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comparison zlib/inftrees.c @ 111:04ced10e8804

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gcc 7
author kono
date Fri, 27 Oct 2017 22:46:09 +0900
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68:561a7518be6b 111:04ced10e8804
1 /* inftrees.c -- generate Huffman trees for efficient decoding 1 /* inftrees.c -- generate Huffman trees for efficient decoding
2 * Copyright (C) 1995-2005 Mark Adler 2 * Copyright (C) 1995-2017 Mark Adler
3 * For conditions of distribution and use, see copyright notice in zlib.h 3 * For conditions of distribution and use, see copyright notice in zlib.h
4 */ 4 */
5 5
6 #include "zutil.h" 6 #include "zutil.h"
7 #include "inftrees.h" 7 #include "inftrees.h"
8 8
9 #define MAXBITS 15 9 #define MAXBITS 15
10 10
11 const char inflate_copyright[] = 11 const char inflate_copyright[] =
12 " inflate 1.2.3 Copyright 1995-2005 Mark Adler "; 12 " inflate 1.2.11 Copyright 1995-2017 Mark Adler ";
13 /* 13 /*
14 If you use the zlib library in a product, an acknowledgment is welcome 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 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 16 include such an acknowledgment, I would appreciate that you keep this
17 copyright string in the executable of your product. 17 copyright string in the executable of your product.
27 on return points to the next available entry's address. bits is the 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 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 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. 30 longest code or if it is less than the shortest code.
31 */ 31 */
32 int inflate_table(type, lens, codes, table, bits, work) 32 int ZLIB_INTERNAL inflate_table(type, lens, codes, table, bits, work)
33 codetype type; 33 codetype type;
34 unsigned short FAR *lens; 34 unsigned short FAR *lens;
35 unsigned codes; 35 unsigned codes;
36 code FAR * FAR *table; 36 code FAR * FAR *table;
37 unsigned FAR *bits; 37 unsigned FAR *bits;
48 unsigned huff; /* Huffman code */ 48 unsigned huff; /* Huffman code */
49 unsigned incr; /* for incrementing code, index */ 49 unsigned incr; /* for incrementing code, index */
50 unsigned fill; /* index for replicating entries */ 50 unsigned fill; /* index for replicating entries */
51 unsigned low; /* low bits for current root entry */ 51 unsigned low; /* low bits for current root entry */
52 unsigned mask; /* mask for low root bits */ 52 unsigned mask; /* mask for low root bits */
53 code this; /* table entry for duplication */ 53 code here; /* table entry for duplication */
54 code FAR *next; /* next available space in table */ 54 code FAR *next; /* next available space in table */
55 const unsigned short FAR *base; /* base value table to use */ 55 const unsigned short FAR *base; /* base value table to use */
56 const unsigned short FAR *extra; /* extra bits table to use */ 56 const unsigned short FAR *extra; /* extra bits table to use */
57 int end; /* use base and extra for symbol > end */ 57 unsigned match; /* use base and extra for symbol >= match */
58 unsigned short count[MAXBITS+1]; /* number of codes of each length */ 58 unsigned short count[MAXBITS+1]; /* number of codes of each length */
59 unsigned short offs[MAXBITS+1]; /* offsets in table for 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 */ 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, 19, 23, 27, 31, 61 3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17, 19, 23, 27, 31,
62 35, 43, 51, 59, 67, 83, 99, 115, 131, 163, 195, 227, 258, 0, 0}; 62 35, 43, 51, 59, 67, 83, 99, 115, 131, 163, 195, 227, 258, 0, 0};
63 static const unsigned short lext[31] = { /* Length codes 257..285 extra */ 63 static const unsigned short lext[31] = { /* Length codes 257..285 extra */
64 16, 16, 16, 16, 16, 16, 16, 16, 17, 17, 17, 17, 18, 18, 18, 18, 64 16, 16, 16, 16, 16, 16, 16, 16, 17, 17, 17, 17, 18, 18, 18, 18,
65 19, 19, 19, 19, 20, 20, 20, 20, 21, 21, 21, 21, 16, 201, 196}; 65 19, 19, 19, 19, 20, 20, 20, 20, 21, 21, 21, 21, 16, 77, 202};
66 static const unsigned short dbase[32] = { /* Distance codes 0..29 base */ 66 static const unsigned short dbase[32] = { /* Distance codes 0..29 base */
67 1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193, 67 1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193,
68 257, 385, 513, 769, 1025, 1537, 2049, 3073, 4097, 6145, 68 257, 385, 513, 769, 1025, 1537, 2049, 3073, 4097, 6145,
69 8193, 12289, 16385, 24577, 0, 0}; 69 8193, 12289, 16385, 24577, 0, 0};
70 static const unsigned short dext[32] = { /* Distance codes 0..29 extra */ 70 static const unsigned short dext[32] = { /* Distance codes 0..29 extra */
113 root = *bits; 113 root = *bits;
114 for (max = MAXBITS; max >= 1; max--) 114 for (max = MAXBITS; max >= 1; max--)
115 if (count[max] != 0) break; 115 if (count[max] != 0) break;
116 if (root > max) root = max; 116 if (root > max) root = max;
117 if (max == 0) { /* no symbols to code at all */ 117 if (max == 0) { /* no symbols to code at all */
118 this.op = (unsigned char)64; /* invalid code marker */ 118 here.op = (unsigned char)64; /* invalid code marker */
119 this.bits = (unsigned char)1; 119 here.bits = (unsigned char)1;
120 this.val = (unsigned short)0; 120 here.val = (unsigned short)0;
121 *(*table)++ = this; /* make a table to force an error */ 121 *(*table)++ = here; /* make a table to force an error */
122 *(*table)++ = this; 122 *(*table)++ = here;
123 *bits = 1; 123 *bits = 1;
124 return 0; /* no symbols, but wait for decoding to report error */ 124 return 0; /* no symbols, but wait for decoding to report error */
125 } 125 }
126 for (min = 1; min <= MAXBITS; min++) 126 for (min = 1; min < max; min++)
127 if (count[min] != 0) break; 127 if (count[min] != 0) break;
128 if (root < min) root = min; 128 if (root < min) root = min;
129 129
130 /* check for an over-subscribed or incomplete set of lengths */ 130 /* check for an over-subscribed or incomplete set of lengths */
131 left = 1; 131 left = 1;
164 code lengths to determine what size sub-table is needed. The length 164 code lengths to determine what size sub-table is needed. The length
165 counts are used for this, and so count[] is decremented as codes are 165 counts are used for this, and so count[] is decremented as codes are
166 entered in the tables. 166 entered in the tables.
167 167
168 used keeps track of how many table entries have been allocated from the 168 used keeps track of how many table entries have been allocated from the
169 provided *table space. It is checked when a LENS table is being made 169 provided *table space. It is checked for LENS and DIST tables against
170 against the space in *table, ENOUGH, minus the maximum space needed by 170 the constants ENOUGH_LENS and ENOUGH_DISTS to guard against changes in
171 the worst case distance code, MAXD. This should never happen, but the 171 the initial root table size constants. See the comments in inftrees.h
172 sufficiency of ENOUGH has not been proven exhaustively, hence the check. 172 for more information.
173 This assumes that when type == LENS, bits == 9.
174 173
175 sym increments through all symbols, and the loop terminates when 174 sym increments through all symbols, and the loop terminates when
176 all codes of length max, i.e. all codes, have been processed. This 175 all codes of length max, i.e. all codes, have been processed. This
177 routine permits incomplete codes, so another loop after this one fills 176 routine permits incomplete codes, so another loop after this one fills
178 in the rest of the decoding tables with invalid code markers. 177 in the rest of the decoding tables with invalid code markers.
180 179
181 /* set up for code type */ 180 /* set up for code type */
182 switch (type) { 181 switch (type) {
183 case CODES: 182 case CODES:
184 base = extra = work; /* dummy value--not used */ 183 base = extra = work; /* dummy value--not used */
185 end = 19; 184 match = 20;
186 break; 185 break;
187 case LENS: 186 case LENS:
188 base = lbase; 187 base = lbase;
189 base -= 257;
190 extra = lext; 188 extra = lext;
191 extra -= 257; 189 match = 257;
192 end = 256;
193 break; 190 break;
194 default: /* DISTS */ 191 default: /* DISTS */
195 base = dbase; 192 base = dbase;
196 extra = dext; 193 extra = dext;
197 end = -1; 194 match = 0;
198 } 195 }
199 196
200 /* initialize state for loop */ 197 /* initialize state for loop */
201 huff = 0; /* starting code */ 198 huff = 0; /* starting code */
202 sym = 0; /* starting code symbol */ 199 sym = 0; /* starting code symbol */
207 low = (unsigned)(-1); /* trigger new sub-table when len > root */ 204 low = (unsigned)(-1); /* trigger new sub-table when len > root */
208 used = 1U << root; /* use root table entries */ 205 used = 1U << root; /* use root table entries */
209 mask = used - 1; /* mask for comparing low */ 206 mask = used - 1; /* mask for comparing low */
210 207
211 /* check available table space */ 208 /* check available table space */
212 if (type == LENS && used >= ENOUGH - MAXD) 209 if ((type == LENS && used > ENOUGH_LENS) ||
210 (type == DISTS && used > ENOUGH_DISTS))
213 return 1; 211 return 1;
214 212
215 /* process all codes and make table entries */ 213 /* process all codes and make table entries */
216 for (;;) { 214 for (;;) {
217 /* create table entry */ 215 /* create table entry */
218 this.bits = (unsigned char)(len - drop); 216 here.bits = (unsigned char)(len - drop);
219 if ((int)(work[sym]) < end) { 217 if (work[sym] + 1U < match) {
220 this.op = (unsigned char)0; 218 here.op = (unsigned char)0;
221 this.val = work[sym]; 219 here.val = work[sym];
222 } 220 }
223 else if ((int)(work[sym]) > end) { 221 else if (work[sym] >= match) {
224 this.op = (unsigned char)(extra[work[sym]]); 222 here.op = (unsigned char)(extra[work[sym] - match]);
225 this.val = base[work[sym]]; 223 here.val = base[work[sym] - match];
226 } 224 }
227 else { 225 else {
228 this.op = (unsigned char)(32 + 64); /* end of block */ 226 here.op = (unsigned char)(32 + 64); /* end of block */
229 this.val = 0; 227 here.val = 0;
230 } 228 }
231 229
232 /* replicate for those indices with low len bits equal to huff */ 230 /* replicate for those indices with low len bits equal to huff */
233 incr = 1U << (len - drop); 231 incr = 1U << (len - drop);
234 fill = 1U << curr; 232 fill = 1U << curr;
235 min = fill; /* save offset to next table */ 233 min = fill; /* save offset to next table */
236 do { 234 do {
237 fill -= incr; 235 fill -= incr;
238 next[(huff >> drop) + fill] = this; 236 next[(huff >> drop) + fill] = here;
239 } while (fill != 0); 237 } while (fill != 0);
240 238
241 /* backwards increment the len-bit code huff */ 239 /* backwards increment the len-bit code huff */
242 incr = 1U << (len - 1); 240 incr = 1U << (len - 1);
243 while (huff & incr) 241 while (huff & incr)
275 left <<= 1; 273 left <<= 1;
276 } 274 }
277 275
278 /* check for enough space */ 276 /* check for enough space */
279 used += 1U << curr; 277 used += 1U << curr;
280 if (type == LENS && used >= ENOUGH - MAXD) 278 if ((type == LENS && used > ENOUGH_LENS) ||
279 (type == DISTS && used > ENOUGH_DISTS))
281 return 1; 280 return 1;
282 281
283 /* point entry in root table to sub-table */ 282 /* point entry in root table to sub-table */
284 low = huff & mask; 283 low = huff & mask;
285 (*table)[low].op = (unsigned char)curr; 284 (*table)[low].op = (unsigned char)curr;
286 (*table)[low].bits = (unsigned char)root; 285 (*table)[low].bits = (unsigned char)root;
287 (*table)[low].val = (unsigned short)(next - *table); 286 (*table)[low].val = (unsigned short)(next - *table);
288 } 287 }
289 } 288 }
290 289
291 /* 290 /* fill in remaining table entry if code is incomplete (guaranteed to have
292 Fill in rest of table for incomplete codes. This loop is similar to the 291 at most one remaining entry, since if the code is incomplete, the
293 loop above in incrementing huff for table indices. It is assumed that 292 maximum code length that was allowed to get this far is one bit) */
294 len is equal to curr + drop, so there is no loop needed to increment 293 if (huff != 0) {
295 through high index bits. When the current sub-table is filled, the loop 294 here.op = (unsigned char)64; /* invalid code marker */
296 drops back to the root table to fill in any remaining entries there. 295 here.bits = (unsigned char)(len - drop);
297 */ 296 here.val = (unsigned short)0;
298 this.op = (unsigned char)64; /* invalid code marker */ 297 next[huff] = here;
299 this.bits = (unsigned char)(len - drop);
300 this.val = (unsigned short)0;
301 while (huff != 0) {
302 /* when done with sub-table, drop back to root table */
303 if (drop != 0 && (huff & mask) != low) {
304 drop = 0;
305 len = root;
306 next = *table;
307 this.bits = (unsigned char)len;
308 }
309
310 /* put invalid code marker in table */
311 next[huff >> drop] = this;
312
313 /* backwards increment the len-bit code huff */
314 incr = 1U << (len - 1);
315 while (huff & incr)
316 incr >>= 1;
317 if (incr != 0) {
318 huff &= incr - 1;
319 huff += incr;
320 }
321 else
322 huff = 0;
323 } 298 }
324 299
325 /* set return parameters */ 300 /* set return parameters */
326 *table += used; 301 *table += used;
327 *bits = root; 302 *bits = root;