1 | /* |
1 | /* |
2 | * Copyright (c) 2000-2007 Marc Alexander Lehmann <schmorp@schmorp.de> |
2 | * Copyright (c) 2000-2008 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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111 | u8 *op = (u8 *)out_data; |
111 | u8 *op = (u8 *)out_data; |
112 | const u8 *in_end = ip + in_len; |
112 | const u8 *in_end = ip + in_len; |
113 | u8 *out_end = op + out_len; |
113 | u8 *out_end = op + out_len; |
114 | const u8 *ref; |
114 | const u8 *ref; |
115 | |
115 | |
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116 | /* off requires a type wide enough to hold a general pointer difference. |
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117 | * ISO C doesn't have that (size_t might not be enough and ptrdiff_t only |
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118 | * works for differences within a single object). We also assume that no |
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119 | * no bit pattern traps. Since the only platform that is both non-POSIX |
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120 | * and fails to support both assumptions is windows 64 bit, we make a |
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121 | * special workaround for it. |
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122 | */ |
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123 | #if defined (WIN32) && defined (_M_X64) |
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124 | unsigned _int64 off; /* workaround for missing POSIX compliance */ |
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125 | #else |
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126 | unsigned long off; |
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127 | #endif |
116 | unsigned int hval; |
128 | unsigned int hval; |
117 | unsigned long off; |
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118 | int lit; |
129 | int lit; |
119 | |
130 | |
120 | if (!in_len || !out_len) |
131 | if (!in_len || !out_len) |
121 | return 0; |
132 | return 0; |
122 | |
133 | |
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136 | hval = NEXT (hval, ip); |
147 | hval = NEXT (hval, ip); |
137 | hslot = htab + IDX (hval); |
148 | hslot = htab + IDX (hval); |
138 | ref = *hslot; *hslot = ip; |
149 | ref = *hslot; *hslot = ip; |
139 | |
150 | |
140 | if (1 |
151 | if (1 |
141 | #if INIT_HTAB && !USE_MEMCPY |
152 | #if INIT_HTAB |
142 | && 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 */ |
143 | #endif |
154 | #endif |
144 | && (off = ip - ref - 1) < MAX_OFF |
155 | && (off = ip - ref - 1) < MAX_OFF |
145 | && ip + 4 < in_end |
156 | && ip + 4 < in_end |
146 | && ref > (u8 *)in_data |
157 | && ref > (u8 *)in_data |
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157 | /* match found at *ref++ */ |
168 | /* match found at *ref++ */ |
158 | unsigned int len = 2; |
169 | unsigned int len = 2; |
159 | unsigned int maxlen = in_end - ip - len; |
170 | unsigned int maxlen = in_end - ip - len; |
160 | maxlen = maxlen > MAX_REF ? MAX_REF : maxlen; |
171 | maxlen = maxlen > MAX_REF ? MAX_REF : maxlen; |
161 | |
172 | |
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173 | if (expect_false (op + 3 + 1 >= out_end)) /* first a faster conservative test */ |
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174 | if (op - !lit + 3 + 1 >= out_end) /* second the exact but rare test */ |
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175 | return 0; |
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176 | |
162 | op [- lit - 1] = lit - 1; /* stop run */ |
177 | op [- lit - 1] = lit - 1; /* stop run */ |
163 | op -= !lit; /* undo run if length is zero */ |
178 | op -= !lit; /* undo run if length is zero */ |
164 | |
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165 | if (expect_false (op + 3 + 1 >= out_end)) |
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166 | return 0; |
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167 | |
179 | |
168 | for (;;) |
180 | for (;;) |
169 | { |
181 | { |
170 | if (expect_true (maxlen > 16)) |
182 | if (expect_true (maxlen > 16)) |
171 | { |
183 | { |
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195 | while (len < maxlen && ref[len] == ip[len]); |
207 | while (len < maxlen && ref[len] == ip[len]); |
196 | |
208 | |
197 | break; |
209 | break; |
198 | } |
210 | } |
199 | |
211 | |
200 | len -= 2; |
212 | len -= 2; /* len is now #octets - 1 */ |
201 | ip++; |
213 | ip++; |
202 | |
214 | |
203 | if (len < 7) |
215 | if (len < 7) |
204 | { |
216 | { |
205 | *op++ = (off >> 8) + (len << 5); |
217 | *op++ = (off >> 8) + (len << 5); |
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209 | *op++ = (off >> 8) + ( 7 << 5); |
221 | *op++ = (off >> 8) + ( 7 << 5); |
210 | *op++ = len - 7; |
222 | *op++ = len - 7; |
211 | } |
223 | } |
212 | |
224 | |
213 | *op++ = off; |
225 | *op++ = off; |
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226 | lit = 0; op++; /* start run */ |
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227 | |
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228 | ip += len + 1; |
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229 | |
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230 | if (expect_false (ip >= in_end - 2)) |
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231 | break; |
214 | |
232 | |
215 | #if ULTRA_FAST || VERY_FAST |
233 | #if ULTRA_FAST || VERY_FAST |
216 | ip += len; |
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217 | #if VERY_FAST && !ULTRA_FAST |
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218 | --ip; |
234 | --ip; |
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235 | # if VERY_FAST && !ULTRA_FAST |
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236 | --ip; |
219 | #endif |
237 | # endif |
220 | hval = FRST (ip); |
238 | hval = FRST (ip); |
221 | |
239 | |
222 | hval = NEXT (hval, ip); |
240 | hval = NEXT (hval, ip); |
223 | htab[IDX (hval)] = ip; |
241 | htab[IDX (hval)] = ip; |
224 | ip++; |
242 | ip++; |
225 | |
243 | |
226 | #if VERY_FAST && !ULTRA_FAST |
244 | # if VERY_FAST && !ULTRA_FAST |
227 | hval = NEXT (hval, ip); |
245 | hval = NEXT (hval, ip); |
228 | htab[IDX (hval)] = ip; |
246 | htab[IDX (hval)] = ip; |
229 | ip++; |
247 | ip++; |
230 | #endif |
248 | # endif |
231 | #else |
249 | #else |
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250 | ip -= len + 1; |
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251 | |
232 | do |
252 | do |
233 | { |
253 | { |
234 | hval = NEXT (hval, ip); |
254 | hval = NEXT (hval, ip); |
235 | htab[IDX (hval)] = ip; |
255 | htab[IDX (hval)] = ip; |
236 | ip++; |
256 | ip++; |
237 | } |
257 | } |
238 | while (len--); |
258 | while (len--); |
239 | #endif |
259 | #endif |
240 | lit = 0; op++; /* start run */ |
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241 | continue; |
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242 | } |
260 | } |
243 | |
261 | else |
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262 | { |
244 | /* one more literal byte we must copy */ |
263 | /* one more literal byte we must copy */ |
245 | |
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246 | if (expect_false (op >= out_end)) |
264 | if (expect_false (op >= out_end)) |
247 | return 0; |
265 | return 0; |
248 | |
266 | |
249 | lit++; |
267 | lit++; *op++ = *ip++; |
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268 | |
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269 | if (expect_false (lit == MAX_LIT)) |
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270 | { |
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271 | op [- lit - 1] = lit - 1; /* stop run */ |
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272 | lit = 0; op++; /* start run */ |
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273 | } |
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274 | } |
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275 | } |
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276 | |
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277 | if (op + 3 > out_end) /* at most 3 bytes can be missing here */ |
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278 | return 0; |
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279 | |
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280 | while (ip < in_end) |
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281 | { |
250 | *op++ = *ip++; |
282 | lit++; *op++ = *ip++; |
251 | |
283 | |
252 | if (expect_false (lit == MAX_LIT)) |
284 | if (expect_false (lit == MAX_LIT)) |
253 | { |
285 | { |
254 | op [- lit - 1] = lit - 1; /* stop run */ |
286 | op [- lit - 1] = lit - 1; /* stop run */ |
255 | lit = 0; op++; /* start run */ |
287 | lit = 0; op++; /* start run */ |
256 | } |
288 | } |
257 | } |
289 | } |
258 | |
290 | |
259 | if (op + 2 >= out_end) |
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260 | return 0; |
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261 | |
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262 | while (ip < in_end) |
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263 | { |
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264 | lit++; |
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265 | *op++ = *ip++; |
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266 | } |
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267 | |
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268 | op [- lit - 1] = lit - 1; /* end run */ |
291 | op [- lit - 1] = lit - 1; /* end run */ |
269 | op -= !lit; /* undo run if length is zero */ |
292 | op -= !lit; /* undo run if length is zero */ |
270 | |
293 | |
271 | return op - (u8 *)out_data; |
294 | return op - (u8 *)out_data; |
272 | } |
295 | } |