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/cvs/liblzf/lzf_c.c
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Comparing liblzf/lzf_c.c (file contents):
Revision 1.35 by root, Sat Aug 30 06:43:38 2008 UTC vs.
Revision 1.41 by root, Tue Jun 1 02:30:06 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,
… …
153 && ref < ip /* the next test will actually take care of this, but this is faster */ 153 && ref < ip /* the next test will actually take care of this, but this is faster */
154#endif 154#endif
155 && (off = ip - ref - 1) < MAX_OFF 155 && (off = ip - ref - 1) < MAX_OFF
156 && ip + 4 < in_end 156 && ip + 4 < in_end
157 && ref > (u8 *)in_data 157 && ref > (u8 *)in_data
158 && ref[2] == ip[2]
158#if STRICT_ALIGN 159#if STRICT_ALIGN
159 && ref[0] == ip[0] 160 && (ref[1] << 8) | ref[0] == (ip[1] << 8) | ip[0]
160 && ref[1] == ip[1]
161 && ref[2] == ip[2]
162#else 161#else
163 && *(u16 *)ref == *(u16 *)ip 162 && *(u16 *)ref == *(u16 *)ip
164 && ref[2] == ip[2]
165#endif 163#endif
166 ) 164 )
167 { 165 {
168 /* match found at *ref++ */ 166 /* match found at *ref++ */
169 unsigned int len = 2; 167 unsigned int len = 2;
170 unsigned int maxlen = in_end - ip - len; 168 unsigned int maxlen = in_end - ip - len;
171 maxlen = maxlen > MAX_REF ? MAX_REF : maxlen; 169 maxlen = maxlen > MAX_REF ? MAX_REF : maxlen;
172 170
171 if (expect_false (op + 3 + 1 >= out_end)) /* first a faster conservative test */
172 if (op - !lit + 3 + 1 >= out_end) /* second the exact but rare test */
173 return 0;
174
173 op [- lit - 1] = lit - 1; /* stop run */ 175 op [- lit - 1] = lit - 1; /* stop run */
174 op -= !lit; /* undo run if length is zero */ 176 op -= !lit; /* undo run if length is zero */
175
176 if (expect_false (op + 3 + 1 >= out_end))
177 return 0;
178 177
179 for (;;) 178 for (;;)
180 { 179 {
181 if (expect_true (maxlen > 16)) 180 if (expect_true (maxlen > 16))
182 { 181 {

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