[redis.git] / src / lzf_c.c

/*
 * Copyright (c) 2000-2008 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])
# if ULTRA_FAST
#  define IDX(h) ((( h             >> (3*8 - HLOG)) - h  ) & (HSIZE - 1))
# elif VERY_FAST
#  define IDX(h) ((( h             >> (3*8 - HLOG)) - h*5) & (HSIZE - 1))
# else
#  define IDX(h) ((((h ^ (h << 5)) >> (3*8 - HLOG)) - h*5) & (HSIZE - 1))
# endif
#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 __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;

  /* off requires a type wide enough to hold a general pointer difference.
   * ISO C doesn't have that (size_t might not be enough and ptrdiff_t only
   * works for differences within a single object). We also assume that no
   * no bit pattern traps. Since the only platform that is both non-POSIX
   * and fails to support both assumptions is windows 64 bit, we make a
   * special workaround for it.
   */
#if defined (WIN32) && defined (_M_X64)
  unsigned _int64 off; /* workaround for missing POSIX compliance */
#else
  unsigned long off;
#endif
  unsigned int hval;
  int lit;

  if (!in_len || !out_len)
    return 0;

#if INIT_HTAB
  memset (htab, 0, sizeof (htab));
# if 0
  for (hslot = htab; hslot < htab + HSIZE; hslot++)
    *hslot++ = ip;
# endif
#endif

  lit = 0; op++; /* start run */

  hval = FRST (ip);
  while (ip < in_end - 2)
    {
      hval = NEXT (hval, ip);
      hslot = htab + IDX (hval);
      ref = *hslot; *hslot = ip;

      if (1
#if INIT_HTAB
          && 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;

          op [- lit - 1] = lit - 1; /* stop run */
          op -= !lit; /* undo run if length is zero */

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

          for (;;)
            {
              if (expect_true (maxlen > 16))
                {
                  len++; if (ref [len] != ip [len]) break;
                  len++; if (ref [len] != ip [len]) break;
                  len++; if (ref [len] != ip [len]) break;
                  len++; if (ref [len] != ip [len]) break;

                  len++; if (ref [len] != ip [len]) break;
                  len++; if (ref [len] != ip [len]) break;
                  len++; if (ref [len] != ip [len]) break;
                  len++; if (ref [len] != ip [len]) break;

                  len++; if (ref [len] != ip [len]) break;
                  len++; if (ref [len] != ip [len]) break;
                  len++; if (ref [len] != ip [len]) break;
                  len++; if (ref [len] != ip [len]) break;

                  len++; if (ref [len] != ip [len]) break;
                  len++; if (ref [len] != ip [len]) break;
                  len++; if (ref [len] != ip [len]) break;
                  len++; if (ref [len] != ip [len]) break;
                }

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

              break;
            }

          len -= 2; /* len is now #octets - 1 */
          ip++;

          if (len < 7)
            {
              *op++ = (off >> 8) + (len << 5);
            }
          else
            {
              *op++ = (off >> 8) + (  7 << 5);
              *op++ = len - 7;
            }

          *op++ = off;
          lit = 0; op++; /* start run */

          ip += len + 1;

          if (expect_false (ip >= in_end - 2))
            break;

#if ULTRA_FAST || VERY_FAST
          --ip;
# 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
          ip -= len + 1;

          do
            {
              hval = NEXT (hval, ip);
              htab[IDX (hval)] = ip;
              ip++;
            }
          while (len--);
#endif
        }
      else
        {
          /* one more literal byte we must copy */
          if (expect_false (op >= out_end))
            return 0;

          lit++; *op++ = *ip++;

          if (expect_false (lit == MAX_LIT))
            {
              op [- lit - 1] = lit - 1; /* stop run */
              lit = 0; op++; /* start run */
            }
        }
    }

  if (op + 3 > out_end) /* at most 3 bytes can be missing here */
    return 0;

  while (ip < in_end)
    {
      lit++; *op++ = *ip++;

      if (expect_false (lit == MAX_LIT))
        {
          op [- lit - 1] = lit - 1; /* stop run */
          lit = 0; op++; /* start run */
        }
    }

  op [- lit - 1] = lit - 1; /* end run */
  op -= !lit; /* undo run if length is zero */

  return op - (u8 *)out_data;
}
Commit	Line	Data
d0751937	1	/*
	2	* Copyright (c) 2000-2008 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	# if ULTRA_FAST
	51	# define IDX(h) ((( h >> (3*8 - HLOG)) - h ) & (HSIZE - 1))
	52	# elif VERY_FAST
	53	# define IDX(h) ((( h >> (38 - HLOG)) - h5) & (HSIZE - 1))
	54	# else
	55	# define IDX(h) ((((h ^ (h << 5)) >> (38 - HLOG)) - h5) & (HSIZE - 1))
	56	# endif
	57	#endif
	58	/*
	59	* IDX works because it is very similar to a multiplicative hash, e.g.
	60	* ((h * 57321 >> (3*8 - HLOG)) & (HSIZE - 1))
	61	* the latter is also quite fast on newer CPUs, and compresses similarly.
	62	*
	63	* the next one is also quite good, albeit slow ;)
	64	* (int)(cos(h & 0xffffff) * 1e6)
65	*/
66
67	#if 0
68	/* original lzv-like hash function, much worse and thus slower */
69	# define FRST(p) (p[0] << 5) ^ p[1]
70	# define NEXT(v,p) ((v) << 5) ^ p[2]
71	# define IDX(h) ((h) & (HSIZE - 1))
72	#endif
73
74	#define MAX_LIT (1 << 5)
75	#define MAX_OFF (1 << 13)
76	#define MAX_REF ((1 << 8) + (1 << 3))
77
78	#if __GNUC__ >= 3
79	# define expect(expr,value) __builtin_expect ((expr),(value))
80	# define inline inline
81	#else
82	# define expect(expr,value) (expr)
83	# define inline static
84	#endif
85
86	#define expect_false(expr) expect ((expr) != 0, 0)
87	#define expect_true(expr) expect ((expr) != 0, 1)
88
89	/*
90	* compressed format
91	*
92	* 000LLLLL <L+1> ; literal
93	* LLLooooo oooooooo ; backref L
94	* 111ooooo LLLLLLLL oooooooo ; backref L+7
95	*
96	*/
97
98	unsigned int
99	lzf_compress (const void *const in_data, unsigned int in_len,
100	void *out_data, unsigned int out_len
101	#if LZF_STATE_ARG
102	, LZF_STATE htab
103	#endif
104	)
105	{
106	#if !LZF_STATE_ARG
107	LZF_STATE htab;
108	#endif
109	const u8 **hslot;
110	const u8 ip = (const u8 )in_data;
111	u8 op = (u8 )out_data;
112	const u8 *in_end = ip + in_len;
113	u8 *out_end = op + out_len;
114	const u8 *ref;
115
116	/* off requires a type wide enough to hold a general pointer difference.
117	* ISO C doesn't have that (size_t might not be enough and ptrdiff_t only
118	* works for differences within a single object). We also assume that no
119	* no bit pattern traps. Since the only platform that is both non-POSIX
120	* and fails to support both assumptions is windows 64 bit, we make a
121	* special workaround for it.
122	*/
123	#if defined (WIN32) && defined (_M_X64)
124	unsigned _int64 off; /* workaround for missing POSIX compliance */
125	#else
126	unsigned long off;
127	#endif
128	unsigned int hval;
129	int lit;
130
131	if (!in_len \|\| !out_len)
132	return 0;
133
134	#if INIT_HTAB
135	memset (htab, 0, sizeof (htab));
136	# if 0
137	for (hslot = htab; hslot < htab + HSIZE; hslot++)
138	*hslot++ = ip;
139	# endif
140	#endif
141
142	lit = 0; op++; /* start run */
143
144	hval = FRST (ip);
145	while (ip < in_end - 2)
146	{
147	hval = NEXT (hval, ip);
148	hslot = htab + IDX (hval);
149	ref = hslot; hslot = ip;
150
151	if (1
152	#if INIT_HTAB
153	&& ref < ip /* the next test will actually take care of this, but this is faster */
154	#endif
155	&& (off = ip - ref - 1) < MAX_OFF
156	&& ip + 4 < in_end
157	&& ref > (u8 *)in_data
158	#if STRICT_ALIGN
159	&& ref[0] == ip[0]
160	&& ref[1] == ip[1]
161	&& ref[2] == ip[2]
162	#else
163	&& (u16 )ref == (u16 )ip
164	&& ref[2] == ip[2]
165	#endif
166	)
167	{
168	/* match found at ref++ /
169	unsigned int len = 2;
170	unsigned int maxlen = in_end - ip - len;
171	maxlen = maxlen > MAX_REF ? MAX_REF : maxlen;
172
173	op [- lit - 1] = lit - 1; /* stop run */
174	op -= !lit; /* undo run if length is zero */
175
176	if (expect_false (op + 3 + 1 >= out_end))
177	return 0;
178
179	for (;;)
180	{
181	if (expect_true (maxlen > 16))
182	{
183	len++; if (ref [len] != ip [len]) break;
184	len++; if (ref [len] != ip [len]) break;
185	len++; if (ref [len] != ip [len]) break;
186	len++; if (ref [len] != ip [len]) break;
187
188	len++; if (ref [len] != ip [len]) break;
189	len++; if (ref [len] != ip [len]) break;
190	len++; if (ref [len] != ip [len]) break;
191	len++; if (ref [len] != ip [len]) break;
192
193	len++; if (ref [len] != ip [len]) break;
194	len++; if (ref [len] != ip [len]) break;
195	len++; if (ref [len] != ip [len]) break;
196	len++; if (ref [len] != ip [len]) break;
197
198	len++; if (ref [len] != ip [len]) break;
199	len++; if (ref [len] != ip [len]) break;
200	len++; if (ref [len] != ip [len]) break;
201	len++; if (ref [len] != ip [len]) break;
202	}
203
204	do
205	len++;
206	while (len < maxlen && ref[len] == ip[len]);
207
208	break;
209	}
210
211	len -= 2; /* len is now #octets - 1 */
212	ip++;
213
214	if (len < 7)
215	{
216	*op++ = (off >> 8) + (len << 5);
217	}
218	else
219	{
220	*op++ = (off >> 8) + ( 7 << 5);
221	*op++ = len - 7;
222	}
223
224	*op++ = off;
225	lit = 0; op++; /* start run */
226
227	ip += len + 1;
228
229	if (expect_false (ip >= in_end - 2))
230	break;
231
232	#if ULTRA_FAST \|\| VERY_FAST
233	--ip;
234	# if VERY_FAST && !ULTRA_FAST
235	--ip;
236	# endif
237	hval = FRST (ip);
238
239	hval = NEXT (hval, ip);
240	htab[IDX (hval)] = ip;
241	ip++;
242
243	# if VERY_FAST && !ULTRA_FAST
244	hval = NEXT (hval, ip);
245	htab[IDX (hval)] = ip;
246	ip++;
247	# endif
248	#else
249	ip -= len + 1;
250
251	do
252	{
253	hval = NEXT (hval, ip);
254	htab[IDX (hval)] = ip;
255	ip++;
256	}
257	while (len--);
258	#endif
259	}
260	else
261	{
262	/* one more literal byte we must copy */
263	if (expect_false (op >= out_end))
264	return 0;
265
266	lit++; op++ = ip++;
267
268	if (expect_false (lit == MAX_LIT))
269	{
270	op [- lit - 1] = lit - 1; /* stop run */
271	lit = 0; op++; /* start run */
272	}
273	}
274	}
275
276	if (op + 3 > out_end) /* at most 3 bytes can be missing here */
277	return 0;
278
279	while (ip < in_end)
280	{
281	lit++; op++ = ip++;
282
283	if (expect_false (lit == MAX_LIT))
284	{
285	op [- lit - 1] = lit - 1; /* stop run */
286	lit = 0; op++; /* start run */
287	}
288	}
289
290	op [- lit - 1] = lit - 1; /* end run */
291	op -= !lit; /* undo run if length is zero */
292
293	return op - (u8 *)out_data;
294	}
295