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

#if __GNUC__ >= 3
# define expect(expr,value)         __builtin_expect ((expr),(value))
# define inline                     inline
#else
# define expect(expr,value)         (expr)
# define inline                     static
#endif

#define expect_false(expr) expect ((expr) != 0, 0)
#define expect_true(expr)  expect ((expr) != 0, 1)

/*
 * 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 (expect_true (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 (expect_false (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 (expect_false (ip == in_end))
        break;

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

      if (expect_false (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:	1.17
Committed:	Tue Nov 13 07:54:18 2007 UTC (16 years, 6 months ago) by root
Content type:	text/plain
Branch:	MAIN
Changes since 1.16:	+15 -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 ("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	#if __GNUC__ >= 3
81	# define expect(expr,value) __builtin_expect ((expr),(value))
82	# define inline inline
83	#else
84	# define expect(expr,value) (expr)
85	# define inline static
86	#endif
87
88	#define expect_false(expr) expect ((expr) != 0, 0)
89	#define expect_true(expr) expect ((expr) != 0, 1)
90
91	/*
92	* compressed format
93	*
94	* 000LLLLL <L+1> ; literal
95	* LLLooooo oooooooo ; backref L
96	* 111ooooo LLLLLLLL oooooooo ; backref L+7
97	*
98	*/
99
100	unsigned int
101	lzf_compress (const void *const in_data, unsigned int in_len,
102	void *out_data, unsigned int out_len
103	#if LZF_STATE_ARG
104	, LZF_STATE htab
105	#endif
106	)
107	{
108	#if !LZF_STATE_ARG
109	LZF_STATE htab;
110	#endif
111	const u8 **hslot;
112	const u8 ip = (const u8 )in_data;
113	u8 op = (u8 )out_data;
114	const u8 *in_end = ip + in_len;
115	u8 *out_end = op + out_len;
116	const u8 *ref;
117
118	unsigned int hval = FRST (ip);
119	unsigned long off;
120	int lit = 0;
121
122	#if INIT_HTAB
123	memset (htab, 0, sizeof (htab));
124	# if 0
125	for (hslot = htab; hslot < htab + HSIZE; hslot++)
126	*hslot++ = ip;
127	# endif
128	#endif
129
130	for (;;)
131	{
132	if (expect_true (ip < in_end - 2))
133	{
134	hval = NEXT (hval, ip);
135	hslot = htab + IDX (hval);
136	ref = hslot; hslot = ip;
137
138	if (1
139	#if INIT_HTAB && !USE_MEMCPY
140	&& ref < ip /* the next test will actually take care of this, but this is faster */
141	#endif
142	&& (off = ip - ref - 1) < MAX_OFF
143	&& ip + 4 < in_end
144	&& ref > (u8 *)in_data
145	#if STRICT_ALIGN
146	&& ref[0] == ip[0]
147	&& ref[1] == ip[1]
148	&& ref[2] == ip[2]
149	#else
150	&& (u16 )ref == (u16 )ip
151	&& ref[2] == ip[2]
152	#endif
153	)
154	{
155	/* match found at ref++ /
156	unsigned int len = 2;
157	unsigned int maxlen = in_end - ip - len;
158	maxlen = maxlen > MAX_REF ? MAX_REF : maxlen;
159
160	if (expect_false (op + lit + 1 + 3 >= out_end))
161	return 0;
162
163	do
164	len++;
165	while (len < maxlen && ref[len] == ip[len]);
166
167	if (lit)
168	{
169	*op++ = lit - 1;
170	lit = -lit;
171	do
172	*op++ = ip[lit];
173	while (++lit);
174	}
175
176	len -= 2;
177	ip++;
178
179	if (len < 7)
180	{
181	*op++ = (off >> 8) + (len << 5);
182	}
183	else
184	{
185	*op++ = (off >> 8) + ( 7 << 5);
186	*op++ = len - 7;
187	}
188
189	*op++ = off;
190
191	#if ULTRA_FAST \|\| VERY_FAST
192	ip += len;
193	#if VERY_FAST && !ULTRA_FAST
194	--ip;
195	#endif
196	hval = FRST (ip);
197
198	hval = NEXT (hval, ip);
199	htab[IDX (hval)] = ip;
200	ip++;
201
202	#if VERY_FAST && !ULTRA_FAST
203	hval = NEXT (hval, ip);
204	htab[IDX (hval)] = ip;
205	ip++;
206	#endif
207	#else
208	do
209	{
210	hval = NEXT (hval, ip);
211	htab[IDX (hval)] = ip;
212	ip++;
213	}
214	while (len--);
215	#endif
216	continue;
217	}
218	}
219	else if (expect_false (ip == in_end))
220	break;
221
222	/* one more literal byte we must copy */
223	lit++;
224	ip++;
225
226	if (expect_false (lit == MAX_LIT))
227	{
228	if (op + 1 + MAX_LIT >= out_end)
229	return 0;
230
231	*op++ = MAX_LIT - 1;
232
233	#ifdef lzf_movsb
234	ip -= lit;
235	lzf_movsb (op, ip, lit);
236	#else
237	lit = -lit;
238	do
239	*op++ = ip[lit];
240	while (++lit);
241	#endif
242	}
243	}
244
245	if (lit)
246	{
247	if (op + lit + 1 >= out_end)
248	return 0;
249
250	*op++ = lit - 1;
251	#ifdef lzf_movsb
252	ip -= lit;
253	lzf_movsb (op, ip, lit);
254	#else
255	lit = -lit;
256	do
257	*op++ = ip[lit];
258	while (++lit);
259	#endif
260	}
261
262	return op - (u8 *) out_data;
263	}
264