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 ;)
 */
#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:	1.14
Committed:	Thu Jun 21 22:11:34 2007 UTC (16 years, 10 months ago) by root
Content type:	text/plain
Branch:	MAIN
Changes since 1.13:	+21 -9 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	#ifndef FRST
50	# define FRST(p) (((p[0]) << 8) \| p[1])
51	# define NEXT(v,p) (((v) << 8) \| p[2])
52	# define IDX(h) ((((h ^ (h << 5)) >> (38 - HLOG)) - h5) & (HSIZE - 1))
53	/# define IDX(h) ((ip[0] 121 ^ ip[1] * 33 ^ ip[2] * 1) & (HSIZE-1))*/
54	#endif
55	/*
56	* IDX works because it is very similar to a multiplicative hash, e.g.
57	* ((h * 57321 >> (3*8 - HLOG)) & (HSIZE - 1))
58	* the latter is also quite fast on newer CPUs, and compresses similarly.
59	*
60	* the next one is also quite good, albeit slow ;)
61	* (int)(cos(h & 0xffffff) * 1e6)
62	*/
63
64	#if 0
65	/* original lzv-like hash function, much worse and thus slower */
66	# define FRST(p) (p[0] << 5) ^ p[1]
67	# define NEXT(v,p) ((v) << 5) ^ p[2]
68	# define IDX(h) ((h) & (HSIZE - 1))
69	#endif
70
71	#define MAX_LIT (1 << 5)
72	#define MAX_OFF (1 << 13)
73	#define MAX_REF ((1 << 8) + (1 << 3))
74
75	#if (__i386 \|\| __amd64) && __GNUC__ >= 3
76	# define lzf_movsb(dst, src, len) \
77	asm ("rep movsb" \
78	: "=D" (dst), "=S" (src), "=c" (len) \
79	: "0" (dst), "1" (src), "2" (len));
80	#endif
81
82	/*
83	* compressed format
84	*
85	* 000LLLLL <L+1> ; literal
86	* LLLooooo oooooooo ; backref L
87	* 111ooooo LLLLLLLL oooooooo ; backref L+7
88	*
89	*/
90
91	unsigned int
92	lzf_compress (const void *const in_data, unsigned int in_len,
93	void *out_data, unsigned int out_len
94	#if LZF_STATE_ARG
95	, LZF_STATE htab
96	#endif
97	)
98	{
99	#if !LZF_STATE_ARG
100	LZF_STATE htab;
101	#endif
102	const u8 **hslot;
103	const u8 ip = (const u8 )in_data;
104	u8 op = (u8 )out_data;
105	const u8 *in_end = ip + in_len;
106	u8 *out_end = op + out_len;
107	const u8 *ref;
108
109	unsigned int hval = FRST (ip);
110	unsigned long off;
111	int lit = 0;
112
113	#if INIT_HTAB
114	memset (htab, 0, sizeof (htab));
115	# if 0
116	for (hslot = htab; hslot < htab + HSIZE; hslot++)
117	*hslot++ = ip;
118	# endif
119	#endif
120
121	for (;;)
122	{
123	if (ip < in_end - 2)
124	{
125	hval = NEXT (hval, ip);
126	hslot = htab + IDX (hval);
127	ref = hslot; hslot = ip;
128
129	if (1
130	#if INIT_HTAB && !USE_MEMCPY
131	&& ref < ip /* the next test will actually take care of this, but this is faster */
132	#endif
133	&& (off = ip - ref - 1) < MAX_OFF
134	&& ip + 4 < in_end
135	&& ref > (u8 *)in_data
136	#if STRICT_ALIGN
137	&& ref[0] == ip[0]
138	&& ref[1] == ip[1]
139	&& ref[2] == ip[2]
140	#else
141	&& (u16 )ref == (u16 )ip
142	&& ref[2] == ip[2]
143	#endif
144	)
145	{
146	/* match found at ref++ /
147	unsigned int len = 2;
148	unsigned int maxlen = in_end - ip - len;
149	maxlen = maxlen > MAX_REF ? MAX_REF : maxlen;
150
151	if (op + lit + 1 + 3 >= out_end)
152	return 0;
153
154	do
155	len++;
156	while (len < maxlen && ref[len] == ip[len]);
157
158	if (lit)
159	{
160	*op++ = lit - 1;
161	lit = -lit;
162	do
163	*op++ = ip[lit];
164	while (++lit);
165	}
166
167	len -= 2;
168	ip++;
169
170	if (len < 7)
171	{
172	*op++ = (off >> 8) + (len << 5);
173	}
174	else
175	{
176	*op++ = (off >> 8) + ( 7 << 5);
177	*op++ = len - 7;
178	}
179
180	*op++ = off;
181
182	#if ULTRA_FAST \|\| VERY_FAST
183	ip += len;
184	#if VERY_FAST && !ULTRA_FAST
185	--ip;
186	#endif
187	hval = FRST (ip);
188
189	hval = NEXT (hval, ip);
190	htab[IDX (hval)] = ip;
191	ip++;
192
193	#if VERY_FAST && !ULTRA_FAST
194	hval = NEXT (hval, ip);
195	htab[IDX (hval)] = ip;
196	ip++;
197	#endif
198	#else
199	do
200	{
201	hval = NEXT (hval, ip);
202	htab[IDX (hval)] = ip;
203	ip++;
204	}
205	while (len--);
206	#endif
207	continue;
208	}
209	}
210	else if (ip == in_end)
211	break;
212
213	/* one more literal byte we must copy */
214	lit++;
215	ip++;
216
217	if (lit == MAX_LIT)
218	{
219	if (op + 1 + MAX_LIT >= out_end)
220	return 0;
221
222	*op++ = MAX_LIT - 1;
223
224	#ifdef lzf_movsb
225	ip -= lit;
226	lzf_movsb (op, ip, lit);
227	#else
228	lit = -lit;
229	do
230	*op++ = ip[lit];
231	while (++lit);
232	#endif
233	}
234	}
235
236	if (lit)
237	{
238	if (op + lit + 1 >= out_end)
239	return 0;
240
241	*op++ = lit - 1;
242	#ifdef lzf_movsb
243	ip -= lit;
244	lzf_movsb (op, ip, lit);
245	#else
246	lit = -lit;
247	do
248	*op++ = ip[lit];
249	while (++lit);
250	#endif
251	}
252
253	return op - (u8 *) out_data;
254	}
255