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, |
… | |
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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]) |
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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 | |
98 | unsigned int |
98 | unsigned int |
99 | lzf_compress (const void *const in_data, unsigned int in_len, |
99 | lzf_compress (const void *const in_data, unsigned int in_len, |
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… | |
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; |
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|
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; |
… | |
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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 |
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|
137 | for (hslot = htab; hslot < htab + HSIZE; hslot++) |
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138 | *hslot++ = ip; |
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|
139 | # endif |
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|
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 | { |
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|
142 | LZF_HSLOT *hslot; |
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|
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 |
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|
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] |
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|
161 | && ref[2] == ip[2] |
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|
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; |
170 | unsigned int maxlen = in_end - ip - len; |
165 | unsigned int maxlen = in_end - ip - len; |
171 | maxlen = maxlen > MAX_REF ? MAX_REF : maxlen; |
166 | maxlen = maxlen > MAX_REF ? MAX_REF : maxlen; |
172 | |
167 | |
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|
168 | if (expect_false (op + 3 + 1 >= out_end)) /* first a faster conservative test */ |
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|
169 | if (op - !lit + 3 + 1 >= out_end) /* second the exact but rare test */ |
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|
170 | return 0; |
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|
171 | |
173 | op [- lit - 1] = lit - 1; /* stop run */ |
172 | op [- lit - 1] = lit - 1; /* stop run */ |
174 | op -= !lit; /* undo run if length is zero */ |
173 | op -= !lit; /* undo run if length is zero */ |
175 | |
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|
176 | if (expect_false (op + 3 + 1 >= out_end)) |
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177 | return 0; |
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178 | |
174 | |
179 | for (;;) |
175 | for (;;) |
180 | { |
176 | { |
181 | if (expect_true (maxlen > 16)) |
177 | if (expect_true (maxlen > 16)) |
182 | { |
178 | { |
… | |
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235 | --ip; |
231 | --ip; |
236 | # endif |
232 | # endif |
237 | hval = FRST (ip); |
233 | hval = FRST (ip); |
238 | |
234 | |
239 | hval = NEXT (hval, ip); |
235 | hval = NEXT (hval, ip); |
240 | htab[IDX (hval)] = ip; |
236 | htab[IDX (hval)] = ip - LZF_HSLOT_BIAS; |
241 | ip++; |
237 | ip++; |
242 | |
238 | |
243 | # if VERY_FAST && !ULTRA_FAST |
239 | # if VERY_FAST && !ULTRA_FAST |
244 | hval = NEXT (hval, ip); |
240 | hval = NEXT (hval, ip); |
245 | htab[IDX (hval)] = ip; |
241 | htab[IDX (hval)] = ip - LZF_HSLOT_BIAS; |
246 | ip++; |
242 | ip++; |
247 | # endif |
243 | # endif |
248 | #else |
244 | #else |
249 | ip -= len + 1; |
245 | ip -= len + 1; |
250 | |
246 | |
251 | do |
247 | do |
252 | { |
248 | { |
253 | hval = NEXT (hval, ip); |
249 | hval = NEXT (hval, ip); |
254 | htab[IDX (hval)] = ip; |
250 | htab[IDX (hval)] = ip - LZF_HSLOT_BIAS; |
255 | ip++; |
251 | ip++; |
256 | } |
252 | } |
257 | while (len--); |
253 | while (len--); |
258 | #endif |
254 | #endif |
259 | } |
255 | } |