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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]) |
50 | # if ULTRA_FAST |
50 | # if ULTRA_FAST |
51 | # define IDX(h) (((h >> (3*8 - HLOG)) - h ) & (HSIZE - 1)) |
51 | # define IDX(h) ((( h >> (3*8 - HLOG)) - h ) & (HSIZE - 1)) |
52 | # elif VERY_FAST |
52 | # elif VERY_FAST |
53 | # define IDX(h) (((h >> (3*8 - HLOG)) - h*5) & (HSIZE - 1)) |
53 | # define IDX(h) ((( h >> (3*8 - HLOG)) - h*5) & (HSIZE - 1)) |
54 | # else |
54 | # else |
55 | # define IDX(h) ((((h ^ (h << 5)) >> (3*8 - HLOG)) - h*5) & (HSIZE - 1)) |
55 | # define IDX(h) ((((h ^ (h << 5)) >> (3*8 - HLOG)) - h*5) & (HSIZE - 1)) |
56 | # endif |
56 | # endif |
57 | /*# define IDX(h) ((ip[0] * 121 ^ ip[1] * 33 ^ ip[2] * 1) & (HSIZE-1))*/ |
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58 | #endif |
57 | #endif |
59 | /* |
58 | /* |
60 | * IDX works because it is very similar to a multiplicative hash, e.g. |
59 | * IDX works because it is very similar to a multiplicative hash, e.g. |
61 | * ((h * 57321 >> (3*8 - HLOG)) & (HSIZE - 1)) |
60 | * ((h * 57321 >> (3*8 - HLOG)) & (HSIZE - 1)) |
62 | * the latter is also quite fast on newer CPUs, and compresses similarly. |
61 | * the latter is also quite fast on newer CPUs, and compresses similarly. |
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113 | const u8 *in_end = ip + in_len; |
112 | const u8 *in_end = ip + in_len; |
114 | u8 *out_end = op + out_len; |
113 | u8 *out_end = op + out_len; |
115 | const u8 *ref; |
114 | const u8 *ref; |
116 | |
115 | |
117 | unsigned int hval; |
116 | unsigned int hval; |
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117 | #if WIN32 |
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118 | unsigned _int64 off; /* workaround for microsoft bug (they claim to support POSIX) */ |
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119 | #else |
118 | unsigned long off; |
120 | unsigned long off; |
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121 | #endif |
119 | int lit; |
122 | int lit; |
120 | |
123 | |
121 | if (!in_len || !out_len) |
124 | if (!in_len || !out_len) |
122 | return 0; |
125 | return 0; |
123 | |
126 | |
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137 | hval = NEXT (hval, ip); |
140 | hval = NEXT (hval, ip); |
138 | hslot = htab + IDX (hval); |
141 | hslot = htab + IDX (hval); |
139 | ref = *hslot; *hslot = ip; |
142 | ref = *hslot; *hslot = ip; |
140 | |
143 | |
141 | if (1 |
144 | if (1 |
142 | #if INIT_HTAB && !USE_MEMCPY |
145 | #if INIT_HTAB |
143 | && ref < ip /* the next test will actually take care of this, but this is faster */ |
146 | && ref < ip /* the next test will actually take care of this, but this is faster */ |
144 | #endif |
147 | #endif |
145 | && (off = ip - ref - 1) < MAX_OFF |
148 | && (off = ip - ref - 1) < MAX_OFF |
146 | && ip + 4 < in_end |
149 | && ip + 4 < in_end |
147 | && ref > (u8 *)in_data |
150 | && ref > (u8 *)in_data |
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158 | /* match found at *ref++ */ |
161 | /* match found at *ref++ */ |
159 | unsigned int len = 2; |
162 | unsigned int len = 2; |
160 | unsigned int maxlen = in_end - ip - len; |
163 | unsigned int maxlen = in_end - ip - len; |
161 | maxlen = maxlen > MAX_REF ? MAX_REF : maxlen; |
164 | maxlen = maxlen > MAX_REF ? MAX_REF : maxlen; |
162 | |
165 | |
163 | if (expect_false (op + 1 + 3 >= out_end)) |
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164 | return 0; |
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165 | |
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166 | op [- lit - 1] = lit - 1; /* stop run */ |
166 | op [- lit - 1] = lit - 1; /* stop run */ |
167 | op -= !lit; /* undo run if length is zero */ |
167 | op -= !lit; /* undo run if length is zero */ |
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168 | |
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169 | if (expect_false (op + 3 + 1 >= out_end)) |
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170 | return 0; |
168 | |
171 | |
169 | for (;;) |
172 | for (;;) |
170 | { |
173 | { |
171 | if (expect_true (maxlen > 16)) |
174 | if (expect_true (maxlen > 16)) |
172 | { |
175 | { |
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236 | htab[IDX (hval)] = ip; |
239 | htab[IDX (hval)] = ip; |
237 | ip++; |
240 | ip++; |
238 | } |
241 | } |
239 | while (len--); |
242 | while (len--); |
240 | #endif |
243 | #endif |
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244 | |
241 | lit = 0; op++; /* start run */ |
245 | lit = 0; op++; /* start run */ |
242 | continue; |
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243 | } |
246 | } |
244 | |
247 | else |
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248 | { |
245 | /* one more literal byte we must copy */ |
249 | /* one more literal byte we must copy */ |
246 | |
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247 | if (expect_false (op >= out_end)) |
250 | if (expect_false (op >= out_end)) |
248 | return 0; |
251 | return 0; |
249 | |
252 | |
250 | lit++; |
253 | lit++; *op++ = *ip++; |
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254 | |
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255 | if (expect_false (lit == MAX_LIT)) |
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256 | { |
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257 | op [- lit - 1] = lit - 1; /* stop run */ |
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258 | lit = 0; op++; /* start run */ |
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259 | } |
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260 | } |
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261 | } |
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262 | |
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263 | if (op + 3 > out_end) /* at most 3 bytes can be missing here */ |
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264 | return 0; |
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265 | |
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266 | while (ip < in_end) |
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267 | { |
251 | *op++ = *ip++; |
268 | lit++; *op++ = *ip++; |
252 | |
269 | |
253 | if (expect_false (lit == MAX_LIT)) |
270 | if (expect_false (lit == MAX_LIT)) |
254 | { |
271 | { |
255 | op [- lit - 1] = lit - 1; /* stop run */ |
272 | op [- lit - 1] = lit - 1; /* stop run */ |
256 | lit = 0; op++; /* start run */ |
273 | lit = 0; op++; /* start run */ |
257 | } |
274 | } |
258 | } |
275 | } |
259 | |
276 | |
260 | if (op + lit + 2 >= out_end) |
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261 | return 0; |
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262 | |
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263 | while (ip < in_end) |
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264 | { |
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265 | lit++; |
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266 | *op++ = *ip++; |
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267 | } |
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268 | |
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269 | op [- lit - 1] = lit - 1; |
277 | op [- lit - 1] = lit - 1; /* end run */ |
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278 | op -= !lit; /* undo run if length is zero */ |
270 | |
279 | |
271 | return op - (u8 *)out_data; |
280 | return op - (u8 *)out_data; |
272 | } |
281 | } |
273 | |
282 | |