Mercurial > hg > CbC > CbC_gcc
comparison zlib/contrib/infback9/inftree9.c @ 51:ae3a4bfb450b
add some files of version 4.4.3 that have been forgotten.
author | kent <kent@cr.ie.u-ryukyu.ac.jp> |
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date | Sun, 07 Feb 2010 18:27:48 +0900 |
parents | |
children | 04ced10e8804 |
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1 /* inftree9.c -- generate Huffman trees for efficient decoding | |
2 * Copyright (C) 1995-2005 Mark Adler | |
3 * For conditions of distribution and use, see copyright notice in zlib.h | |
4 */ | |
5 | |
6 #include "zutil.h" | |
7 #include "inftree9.h" | |
8 | |
9 #define MAXBITS 15 | |
10 | |
11 const char inflate9_copyright[] = | |
12 " inflate9 1.2.3 Copyright 1995-2005 Mark Adler "; | |
13 /* | |
14 If you use the zlib library in a product, an acknowledgment is welcome | |
15 in the documentation of your product. If for some reason you cannot | |
16 include such an acknowledgment, I would appreciate that you keep this | |
17 copyright string in the executable of your product. | |
18 */ | |
19 | |
20 /* | |
21 Build a set of tables to decode the provided canonical Huffman code. | |
22 The code lengths are lens[0..codes-1]. The result starts at *table, | |
23 whose indices are 0..2^bits-1. work is a writable array of at least | |
24 lens shorts, which is used as a work area. type is the type of code | |
25 to be generated, CODES, LENS, or DISTS. On return, zero is success, | |
26 -1 is an invalid code, and +1 means that ENOUGH isn't enough. table | |
27 on return points to the next available entry's address. bits is the | |
28 requested root table index bits, and on return it is the actual root | |
29 table index bits. It will differ if the request is greater than the | |
30 longest code or if it is less than the shortest code. | |
31 */ | |
32 int inflate_table9(type, lens, codes, table, bits, work) | |
33 codetype type; | |
34 unsigned short FAR *lens; | |
35 unsigned codes; | |
36 code FAR * FAR *table; | |
37 unsigned FAR *bits; | |
38 unsigned short FAR *work; | |
39 { | |
40 unsigned len; /* a code's length in bits */ | |
41 unsigned sym; /* index of code symbols */ | |
42 unsigned min, max; /* minimum and maximum code lengths */ | |
43 unsigned root; /* number of index bits for root table */ | |
44 unsigned curr; /* number of index bits for current table */ | |
45 unsigned drop; /* code bits to drop for sub-table */ | |
46 int left; /* number of prefix codes available */ | |
47 unsigned used; /* code entries in table used */ | |
48 unsigned huff; /* Huffman code */ | |
49 unsigned incr; /* for incrementing code, index */ | |
50 unsigned fill; /* index for replicating entries */ | |
51 unsigned low; /* low bits for current root entry */ | |
52 unsigned mask; /* mask for low root bits */ | |
53 code this; /* table entry for duplication */ | |
54 code FAR *next; /* next available space in table */ | |
55 const unsigned short FAR *base; /* base value table to use */ | |
56 const unsigned short FAR *extra; /* extra bits table to use */ | |
57 int end; /* use base and extra for symbol > end */ | |
58 unsigned short count[MAXBITS+1]; /* number of codes of each length */ | |
59 unsigned short offs[MAXBITS+1]; /* offsets in table for each length */ | |
60 static const unsigned short lbase[31] = { /* Length codes 257..285 base */ | |
61 3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17, | |
62 19, 23, 27, 31, 35, 43, 51, 59, 67, 83, 99, 115, | |
63 131, 163, 195, 227, 3, 0, 0}; | |
64 static const unsigned short lext[31] = { /* Length codes 257..285 extra */ | |
65 128, 128, 128, 128, 128, 128, 128, 128, 129, 129, 129, 129, | |
66 130, 130, 130, 130, 131, 131, 131, 131, 132, 132, 132, 132, | |
67 133, 133, 133, 133, 144, 201, 196}; | |
68 static const unsigned short dbase[32] = { /* Distance codes 0..31 base */ | |
69 1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, | |
70 65, 97, 129, 193, 257, 385, 513, 769, 1025, 1537, 2049, 3073, | |
71 4097, 6145, 8193, 12289, 16385, 24577, 32769, 49153}; | |
72 static const unsigned short dext[32] = { /* Distance codes 0..31 extra */ | |
73 128, 128, 128, 128, 129, 129, 130, 130, 131, 131, 132, 132, | |
74 133, 133, 134, 134, 135, 135, 136, 136, 137, 137, 138, 138, | |
75 139, 139, 140, 140, 141, 141, 142, 142}; | |
76 | |
77 /* | |
78 Process a set of code lengths to create a canonical Huffman code. The | |
79 code lengths are lens[0..codes-1]. Each length corresponds to the | |
80 symbols 0..codes-1. The Huffman code is generated by first sorting the | |
81 symbols by length from short to long, and retaining the symbol order | |
82 for codes with equal lengths. Then the code starts with all zero bits | |
83 for the first code of the shortest length, and the codes are integer | |
84 increments for the same length, and zeros are appended as the length | |
85 increases. For the deflate format, these bits are stored backwards | |
86 from their more natural integer increment ordering, and so when the | |
87 decoding tables are built in the large loop below, the integer codes | |
88 are incremented backwards. | |
89 | |
90 This routine assumes, but does not check, that all of the entries in | |
91 lens[] are in the range 0..MAXBITS. The caller must assure this. | |
92 1..MAXBITS is interpreted as that code length. zero means that that | |
93 symbol does not occur in this code. | |
94 | |
95 The codes are sorted by computing a count of codes for each length, | |
96 creating from that a table of starting indices for each length in the | |
97 sorted table, and then entering the symbols in order in the sorted | |
98 table. The sorted table is work[], with that space being provided by | |
99 the caller. | |
100 | |
101 The length counts are used for other purposes as well, i.e. finding | |
102 the minimum and maximum length codes, determining if there are any | |
103 codes at all, checking for a valid set of lengths, and looking ahead | |
104 at length counts to determine sub-table sizes when building the | |
105 decoding tables. | |
106 */ | |
107 | |
108 /* accumulate lengths for codes (assumes lens[] all in 0..MAXBITS) */ | |
109 for (len = 0; len <= MAXBITS; len++) | |
110 count[len] = 0; | |
111 for (sym = 0; sym < codes; sym++) | |
112 count[lens[sym]]++; | |
113 | |
114 /* bound code lengths, force root to be within code lengths */ | |
115 root = *bits; | |
116 for (max = MAXBITS; max >= 1; max--) | |
117 if (count[max] != 0) break; | |
118 if (root > max) root = max; | |
119 if (max == 0) return -1; /* no codes! */ | |
120 for (min = 1; min <= MAXBITS; min++) | |
121 if (count[min] != 0) break; | |
122 if (root < min) root = min; | |
123 | |
124 /* check for an over-subscribed or incomplete set of lengths */ | |
125 left = 1; | |
126 for (len = 1; len <= MAXBITS; len++) { | |
127 left <<= 1; | |
128 left -= count[len]; | |
129 if (left < 0) return -1; /* over-subscribed */ | |
130 } | |
131 if (left > 0 && (type == CODES || max != 1)) | |
132 return -1; /* incomplete set */ | |
133 | |
134 /* generate offsets into symbol table for each length for sorting */ | |
135 offs[1] = 0; | |
136 for (len = 1; len < MAXBITS; len++) | |
137 offs[len + 1] = offs[len] + count[len]; | |
138 | |
139 /* sort symbols by length, by symbol order within each length */ | |
140 for (sym = 0; sym < codes; sym++) | |
141 if (lens[sym] != 0) work[offs[lens[sym]]++] = (unsigned short)sym; | |
142 | |
143 /* | |
144 Create and fill in decoding tables. In this loop, the table being | |
145 filled is at next and has curr index bits. The code being used is huff | |
146 with length len. That code is converted to an index by dropping drop | |
147 bits off of the bottom. For codes where len is less than drop + curr, | |
148 those top drop + curr - len bits are incremented through all values to | |
149 fill the table with replicated entries. | |
150 | |
151 root is the number of index bits for the root table. When len exceeds | |
152 root, sub-tables are created pointed to by the root entry with an index | |
153 of the low root bits of huff. This is saved in low to check for when a | |
154 new sub-table should be started. drop is zero when the root table is | |
155 being filled, and drop is root when sub-tables are being filled. | |
156 | |
157 When a new sub-table is needed, it is necessary to look ahead in the | |
158 code lengths to determine what size sub-table is needed. The length | |
159 counts are used for this, and so count[] is decremented as codes are | |
160 entered in the tables. | |
161 | |
162 used keeps track of how many table entries have been allocated from the | |
163 provided *table space. It is checked when a LENS table is being made | |
164 against the space in *table, ENOUGH, minus the maximum space needed by | |
165 the worst case distance code, MAXD. This should never happen, but the | |
166 sufficiency of ENOUGH has not been proven exhaustively, hence the check. | |
167 This assumes that when type == LENS, bits == 9. | |
168 | |
169 sym increments through all symbols, and the loop terminates when | |
170 all codes of length max, i.e. all codes, have been processed. This | |
171 routine permits incomplete codes, so another loop after this one fills | |
172 in the rest of the decoding tables with invalid code markers. | |
173 */ | |
174 | |
175 /* set up for code type */ | |
176 switch (type) { | |
177 case CODES: | |
178 base = extra = work; /* dummy value--not used */ | |
179 end = 19; | |
180 break; | |
181 case LENS: | |
182 base = lbase; | |
183 base -= 257; | |
184 extra = lext; | |
185 extra -= 257; | |
186 end = 256; | |
187 break; | |
188 default: /* DISTS */ | |
189 base = dbase; | |
190 extra = dext; | |
191 end = -1; | |
192 } | |
193 | |
194 /* initialize state for loop */ | |
195 huff = 0; /* starting code */ | |
196 sym = 0; /* starting code symbol */ | |
197 len = min; /* starting code length */ | |
198 next = *table; /* current table to fill in */ | |
199 curr = root; /* current table index bits */ | |
200 drop = 0; /* current bits to drop from code for index */ | |
201 low = (unsigned)(-1); /* trigger new sub-table when len > root */ | |
202 used = 1U << root; /* use root table entries */ | |
203 mask = used - 1; /* mask for comparing low */ | |
204 | |
205 /* check available table space */ | |
206 if (type == LENS && used >= ENOUGH - MAXD) | |
207 return 1; | |
208 | |
209 /* process all codes and make table entries */ | |
210 for (;;) { | |
211 /* create table entry */ | |
212 this.bits = (unsigned char)(len - drop); | |
213 if ((int)(work[sym]) < end) { | |
214 this.op = (unsigned char)0; | |
215 this.val = work[sym]; | |
216 } | |
217 else if ((int)(work[sym]) > end) { | |
218 this.op = (unsigned char)(extra[work[sym]]); | |
219 this.val = base[work[sym]]; | |
220 } | |
221 else { | |
222 this.op = (unsigned char)(32 + 64); /* end of block */ | |
223 this.val = 0; | |
224 } | |
225 | |
226 /* replicate for those indices with low len bits equal to huff */ | |
227 incr = 1U << (len - drop); | |
228 fill = 1U << curr; | |
229 do { | |
230 fill -= incr; | |
231 next[(huff >> drop) + fill] = this; | |
232 } while (fill != 0); | |
233 | |
234 /* backwards increment the len-bit code huff */ | |
235 incr = 1U << (len - 1); | |
236 while (huff & incr) | |
237 incr >>= 1; | |
238 if (incr != 0) { | |
239 huff &= incr - 1; | |
240 huff += incr; | |
241 } | |
242 else | |
243 huff = 0; | |
244 | |
245 /* go to next symbol, update count, len */ | |
246 sym++; | |
247 if (--(count[len]) == 0) { | |
248 if (len == max) break; | |
249 len = lens[work[sym]]; | |
250 } | |
251 | |
252 /* create new sub-table if needed */ | |
253 if (len > root && (huff & mask) != low) { | |
254 /* if first time, transition to sub-tables */ | |
255 if (drop == 0) | |
256 drop = root; | |
257 | |
258 /* increment past last table */ | |
259 next += 1U << curr; | |
260 | |
261 /* determine length of next table */ | |
262 curr = len - drop; | |
263 left = (int)(1 << curr); | |
264 while (curr + drop < max) { | |
265 left -= count[curr + drop]; | |
266 if (left <= 0) break; | |
267 curr++; | |
268 left <<= 1; | |
269 } | |
270 | |
271 /* check for enough space */ | |
272 used += 1U << curr; | |
273 if (type == LENS && used >= ENOUGH - MAXD) | |
274 return 1; | |
275 | |
276 /* point entry in root table to sub-table */ | |
277 low = huff & mask; | |
278 (*table)[low].op = (unsigned char)curr; | |
279 (*table)[low].bits = (unsigned char)root; | |
280 (*table)[low].val = (unsigned short)(next - *table); | |
281 } | |
282 } | |
283 | |
284 /* | |
285 Fill in rest of table for incomplete codes. This loop is similar to the | |
286 loop above in incrementing huff for table indices. It is assumed that | |
287 len is equal to curr + drop, so there is no loop needed to increment | |
288 through high index bits. When the current sub-table is filled, the loop | |
289 drops back to the root table to fill in any remaining entries there. | |
290 */ | |
291 this.op = (unsigned char)64; /* invalid code marker */ | |
292 this.bits = (unsigned char)(len - drop); | |
293 this.val = (unsigned short)0; | |
294 while (huff != 0) { | |
295 /* when done with sub-table, drop back to root table */ | |
296 if (drop != 0 && (huff & mask) != low) { | |
297 drop = 0; | |
298 len = root; | |
299 next = *table; | |
300 curr = root; | |
301 this.bits = (unsigned char)len; | |
302 } | |
303 | |
304 /* put invalid code marker in table */ | |
305 next[huff >> drop] = this; | |
306 | |
307 /* backwards increment the len-bit code huff */ | |
308 incr = 1U << (len - 1); | |
309 while (huff & incr) | |
310 incr >>= 1; | |
311 if (incr != 0) { | |
312 huff &= incr - 1; | |
313 huff += incr; | |
314 } | |
315 else | |
316 huff = 0; | |
317 } | |
318 | |
319 /* set return parameters */ | |
320 *table += used; | |
321 *bits = root; | |
322 return 0; | |
323 } |