1 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
2 * Copyright by The HDF Group. *
3 * Copyright by the Board of Trustees of the University of Illinois. *
4 * All rights reserved. *
5 * *
6 * This file is part of HDF5. The full HDF5 copyright notice, including *
7 * terms governing use, modification, and redistribution, is contained in *
8 * the COPYING file, which can be found at the root of the source code *
9 * distribution tree, or in https://support.hdfgroup.org/ftp/HDF5/releases. *
10 * If you do not have access to either file, you may request a copy from *
11 * help@hdfgroup.org. *
12 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
13
14 /*
15 * hdfgifwr.c - handles writing of GIF files.
16 *
17 * Contains:
18 * hdfWriteGIF(fp, pic, ptype, w, h, rmap, gmap, bmap, numcols, colorstyle,
19 * comment)
20 *
21 * Note: slightly brain-damaged, in that it'll only write non-interlaced
22 * GIF files (in the interests of speed, or something)
23 */
24
25 /*****************************************************************
26 * Portions of this code Copyright (C) 1989 by Michael Mauldin.
27 * Permission is granted to use this file in whole or in
28 * part for any purpose, educational, recreational or commercial,
29 * provided that this copyright notice is retained unchanged.
30 * This software is available to all free of charge by anonymous
31 * FTP and in the UUNET archives.
32 *
33 *
34 * Authors: Michael Mauldin (mlm@cs.cmu.edu)
35 * David Rowley (mgardi@watdcsu.waterloo.edu)
36 *
37 * Based on: compress.c - File compression ala IEEE Computer, June 1984.
38 *
39 * Spencer W. Thomas (decvax!harpo!utah-cs!utah-gr!thomas)
40 * Jim McKie (decvax!mcvax!jim)
41 * Steve Davies (decvax!vax135!petsd!peora!srd)
42 * Ken Turkowski (decvax!decwrl!turtlevax!ken)
43 * James A. Woods (decvax!ihnp4!ames!jaw)
44 * Joe Orost (decvax!vax135!petsd!joe)
45 *****************************************************************/
46
47
48 #include <stdio.h>
49 #include <stdlib.h>
50 #include <string.h>
51
52 #include "gif.h"
53
54 typedef BYTE byte;
55 typedef long int count_int;
56
57 #ifdef __STDC__
58 static void compress(int, FILE *, byte *, int);
59 static void output(int);
60 static void cl_block(void);
61 static void cl_hash(count_int);
62 static void char_init(void);
63 static void char_out(int);
64 static void flush_char(void);
65 #else
66 static void compress(), output(), cl_block(), cl_hash();
67 static void char_init(), char_out(), flush_char();
68 #endif /* __STDC__ */
69
70 static byte pc2nc[256];
71
72 /*************************************************************/
hdfWriteGIF(FILE * fp,byte * pic,int ptype,int w,int h,byte * rmap,byte * gmap,byte * bmap,byte * pc2ncmap,int numcols,int colorstyle,int BitsPerPixel)73 int hdfWriteGIF(FILE *fp, byte *pic, int ptype, int w, int h, byte *rmap,
74 byte *gmap, byte *bmap, byte *pc2ncmap, int numcols,
75 int colorstyle, int BitsPerPixel)
76 {
77 int InitCodeSize;
78 int i;
79 byte *pic8 = pic;
80
81 /* Shut compiler up... */
82 ptype=ptype;
83 rmap=rmap;
84 gmap=gmap;
85 bmap=bmap;
86 numcols=numcols;
87 colorstyle=colorstyle;
88
89 for (i = 0; i < 256; i++) {
90 pc2nc[i] = pc2ncmap[i];
91 }
92
93 if (BitsPerPixel <= 1)
94 InitCodeSize = 2;
95 else
96 InitCodeSize = BitsPerPixel;
97
98 if (!fp) {
99 fprintf(stderr, "WriteGIF: file not open for writing\n" );
100 return (1);
101 }
102
103 compress(InitCodeSize+1, fp, pic8, w*h);
104
105 if (ferror(fp))
106 return -1;
107
108 return 0 ;
109 }
110
111 /***********************************************************************/
112 static unsigned long cur_accum = 0;
113 static int cur_bits = 0;
114
115 #define MAXCODE(n_bits) ( (1 << (n_bits)) - 1)
116 #define XV_BITS 12 /* BITS was already defined on some systems */
117 #define HSIZE 5003 /* 80% occupancy */
118
119 typedef unsigned char char_type;
120
121 static int n_bits; /* number of bits/code */
122 static int maxbits = XV_BITS; /* user settable max # bits/code */
123 static int maxcode; /* maximum code, given n_bits */
124 static int maxmaxcode = 1 << XV_BITS; /* NEVER generate this */
125
126 static count_int htab [HSIZE];
127 static unsigned short codetab [HSIZE];
128
129 #define HashTabOf(i) htab[i]
130 #define CodeTabOf(i) codetab[i]
131
132 static int hsize = HSIZE; /* for dynamic table sizing */
133
134 /*
135 * To save much memory, we overlay the table used by compress() with those
136 * used by decompress(). The tab_prefix table is the same size and type as
137 * the codetab. The tab_suffix table needs 2**BITS characters. We get this
138 * from the beginning of htab. The output stack uses the rest of htab, and
139 * contains characters. There is plenty of room for any possible stack (stack
140 * used to be 8000 characters).
141 */
142
143 static int free_ent = 0; /* first unused entry */
144
145 /*
146 * block compression parameters -- after all codes are used up,
147 * and compression rate changes, start over.
148 */
149 static int clear_flg = 0;
150
151 static long int in_count = 1; /* length of input */
152 static long int out_count = 0; /* # of codes output (for debugging) */
153
154 /*
155 * compress stdin to stdout
156 *
157 * Algorithm: use open addressing double hashing (no chaining) on the prefix
158 * code / next character combination. We do a variant of Knuth's algorithm D
159 * (vol. 3, sec. 6.4) along with G. Knott's relatively-prime secondary probe.
160 * Here, the modular division first probe is gives way to a faster
161 * exclusive-or manipulation. Also do block compression with an adaptive
162 * reset, whereby the code table is cleared when the compression ratio
163 * decreases, but after the table fills. The variable-length output codes are
164 * re-sized at this point, and a special CLEAR code is generated for the
165 * decompressor. Late addition: construct the table according to file size
166 * for noticeable speed improvement on small files. Please direct questions
167 * about this implementation to ames!jaw.
168 */
169
170 static int g_init_bits;
171 static FILE *g_outfile;
172
173 static int ClearCode;
174 static int EOFCode;
175
176 /********************************************************/
compress(int init_bits,FILE * outfile,byte * data,int len)177 static void compress(int init_bits, FILE *outfile, byte *data, int len)
178 {
179 register long fcode;
180 register int i = 0;
181 register int c;
182 register int ent;
183 register int disp;
184 register int hsize_reg;
185 register int hshift;
186
187 /*
188 * Set up the globals: g_init_bits - initial number of bits g_outfile -
189 * pointer to output file
190 */
191 g_init_bits = init_bits;
192 g_outfile = outfile;
193
194 /* initialize 'compress' globals */
195 maxbits = XV_BITS;
196 maxmaxcode = 1<<XV_BITS;
197 memset(htab, 0, sizeof(htab));
198 memset(codetab, 0, sizeof(codetab));
199 hsize = HSIZE;
200 free_ent = 0;
201 clear_flg = 0;
202 in_count = 1;
203 out_count = 0;
204 cur_accum = 0;
205 cur_bits = 0;
206
207 /* Set up the necessary values */
208 out_count = 0;
209 clear_flg = 0;
210 in_count = 1;
211 maxcode = MAXCODE(n_bits = g_init_bits);
212
213 ClearCode = (1 << (init_bits - 1));
214 EOFCode = ClearCode + 1;
215 free_ent = ClearCode + 2;
216
217 char_init();
218 ent = pc2nc[*data++];
219 len--;
220
221 hshift = 0;
222 for (fcode = (long)hsize; fcode < 65536L; fcode *= 2L )
223 hshift++;
224
225 hshift = 8 - hshift; /* set hash code range bound */
226
227 hsize_reg = hsize;
228 cl_hash( (count_int) hsize_reg); /* clear hash table */
229
230 output(ClearCode);
231
232 while (len) {
233 c = pc2nc[*data++];
234 len--;
235 in_count++;
236
237 fcode = (long)(((long) c << maxbits) + ent);
238 i = (((int) c << hshift) ^ ent); /* xor hashing */
239
240 if ( HashTabOf (i) == fcode ) {
241 ent = CodeTabOf (i);
242 continue;
243 } else if ( (long)HashTabOf (i) < 0) {
244 /* empty slot */
245 goto nomatch;
246 }
247
248 disp = hsize_reg - i; /* secondary hash (after G. Knott) */
249
250 if ( i == 0 )
251 disp = 1;
252
253 probe:
254 if ((i -= disp) < 0)
255 i += hsize_reg;
256
257 if (HashTabOf (i) == fcode) {
258 ent = CodeTabOf (i);
259 continue;
260 }
261
262 if ((long)HashTabOf (i) >= 0)
263 goto probe;
264
265 nomatch:
266 output(ent);
267 out_count++;
268 ent = c;
269
270 if (free_ent < maxmaxcode) {
271 CodeTabOf (i) = (unsigned short)free_ent++; /* code -> hashtable */
272 HashTabOf (i) = fcode;
273 } else {
274 cl_block();
275 }
276 }
277
278 /* Put out the final code */
279 output(ent);
280 out_count++;
281 output(EOFCode);
282 }
283
284
285 /*****************************************************************
286 * TAG( output )
287 *
288 * Output the given code.
289 * Inputs:
290 * code: A n_bits-bit integer. If == -1, then EOF. This assumes
291 * that n_bits =< (long)wordsize - 1.
292 * Outputs:
293 * Outputs code to the file.
294 * Assumptions:
295 * Chars are 8 bits long.
296 * Algorithm:
297 * Maintain a BITS character long buffer (so that 8 codes will
298 * fit in it exactly). Use the VAX insv instruction to insert each
299 * code in turn. When the buffer fills up empty it and start over.
300 */
301
302 static
303 unsigned long masks[] = { 0x0000, 0x0001, 0x0003, 0x0007, 0x000F,
304 0x001F, 0x003F, 0x007F, 0x00FF,
305 0x01FF, 0x03FF, 0x07FF, 0x0FFF,
306 0x1FFF, 0x3FFF, 0x7FFF, 0xFFFF };
307
308 static void
output(int code)309 output(int code)
310 {
311 cur_accum &= masks[cur_bits];
312
313 if (cur_bits > 0)
314 cur_accum |= (unsigned long)((long)code << cur_bits);
315 else
316 cur_accum = (unsigned long)code;
317
318 cur_bits += n_bits;
319
320 while( cur_bits >= 8 ) {
321 char_out( (int)((unsigned int) cur_accum & 0xff) );
322 cur_accum >>= 8;
323 cur_bits -= 8;
324 }
325
326 /*
327 * If the next entry is going to be too big for the code size, then
328 * increase it, if possible.
329 */
330 if (free_ent > maxcode || clear_flg) {
331 if (clear_flg) {
332 maxcode = MAXCODE (n_bits = g_init_bits);
333 clear_flg = 0;
334 } else {
335 n_bits++;
336
337 if ( n_bits == maxbits )
338 maxcode = maxmaxcode;
339 else
340 maxcode = MAXCODE(n_bits);
341 }
342 }
343
344 if (code == EOFCode) {
345 /* At EOF, write the rest of the buffer */
346 while( cur_bits > 0 ) {
347 char_out( (int)((unsigned int)cur_accum & 0xff) );
348 cur_accum >>= 8;
349 cur_bits -= 8;
350 }
351
352 flush_char();
353 fflush( g_outfile );
354
355 #ifdef FOO
356 if(ferror( g_outfile))
357 FatalError("unable to write GIF file");
358 #endif
359 }
360 }
361
362 /********************************/
363 static void
cl_block(void)364 cl_block(void) /* table clear for block compress */
365 {
366 /* Clear out the hash table */
367 cl_hash((count_int) hsize);
368 free_ent = ClearCode + 2;
369 clear_flg = 1;
370 output(ClearCode);
371 }
372
373 /********************************/
374 static void
cl_hash(count_int hashsize)375 cl_hash(count_int hashsize) /* reset code table */
376 {
377 count_int *htab_p = htab+hashsize;
378 long i, m1 = -1;
379
380 i = hashsize - 16;
381
382 do { /* might use Sys V memset(3) here */
383 *(htab_p-16) = m1;
384 *(htab_p-15) = m1;
385 *(htab_p-14) = m1;
386 *(htab_p-13) = m1;
387 *(htab_p-12) = m1;
388 *(htab_p-11) = m1;
389 *(htab_p-10) = m1;
390 *(htab_p-9) = m1;
391 *(htab_p-8) = m1;
392 *(htab_p-7) = m1;
393 *(htab_p-6) = m1;
394 *(htab_p-5) = m1;
395 *(htab_p-4) = m1;
396 *(htab_p-3) = m1;
397 *(htab_p-2) = m1;
398 *(htab_p-1) = m1;
399 htab_p -= 16;
400 } while ((i -= 16) >= 0);
401
402 for ( i += 16; i > 0; i-- )
403 *--htab_p = m1;
404 }
405
406 /******************************************************************************
407 *
408 * GIF Specific routines
409 *
410 ******************************************************************************/
411
412 /*
413 * Number of characters so far in this 'packet'
414 */
415 static int a_count;
416
417 /*
418 * Set up the 'byte output' routine
419 */
420 static void
char_init(void)421 char_init(void)
422 {
423 a_count = 0;
424 }
425
426 /*
427 * Define the storage for the packet accumulator
428 */
429 static char accum[ 256 ];
430
431 /*
432 * Add a character to the end of the current packet, and if it is 254
433 * characters, flush the packet to disk.
434 */
435 static void
char_out(int c)436 char_out(int c)
437 {
438 accum[ a_count++ ] = (char)c;
439
440 if (a_count >= 254)
441 flush_char();
442 }
443
444 /*
445 * Flush the packet to disk, and reset the accumulator
446 */
447 static void
flush_char(void)448 flush_char(void)
449 {
450 if (a_count > 0) {
451 fputc( a_count, g_outfile );
452 fwrite( accum, (size_t)1, (size_t)a_count, g_outfile);
453 a_count = 0;
454 }
455 }
456