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Comparing liblzf/lzf_c.c (file contents):
Revision 1.6 by pcg, Tue Apr 20 18:11:58 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*3) & (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)) 57 * ((h * 57321 >> (3*8 - HLOG)) & (HSIZE - 1))
58 * the latter is also quite fast on newer CPUs, and compresses similarly.
59 *
55 * the next one is also quite good, albeit slow ;) 60 * the next one is also quite good, albeit slow ;)
56 * (int)(cos(h & 0xffffff) * 1e6) 61 * (int)(cos(h & 0xffffff) * 1e6)
57 */ 62 */
58 63
59#if 0 64#if 0
60/* original lzv-like hash function */ 65/* original lzv-like hash function, much worse and thus slower */
61# define FRST(p) (p[0] << 5) ^ p[1] 66# define FRST(p) (p[0] << 5) ^ p[1]
62# define NEXT(v,p) ((v) << 5) ^ p[2] 67# define NEXT(v,p) ((v) << 5) ^ p[2]
63# define IDX(h) ((h) & (HSIZE - 1)) 68# define IDX(h) ((h) & (HSIZE - 1))
64#endif 69#endif
65 70
66#define MAX_LIT (1 << 5) 71#define MAX_LIT (1 << 5)
67#define MAX_OFF (1 << 13) 72#define MAX_OFF (1 << 13)
68#define MAX_REF ((1 << 8) + (1 << 3)) 73#define MAX_REF ((1 << 8) + (1 << 3))
69 74
70/* 75/*
71 * compressed format 76 * compressed format
72 * 77 *
73 * 000LLLLL <L+1> ; literal 78 * 000LLLLL <L+1> ; literal
74 * LLLOOOOO oooooooo ; backref L 79 * LLLooooo oooooooo ; backref L
75 * 111OOOOO LLLLLLLL oooooooo ; backref L+7 80 * 111ooooo LLLLLLLL oooooooo ; backref L+7
76 * 81 *
77 */ 82 */
78 83
79unsigned int 84unsigned int
80lzf_compress (const void *const in_data, unsigned int in_len, 85lzf_compress (const void *const in_data, unsigned int in_len,
81 void *out_data, unsigned int out_len 86 void *out_data, unsigned int out_len
82#if LZF_STATE_ARG 87#if LZF_STATE_ARG
83 , LZF_STATE *htab 88 , LZF_STATE htab
84#endif 89#endif
85 ) 90 )
86{ 91{
87#if !LZF_STATE_ARG 92#if !LZF_STATE_ARG
88 LZF_STATE htab; 93 LZF_STATE htab;
… …
135 /* match found at *ref++ */ 140 /* match found at *ref++ */
136 unsigned int len = 2; 141 unsigned int len = 2;
137 unsigned int maxlen = in_end - ip - len; 142 unsigned int maxlen = in_end - ip - len;
138 maxlen = maxlen > MAX_REF ? MAX_REF : maxlen; 143 maxlen = maxlen > MAX_REF ? MAX_REF : maxlen;
139 144
145 if (op + lit + 1 + 3 >= out_end)
146 return 0;
147
140 do 148 do
141 len++; 149 len++;
142 while (len < maxlen && ref[len] == ip[len]); 150 while (len < maxlen && ref[len] == ip[len]);
143
144 if (op + lit + 1 + 3 >= out_end)
145 return 0;
146 151
147 if (lit) 152 if (lit)
148 { 153 {
149 *op++ = lit - 1; 154 *op++ = lit - 1;
150 lit = -lit; 155 lit = -lit;
… …
166 *op++ = len - 7; 171 *op++ = len - 7;
167 } 172 }
168 173
169 *op++ = off; 174 *op++ = off;
170 175
171#if ULTRA_FAST 176#if ULTRA_FAST || VERY_FAST
172 ip += len; 177 ip += len;
178#if VERY_FAST && !ULTRA_FAST
179 --ip;
180#endif
173 hval = FRST (ip); 181 hval = FRST (ip);
182
174 hval = NEXT (hval, ip); 183 hval = NEXT (hval, ip);
175 htab[IDX (hval)] = ip; 184 htab[IDX (hval)] = ip;
176 ip++; 185 ip++;
186
187#if VERY_FAST && !ULTRA_FAST
188 hval = NEXT (hval, ip);
189 htab[IDX (hval)] = ip;
190 ip++;
191#endif
177#else 192#else
178 do 193 do
179 { 194 {
180 hval = NEXT (hval, ip); 195 hval = NEXT (hval, ip);
181 htab[IDX (hval)] = ip; 196 htab[IDX (hval)] = ip;

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