lemon-project-template-glpk
comparison deps/glpk/src/zlib/inffast.c @ 11:4fc6ad2fb8a6
Test GLPK in src/main.cc
author | Alpar Juttner <alpar@cs.elte.hu> |
---|---|
date | Sun, 06 Nov 2011 21:43:29 +0100 |
parents | |
children |
comparison
equal
deleted
inserted
replaced
-1:000000000000 | 0:d91379e5abf2 |
---|---|
1 /* inffast.c -- fast decoding | |
2 * Copyright (C) 1995-2008, 2010 Mark Adler | |
3 * For conditions of distribution and use, see copyright notice in zlib.h | |
4 */ | |
5 | |
6 #include "zutil.h" | |
7 #include "inftrees.h" | |
8 #include "inflate.h" | |
9 #include "inffast.h" | |
10 | |
11 #ifndef ASMINF | |
12 | |
13 /* Allow machine dependent optimization for post-increment or pre-increment. | |
14 Based on testing to date, | |
15 Pre-increment preferred for: | |
16 - PowerPC G3 (Adler) | |
17 - MIPS R5000 (Randers-Pehrson) | |
18 Post-increment preferred for: | |
19 - none | |
20 No measurable difference: | |
21 - Pentium III (Anderson) | |
22 - M68060 (Nikl) | |
23 */ | |
24 #ifdef POSTINC | |
25 # define OFF 0 | |
26 # define PUP(a) *(a)++ | |
27 #else | |
28 # define OFF 1 | |
29 # define PUP(a) *++(a) | |
30 #endif | |
31 | |
32 /* | |
33 Decode literal, length, and distance codes and write out the resulting | |
34 literal and match bytes until either not enough input or output is | |
35 available, an end-of-block is encountered, or a data error is encountered. | |
36 When large enough input and output buffers are supplied to inflate(), for | |
37 example, a 16K input buffer and a 64K output buffer, more than 95% of the | |
38 inflate execution time is spent in this routine. | |
39 | |
40 Entry assumptions: | |
41 | |
42 state->mode == LEN | |
43 strm->avail_in >= 6 | |
44 strm->avail_out >= 258 | |
45 start >= strm->avail_out | |
46 state->bits < 8 | |
47 | |
48 On return, state->mode is one of: | |
49 | |
50 LEN -- ran out of enough output space or enough available input | |
51 TYPE -- reached end of block code, inflate() to interpret next block | |
52 BAD -- error in block data | |
53 | |
54 Notes: | |
55 | |
56 - The maximum input bits used by a length/distance pair is 15 bits for the | |
57 length code, 5 bits for the length extra, 15 bits for the distance code, | |
58 and 13 bits for the distance extra. This totals 48 bits, or six bytes. | |
59 Therefore if strm->avail_in >= 6, then there is enough input to avoid | |
60 checking for available input while decoding. | |
61 | |
62 - The maximum bytes that a single length/distance pair can output is 258 | |
63 bytes, which is the maximum length that can be coded. inflate_fast() | |
64 requires strm->avail_out >= 258 for each loop to avoid checking for | |
65 output space. | |
66 */ | |
67 void ZLIB_INTERNAL inflate_fast(strm, start) | |
68 z_streamp strm; | |
69 unsigned start; /* inflate()'s starting value for strm->avail_out */ | |
70 { | |
71 struct inflate_state FAR *state; | |
72 unsigned char FAR *in; /* local strm->next_in */ | |
73 unsigned char FAR *last; /* while in < last, enough input available */ | |
74 unsigned char FAR *out; /* local strm->next_out */ | |
75 unsigned char FAR *beg; /* inflate()'s initial strm->next_out */ | |
76 unsigned char FAR *end; /* while out < end, enough space available */ | |
77 #ifdef INFLATE_STRICT | |
78 unsigned dmax; /* maximum distance from zlib header */ | |
79 #endif | |
80 unsigned wsize; /* window size or zero if not using window */ | |
81 unsigned whave; /* valid bytes in the window */ | |
82 unsigned wnext; /* window write index */ | |
83 unsigned char FAR *window; /* allocated sliding window, if wsize != 0 */ | |
84 unsigned long hold; /* local strm->hold */ | |
85 unsigned bits; /* local strm->bits */ | |
86 code const FAR *lcode; /* local strm->lencode */ | |
87 code const FAR *dcode; /* local strm->distcode */ | |
88 unsigned lmask; /* mask for first level of length codes */ | |
89 unsigned dmask; /* mask for first level of distance codes */ | |
90 code here; /* retrieved table entry */ | |
91 unsigned op; /* code bits, operation, extra bits, or */ | |
92 /* window position, window bytes to copy */ | |
93 unsigned len; /* match length, unused bytes */ | |
94 unsigned dist; /* match distance */ | |
95 unsigned char FAR *from; /* where to copy match from */ | |
96 | |
97 /* copy state to local variables */ | |
98 state = (struct inflate_state FAR *)strm->state; | |
99 in = strm->next_in - OFF; | |
100 last = in + (strm->avail_in - 5); | |
101 out = strm->next_out - OFF; | |
102 beg = out - (start - strm->avail_out); | |
103 end = out + (strm->avail_out - 257); | |
104 #ifdef INFLATE_STRICT | |
105 dmax = state->dmax; | |
106 #endif | |
107 wsize = state->wsize; | |
108 whave = state->whave; | |
109 wnext = state->wnext; | |
110 window = state->window; | |
111 hold = state->hold; | |
112 bits = state->bits; | |
113 lcode = state->lencode; | |
114 dcode = state->distcode; | |
115 lmask = (1U << state->lenbits) - 1; | |
116 dmask = (1U << state->distbits) - 1; | |
117 | |
118 /* decode literals and length/distances until end-of-block or not enough | |
119 input data or output space */ | |
120 do { | |
121 if (bits < 15) { | |
122 hold += (unsigned long)(PUP(in)) << bits; | |
123 bits += 8; | |
124 hold += (unsigned long)(PUP(in)) << bits; | |
125 bits += 8; | |
126 } | |
127 here = lcode[hold & lmask]; | |
128 dolen: | |
129 op = (unsigned)(here.bits); | |
130 hold >>= op; | |
131 bits -= op; | |
132 op = (unsigned)(here.op); | |
133 if (op == 0) { /* literal */ | |
134 Tracevv((stderr, here.val >= 0x20 && here.val < 0x7f ? | |
135 "inflate: literal '%c'\n" : | |
136 "inflate: literal 0x%02x\n", here.val)); | |
137 PUP(out) = (unsigned char)(here.val); | |
138 } | |
139 else if (op & 16) { /* length base */ | |
140 len = (unsigned)(here.val); | |
141 op &= 15; /* number of extra bits */ | |
142 if (op) { | |
143 if (bits < op) { | |
144 hold += (unsigned long)(PUP(in)) << bits; | |
145 bits += 8; | |
146 } | |
147 len += (unsigned)hold & ((1U << op) - 1); | |
148 hold >>= op; | |
149 bits -= op; | |
150 } | |
151 Tracevv((stderr, "inflate: length %u\n", len)); | |
152 if (bits < 15) { | |
153 hold += (unsigned long)(PUP(in)) << bits; | |
154 bits += 8; | |
155 hold += (unsigned long)(PUP(in)) << bits; | |
156 bits += 8; | |
157 } | |
158 here = dcode[hold & dmask]; | |
159 dodist: | |
160 op = (unsigned)(here.bits); | |
161 hold >>= op; | |
162 bits -= op; | |
163 op = (unsigned)(here.op); | |
164 if (op & 16) { /* distance base */ | |
165 dist = (unsigned)(here.val); | |
166 op &= 15; /* number of extra bits */ | |
167 if (bits < op) { | |
168 hold += (unsigned long)(PUP(in)) << bits; | |
169 bits += 8; | |
170 if (bits < op) { | |
171 hold += (unsigned long)(PUP(in)) << bits; | |
172 bits += 8; | |
173 } | |
174 } | |
175 dist += (unsigned)hold & ((1U << op) - 1); | |
176 #ifdef INFLATE_STRICT | |
177 if (dist > dmax) { | |
178 strm->msg = (char *)"invalid distance too far back"; | |
179 state->mode = BAD; | |
180 break; | |
181 } | |
182 #endif | |
183 hold >>= op; | |
184 bits -= op; | |
185 Tracevv((stderr, "inflate: distance %u\n", dist)); | |
186 op = (unsigned)(out - beg); /* max distance in output */ | |
187 if (dist > op) { /* see if copy from window */ | |
188 op = dist - op; /* distance back in window */ | |
189 if (op > whave) { | |
190 if (state->sane) { | |
191 strm->msg = | |
192 (char *)"invalid distance too far back"; | |
193 state->mode = BAD; | |
194 break; | |
195 } | |
196 #ifdef INFLATE_ALLOW_INVALID_DISTANCE_TOOFAR_ARRR | |
197 if (len <= op - whave) { | |
198 do { | |
199 PUP(out) = 0; | |
200 } while (--len); | |
201 continue; | |
202 } | |
203 len -= op - whave; | |
204 do { | |
205 PUP(out) = 0; | |
206 } while (--op > whave); | |
207 if (op == 0) { | |
208 from = out - dist; | |
209 do { | |
210 PUP(out) = PUP(from); | |
211 } while (--len); | |
212 continue; | |
213 } | |
214 #endif | |
215 } | |
216 from = window - OFF; | |
217 if (wnext == 0) { /* very common case */ | |
218 from += wsize - op; | |
219 if (op < len) { /* some from window */ | |
220 len -= op; | |
221 do { | |
222 PUP(out) = PUP(from); | |
223 } while (--op); | |
224 from = out - dist; /* rest from output */ | |
225 } | |
226 } | |
227 else if (wnext < op) { /* wrap around window */ | |
228 from += wsize + wnext - op; | |
229 op -= wnext; | |
230 if (op < len) { /* some from end of window */ | |
231 len -= op; | |
232 do { | |
233 PUP(out) = PUP(from); | |
234 } while (--op); | |
235 from = window - OFF; | |
236 if (wnext < len) { /* some from start of window */ | |
237 op = wnext; | |
238 len -= op; | |
239 do { | |
240 PUP(out) = PUP(from); | |
241 } while (--op); | |
242 from = out - dist; /* rest from output */ | |
243 } | |
244 } | |
245 } | |
246 else { /* contiguous in window */ | |
247 from += wnext - op; | |
248 if (op < len) { /* some from window */ | |
249 len -= op; | |
250 do { | |
251 PUP(out) = PUP(from); | |
252 } while (--op); | |
253 from = out - dist; /* rest from output */ | |
254 } | |
255 } | |
256 while (len > 2) { | |
257 PUP(out) = PUP(from); | |
258 PUP(out) = PUP(from); | |
259 PUP(out) = PUP(from); | |
260 len -= 3; | |
261 } | |
262 if (len) { | |
263 PUP(out) = PUP(from); | |
264 if (len > 1) | |
265 PUP(out) = PUP(from); | |
266 } | |
267 } | |
268 else { | |
269 from = out - dist; /* copy direct from output */ | |
270 do { /* minimum length is three */ | |
271 PUP(out) = PUP(from); | |
272 PUP(out) = PUP(from); | |
273 PUP(out) = PUP(from); | |
274 len -= 3; | |
275 } while (len > 2); | |
276 if (len) { | |
277 PUP(out) = PUP(from); | |
278 if (len > 1) | |
279 PUP(out) = PUP(from); | |
280 } | |
281 } | |
282 } | |
283 else if ((op & 64) == 0) { /* 2nd level distance code */ | |
284 here = dcode[here.val + (hold & ((1U << op) - 1))]; | |
285 goto dodist; | |
286 } | |
287 else { | |
288 strm->msg = (char *)"invalid distance code"; | |
289 state->mode = BAD; | |
290 break; | |
291 } | |
292 } | |
293 else if ((op & 64) == 0) { /* 2nd level length code */ | |
294 here = lcode[here.val + (hold & ((1U << op) - 1))]; | |
295 goto dolen; | |
296 } | |
297 else if (op & 32) { /* end-of-block */ | |
298 Tracevv((stderr, "inflate: end of block\n")); | |
299 state->mode = TYPE; | |
300 break; | |
301 } | |
302 else { | |
303 strm->msg = (char *)"invalid literal/length code"; | |
304 state->mode = BAD; | |
305 break; | |
306 } | |
307 } while (in < last && out < end); | |
308 | |
309 /* return unused bytes (on entry, bits < 8, so in won't go too far back) */ | |
310 len = bits >> 3; | |
311 in -= len; | |
312 bits -= len << 3; | |
313 hold &= (1U << bits) - 1; | |
314 | |
315 /* update state and return */ | |
316 strm->next_in = in + OFF; | |
317 strm->next_out = out + OFF; | |
318 strm->avail_in = (unsigned)(in < last ? 5 + (last - in) : 5 - (in - last)); | |
319 strm->avail_out = (unsigned)(out < end ? | |
320 257 + (end - out) : 257 - (out - end)); | |
321 state->hold = hold; | |
322 state->bits = bits; | |
323 return; | |
324 } | |
325 | |
326 /* | |
327 inflate_fast() speedups that turned out slower (on a PowerPC G3 750CXe): | |
328 - Using bit fields for code structure | |
329 - Different op definition to avoid & for extra bits (do & for table bits) | |
330 - Three separate decoding do-loops for direct, window, and wnext == 0 | |
331 - Special case for distance > 1 copies to do overlapped load and store copy | |
332 - Explicit branch predictions (based on measured branch probabilities) | |
333 - Deferring match copy and interspersed it with decoding subsequent codes | |
334 - Swapping literal/length else | |
335 - Swapping window/direct else | |
336 - Larger unrolled copy loops (three is about right) | |
337 - Moving len -= 3 statement into middle of loop | |
338 */ | |
339 | |
340 #endif /* !ASMINF */ |