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 <draw.h>
  4 28994509 2004-04-21 devnull #include <memdraw.h>
  5 28994509 2004-04-21 devnull #include <bio.h>
  6 28994509 2004-04-21 devnull #include "imagefile.h"
  7 28994509 2004-04-21 devnull 
  8 28994509 2004-04-21 devnull enum
  9 28994509 2004-04-21 devnull {
 10 28994509 2004-04-21 devnull 	Nhash	= 4001,
 11 cbeb0b26 2006-04-01 devnull 	Nbuf		= 300
 12 28994509 2004-04-21 devnull };
 13 28994509 2004-04-21 devnull 
 14 28994509 2004-04-21 devnull typedef struct Entry Entry;
 15 28994509 2004-04-21 devnull typedef struct IO IO;
 16 28994509 2004-04-21 devnull 
 17 28994509 2004-04-21 devnull 
 18 28994509 2004-04-21 devnull struct Entry
 19 28994509 2004-04-21 devnull {
 20 28994509 2004-04-21 devnull 	int		index;
 21 28994509 2004-04-21 devnull 	int		prefix;
 22 28994509 2004-04-21 devnull 	int		exten;
 23 28994509 2004-04-21 devnull 	Entry	*next;
 24 28994509 2004-04-21 devnull };
 25 28994509 2004-04-21 devnull 
 26 28994509 2004-04-21 devnull struct IO
 27 28994509 2004-04-21 devnull {
 28 28994509 2004-04-21 devnull 	Biobuf	*fd;
 29 28994509 2004-04-21 devnull 	uchar	buf[Nbuf];
 30 28994509 2004-04-21 devnull 	int		i;
 31 28994509 2004-04-21 devnull 	int		nbits;	/* bits in right side of shift register */
 32 28994509 2004-04-21 devnull 	int		sreg;		/* shift register */
 33 28994509 2004-04-21 devnull };
 34 28994509 2004-04-21 devnull 
 35 28994509 2004-04-21 devnull static Rectangle	mainrect;
 36 28994509 2004-04-21 devnull static Entry	tbl[4096];
 37 28994509 2004-04-21 devnull static uchar	*colormap[5];	/* one for each ldepth: GREY1 GREY2 GREY4 CMAP8=rgbv plus GREY8 */
 38 28994509 2004-04-21 devnull #define	GREYMAP	4
 39 28994509 2004-04-21 devnull static int		colormapsize[] = { 2, 4, 16, 256, 256 };	/* 2 for zero is an odd property of GIF */
 40 28994509 2004-04-21 devnull 
 41 28994509 2004-04-21 devnull static void		writeheader(Biobuf*, Rectangle, int, ulong, int);
 42 28994509 2004-04-21 devnull static void		writedescriptor(Biobuf*, Rectangle);
 43 28994509 2004-04-21 devnull static char*	writedata(Biobuf*, Image*, Memimage*);
 44 28994509 2004-04-21 devnull static void		writecomment(Biobuf *fd, char*);
 45 28994509 2004-04-21 devnull static void		writegraphiccontrol(Biobuf *fd, int, int);
 46 28994509 2004-04-21 devnull static void*	gifmalloc(ulong);
 47 28994509 2004-04-21 devnull static void		encode(Biobuf*, Rectangle, int, uchar*, uint);
 48 28994509 2004-04-21 devnull 
 49 28994509 2004-04-21 devnull static
 50 28994509 2004-04-21 devnull char*
 51 28994509 2004-04-21 devnull startgif0(Biobuf *fd, ulong chan, Rectangle r, int depth, int loopcount)
 52 28994509 2004-04-21 devnull {
 53 28994509 2004-04-21 devnull 	int i;
 54 28994509 2004-04-21 devnull 
 55 840bb968 2004-04-25 devnull 	for(i=0; i<nelem(tbl); i++){
 56 840bb968 2004-04-25 devnull 		tbl[i].index = i;
 57 840bb968 2004-04-25 devnull 		tbl[i].prefix = -1;
 58 840bb968 2004-04-25 devnull 		tbl[i].exten = i;
 59 840bb968 2004-04-25 devnull 	}
 60 28994509 2004-04-21 devnull 
 61 28994509 2004-04-21 devnull 	switch(chan){
 62 28994509 2004-04-21 devnull 	case GREY1:
 63 28994509 2004-04-21 devnull 	case GREY2:
 64 28994509 2004-04-21 devnull 	case GREY4:
 65 28994509 2004-04-21 devnull 	case CMAP8:
 66 28994509 2004-04-21 devnull 	case GREY8:
 67 28994509 2004-04-21 devnull 		break;
 68 28994509 2004-04-21 devnull 	default:
 69 28994509 2004-04-21 devnull 		return "WriteGIF: can't handle channel type";
 70 28994509 2004-04-21 devnull 	}
 71 28994509 2004-04-21 devnull 
 72 28994509 2004-04-21 devnull 	mainrect = r;
 73 28994509 2004-04-21 devnull 	writeheader(fd, r, depth, chan, loopcount);
 74 28994509 2004-04-21 devnull 	return nil;
 75 28994509 2004-04-21 devnull }
 76 28994509 2004-04-21 devnull 
 77 28994509 2004-04-21 devnull char*
 78 28994509 2004-04-21 devnull startgif(Biobuf *fd, Image *image, int loopcount)
 79 28994509 2004-04-21 devnull {
 80 28994509 2004-04-21 devnull 	return startgif0(fd, image->chan, image->r, image->depth, loopcount);
 81 28994509 2004-04-21 devnull }
 82 28994509 2004-04-21 devnull 
 83 28994509 2004-04-21 devnull char*
 84 28994509 2004-04-21 devnull memstartgif(Biobuf *fd, Memimage *memimage, int loopcount)
 85 28994509 2004-04-21 devnull {
 86 28994509 2004-04-21 devnull 	return startgif0(fd, memimage->chan, memimage->r, memimage->depth, loopcount);
 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 char*
 91 28994509 2004-04-21 devnull writegif0(Biobuf *fd, Image *image, Memimage *memimage, ulong chan, Rectangle r, char *comment, int dt, int trans)
 92 28994509 2004-04-21 devnull {
 93 28994509 2004-04-21 devnull 	char *err;
 94 28994509 2004-04-21 devnull 
 95 28994509 2004-04-21 devnull 	switch(chan){
 96 28994509 2004-04-21 devnull 	case GREY1:
 97 28994509 2004-04-21 devnull 	case GREY2:
 98 28994509 2004-04-21 devnull 	case GREY4:
 99 28994509 2004-04-21 devnull 	case CMAP8:
100 28994509 2004-04-21 devnull 	case GREY8:
101 28994509 2004-04-21 devnull 		break;
102 28994509 2004-04-21 devnull 	default:
103 28994509 2004-04-21 devnull 		return "WriteGIF: can't handle channel type";
104 28994509 2004-04-21 devnull 	}
105 28994509 2004-04-21 devnull 
106 28994509 2004-04-21 devnull 	writecomment(fd, comment);
107 28994509 2004-04-21 devnull 	writegraphiccontrol(fd, dt, trans);
108 28994509 2004-04-21 devnull 	writedescriptor(fd, r);
109 28994509 2004-04-21 devnull 
110 28994509 2004-04-21 devnull 	err = writedata(fd, image, memimage);
111 28994509 2004-04-21 devnull 	if(err != nil)
112 28994509 2004-04-21 devnull 		return err;
113 28994509 2004-04-21 devnull 
114 28994509 2004-04-21 devnull 	return nil;
115 28994509 2004-04-21 devnull }
116 28994509 2004-04-21 devnull 
117 28994509 2004-04-21 devnull char*
118 28994509 2004-04-21 devnull writegif(Biobuf *fd, Image *image, char *comment, int dt, int trans)
119 28994509 2004-04-21 devnull {
120 28994509 2004-04-21 devnull 	return writegif0(fd, image, nil, image->chan, image->r, comment, dt, trans);
121 28994509 2004-04-21 devnull }
122 28994509 2004-04-21 devnull 
123 28994509 2004-04-21 devnull char*
124 28994509 2004-04-21 devnull memwritegif(Biobuf *fd, Memimage *memimage, char *comment, int dt, int trans)
125 28994509 2004-04-21 devnull {
126 28994509 2004-04-21 devnull 	return writegif0(fd, nil, memimage, memimage->chan, memimage->r, comment, dt, trans);
127 28994509 2004-04-21 devnull }
128 28994509 2004-04-21 devnull 
129 28994509 2004-04-21 devnull /*
130 28994509 2004-04-21 devnull  * Write little-endian 16-bit integer
131 28994509 2004-04-21 devnull  */
132 28994509 2004-04-21 devnull static
133 28994509 2004-04-21 devnull void
134 28994509 2004-04-21 devnull put2(Biobuf *fd, int i)
135 28994509 2004-04-21 devnull {
136 28994509 2004-04-21 devnull 	Bputc(fd, i);
137 28994509 2004-04-21 devnull 	Bputc(fd, i>>8);
138 28994509 2004-04-21 devnull }
139 28994509 2004-04-21 devnull 
140 28994509 2004-04-21 devnull /*
141 28994509 2004-04-21 devnull  * Get color map for all ldepths, in format suitable for writing out
142 28994509 2004-04-21 devnull  */
143 28994509 2004-04-21 devnull static
144 28994509 2004-04-21 devnull void
145 28994509 2004-04-21 devnull getcolormap(void)
146 28994509 2004-04-21 devnull {
147 28994509 2004-04-21 devnull 	int i, col;
148 28994509 2004-04-21 devnull 	ulong rgb;
149 28994509 2004-04-21 devnull 	uchar *c;
150 28994509 2004-04-21 devnull 
151 28994509 2004-04-21 devnull 	if(colormap[0] != nil)
152 28994509 2004-04-21 devnull 		return;
153 28994509 2004-04-21 devnull 	for(i=0; i<nelem(colormap); i++)
154 28994509 2004-04-21 devnull 		colormap[i] = gifmalloc(3* colormapsize[i]);
155 28994509 2004-04-21 devnull 	c = colormap[GREYMAP];	/* GREY8 */
156 28994509 2004-04-21 devnull 	for(i=0; i<256; i++){
157 28994509 2004-04-21 devnull 		c[3*i+0] = i;	/* red */
158 28994509 2004-04-21 devnull 		c[3*i+1] = i;	/* green */
159 28994509 2004-04-21 devnull 		c[3*i+2] = i;	/* blue */
160 28994509 2004-04-21 devnull 	}
161 28994509 2004-04-21 devnull 	c = colormap[3];	/* RGBV */
162 28994509 2004-04-21 devnull 	for(i=0; i<256; i++){
163 28994509 2004-04-21 devnull 		rgb = cmap2rgb(i);
164 28994509 2004-04-21 devnull 		c[3*i+0] = (rgb>>16) & 0xFF;	/* red */
165 28994509 2004-04-21 devnull 		c[3*i+1] = (rgb>> 8) & 0xFF;	/* green */
166 28994509 2004-04-21 devnull 		c[3*i+2] = (rgb>> 0) & 0xFF;	/* blue */
167 28994509 2004-04-21 devnull 	}
168 28994509 2004-04-21 devnull 	c = colormap[2];	/* GREY4 */
169 28994509 2004-04-21 devnull 	for(i=0; i<16; i++){
170 28994509 2004-04-21 devnull 		col = (i<<4)|i;
171 28994509 2004-04-21 devnull 		rgb = cmap2rgb(col);
172 28994509 2004-04-21 devnull 		c[3*i+0] = (rgb>>16) & 0xFF;	/* red */
173 28994509 2004-04-21 devnull 		c[3*i+1] = (rgb>> 8) & 0xFF;	/* green */
174 28994509 2004-04-21 devnull 		c[3*i+2] = (rgb>> 0) & 0xFF;	/* blue */
175 28994509 2004-04-21 devnull 	}
176 28994509 2004-04-21 devnull 	c = colormap[1];	/* GREY2 */
177 28994509 2004-04-21 devnull 	for(i=0; i<4; i++){
178 28994509 2004-04-21 devnull 		col = (i<<6)|(i<<4)|(i<<2)|i;
179 28994509 2004-04-21 devnull 		rgb = cmap2rgb(col);
180 28994509 2004-04-21 devnull 		c[3*i+0] = (rgb>>16) & 0xFF;	/* red */
181 28994509 2004-04-21 devnull 		c[3*i+1] = (rgb>> 8) & 0xFF;	/* green */
182 28994509 2004-04-21 devnull 		c[3*i+2] = (rgb>> 0) & 0xFF;	/* blue */
183 28994509 2004-04-21 devnull 	}
184 28994509 2004-04-21 devnull 	c = colormap[0];	/* GREY1 */
185 28994509 2004-04-21 devnull 	for(i=0; i<2; i++){
186 28994509 2004-04-21 devnull 		if(i == 0)
187 28994509 2004-04-21 devnull 			col = 0;
188 28994509 2004-04-21 devnull 		else
189 28994509 2004-04-21 devnull 			col = 0xFF;
190 28994509 2004-04-21 devnull 		rgb = cmap2rgb(col);
191 28994509 2004-04-21 devnull 		c[3*i+0] = (rgb>>16) & 0xFF;	/* red */
192 28994509 2004-04-21 devnull 		c[3*i+1] = (rgb>> 8) & 0xFF;	/* green */
193 28994509 2004-04-21 devnull 		c[3*i+2] = (rgb>> 0) & 0xFF;	/* blue */
194 28994509 2004-04-21 devnull 	}
195 28994509 2004-04-21 devnull }
196 28994509 2004-04-21 devnull 
197 28994509 2004-04-21 devnull /*
198 28994509 2004-04-21 devnull  * Write header, logical screen descriptor, and color map
199 28994509 2004-04-21 devnull  */
200 28994509 2004-04-21 devnull static
201 28994509 2004-04-21 devnull void
202 28994509 2004-04-21 devnull writeheader(Biobuf *fd, Rectangle r, int depth, ulong chan, int loopcount)
203 28994509 2004-04-21 devnull {
204 28994509 2004-04-21 devnull 	/* Header */
205 28994509 2004-04-21 devnull 	Bprint(fd, "%s", "GIF89a");
206 28994509 2004-04-21 devnull 
207 28994509 2004-04-21 devnull 	/*  Logical Screen Descriptor */
208 28994509 2004-04-21 devnull 	put2(fd, Dx(r));
209 28994509 2004-04-21 devnull 	put2(fd, Dy(r));
210 28994509 2004-04-21 devnull 
211 28994509 2004-04-21 devnull 	/* Color table present, 4 bits per color (for RGBV best case), size of color map */
212 28994509 2004-04-21 devnull 	Bputc(fd, (1<<7)|(3<<4)|(depth-1));	/* not right for GREY8, but GIF doesn't let us specify enough bits */
213 28994509 2004-04-21 devnull 	Bputc(fd, 0xFF);	/* white background (doesn't matter anyway) */
214 28994509 2004-04-21 devnull 	Bputc(fd, 0);	/* pixel aspect ratio - unused */
215 28994509 2004-04-21 devnull 
216 28994509 2004-04-21 devnull 	/* Global Color Table */
217 28994509 2004-04-21 devnull 	getcolormap();
218 28994509 2004-04-21 devnull 	if(chan == GREY8)
219 28994509 2004-04-21 devnull 		depth = GREYMAP;
220 28994509 2004-04-21 devnull 	else
221 28994509 2004-04-21 devnull 		depth = drawlog2[depth];
222 28994509 2004-04-21 devnull 	Bwrite(fd, colormap[depth], 3*colormapsize[depth]);
223 28994509 2004-04-21 devnull 
224 28994509 2004-04-21 devnull 	if(loopcount >= 0){	/* hard-to-discover way to force cycled animation */
225 28994509 2004-04-21 devnull 		/* Application Extension with (1 loopcountlo loopcounthi) as data */
226 28994509 2004-04-21 devnull 		Bputc(fd, 0x21);
227 28994509 2004-04-21 devnull 		Bputc(fd, 0xFF);
228 28994509 2004-04-21 devnull 		Bputc(fd, 11);
229 28994509 2004-04-21 devnull 		Bwrite(fd, "NETSCAPE2.0", 11);
230 28994509 2004-04-21 devnull 		Bputc(fd, 3);
231 28994509 2004-04-21 devnull 		Bputc(fd, 1);
232 28994509 2004-04-21 devnull 		put2(fd, loopcount);
233 28994509 2004-04-21 devnull 		Bputc(fd, 0);
234 28994509 2004-04-21 devnull 	}
235 28994509 2004-04-21 devnull }
236 28994509 2004-04-21 devnull 
237 28994509 2004-04-21 devnull /*
238 28994509 2004-04-21 devnull  * Write optional comment block
239 28994509 2004-04-21 devnull  */
240 28994509 2004-04-21 devnull static
241 28994509 2004-04-21 devnull void
242 28994509 2004-04-21 devnull writecomment(Biobuf *fd, char *comment)
243 28994509 2004-04-21 devnull {
244 28994509 2004-04-21 devnull 	int n;
245 28994509 2004-04-21 devnull 
246 28994509 2004-04-21 devnull 	if(comment==nil || comment[0]=='\0')
247 28994509 2004-04-21 devnull 		return;
248 28994509 2004-04-21 devnull 
249 28994509 2004-04-21 devnull 	/* Comment extension and label */
250 28994509 2004-04-21 devnull 	Bputc(fd, 0x21);
251 28994509 2004-04-21 devnull 	Bputc(fd, 0xFE);
252 28994509 2004-04-21 devnull 
253 28994509 2004-04-21 devnull 	/* Comment data */
254 28994509 2004-04-21 devnull 	n = strlen(comment);
255 28994509 2004-04-21 devnull 	if(n > 255)
256 28994509 2004-04-21 devnull 		n = 255;
257 28994509 2004-04-21 devnull 	Bputc(fd, n);
258 28994509 2004-04-21 devnull 	Bwrite(fd, comment, n);
259 28994509 2004-04-21 devnull 
260 28994509 2004-04-21 devnull 	/* Block terminator */
261 28994509 2004-04-21 devnull 	Bputc(fd, 0x00);
262 28994509 2004-04-21 devnull }
263 28994509 2004-04-21 devnull 
264 28994509 2004-04-21 devnull /*
265 28994509 2004-04-21 devnull  * Write optional control block (sets Delay Time)
266 28994509 2004-04-21 devnull  */
267 28994509 2004-04-21 devnull static
268 28994509 2004-04-21 devnull void
269 28994509 2004-04-21 devnull writegraphiccontrol(Biobuf *fd, int dt, int trans)
270 28994509 2004-04-21 devnull {
271 28994509 2004-04-21 devnull 	if(dt < 0 && trans < 0)
272 28994509 2004-04-21 devnull 		return;
273 28994509 2004-04-21 devnull 
274 28994509 2004-04-21 devnull 	/* Comment extension and label and block size*/
275 28994509 2004-04-21 devnull 	Bputc(fd, 0x21);
276 28994509 2004-04-21 devnull 	Bputc(fd, 0xF9);
277 28994509 2004-04-21 devnull 	Bputc(fd, 0x04);
278 28994509 2004-04-21 devnull 
279 28994509 2004-04-21 devnull 	/* Disposal method and other flags (none) */
280 28994509 2004-04-21 devnull 	if(trans >= 0)
281 28994509 2004-04-21 devnull 		Bputc(fd, 0x01);
282 28994509 2004-04-21 devnull 	else
283 28994509 2004-04-21 devnull 		Bputc(fd, 0x00);
284 28994509 2004-04-21 devnull 	
285 28994509 2004-04-21 devnull 	/* Delay time, in centisec (argument is millisec for sanity) */
286 28994509 2004-04-21 devnull 	if(dt < 0)
287 28994509 2004-04-21 devnull 		dt = 0;
288 28994509 2004-04-21 devnull 	else if(dt < 10)
289 28994509 2004-04-21 devnull 		dt = 1;
290 28994509 2004-04-21 devnull 	else
291 28994509 2004-04-21 devnull 		dt = (dt+5)/10;
292 28994509 2004-04-21 devnull 	put2(fd, dt);
293 28994509 2004-04-21 devnull 
294 28994509 2004-04-21 devnull 	/* Transparency index */
295 28994509 2004-04-21 devnull 	if(trans < 0)
296 28994509 2004-04-21 devnull 		trans = 0;
297 28994509 2004-04-21 devnull 	Bputc(fd, trans);
298 28994509 2004-04-21 devnull 
299 28994509 2004-04-21 devnull 	/* Block terminator */
300 28994509 2004-04-21 devnull 	Bputc(fd, 0x00);
301 28994509 2004-04-21 devnull }
302 28994509 2004-04-21 devnull 
303 28994509 2004-04-21 devnull /*
304 28994509 2004-04-21 devnull  * Write image descriptor
305 28994509 2004-04-21 devnull  */
306 28994509 2004-04-21 devnull static
307 28994509 2004-04-21 devnull void
308 28994509 2004-04-21 devnull writedescriptor(Biobuf *fd, Rectangle r)
309 28994509 2004-04-21 devnull {
310 28994509 2004-04-21 devnull 	/* Image Separator */
311 28994509 2004-04-21 devnull 	Bputc(fd, 0x2C);
312 28994509 2004-04-21 devnull 
313 28994509 2004-04-21 devnull 	/* Left, top, width, height */
314 28994509 2004-04-21 devnull 	put2(fd, r.min.x-mainrect.min.x);
315 28994509 2004-04-21 devnull 	put2(fd, r.min.y-mainrect.min.y);
316 28994509 2004-04-21 devnull 	put2(fd, Dx(r));
317 28994509 2004-04-21 devnull 	put2(fd, Dy(r));
318 28994509 2004-04-21 devnull 	/* no special processing */
319 28994509 2004-04-21 devnull 	Bputc(fd, 0);
320 28994509 2004-04-21 devnull }
321 28994509 2004-04-21 devnull 
322 28994509 2004-04-21 devnull /*
323 28994509 2004-04-21 devnull  * Write data
324 28994509 2004-04-21 devnull  */
325 28994509 2004-04-21 devnull static
326 28994509 2004-04-21 devnull char*
327 28994509 2004-04-21 devnull writedata(Biobuf *fd, Image *image, Memimage *memimage)
328 28994509 2004-04-21 devnull {
329 28994509 2004-04-21 devnull 	char *err;
330 28994509 2004-04-21 devnull 	uchar *data;
331 28994509 2004-04-21 devnull 	int ndata, depth;
332 28994509 2004-04-21 devnull 	Rectangle r;
333 28994509 2004-04-21 devnull 
334 28994509 2004-04-21 devnull 	if(memimage != nil){
335 28994509 2004-04-21 devnull 		r = memimage->r;
336 28994509 2004-04-21 devnull 		depth = memimage->depth;
337 28994509 2004-04-21 devnull 	}else{
338 28994509 2004-04-21 devnull 		r = image->r;
339 28994509 2004-04-21 devnull 		depth = image->depth;
340 28994509 2004-04-21 devnull 	}
341 28994509 2004-04-21 devnull 
342 28994509 2004-04-21 devnull 	/* LZW Minimum code size */
343 28994509 2004-04-21 devnull 	if(depth == 1)
344 28994509 2004-04-21 devnull 		Bputc(fd, 2);
345 28994509 2004-04-21 devnull 	else
346 28994509 2004-04-21 devnull 		Bputc(fd, depth);
347 28994509 2004-04-21 devnull 
348 28994509 2004-04-21 devnull 	/* 
349 28994509 2004-04-21 devnull 	 * Read image data into memory
350 28994509 2004-04-21 devnull 	 * potentially one extra byte on each end of each scan line
351 28994509 2004-04-21 devnull 	 */
352 28994509 2004-04-21 devnull 	ndata = Dy(r)*(2+(Dx(r)>>(3-drawlog2[depth])));
353 28994509 2004-04-21 devnull 	data = gifmalloc(ndata);
354 28994509 2004-04-21 devnull 	if(memimage != nil)
355 28994509 2004-04-21 devnull 		ndata = unloadmemimage(memimage, r, data, ndata);
356 28994509 2004-04-21 devnull 	else
357 28994509 2004-04-21 devnull 		ndata = unloadimage(image, r, data, ndata);
358 28994509 2004-04-21 devnull 	if(ndata < 0){
359 28994509 2004-04-21 devnull 		err = gifmalloc(ERRMAX);
360 28994509 2004-04-21 devnull 		snprint(err, ERRMAX, "WriteGIF: %r");
361 28994509 2004-04-21 devnull 		free(data);
362 28994509 2004-04-21 devnull 		return err;
363 28994509 2004-04-21 devnull 	}
364 28994509 2004-04-21 devnull 
365 28994509 2004-04-21 devnull 	/* Encode and emit the data */
366 28994509 2004-04-21 devnull 	encode(fd, r, depth, data, ndata);
367 28994509 2004-04-21 devnull 	free(data);
368 28994509 2004-04-21 devnull 
369 28994509 2004-04-21 devnull 	/*  Block Terminator */
370 28994509 2004-04-21 devnull 	Bputc(fd, 0);
371 28994509 2004-04-21 devnull 	return nil;
372 28994509 2004-04-21 devnull }
373 28994509 2004-04-21 devnull 
374 28994509 2004-04-21 devnull /*
375 28994509 2004-04-21 devnull  * Write trailer
376 28994509 2004-04-21 devnull  */
377 28994509 2004-04-21 devnull void
378 28994509 2004-04-21 devnull endgif(Biobuf *fd)
379 28994509 2004-04-21 devnull {
380 28994509 2004-04-21 devnull 	Bputc(fd, 0x3B);
381 28994509 2004-04-21 devnull 	Bflush(fd);
382 28994509 2004-04-21 devnull }
383 28994509 2004-04-21 devnull 
384 28994509 2004-04-21 devnull void
385 28994509 2004-04-21 devnull memendgif(Biobuf *fd)
386 28994509 2004-04-21 devnull {
387 28994509 2004-04-21 devnull 	endgif(fd);
388 28994509 2004-04-21 devnull }
389 28994509 2004-04-21 devnull 
390 28994509 2004-04-21 devnull /*
391 28994509 2004-04-21 devnull  * Put n bits of c into output at io.buf[i];
392 28994509 2004-04-21 devnull  */
393 28994509 2004-04-21 devnull static
394 28994509 2004-04-21 devnull void
395 28994509 2004-04-21 devnull output(IO *io, int c, int n)
396 28994509 2004-04-21 devnull {
397 28994509 2004-04-21 devnull 	if(c < 0){
398 28994509 2004-04-21 devnull 		if(io->nbits != 0)
399 28994509 2004-04-21 devnull 			io->buf[io->i++] = io->sreg;
400 28994509 2004-04-21 devnull 		Bputc(io->fd, io->i);
401 28994509 2004-04-21 devnull 		Bwrite(io->fd, io->buf, io->i);
402 28994509 2004-04-21 devnull 		io->nbits = 0;
403 28994509 2004-04-21 devnull 		return;
404 28994509 2004-04-21 devnull 	}
405 28994509 2004-04-21 devnull 
406 28994509 2004-04-21 devnull 	if(io->nbits+n >= 31){
407 28994509 2004-04-21 devnull 		fprint(2, "panic: WriteGIF sr overflow\n");
408 28994509 2004-04-21 devnull 		exits("WriteGIF panic");
409 28994509 2004-04-21 devnull 	}
410 28994509 2004-04-21 devnull 	io->sreg |= c<<io->nbits;
411 28994509 2004-04-21 devnull 	io->nbits += n;
412 28994509 2004-04-21 devnull 
413 28994509 2004-04-21 devnull 	while(io->nbits >= 8){
414 28994509 2004-04-21 devnull 		io->buf[io->i++] = io->sreg;
415 28994509 2004-04-21 devnull 		io->sreg >>= 8;
416 28994509 2004-04-21 devnull 		io->nbits -= 8;
417 28994509 2004-04-21 devnull 	}
418 28994509 2004-04-21 devnull 
419 28994509 2004-04-21 devnull 	if(io->i >= 255){
420 28994509 2004-04-21 devnull 		Bputc(io->fd, 255);
421 28994509 2004-04-21 devnull 		Bwrite(io->fd, io->buf, 255);
422 28994509 2004-04-21 devnull 		memmove(io->buf, io->buf+255, io->i-255);
423 28994509 2004-04-21 devnull 		io->i -= 255;
424 28994509 2004-04-21 devnull 	}
425 28994509 2004-04-21 devnull }
426 28994509 2004-04-21 devnull 
427 28994509 2004-04-21 devnull /*
428 28994509 2004-04-21 devnull  * LZW encoder
429 28994509 2004-04-21 devnull  */
430 28994509 2004-04-21 devnull static
431 28994509 2004-04-21 devnull void
432 28994509 2004-04-21 devnull encode(Biobuf *fd, Rectangle r, int depth, uchar *data, uint ndata)
433 28994509 2004-04-21 devnull {
434 28994509 2004-04-21 devnull 	int i, c, h, csize, prefix, first, sreg, nbits, bitsperpixel;
435 28994509 2004-04-21 devnull 	int CTM, EOD, codesize, ld0, datai, x, ld, pm;
436 28994509 2004-04-21 devnull 	int nentry, maxentry, early;
437 28994509 2004-04-21 devnull 	Entry *e, *oe;
438 28994509 2004-04-21 devnull 	IO *io;
439 28994509 2004-04-21 devnull 	Entry **hash;
440 28994509 2004-04-21 devnull 
441 28994509 2004-04-21 devnull 	first = 1;
442 28994509 2004-04-21 devnull 	ld = drawlog2[depth];
443 28994509 2004-04-21 devnull 	/* ldepth 0 must generate codesize 2 with values 0 and 1 (see the spec.) */
444 28994509 2004-04-21 devnull 	ld0 = ld;
445 28994509 2004-04-21 devnull 	if(ld0 == 0)
446 28994509 2004-04-21 devnull 		ld0 = 1;
447 28994509 2004-04-21 devnull 	codesize = (1<<ld0);
448 28994509 2004-04-21 devnull 	CTM = 1<<codesize;
449 28994509 2004-04-21 devnull 	EOD = CTM+1;
450 28994509 2004-04-21 devnull 
451 28994509 2004-04-21 devnull 	io = gifmalloc(sizeof(IO));
452 28994509 2004-04-21 devnull 	io->fd = fd;
453 28994509 2004-04-21 devnull 	sreg = 0;
454 28994509 2004-04-21 devnull 	nbits = 0;
455 28994509 2004-04-21 devnull 	bitsperpixel = 1<<ld;
456 28994509 2004-04-21 devnull 	pm = (1<<bitsperpixel)-1;
457 28994509 2004-04-21 devnull 
458 28994509 2004-04-21 devnull 	datai = 0;
459 28994509 2004-04-21 devnull 	x = r.min.x;
460 28994509 2004-04-21 devnull 	hash = gifmalloc(Nhash*sizeof(Entry*));
461 28994509 2004-04-21 devnull 
462 28994509 2004-04-21 devnull Init:
463 28994509 2004-04-21 devnull 	memset(hash, 0, Nhash*sizeof(Entry*));
464 28994509 2004-04-21 devnull 	csize = codesize+1;
465 28994509 2004-04-21 devnull 	nentry = EOD+1;
466 28994509 2004-04-21 devnull 	maxentry = (1<<csize);
467 28994509 2004-04-21 devnull 	for(i = 0; i<nentry; i++){
468 28994509 2004-04-21 devnull 		e = &tbl[i];
469 28994509 2004-04-21 devnull 		h = (e->prefix<<24) | (e->exten<<8);
470 28994509 2004-04-21 devnull 		h %= Nhash;
471 28994509 2004-04-21 devnull 		if(h < 0)
472 28994509 2004-04-21 devnull 			h += Nhash;
473 28994509 2004-04-21 devnull 		e->next = hash[h];
474 28994509 2004-04-21 devnull 		hash[h] = e;
475 28994509 2004-04-21 devnull 	}
476 28994509 2004-04-21 devnull 	prefix = -1;
477 28994509 2004-04-21 devnull 	if(first)
478 28994509 2004-04-21 devnull 		output(io, CTM, csize);
479 28994509 2004-04-21 devnull 	first = 0;
480 28994509 2004-04-21 devnull 
481 28994509 2004-04-21 devnull 	/*
482 28994509 2004-04-21 devnull 	 * Scan over pixels.  Because of partially filled bytes on ends of scan lines,
483 28994509 2004-04-21 devnull 	 * which must be ignored in the data stream passed to GIF, this is more
484 28994509 2004-04-21 devnull 	 * complex than we'd like.
485 28994509 2004-04-21 devnull 	 */
486 28994509 2004-04-21 devnull Next:
487 28994509 2004-04-21 devnull 	for(;;){
488 28994509 2004-04-21 devnull 		if(ld != 3){
489 28994509 2004-04-21 devnull 			/* beginning of scan line is difficult; prime the shift register */
490 28994509 2004-04-21 devnull 			if(x == r.min.x){
491 28994509 2004-04-21 devnull 				if(datai == ndata)
492 28994509 2004-04-21 devnull 					break;
493 28994509 2004-04-21 devnull 				sreg = data[datai++];
494 28994509 2004-04-21 devnull 				nbits = 8-((x&(7>>ld))<<ld);
495 28994509 2004-04-21 devnull 			}
496 28994509 2004-04-21 devnull 			x++;
497 28994509 2004-04-21 devnull 			if(x == r.max.x)
498 28994509 2004-04-21 devnull 				x = r.min.x;
499 28994509 2004-04-21 devnull 		}
500 28994509 2004-04-21 devnull 		if(nbits == 0){
501 28994509 2004-04-21 devnull 			if(datai == ndata)
502 28994509 2004-04-21 devnull 				break;
503 28994509 2004-04-21 devnull 			sreg = data[datai++];
504 28994509 2004-04-21 devnull 			nbits = 8;
505 28994509 2004-04-21 devnull 		}
506 28994509 2004-04-21 devnull 		nbits -= bitsperpixel;
507 28994509 2004-04-21 devnull 		c = sreg>>nbits & pm;
508 28994509 2004-04-21 devnull 		h = prefix<<24 | c<<8;
509 28994509 2004-04-21 devnull 		h %= Nhash;
510 28994509 2004-04-21 devnull 		if(h < 0)
511 28994509 2004-04-21 devnull 			h += Nhash;
512 28994509 2004-04-21 devnull 		oe = nil;
513 28994509 2004-04-21 devnull 		for(e = hash[h]; e!=nil; e=e->next){
514 28994509 2004-04-21 devnull 			if(e->prefix == prefix && e->exten == c){
515 28994509 2004-04-21 devnull 				if(oe != nil){
516 28994509 2004-04-21 devnull 					oe->next = e->next;
517 28994509 2004-04-21 devnull 					e->next = hash[h];
518 28994509 2004-04-21 devnull 					hash[h] = e;
519 28994509 2004-04-21 devnull 				}
520 28994509 2004-04-21 devnull 				prefix = e->index;
521 28994509 2004-04-21 devnull 				goto Next;
522 28994509 2004-04-21 devnull 			}
523 28994509 2004-04-21 devnull 			oe = e;
524 28994509 2004-04-21 devnull 		}
525 28994509 2004-04-21 devnull 
526 28994509 2004-04-21 devnull 		output(io, prefix, csize);
527 28994509 2004-04-21 devnull 		early = 0; /* peculiar tiff feature here for reference */
528 28994509 2004-04-21 devnull 		if(nentry == maxentry-early){
529 28994509 2004-04-21 devnull 			if(csize == 12){
530 28994509 2004-04-21 devnull 				nbits += bitsperpixel;	/* unget pixel */
531 28994509 2004-04-21 devnull 				x--;
532 28994509 2004-04-21 devnull 				if(ld != 3 && x == r.min.x)
533 28994509 2004-04-21 devnull 					datai--;
534 28994509 2004-04-21 devnull 				output(io, CTM, csize);
535 28994509 2004-04-21 devnull 				goto Init;
536 28994509 2004-04-21 devnull 			}
537 28994509 2004-04-21 devnull 			csize++;
538 28994509 2004-04-21 devnull 			maxentry = (1<<csize);
539 28994509 2004-04-21 devnull 		}
540 28994509 2004-04-21 devnull 
541 28994509 2004-04-21 devnull 		e = &tbl[nentry];
542 28994509 2004-04-21 devnull 		e->prefix = prefix;
543 28994509 2004-04-21 devnull 		e->exten = c;
544 28994509 2004-04-21 devnull 		e->next = hash[h];
545 28994509 2004-04-21 devnull 		hash[h] = e;
546 28994509 2004-04-21 devnull 
547 28994509 2004-04-21 devnull 		prefix = c;
548 28994509 2004-04-21 devnull 		nentry++;
549 28994509 2004-04-21 devnull 	}
550 28994509 2004-04-21 devnull 
551 28994509 2004-04-21 devnull 	output(io, prefix, csize);
552 28994509 2004-04-21 devnull 	output(io, EOD, csize);
553 28994509 2004-04-21 devnull 	output(io, -1, csize);
554 28994509 2004-04-21 devnull 	free(io);
555 28994509 2004-04-21 devnull 	free(hash);
556 28994509 2004-04-21 devnull }
557 28994509 2004-04-21 devnull 
558 28994509 2004-04-21 devnull static
559 28994509 2004-04-21 devnull void*
560 28994509 2004-04-21 devnull gifmalloc(ulong sz)
561 28994509 2004-04-21 devnull {
562 28994509 2004-04-21 devnull 	void *v;
563 28994509 2004-04-21 devnull 	v = malloc(sz);
564 28994509 2004-04-21 devnull 	if(v == nil) {
565 28994509 2004-04-21 devnull 		fprint(2, "WriteGIF: out of memory allocating %ld\n", sz);
566 28994509 2004-04-21 devnull abort();
567 28994509 2004-04-21 devnull 		exits("mem");
568 28994509 2004-04-21 devnull 	}
569 28994509 2004-04-21 devnull 	memset(v, 0, sz);
570 28994509 2004-04-21 devnull 	return v;
571 28994509 2004-04-21 devnull }