op++ = ip[lit];
246	while (++lit);
247	#endif
248	}
249
250	return op - (u8 *) out_data;
251	}
252