1 28994509 2004-04-21 devnull #include <u.h>
  2 28994509 2004-04-21 devnull #include <libc.h>
  3 28994509 2004-04-21 devnull #include <bio.h>
  4 28994509 2004-04-21 devnull #include <draw.h>
  5 28994509 2004-04-21 devnull #include "imagefile.h"
  6 28994509 2004-04-21 devnull 
  7 28994509 2004-04-21 devnull typedef struct Entry Entry;
  8 28994509 2004-04-21 devnull typedef struct Header Header;
  9 28994509 2004-04-21 devnull 
 10 28994509 2004-04-21 devnull struct Entry{
 11 28994509 2004-04-21 devnull 	int		prefix;
 12 28994509 2004-04-21 devnull 	int		exten;
 13 28994509 2004-04-21 devnull };
 14 28994509 2004-04-21 devnull 
 15 28994509 2004-04-21 devnull 
 16 28994509 2004-04-21 devnull struct Header{
 17 28994509 2004-04-21 devnull 	Biobuf	*fd;
 18 28994509 2004-04-21 devnull 	char		err[256];
 19 28994509 2004-04-21 devnull 	jmp_buf	errlab;
 20 28994509 2004-04-21 devnull 	uchar 	buf[3*256];
 21 28994509 2004-04-21 devnull 	char 		vers[8];
 22 28994509 2004-04-21 devnull 	uchar 	*globalcmap;
 23 28994509 2004-04-21 devnull 	int		screenw;
 24 28994509 2004-04-21 devnull 	int		screenh;
 25 28994509 2004-04-21 devnull 	int		fields;
 26 28994509 2004-04-21 devnull 	int		bgrnd;
 27 28994509 2004-04-21 devnull 	int		aspect;
 28 28994509 2004-04-21 devnull 	int		flags;
 29 28994509 2004-04-21 devnull 	int		delay;
 30 28994509 2004-04-21 devnull 	int		trindex;
 31 28994509 2004-04-21 devnull 	int		loopcount;
 32 28994509 2004-04-21 devnull 	Entry	tbl[4096];
 33 28994509 2004-04-21 devnull 	Rawimage	**array;
 34 28994509 2004-04-21 devnull 	Rawimage	*new;
 35 28994509 2004-04-21 devnull 
 36 28994509 2004-04-21 devnull 	uchar	*pic;
 37 28994509 2004-04-21 devnull };
 38 28994509 2004-04-21 devnull 
 39 28994509 2004-04-21 devnull static char		readerr[] = "ReadGIF: read error: %r";
 40 28994509 2004-04-21 devnull static char		extreaderr[] = "ReadGIF: can't read extension: %r";
 41 28994509 2004-04-21 devnull static char		memerr[] = "ReadGIF: malloc failed: %r";
 42 28994509 2004-04-21 devnull 
 43 28994509 2004-04-21 devnull static Rawimage**	readarray(Header*);
 44 28994509 2004-04-21 devnull static Rawimage*	readone(Header*);
 45 28994509 2004-04-21 devnull static void			readheader(Header*);
 46 28994509 2004-04-21 devnull static void			skipextension(Header*);
 47 28994509 2004-04-21 devnull static uchar*		readcmap(Header*, int);
 48 28994509 2004-04-21 devnull static uchar*		decode(Header*, Rawimage*, Entry*);
 49 28994509 2004-04-21 devnull static void			interlace(Header*, Rawimage*);
 50 28994509 2004-04-21 devnull 
 51 28994509 2004-04-21 devnull static
 52 28994509 2004-04-21 devnull void
 53 28994509 2004-04-21 devnull clear(void *pp)
 54 28994509 2004-04-21 devnull {
 55 28994509 2004-04-21 devnull 	void **p = (void**)pp;
 56 28994509 2004-04-21 devnull 
 57 28994509 2004-04-21 devnull 	if(*p){
 58 28994509 2004-04-21 devnull 		free(*p);
 59 28994509 2004-04-21 devnull 		*p = nil;
 60 28994509 2004-04-21 devnull 	}
 61 28994509 2004-04-21 devnull }
 62 28994509 2004-04-21 devnull 
 63 28994509 2004-04-21 devnull static
 64 28994509 2004-04-21 devnull void
 65 28994509 2004-04-21 devnull giffreeall(Header *h, int freeimage)
 66 28994509 2004-04-21 devnull {
 67 28994509 2004-04-21 devnull 	int i;
 68 28994509 2004-04-21 devnull 
 69 28994509 2004-04-21 devnull 	if(h->fd){
 70 28994509 2004-04-21 devnull 		Bterm(h->fd);
 71 28994509 2004-04-21 devnull 		h->fd = nil;
 72 28994509 2004-04-21 devnull 	}
 73 28994509 2004-04-21 devnull 	clear(&h->pic);
 74 28994509 2004-04-21 devnull 	if(h->new){
 75 28994509 2004-04-21 devnull 		clear(&h->new->cmap);
 76 28994509 2004-04-21 devnull 		clear(&h->new->chans[0]);
 77 28994509 2004-04-21 devnull 		clear(&h->new);
 78 28994509 2004-04-21 devnull 	}
 79 28994509 2004-04-21 devnull 	clear(&h->globalcmap);
 80 28994509 2004-04-21 devnull 	if(freeimage && h->array!=nil){
 81 28994509 2004-04-21 devnull 		for(i=0; h->array[i]; i++){
 82 28994509 2004-04-21 devnull 			clear(&h->array[i]->cmap);
 83 28994509 2004-04-21 devnull 			clear(&h->array[i]->chans[0]);
 84 28994509 2004-04-21 devnull 		}
 85 28994509 2004-04-21 devnull 		clear(&h->array);
 86 28994509 2004-04-21 devnull 	}
 87 28994509 2004-04-21 devnull }
 88 28994509 2004-04-21 devnull 
 89 28994509 2004-04-21 devnull static
 90 28994509 2004-04-21 devnull void
 91 28994509 2004-04-21 devnull giferror(Header *h, char *fmt, ...)
 92 28994509 2004-04-21 devnull {
 93 28994509 2004-04-21 devnull 	va_list arg;
 94 28994509 2004-04-21 devnull 
 95 28994509 2004-04-21 devnull 	va_start(arg, fmt);
 96 28994509 2004-04-21 devnull 	vseprint(h->err, h->err+sizeof h->err, fmt, arg);
 97 28994509 2004-04-21 devnull 	va_end(arg);
 98 28994509 2004-04-21 devnull 
 99 28994509 2004-04-21 devnull 	werrstr(h->err);
100 28994509 2004-04-21 devnull 	giffreeall(h, 1);
101 28994509 2004-04-21 devnull 	longjmp(h->errlab, 1);
102 28994509 2004-04-21 devnull }
103 28994509 2004-04-21 devnull 
104 28994509 2004-04-21 devnull 
105 28994509 2004-04-21 devnull Rawimage**
106 28994509 2004-04-21 devnull readgif(int fd, int colorspace)
107 28994509 2004-04-21 devnull {
108 28994509 2004-04-21 devnull 	Rawimage **a;
109 28994509 2004-04-21 devnull 	Biobuf b;
110 28994509 2004-04-21 devnull 	Header *h;
111 28994509 2004-04-21 devnull 	char buf[ERRMAX];
112 28994509 2004-04-21 devnull 
113 28994509 2004-04-21 devnull 	buf[0] = '\0';
114 28994509 2004-04-21 devnull 	USED(colorspace);
115 28994509 2004-04-21 devnull 	if(Binit(&b, fd, OREAD) < 0)
116 28994509 2004-04-21 devnull 		return nil;
117 28994509 2004-04-21 devnull 	h = malloc(sizeof(Header));
118 28994509 2004-04-21 devnull 	if(h == nil){
119 28994509 2004-04-21 devnull 		Bterm(&b);
120 28994509 2004-04-21 devnull 		return nil;
121 28994509 2004-04-21 devnull 	}
122 28994509 2004-04-21 devnull 	memset(h, 0, sizeof(Header));
123 28994509 2004-04-21 devnull 	h->fd = &b;
124 28994509 2004-04-21 devnull 	errstr(buf, sizeof buf);	/* throw it away */
125 28994509 2004-04-21 devnull 	if(setjmp(h->errlab))
126 28994509 2004-04-21 devnull 		a = nil;
127 28994509 2004-04-21 devnull 	else
128 28994509 2004-04-21 devnull 		a = readarray(h);
129 28994509 2004-04-21 devnull 	giffreeall(h, 0);
130 28994509 2004-04-21 devnull 	free(h);
131 28994509 2004-04-21 devnull 	return a;
132 28994509 2004-04-21 devnull }
133 28994509 2004-04-21 devnull 
134 28994509 2004-04-21 devnull static
135 28994509 2004-04-21 devnull void
136 28994509 2004-04-21 devnull inittbl(Header *h)
137 28994509 2004-04-21 devnull {
138 28994509 2004-04-21 devnull 	int i;
139 28994509 2004-04-21 devnull 	Entry *tbl;
140 28994509 2004-04-21 devnull 
141 28994509 2004-04-21 devnull 	tbl = h->tbl;
142 28994509 2004-04-21 devnull 	for(i=0; i<258; i++) {
143 28994509 2004-04-21 devnull 		tbl[i].prefix = -1;
144 28994509 2004-04-21 devnull 		tbl[i].exten = i;
145 28994509 2004-04-21 devnull 	}
146 28994509 2004-04-21 devnull }
147 28994509 2004-04-21 devnull 
148 28994509 2004-04-21 devnull static
149 28994509 2004-04-21 devnull Rawimage**
150 28994509 2004-04-21 devnull readarray(Header *h)
151 28994509 2004-04-21 devnull {
152 28994509 2004-04-21 devnull 	Entry *tbl;
153 28994509 2004-04-21 devnull 	Rawimage *new, **array;
154 28994509 2004-04-21 devnull 	int c, nimages;
155 28994509 2004-04-21 devnull 
156 28994509 2004-04-21 devnull 	tbl = h->tbl;
157 28994509 2004-04-21 devnull 
158 28994509 2004-04-21 devnull 	readheader(h);
159 28994509 2004-04-21 devnull 
160 28994509 2004-04-21 devnull 	if(h->fields & 0x80)
161 28994509 2004-04-21 devnull 		h->globalcmap = readcmap(h, (h->fields&7)+1);
162 28994509 2004-04-21 devnull 
163 28994509 2004-04-21 devnull 	array = malloc(sizeof(Rawimage**));
164 28994509 2004-04-21 devnull 	if(array == nil)
165 28994509 2004-04-21 devnull 		giferror(h, memerr);
166 28994509 2004-04-21 devnull 	nimages = 0;
167 28994509 2004-04-21 devnull 	array[0] = nil;
168 28994509 2004-04-21 devnull 	h->array = array;
169 fa325e9b 2020-01-10 cross 
170 28994509 2004-04-21 devnull 	for(;;){
171 28994509 2004-04-21 devnull 		switch(c = Bgetc(h->fd)){
172 28994509 2004-04-21 devnull 		case Beof:
173 28994509 2004-04-21 devnull 			goto Return;
174 28994509 2004-04-21 devnull 
175 28994509 2004-04-21 devnull 		case 0x21:	/* Extension (ignored) */
176 28994509 2004-04-21 devnull 			skipextension(h);
177 28994509 2004-04-21 devnull 			break;
178 28994509 2004-04-21 devnull 
179 28994509 2004-04-21 devnull 		case 0x2C:	/* Image Descriptor */
180 28994509 2004-04-21 devnull 			inittbl(h);
181 28994509 2004-04-21 devnull 			new = readone(h);
182 28994509 2004-04-21 devnull 			if(new->fields & 0x80){
183 28994509 2004-04-21 devnull 				new->cmaplen = 3*(1<<((new->fields&7)+1));
184 28994509 2004-04-21 devnull 				new->cmap = readcmap(h, (new->fields&7)+1);
185 28994509 2004-04-21 devnull 			}else{
186 28994509 2004-04-21 devnull 				new->cmaplen = 3*(1<<((h->fields&7)+1));
187 28994509 2004-04-21 devnull 				new->cmap = malloc(new->cmaplen);
188 28994509 2004-04-21 devnull 				memmove(new->cmap, h->globalcmap, new->cmaplen);
189 28994509 2004-04-21 devnull 			}
190 28994509 2004-04-21 devnull 			h->new = new;
191 28994509 2004-04-21 devnull 			new->chans[0] = decode(h, new, tbl);
192 28994509 2004-04-21 devnull 			if(new->fields & 0x40)
193 28994509 2004-04-21 devnull 				interlace(h, new);
194 28994509 2004-04-21 devnull 			new->gifflags = h->flags;
195 28994509 2004-04-21 devnull 			new->gifdelay = h->delay;
196 28994509 2004-04-21 devnull 			new->giftrindex = h->trindex;
197 28994509 2004-04-21 devnull 			new->gifloopcount = h->loopcount;
198 28994509 2004-04-21 devnull 			array = realloc(h->array, (nimages+2)*sizeof(Rawimage*));
199 28994509 2004-04-21 devnull 			if(array == nil)
200 28994509 2004-04-21 devnull 				giferror(h, memerr);
201 28994509 2004-04-21 devnull 			array[nimages++] = new;
202 28994509 2004-04-21 devnull 			array[nimages] = nil;
203 28994509 2004-04-21 devnull 			h->array = array;
204 28994509 2004-04-21 devnull 			h->new = nil;
205 28994509 2004-04-21 devnull 			break;
206 28994509 2004-04-21 devnull 
207 28994509 2004-04-21 devnull 		case 0x3B:	/* Trailer */
208 28994509 2004-04-21 devnull 			goto Return;
209 28994509 2004-04-21 devnull 
210 28994509 2004-04-21 devnull 		default:
211 28994509 2004-04-21 devnull 			fprint(2, "ReadGIF: unknown block type: 0x%.2x\n", c);
212 28994509 2004-04-21 devnull 			goto Return;
213 28994509 2004-04-21 devnull 		}
214 28994509 2004-04-21 devnull 	}
215 28994509 2004-04-21 devnull 
216 28994509 2004-04-21 devnull    Return:
217 28994509 2004-04-21 devnull 	if(array[0]==nil || array[0]->chans[0] == nil)
218 28994509 2004-04-21 devnull 		giferror(h, "ReadGIF: no picture in file");
219 28994509 2004-04-21 devnull 
220 28994509 2004-04-21 devnull 	return array;
221 28994509 2004-04-21 devnull }
222 28994509 2004-04-21 devnull 
223 28994509 2004-04-21 devnull static
224 28994509 2004-04-21 devnull void
225 28994509 2004-04-21 devnull readheader(Header *h)
226 28994509 2004-04-21 devnull {
227 28994509 2004-04-21 devnull 	if(Bread(h->fd, h->buf, 13) != 13)
228 28994509 2004-04-21 devnull 		giferror(h, "ReadGIF: can't read header: %r");
229 28994509 2004-04-21 devnull 	memmove(h->vers, h->buf, 6);
230 28994509 2004-04-21 devnull 	if(strcmp(h->vers, "GIF87a")!=0 &&  strcmp(h->vers, "GIF89a")!=0)
231 28994509 2004-04-21 devnull 		giferror(h, "ReadGIF: can't recognize format %s", h->vers);
232 28994509 2004-04-21 devnull 	h->screenw = h->buf[6]+(h->buf[7]<<8);
233 28994509 2004-04-21 devnull 	h->screenh = h->buf[8]+(h->buf[9]<<8);
234 28994509 2004-04-21 devnull 	h->fields = h->buf[10];
235 28994509 2004-04-21 devnull 	h->bgrnd = h->buf[11];
236 28994509 2004-04-21 devnull 	h->aspect = h->buf[12];
237 28994509 2004-04-21 devnull 	h->flags = 0;
238 28994509 2004-04-21 devnull 	h->delay = 0;
239 28994509 2004-04-21 devnull 	h->trindex = 0;
240 28994509 2004-04-21 devnull 	h->loopcount = -1;
241 28994509 2004-04-21 devnull }
242 28994509 2004-04-21 devnull 
243 28994509 2004-04-21 devnull static
244 28994509 2004-04-21 devnull uchar*
245 28994509 2004-04-21 devnull readcmap(Header *h, int size)
246 28994509 2004-04-21 devnull {
247 28994509 2004-04-21 devnull 	uchar *map;
248 28994509 2004-04-21 devnull 
249 28994509 2004-04-21 devnull 	if(size > 8)
250 28994509 2004-04-21 devnull 		giferror(h, "ReadGIF: can't handles %d bits per pixel", size);
251 28994509 2004-04-21 devnull 	size = 3*(1<<size);
252 28994509 2004-04-21 devnull 	if(Bread(h->fd, h->buf, size) != size)
253 28994509 2004-04-21 devnull 		giferror(h, "ReadGIF: short read on color map");
254 28994509 2004-04-21 devnull 	map = malloc(size);
255 28994509 2004-04-21 devnull 	if(map == nil)
256 28994509 2004-04-21 devnull 		giferror(h, memerr);
257 28994509 2004-04-21 devnull 	memmove(map, h->buf, size);
258 28994509 2004-04-21 devnull 	return map;
259 28994509 2004-04-21 devnull }
260 28994509 2004-04-21 devnull 
261 28994509 2004-04-21 devnull static
262 28994509 2004-04-21 devnull Rawimage*
263 28994509 2004-04-21 devnull readone(Header *h)
264 28994509 2004-04-21 devnull {
265 28994509 2004-04-21 devnull 	Rawimage *i;
266 28994509 2004-04-21 devnull 	int left, top, width, height;
267 28994509 2004-04-21 devnull 
268 28994509 2004-04-21 devnull 	if(Bread(h->fd, h->buf, 9) != 9)
269 28994509 2004-04-21 devnull 		giferror(h, "ReadGIF: can't read image descriptor: %r");
270 28994509 2004-04-21 devnull 	i = malloc(sizeof(Rawimage));
271 28994509 2004-04-21 devnull 	if(i == nil)
272 28994509 2004-04-21 devnull 		giferror(h, memerr);
273 28994509 2004-04-21 devnull 	left = h->buf[0]+(h->buf[1]<<8);
274 28994509 2004-04-21 devnull 	top = h->buf[2]+(h->buf[3]<<8);
275 28994509 2004-04-21 devnull 	width = h->buf[4]+(h->buf[5]<<8);
276 28994509 2004-04-21 devnull 	height = h->buf[6]+(h->buf[7]<<8);
277 28994509 2004-04-21 devnull 	i->fields = h->buf[8];
278 28994509 2004-04-21 devnull 	i->r.min.x = left;
279 28994509 2004-04-21 devnull 	i->r.min.y = top;
280 28994509 2004-04-21 devnull 	i->r.max.x = left+width;
281 28994509 2004-04-21 devnull 	i->r.max.y = top+height;
282 28994509 2004-04-21 devnull 	i->nchans = 1;
283 28994509 2004-04-21 devnull 	i->chandesc = CRGB1;
284 28994509 2004-04-21 devnull 	return i;
285 28994509 2004-04-21 devnull }
286 28994509 2004-04-21 devnull 
287 28994509 2004-04-21 devnull 
288 28994509 2004-04-21 devnull static
289 28994509 2004-04-21 devnull int
290 28994509 2004-04-21 devnull readdata(Header *h, uchar *data)
291 28994509 2004-04-21 devnull {
292 28994509 2004-04-21 devnull 	int nbytes, n;
293 28994509 2004-04-21 devnull 
294 28994509 2004-04-21 devnull 	nbytes = Bgetc(h->fd);
295 28994509 2004-04-21 devnull 	if(nbytes < 0)
296 28994509 2004-04-21 devnull 		giferror(h, "ReadGIF: can't read data: %r");
297 28994509 2004-04-21 devnull 	if(nbytes == 0)
298 28994509 2004-04-21 devnull 		return 0;
299 28994509 2004-04-21 devnull 	n = Bread(h->fd, data, nbytes);
300 28994509 2004-04-21 devnull 	if(n < 0)
301 28994509 2004-04-21 devnull 		giferror(h, "ReadGIF: can't read data: %r");
302 28994509 2004-04-21 devnull 	if(n != nbytes)
303 28994509 2004-04-21 devnull 		fprint(2, "ReadGIF: short data subblock\n");
304 28994509 2004-04-21 devnull 	return n;
305 28994509 2004-04-21 devnull }
306 28994509 2004-04-21 devnull 
307 28994509 2004-04-21 devnull static
308 28994509 2004-04-21 devnull void
309 28994509 2004-04-21 devnull graphiccontrol(Header *h)
310 28994509 2004-04-21 devnull {
311 28994509 2004-04-21 devnull 	if(Bread(h->fd, h->buf, 5+1) != 5+1)
312 28994509 2004-04-21 devnull 		giferror(h, readerr);
313 28994509 2004-04-21 devnull 	h->flags = h->buf[1];
314 28994509 2004-04-21 devnull 	h->delay = h->buf[2]+(h->buf[3]<<8);
315 28994509 2004-04-21 devnull 	h->trindex = h->buf[4];
316 28994509 2004-04-21 devnull }
317 28994509 2004-04-21 devnull 
318 28994509 2004-04-21 devnull static
319 28994509 2004-04-21 devnull void
320 28994509 2004-04-21 devnull skipextension(Header *h)
321 28994509 2004-04-21 devnull {
322 28994509 2004-04-21 devnull 	int type, hsize, hasdata, n;
323 28994509 2004-04-21 devnull 	uchar data[256];
324 28994509 2004-04-21 devnull 
325 28994509 2004-04-21 devnull 	hsize = 0;
326 28994509 2004-04-21 devnull 	hasdata = 0;
327 28994509 2004-04-21 devnull 
328 28994509 2004-04-21 devnull 	type = Bgetc(h->fd);
329 28994509 2004-04-21 devnull 	switch(type){
330 28994509 2004-04-21 devnull 	case Beof:
331 28994509 2004-04-21 devnull 		giferror(h, extreaderr);
332 28994509 2004-04-21 devnull 		break;
333 28994509 2004-04-21 devnull 	case 0x01:	/* Plain Text Extension */
334 28994509 2004-04-21 devnull 		hsize = 13;
335 28994509 2004-04-21 devnull 		hasdata = 1;
336 28994509 2004-04-21 devnull 		break;
337 28994509 2004-04-21 devnull 	case 0xF9:	/* Graphic Control Extension */
338 28994509 2004-04-21 devnull 		graphiccontrol(h);
339 28994509 2004-04-21 devnull 		return;
340 28994509 2004-04-21 devnull 	case 0xFE:	/* Comment Extension */
341 28994509 2004-04-21 devnull 		hasdata = 1;
342 28994509 2004-04-21 devnull 		break;
343 28994509 2004-04-21 devnull 	case 0xFF:	/* Application Extension */
344 28994509 2004-04-21 devnull 		hsize = Bgetc(h->fd);
345 28994509 2004-04-21 devnull 		/* standard says this must be 11, but Adobe likes to put out 10-byte ones,
346 28994509 2004-04-21 devnull 		 * so we pay attention to the field. */
347 28994509 2004-04-21 devnull 		hasdata = 1;
348 28994509 2004-04-21 devnull 		break;
349 28994509 2004-04-21 devnull 	default:
350 28994509 2004-04-21 devnull 		giferror(h, "ReadGIF: unknown extension");
351 28994509 2004-04-21 devnull 	}
352 28994509 2004-04-21 devnull 	if(hsize>0 && Bread(h->fd, h->buf, hsize) != hsize)
353 28994509 2004-04-21 devnull 		giferror(h, extreaderr);
354 ada24b40 2008-05-10 rsc 	if(!hasdata)
355 28994509 2004-04-21 devnull 		return;
356 28994509 2004-04-21 devnull 
357 28994509 2004-04-21 devnull 	/* loop counter: Application Extension with NETSCAPE2.0 as string and 1 <loop.count> in data */
358 28994509 2004-04-21 devnull 	if(type == 0xFF && hsize==11 && memcmp(h->buf, "NETSCAPE2.0", 11)==0){
359 28994509 2004-04-21 devnull 		n = readdata(h, data);
360 28994509 2004-04-21 devnull 		if(n == 0)
361 28994509 2004-04-21 devnull 			return;
362 28994509 2004-04-21 devnull 		if(n==3 && data[0]==1)
363 28994509 2004-04-21 devnull 			h->loopcount = data[1] | (data[2]<<8);
364 28994509 2004-04-21 devnull 	}
365 28994509 2004-04-21 devnull 	while(readdata(h, data) != 0)
366 28994509 2004-04-21 devnull 		;
367 28994509 2004-04-21 devnull }
368 28994509 2004-04-21 devnull 
369 28994509 2004-04-21 devnull static
370 28994509 2004-04-21 devnull uchar*
371 28994509 2004-04-21 devnull decode(Header *h, Rawimage *i, Entry *tbl)
372 28994509 2004-04-21 devnull {
373 28994509 2004-04-21 devnull 	int c, incode, codesize, CTM, EOD, pici, datai, stacki, nbits, sreg, fc, code, piclen;
374 28994509 2004-04-21 devnull 	int csize, nentry, maxentry, first, ocode, ndata, nb;
375 28994509 2004-04-21 devnull 	uchar *pic;
376 28994509 2004-04-21 devnull 	uchar stack[4096], data[256];
377 28994509 2004-04-21 devnull 
378 28994509 2004-04-21 devnull 	if(Bread(h->fd, h->buf, 1) != 1)
379 28994509 2004-04-21 devnull 		giferror(h, "ReadGIF: can't read data: %r");
380 28994509 2004-04-21 devnull 	codesize = h->buf[0];
381 28994509 2004-04-21 devnull 	if(codesize>8 || 0>codesize)
382 28994509 2004-04-21 devnull 		giferror(h, "ReadGIF: can't handle codesize %d", codesize);
383 28994509 2004-04-21 devnull 	if(i->cmap!=nil && i->cmaplen!=3*(1<<codesize)
384 28994509 2004-04-21 devnull 	  && (codesize!=2 || i->cmaplen!=3*2)) /* peculiar GIF bitmap files... */
385 28994509 2004-04-21 devnull 		giferror(h, "ReadGIF: codesize %d doesn't match color map 3*%d", codesize, i->cmaplen/3);
386 28994509 2004-04-21 devnull 
387 28994509 2004-04-21 devnull 	CTM =1<<codesize;
388 28994509 2004-04-21 devnull 	EOD = CTM+1;
389 28994509 2004-04-21 devnull 
390 28994509 2004-04-21 devnull 	piclen = (i->r.max.x-i->r.min.x)*(i->r.max.y-i->r.min.y);
391 28994509 2004-04-21 devnull 	i->chanlen = piclen;
392 28994509 2004-04-21 devnull 	pic = malloc(piclen);
393 28994509 2004-04-21 devnull 	if(pic == nil)
394 28994509 2004-04-21 devnull 		giferror(h, memerr);
395 28994509 2004-04-21 devnull 	h->pic = pic;
396 28994509 2004-04-21 devnull 	pici = 0;
397 28994509 2004-04-21 devnull 	ndata = 0;
398 28994509 2004-04-21 devnull 	datai = 0;
399 28994509 2004-04-21 devnull 	nbits = 0;
400 28994509 2004-04-21 devnull 	sreg = 0;
401 28994509 2004-04-21 devnull 	fc = 0;
402 28994509 2004-04-21 devnull 
403 28994509 2004-04-21 devnull     Loop:
404 28994509 2004-04-21 devnull 	for(;;){
405 28994509 2004-04-21 devnull 		csize = codesize+1;
406 28994509 2004-04-21 devnull 		nentry = EOD+1;
407 28994509 2004-04-21 devnull 		maxentry = (1<<csize)-1;
408 28994509 2004-04-21 devnull 		first = 1;
409 28994509 2004-04-21 devnull 		ocode = -1;
410 28994509 2004-04-21 devnull 
411 28994509 2004-04-21 devnull 		for(;; ocode = incode) {
412 28994509 2004-04-21 devnull 			while(nbits < csize) {
413 28994509 2004-04-21 devnull 				if(datai == ndata){
414 28994509 2004-04-21 devnull 					ndata = readdata(h, data);
415 28994509 2004-04-21 devnull 					if(ndata == 0)
416 28994509 2004-04-21 devnull 						goto Return;
417 28994509 2004-04-21 devnull 					datai = 0;
418 28994509 2004-04-21 devnull 				}
419 28994509 2004-04-21 devnull 				c = data[datai++];
420 28994509 2004-04-21 devnull 				sreg |= c<<nbits;
421 28994509 2004-04-21 devnull 				nbits += 8;
422 28994509 2004-04-21 devnull 			}
423 28994509 2004-04-21 devnull 			code = sreg & ((1<<csize) - 1);
424 28994509 2004-04-21 devnull 			sreg >>= csize;
425 28994509 2004-04-21 devnull 			nbits -= csize;
426 28994509 2004-04-21 devnull 
427 28994509 2004-04-21 devnull 			if(code == EOD){
428 28994509 2004-04-21 devnull 				ndata = readdata(h, data);
429 28994509 2004-04-21 devnull 				if(ndata != 0)
430 28994509 2004-04-21 devnull 					fprint(2, "ReadGIF: unexpected data past EOD");
431 28994509 2004-04-21 devnull 				goto Return;
432 28994509 2004-04-21 devnull 			}
433 28994509 2004-04-21 devnull 
434 28994509 2004-04-21 devnull 			if(code == CTM)
435 28994509 2004-04-21 devnull 				goto Loop;
436 28994509 2004-04-21 devnull 
437 28994509 2004-04-21 devnull 			stacki = (sizeof stack)-1;
438 28994509 2004-04-21 devnull 
439 28994509 2004-04-21 devnull 			incode = code;
440 28994509 2004-04-21 devnull 
441 28994509 2004-04-21 devnull 			/* special case for KwKwK */
442 28994509 2004-04-21 devnull 			if(code == nentry) {
443 28994509 2004-04-21 devnull 				stack[stacki--] = fc;
444 28994509 2004-04-21 devnull 				code = ocode;
445 28994509 2004-04-21 devnull 			}
446 28994509 2004-04-21 devnull 
447 28994509 2004-04-21 devnull 			if(code > nentry)
448 28994509 2004-04-21 devnull 				giferror(h, "ReadGIF: bad code %x %x", code, nentry);
449 28994509 2004-04-21 devnull 
450 28994509 2004-04-21 devnull 			for(c=code; c>=0; c=tbl[c].prefix)
451 28994509 2004-04-21 devnull 				stack[stacki--] = tbl[c].exten;
452 28994509 2004-04-21 devnull 
453 28994509 2004-04-21 devnull 			nb = (sizeof stack)-(stacki+1);
454 28994509 2004-04-21 devnull 			if(pici+nb > piclen){
455 28994509 2004-04-21 devnull 				/* this common error is harmless
456 28994509 2004-04-21 devnull 				 * we have to keep reading to keep the blocks in sync */
457 28994509 2004-04-21 devnull 				;
458 28994509 2004-04-21 devnull 			}else{
459 28994509 2004-04-21 devnull 				memmove(pic+pici, stack+stacki+1, sizeof stack - (stacki+1));
460 28994509 2004-04-21 devnull 				pici += nb;
461 28994509 2004-04-21 devnull 			}
462 28994509 2004-04-21 devnull 
463 28994509 2004-04-21 devnull 			fc = stack[stacki+1];
464 28994509 2004-04-21 devnull 
465 28994509 2004-04-21 devnull 			if(first){
466 28994509 2004-04-21 devnull 				first = 0;
467 28994509 2004-04-21 devnull 				continue;
468 28994509 2004-04-21 devnull 			}
469 28994509 2004-04-21 devnull 			#define early 0 /* peculiar tiff feature here for reference */
470 28994509 2004-04-21 devnull 			if(nentry == maxentry-early) {
471 28994509 2004-04-21 devnull 				if(csize >= 12)
472 28994509 2004-04-21 devnull 					continue;
473 28994509 2004-04-21 devnull 				csize++;
474 28994509 2004-04-21 devnull 				maxentry = (1<<csize);
475 28994509 2004-04-21 devnull 				if(csize < 12)
476 28994509 2004-04-21 devnull 					maxentry--;
477 28994509 2004-04-21 devnull 			}
478 28994509 2004-04-21 devnull 			tbl[nentry].prefix = ocode;
479 28994509 2004-04-21 devnull 			tbl[nentry].exten = fc;
480 28994509 2004-04-21 devnull 			nentry++;
481 28994509 2004-04-21 devnull 		}
482 28994509 2004-04-21 devnull 	}
483 28994509 2004-04-21 devnull 
484 28994509 2004-04-21 devnull Return:
485 28994509 2004-04-21 devnull 	h->pic = nil;
486 28994509 2004-04-21 devnull 	return pic;
487 28994509 2004-04-21 devnull }
488 28994509 2004-04-21 devnull 
489 28994509 2004-04-21 devnull static
490 28994509 2004-04-21 devnull void
491 28994509 2004-04-21 devnull interlace(Header *h, Rawimage *image)
492 28994509 2004-04-21 devnull {
493 28994509 2004-04-21 devnull 	uchar *pic;
494 28994509 2004-04-21 devnull 	Rectangle r;
495 28994509 2004-04-21 devnull 	int dx, yy, y;
496 28994509 2004-04-21 devnull 	uchar *ipic;
497 28994509 2004-04-21 devnull 
498 28994509 2004-04-21 devnull 	pic = image->chans[0];
499 28994509 2004-04-21 devnull 	r = image->r;
500 28994509 2004-04-21 devnull 	dx = r.max.x-r.min.x;
501 28994509 2004-04-21 devnull 	ipic = malloc(dx*(r.max.y-r.min.y));
502 28994509 2004-04-21 devnull 	if(ipic == nil)
503 28994509 2004-04-21 devnull 		giferror(h, nil);
504 28994509 2004-04-21 devnull 
505 28994509 2004-04-21 devnull 	/* Group 1: every 8th row, starting with row 0 */
506 28994509 2004-04-21 devnull 	yy = 0;
507 28994509 2004-04-21 devnull 	for(y=r.min.y; y<r.max.y; y+=8){
508 28994509 2004-04-21 devnull 		memmove(&ipic[(y-r.min.y)*dx], &pic[yy*dx], dx);
509 28994509 2004-04-21 devnull 		yy++;
510 28994509 2004-04-21 devnull 	}
511 28994509 2004-04-21 devnull 
512 28994509 2004-04-21 devnull 	/* Group 2: every 8th row, starting with row 4 */
513 28994509 2004-04-21 devnull 	for(y=r.min.y+4; y<r.max.y; y+=8){
514 28994509 2004-04-21 devnull 		memmove(&ipic[(y-r.min.y)*dx], &pic[yy*dx], dx);
515 28994509 2004-04-21 devnull 		yy++;
516 28994509 2004-04-21 devnull 	}
517 28994509 2004-04-21 devnull 
518 28994509 2004-04-21 devnull 	/* Group 3: every 4th row, starting with row 2 */
519 28994509 2004-04-21 devnull 	for(y=r.min.y+2; y<r.max.y; y+=4){
520 28994509 2004-04-21 devnull 		memmove(&ipic[(y-r.min.y)*dx], &pic[yy*dx], dx);
521 28994509 2004-04-21 devnull 		yy++;
522 28994509 2004-04-21 devnull 	}
523 28994509 2004-04-21 devnull 
524 28994509 2004-04-21 devnull 	/* Group 4: every 2nd row, starting with row 1 */
525 28994509 2004-04-21 devnull 	for(y=r.min.y+1; y<r.max.y; y+=2){
526 28994509 2004-04-21 devnull 		memmove(&ipic[(y-r.min.y)*dx], &pic[yy*dx], dx);
527 28994509 2004-04-21 devnull 		yy++;
528 28994509 2004-04-21 devnull 	}
529 28994509 2004-04-21 devnull 
530 28994509 2004-04-21 devnull 	free(image->chans[0]);
531 28994509 2004-04-21 devnull 	image->chans[0] = ipic;
532 28994509 2004-04-21 devnull }