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/cvs/liblzf/lzf_c.c
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Comparing liblzf/lzf_c.c (file contents):
Revision 1.7 by root, Tue Aug 3 15:37:48 2004 UTC vs.
Revision 1.12 by root, Tue Jun 19 21:25:01 2007 UTC

1/* 1/*
2 * Copyright (c) 2000-2003 Marc Alexander Lehmann <pcg@goof.com> 2 * Copyright (c) 2000-2005 Marc Alexander Lehmann <schmorp@schmorp.de>
3 * 3 *
4 * Redistribution and use in source and binary forms, with or without modifica- 4 * Redistribution and use in source and binary forms, with or without modifica-
5 * tion, are permitted provided that the following conditions are met: 5 * tion, are permitted provided that the following conditions are met:
6 * 6 *
7 * 1. Redistributions of source code must retain the above copyright notice, 7 * 1. Redistributions of source code must retain the above copyright notice,
… …
44 * don't play with this unless you benchmark! 44 * don't play with this unless you benchmark!
45 * decompression is not dependent on the hash function 45 * decompression is not dependent on the hash function
46 * the hashing function might seem strange, just believe me 46 * the hashing function might seem strange, just believe me
47 * it works ;) 47 * it works ;)
48 */ 48 */
49#ifndef FRST
49#define FRST(p) (((p[0]) << 8) + p[1]) 50# define FRST(p) (((p[0]) << 8) | p[1])
50#define NEXT(v,p) (((v) << 8) + p[2]) 51# define NEXT(v,p) (((v) << 8) | p[2])
51#define IDX(h) ((((h ^ (h << 5)) >> (3*8 - HLOG)) - h*5) & (HSIZE - 1)) 52# define IDX(h) ((((h ^ (h << 5)) >> (3*8 - HLOG)) - h*5) & (HSIZE - 1))
53//# define IDX(h) ((ip[0] * 121 ^ ip[1] * 33 ^ ip[2] * 1) & (HSIZE-1))
54#endif
52/* 55/*
53 * IDX works because it is very similar to a multiplicative hash, e.g. 56 * IDX works because it is very similar to a multiplicative hash, e.g.
54 * ((h * 57321 >> (3*8 - HLOG)) & (HSIZE - 1)) 57 * ((h * 57321 >> (3*8 - HLOG)) & (HSIZE - 1))
55 * the latter is also quite fast on newer CPUs, and sligthly better 58 * the latter is also quite fast on newer CPUs, and compresses similarly.
56 * 59 *
57 * the next one is also quite good, albeit slow ;) 60 * the next one is also quite good, albeit slow ;)
58 * (int)(cos(h & 0xffffff) * 1e6) 61 * (int)(cos(h & 0xffffff) * 1e6)
59 */ 62 */
60 63
… …
65# define IDX(h) ((h) & (HSIZE - 1)) 68# define IDX(h) ((h) & (HSIZE - 1))
66#endif 69#endif
67 70
68#define MAX_LIT (1 << 5) 71#define MAX_LIT (1 << 5)
69#define MAX_OFF (1 << 13) 72#define MAX_OFF (1 << 13)
70#define MAX_REF ((1 << 8) + (1 << 3)) 73#define MAX_REF ((1 << 8) + (1 << 3))
71 74
72/* 75/*
73 * compressed format 76 * compressed format
74 * 77 *
75 * 000LLLLL <L+1> ; literal 78 * 000LLLLL <L+1> ; literal
76 * LLLOOOOO oooooooo ; backref L 79 * LLLooooo oooooooo ; backref L
77 * 111OOOOO LLLLLLLL oooooooo ; backref L+7 80 * 111ooooo LLLLLLLL oooooooo ; backref L+7
78 * 81 *
79 */ 82 */
80 83
81unsigned int 84unsigned int
82lzf_compress (const void *const in_data, unsigned int in_len, 85lzf_compress (const void *const in_data, unsigned int in_len,
83 void *out_data, unsigned int out_len 86 void *out_data, unsigned int out_len
84#if LZF_STATE_ARG 87#if LZF_STATE_ARG
85 , LZF_STATE *htab 88 , LZF_STATE htab
86#endif 89#endif
87 ) 90 )
88{ 91{
89#if !LZF_STATE_ARG 92#if !LZF_STATE_ARG
90 LZF_STATE htab; 93 LZF_STATE htab;
… …
137 /* match found at *ref++ */ 140 /* match found at *ref++ */
138 unsigned int len = 2; 141 unsigned int len = 2;
139 unsigned int maxlen = in_end - ip - len; 142 unsigned int maxlen = in_end - ip - len;
140 maxlen = maxlen > MAX_REF ? MAX_REF : maxlen; 143 maxlen = maxlen > MAX_REF ? MAX_REF : maxlen;
141 144
145 if (op + lit + 1 + 3 >= out_end)
146 return 0;
147
142 do 148 do
143 len++; 149 len++;
144 while (len < maxlen && ref[len] == ip[len]); 150 while (len < maxlen && ref[len] == ip[len]);
145
146 if (op + lit + 1 + 3 >= out_end)
147 return 0;
148 151
149 if (lit) 152 if (lit)
150 { 153 {
151 *op++ = lit - 1; 154 *op++ = lit - 1;
152 lit = -lit; 155 lit = -lit;
… …
168 *op++ = len - 7; 171 *op++ = len - 7;
169 } 172 }
170 173
171 *op++ = off; 174 *op++ = off;
172 175
173#if ULTRA_FAST 176#if ULTRA_FAST || VERY_FAST
174 ip += len; 177 ip += len;
178#if VERY_FAST && !ULTRA_FAST
179 --ip;
180#endif
175 hval = FRST (ip); 181 hval = FRST (ip);
182
176 hval = NEXT (hval, ip); 183 hval = NEXT (hval, ip);
177 htab[IDX (hval)] = ip; 184 htab[IDX (hval)] = ip;
178 ip++; 185 ip++;
186
187#if VERY_FAST && !ULTRA_FAST
188 hval = NEXT (hval, ip);
189 htab[IDX (hval)] = ip;
190 ip++;
191#endif
179#else 192#else
180 do 193 do
181 { 194 {
182 hval = NEXT (hval, ip); 195 hval = NEXT (hval, ip);
183 htab[IDX (hval)] = ip; 196 htab[IDX (hval)] = ip;

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