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/cvs/liblzf/lzf_c.c
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Comparing liblzf/lzf_c.c (file contents):
Revision 1.36 by root, Fri May 1 00:30:53 2009 UTC vs.
Revision 1.42 by root, Tue Jun 1 03:17:06 2010 UTC

1/* 1/*
2 * Copyright (c) 2000-2008 Marc Alexander Lehmann <schmorp@schmorp.de> 2 * Copyright (c) 2000-2010 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,
… …
38 38
39#define HSIZE (1 << (HLOG)) 39#define HSIZE (1 << (HLOG))
40 40
41/* 41/*
42 * don't play with this unless you benchmark! 42 * don't play with this unless you benchmark!
43 * decompression is not dependent on the hash function 43 * the data format is not dependent on the hash function.
44 * the hashing function might seem strange, just believe me 44 * the hash function might seem strange, just believe me,
45 * it works ;) 45 * it works ;)
46 */ 46 */
47#ifndef FRST 47#ifndef FRST
48# define FRST(p) (((p[0]) << 8) | p[1]) 48# define FRST(p) (((p[0]) << 8) | p[1])
49# define NEXT(v,p) (((v) << 8) | p[2]) 49# define NEXT(v,p) (((v) << 8) | p[2])
… …
87#define expect_true(expr) expect ((expr) != 0, 1) 87#define expect_true(expr) expect ((expr) != 0, 1)
88 88
89/* 89/*
90 * compressed format 90 * compressed format
91 * 91 *
92 * 000LLLLL <L+1> ; literal 92 * 000LLLLL <L+1> ; literal, L+1=1..33 octets
93 * LLLooooo oooooooo ; backref L 93 * LLLooooo oooooooo ; backref L+1=1..7 octets, o+1=1..4096 offset
94 * 111ooooo LLLLLLLL oooooooo ; backref L+7 94 * 111ooooo LLLLLLLL oooooooo ; backref L+8 octets, o+1=1..4096 offset
95 * 95 *
96 */ 96 */
97 97
98unsigned int 98unsigned int
99lzf_compress (const void *const in_data, unsigned int in_len, 99lzf_compress (const void *const in_data, unsigned int in_len,
… …
104 ) 104 )
105{ 105{
106#if !LZF_STATE_ARG 106#if !LZF_STATE_ARG
107 LZF_STATE htab; 107 LZF_STATE htab;
108#endif 108#endif
109 const u8 **hslot;
110 const u8 *ip = (const u8 *)in_data; 109 const u8 *ip = (const u8 *)in_data;
111 u8 *op = (u8 *)out_data; 110 u8 *op = (u8 *)out_data;
112 const u8 *in_end = ip + in_len; 111 const u8 *in_end = ip + in_len;
113 u8 *out_end = op + out_len; 112 u8 *out_end = op + out_len;
114 const u8 *ref; 113 const u8 *ref;
… …
131 if (!in_len || !out_len) 130 if (!in_len || !out_len)
132 return 0; 131 return 0;
133 132
134#if INIT_HTAB 133#if INIT_HTAB
135 memset (htab, 0, sizeof (htab)); 134 memset (htab, 0, sizeof (htab));
136# if 0
137 for (hslot = htab; hslot < htab + HSIZE; hslot++)
138 *hslot++ = ip;
139# endif
140#endif 135#endif
141 136
142 lit = 0; op++; /* start run */ 137 lit = 0; op++; /* start run */
143 138
144 hval = FRST (ip); 139 hval = FRST (ip);
145 while (ip < in_end - 2) 140 while (ip < in_end - 2)
146 { 141 {
142 LZF_HSLOT *hslot;
143
147 hval = NEXT (hval, ip); 144 hval = NEXT (hval, ip);
148 hslot = htab + IDX (hval); 145 hslot = htab + IDX (hval);
149 ref = *hslot; *hslot = ip; 146 ref = *hslot + LZF_HSLOT_BIAS; *hslot = ip - LZF_HSLOT_BIAS;
150 147
151 if (1 148 if (1
152#if INIT_HTAB 149#if INIT_HTAB
153 && ref < ip /* the next test will actually take care of this, but this is faster */ 150 && ref < ip /* the next test will actually take care of this, but this is faster */
154#endif 151#endif
155 && (off = ip - ref - 1) < MAX_OFF 152 && (off = ip - ref - 1) < MAX_OFF
156 && ip + 4 < in_end 153 && ip + 4 < in_end
157 && ref > (u8 *)in_data 154 && ref > (u8 *)in_data
155 && ref[2] == ip[2]
158#if STRICT_ALIGN 156#if STRICT_ALIGN
159 && ref[0] == ip[0] 157 && (ref[1] << 8) | ref[0] == (ip[1] << 8) | ip[0]
160 && ref[1] == ip[1]
161 && ref[2] == ip[2]
162#else 158#else
163 && *(u16 *)ref == *(u16 *)ip 159 && *(u16 *)ref == *(u16 *)ip
164 && ref[2] == ip[2]
165#endif 160#endif
166 ) 161 )
167 { 162 {
168 /* match found at *ref++ */ 163 /* match found at *ref++ */
169 unsigned int len = 2; 164 unsigned int len = 2;
… …
236 --ip; 231 --ip;
237# endif 232# endif
238 hval = FRST (ip); 233 hval = FRST (ip);
239 234
240 hval = NEXT (hval, ip); 235 hval = NEXT (hval, ip);
241 htab[IDX (hval)] = ip; 236 htab[IDX (hval)] = ip - LZF_HSLOT_BIAS;
242 ip++; 237 ip++;
243 238
244# if VERY_FAST && !ULTRA_FAST 239# if VERY_FAST && !ULTRA_FAST
245 hval = NEXT (hval, ip); 240 hval = NEXT (hval, ip);
246 htab[IDX (hval)] = ip; 241 htab[IDX (hval)] = ip - LZF_HSLOT_BIAS;
247 ip++; 242 ip++;
248# endif 243# endif
249#else 244#else
250 ip -= len + 1; 245 ip -= len + 1;
251 246
252 do 247 do
253 { 248 {
254 hval = NEXT (hval, ip); 249 hval = NEXT (hval, ip);
255 htab[IDX (hval)] = ip; 250 htab[IDX (hval)] = ip - LZF_HSLOT_BIAS;
256 ip++; 251 ip++;
257 } 252 }
258 while (len--); 253 while (len--);
259#endif 254#endif
260 } 255 }

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