2 * Copyright (c) 2000-2008 Marc Alexander Lehmann <schmorp@schmorp.de>
4 * Redistribution and use in source and binary forms, with or without modifica-
5 * tion, are permitted provided that the following conditions are met:
7 * 1. Redistributions of source code must retain the above copyright notice,
8 * this list of conditions and the following disclaimer.
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.
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-
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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.
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26 * the GNU General Public License ("GPL") version 2 or any later version,
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34 * either the BSD or the GPL.
39 #define HSIZE (1 << (HLOG))
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
48 # define FRST(p) (((p[0]) << 8) | p[1])
49 # define NEXT(v,p) (((v) << 8) | p[2])
51 # define IDX(h) ((( h >> (3*8 - HLOG)) - h ) & (HSIZE - 1))
53 # define IDX(h) ((( h >> (3*8 - HLOG)) - h*5) & (HSIZE - 1))
55 # define IDX(h) ((((h ^ (h << 5)) >> (3*8 - HLOG)) - h*5) & (HSIZE - 1))
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.
63 * the next one is also quite good, albeit slow ;)
64 * (int)(cos(h & 0xffffff) * 1e6)
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))
74 #define MAX_LIT (1 << 5)
75 #define MAX_OFF (1 << 13)
76 #define MAX_REF ((1 << 8) + (1 << 3))
79 # define expect(expr,value) __builtin_expect ((expr),(value))
80 # define inline inline
82 # define expect(expr,value) (expr)
83 # define inline static
86 #define expect_false(expr) expect ((expr) != 0, 0)
87 #define expect_true(expr) expect ((expr) != 0, 1)
92 * 000LLLLL <L+1> ; literal
93 * LLLooooo oooooooo ; backref L
94 * 111ooooo LLLLLLLL oooooooo ; backref L+7
99 lzf_compress (const void *const in_data
, unsigned int in_len
,
100 void *out_data
, unsigned int out_len
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
;
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.
123 #if defined (WIN32) && defined (_M_X64)
124 unsigned _int64 off
; /* workaround for missing POSIX compliance */
131 if (!in_len
|| !out_len
)
135 memset (htab
, 0, sizeof (htab
));
137 for (hslot
= htab
; hslot
< htab
+ HSIZE
; hslot
++)
142 lit
= 0; op
++; /* start run */
145 while (ip
< in_end
- 2)
147 hval
= NEXT (hval
, ip
);
148 hslot
= htab
+ IDX (hval
);
149 ref
= *hslot
; *hslot
= ip
;
153 && ref
< ip
/* the next test will actually take care of this, but this is faster */
155 && (off
= ip
- ref
- 1) < MAX_OFF
157 && ref
> (u8
*)in_data
163 && *(u16
*)ref
== *(u16
*)ip
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
;
173 op
[- lit
- 1] = lit
- 1; /* stop run */
174 op
-= !lit
; /* undo run if length is zero */
176 if (expect_false (op
+ 3 + 1 >= out_end
))
181 if (expect_true (maxlen
> 16))
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;
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;
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;
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;
206 while (len
< maxlen
&& ref
[len
] == ip
[len
]);
211 len
-= 2; /* len is now #octets - 1 */
216 *op
++ = (off
>> 8) + (len
<< 5);
220 *op
++ = (off
>> 8) + ( 7 << 5);
225 lit
= 0; op
++; /* start run */
229 if (expect_false (ip
>= in_end
- 2))
232 #if ULTRA_FAST || VERY_FAST
234 # if VERY_FAST && !ULTRA_FAST
239 hval
= NEXT (hval
, ip
);
240 htab
[IDX (hval
)] = ip
;
243 # if VERY_FAST && !ULTRA_FAST
244 hval
= NEXT (hval
, ip
);
245 htab
[IDX (hval
)] = ip
;
253 hval
= NEXT (hval
, ip
);
254 htab
[IDX (hval
)] = ip
;
262 /* one more literal byte we must copy */
263 if (expect_false (op
>= out_end
))
266 lit
++; *op
++ = *ip
++;
268 if (expect_false (lit
== MAX_LIT
))
270 op
[- lit
- 1] = lit
- 1; /* stop run */
271 lit
= 0; op
++; /* start run */
276 if (op
+ 3 > out_end
) /* at most 3 bytes can be missing here */
281 lit
++; *op
++ = *ip
++;
283 if (expect_false (lit
== MAX_LIT
))
285 op
[- lit
- 1] = lit
- 1; /* stop run */
286 lit
= 0; op
++; /* start run */
290 op
[- lit
- 1] = lit
- 1; /* end run */
291 op
-= !lit
; /* undo run if length is zero */
293 return op
- (u8
*)out_data
;