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author | Maurus Cuelenaere <mcuelenaere@gmail.com> | 2008-07-11 15:50:46 +0000 |
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committer | Maurus Cuelenaere <mcuelenaere@gmail.com> | 2008-07-11 15:50:46 +0000 |
commit | 14c7f45cdae826f88dc539c8c38dd95caf305731 (patch) | |
tree | 832da054b7cfb2dc6fd63339af736625f31d21aa /utils/zenutils/libraries/zlib123/zlib/inffast.c | |
parent | 7c84ede3781c27db73403bd6302f320c76a58c8c (diff) | |
download | rockbox-14c7f45cdae826f88dc539c8c38dd95caf305731.tar.gz rockbox-14c7f45cdae826f88dc539c8c38dd95caf305731.zip |
Add zook's ZenUtils to SVN
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@18010 a1c6a512-1295-4272-9138-f99709370657
Diffstat (limited to 'utils/zenutils/libraries/zlib123/zlib/inffast.c')
-rwxr-xr-x | utils/zenutils/libraries/zlib123/zlib/inffast.c | 318 |
1 files changed, 318 insertions, 0 deletions
diff --git a/utils/zenutils/libraries/zlib123/zlib/inffast.c b/utils/zenutils/libraries/zlib123/zlib/inffast.c new file mode 100755 index 0000000000..fa31cad905 --- /dev/null +++ b/utils/zenutils/libraries/zlib123/zlib/inffast.c | |||
@@ -0,0 +1,318 @@ | |||
1 | /* inffast.c -- fast decoding | ||
2 | * Copyright (C) 1995-2004 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 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 write; /* 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 this; /* 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 | write = state->write; | ||
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 | this = lcode[hold & lmask]; | ||
128 | dolen: | ||
129 | op = (unsigned)(this.bits); | ||
130 | hold >>= op; | ||
131 | bits -= op; | ||
132 | op = (unsigned)(this.op); | ||
133 | if (op == 0) { /* literal */ | ||
134 | Tracevv((stderr, this.val >= 0x20 && this.val < 0x7f ? | ||
135 | "inflate: literal '%c'\n" : | ||
136 | "inflate: literal 0x%02x\n", this.val)); | ||
137 | PUP(out) = (unsigned char)(this.val); | ||
138 | } | ||
139 | else if (op & 16) { /* length base */ | ||
140 | len = (unsigned)(this.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 | this = dcode[hold & dmask]; | ||
159 | dodist: | ||
160 | op = (unsigned)(this.bits); | ||
161 | hold >>= op; | ||
162 | bits -= op; | ||
163 | op = (unsigned)(this.op); | ||
164 | if (op & 16) { /* distance base */ | ||
165 | dist = (unsigned)(this.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 | strm->msg = (char *)"invalid distance too far back"; | ||
191 | state->mode = BAD; | ||
192 | break; | ||
193 | } | ||
194 | from = window - OFF; | ||
195 | if (write == 0) { /* very common case */ | ||
196 | from += wsize - op; | ||
197 | if (op < len) { /* some from window */ | ||
198 | len -= op; | ||
199 | do { | ||
200 | PUP(out) = PUP(from); | ||
201 | } while (--op); | ||
202 | from = out - dist; /* rest from output */ | ||
203 | } | ||
204 | } | ||
205 | else if (write < op) { /* wrap around window */ | ||
206 | from += wsize + write - op; | ||
207 | op -= write; | ||
208 | if (op < len) { /* some from end of window */ | ||
209 | len -= op; | ||
210 | do { | ||
211 | PUP(out) = PUP(from); | ||
212 | } while (--op); | ||
213 | from = window - OFF; | ||
214 | if (write < len) { /* some from start of window */ | ||
215 | op = write; | ||
216 | len -= op; | ||
217 | do { | ||
218 | PUP(out) = PUP(from); | ||
219 | } while (--op); | ||
220 | from = out - dist; /* rest from output */ | ||
221 | } | ||
222 | } | ||
223 | } | ||
224 | else { /* contiguous in window */ | ||
225 | from += write - op; | ||
226 | if (op < len) { /* some from window */ | ||
227 | len -= op; | ||
228 | do { | ||
229 | PUP(out) = PUP(from); | ||
230 | } while (--op); | ||
231 | from = out - dist; /* rest from output */ | ||
232 | } | ||
233 | } | ||
234 | while (len > 2) { | ||
235 | PUP(out) = PUP(from); | ||
236 | PUP(out) = PUP(from); | ||
237 | PUP(out) = PUP(from); | ||
238 | len -= 3; | ||
239 | } | ||
240 | if (len) { | ||
241 | PUP(out) = PUP(from); | ||
242 | if (len > 1) | ||
243 | PUP(out) = PUP(from); | ||
244 | } | ||
245 | } | ||
246 | else { | ||
247 | from = out - dist; /* copy direct from output */ | ||
248 | do { /* minimum length is three */ | ||
249 | PUP(out) = PUP(from); | ||
250 | PUP(out) = PUP(from); | ||
251 | PUP(out) = PUP(from); | ||
252 | len -= 3; | ||
253 | } while (len > 2); | ||
254 | if (len) { | ||
255 | PUP(out) = PUP(from); | ||
256 | if (len > 1) | ||
257 | PUP(out) = PUP(from); | ||
258 | } | ||
259 | } | ||
260 | } | ||
261 | else if ((op & 64) == 0) { /* 2nd level distance code */ | ||
262 | this = dcode[this.val + (hold & ((1U << op) - 1))]; | ||
263 | goto dodist; | ||
264 | } | ||
265 | else { | ||
266 | strm->msg = (char *)"invalid distance code"; | ||
267 | state->mode = BAD; | ||
268 | break; | ||
269 | } | ||
270 | } | ||
271 | else if ((op & 64) == 0) { /* 2nd level length code */ | ||
272 | this = lcode[this.val + (hold & ((1U << op) - 1))]; | ||
273 | goto dolen; | ||
274 | } | ||
275 | else if (op & 32) { /* end-of-block */ | ||
276 | Tracevv((stderr, "inflate: end of block\n")); | ||
277 | state->mode = TYPE; | ||
278 | break; | ||
279 | } | ||
280 | else { | ||
281 | strm->msg = (char *)"invalid literal/length code"; | ||
282 | state->mode = BAD; | ||
283 | break; | ||
284 | } | ||
285 | } while (in < last && out < end); | ||
286 | |||
287 | /* return unused bytes (on entry, bits < 8, so in won't go too far back) */ | ||
288 | len = bits >> 3; | ||
289 | in -= len; | ||
290 | bits -= len << 3; | ||
291 | hold &= (1U << bits) - 1; | ||
292 | |||
293 | /* update state and return */ | ||
294 | strm->next_in = in + OFF; | ||
295 | strm->next_out = out + OFF; | ||
296 | strm->avail_in = (unsigned)(in < last ? 5 + (last - in) : 5 - (in - last)); | ||
297 | strm->avail_out = (unsigned)(out < end ? | ||
298 | 257 + (end - out) : 257 - (out - end)); | ||
299 | state->hold = hold; | ||
300 | state->bits = bits; | ||
301 | return; | ||
302 | } | ||
303 | |||
304 | /* | ||
305 | inflate_fast() speedups that turned out slower (on a PowerPC G3 750CXe): | ||
306 | - Using bit fields for code structure | ||
307 | - Different op definition to avoid & for extra bits (do & for table bits) | ||
308 | - Three separate decoding do-loops for direct, window, and write == 0 | ||
309 | - Special case for distance > 1 copies to do overlapped load and store copy | ||
310 | - Explicit branch predictions (based on measured branch probabilities) | ||
311 | - Deferring match copy and interspersed it with decoding subsequent codes | ||
312 | - Swapping literal/length else | ||
313 | - Swapping window/direct else | ||
314 | - Larger unrolled copy loops (three is about right) | ||
315 | - Moving len -= 3 statement into middle of loop | ||
316 | */ | ||
317 | |||
318 | #endif /* !ASMINF */ | ||