aboutsummaryrefslogtreecommitdiffstats
path: root/src/gdisp/gdisp_image_gif.c
blob: 5b29ec0687b629bd103a46250e7b83640e3423c1 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
/*
 * This file is subject to the terms of the GFX License. If a copy of
 * the license was not distributed with this file, you can obtain one at:
 *
 *              http://ugfx.org/license.html
 */

#include "../../gfx.h"

#if GFX_USE_GDISP && GDISP_NEED_IMAGE && GDISP_NEED_IMAGE_GIF

#include "gdisp_image_support.h"

/**
 * How big an array to allocate for blitting (in pixels)
 * Bigger is faster but uses more RAM.
 */
#define BLIT_BUFFER_SIZE_GIF	32

// We need a special error to indicate the end of file (which may not actually be an error)
#define GDISP_IMAGE_GIF_EOF		((gdispImageError)-1)
#define GDISP_IMAGE_GIF_LOOP	((gdispImageError)-2)

#define GIF_MAX_CODE_BITS		12
#define GIF_CODE_MAX			((1<<GIF_MAX_CODE_BITS)-1)	// Maximum legal code value
#define GIF_CODE_FLUSH			(GIF_CODE_MAX+1)			// Illegal code to signal flush
#define GIF_CODE_FIRST			(GIF_CODE_MAX+2)			// Illegal code to signal first
#define GIF_CODE_NONE			(GIF_CODE_MAX+3)			// Illegal code to signal empty

// Convert bits to masks for that number of bits
static const uint16_t GifBitMask[] = {
		0x0000, 0x0001, 0x0003, 0x0007,
		0x000f, 0x001f, 0x003f, 0x007f,
		0x00ff, 0x01ff, 0x03ff, 0x07ff,
		0x0fff
		};

// Structure for decoding a single frame
typedef struct gifimgdecode {
	uint8_t		blocksz;								// The size of the block currently being processed
	uint8_t		maxpixel;								// The maximum allowed pixel value
	uint8_t		bitsperpixel;
	uint8_t		bitspercode;
	uint8_t		shiftbits;
	uint16_t	maxcodesz;
	uint16_t	stackcnt;								// The number of items on the stack
	uint16_t	code_clear;
	uint16_t	code_eof;
	uint16_t	code_max;
	uint16_t	code_last;
	uint32_t	shiftdata;
	color_t *	palette;
	uint8_t		buf[BLIT_BUFFER_SIZE_GIF];					// Buffer for decoded pixels
	uint16_t	prefix[1<<GIF_MAX_CODE_BITS];				// The LZW table
    uint8_t		suffix[1<<GIF_MAX_CODE_BITS]; 				// So we can trace the codes
    uint8_t 	stack[1<<GIF_MAX_CODE_BITS];				// Decoded pixels might be stacked here
} gifimgdecode;

// The data on a single frame
typedef struct gifimgframe {
	coord_t				x, y;							// position relative to full image
	coord_t				width, height;					// size of frame
	uint16_t			delay;							// delay after processing
	uint8_t				flags;							// Local flags
		#define GIFL_TRANSPARENT	0x01					// There exists a transparent color
		#define GIFL_DISPOSECLEAR	0x02					// Dispose this frame by clearing
		#define GIFL_DISPOSEREST	0x04					// Dispose this frame by restoring
		#define GIFL_INTERLACE		0x08					// Current frame is interlaced
	uint8_t				paltrans;						// Transparency
	uint16_t			palsize;						// Local palette size
	size_t				posstart;						// The file position of the start of the image
	size_t				pospal;							// The file position of the palette
	size_t				posimg;							// The file position of the image bits
	size_t				posend;							// The file position of the end of the frame
} gifimgframe;

// The data for a cache
typedef struct gifimgcache {
	gifimgframe			frame;
	color_t *			palette;						// Local palette
	uint8_t *			imagebits;						// Image bits - only saved when caching
	struct gifimgcache *next;							// Next cached frame
} gifimgcache;

// The data for a dispose area
typedef struct gifimgdispose {
	uint8_t				flags;							// Frame flags
	uint8_t				paltrans;						// Transparency
	coord_t				x, y;							// position relative to full image
	coord_t				width, height;					// size of dispose area
} gifimgdispose;

typedef struct gdispImagePrivate_GIF {
	uint8_t			flags;						// Flags (global)
		#define GIF_LOOP			0x01			// Loop back to first frame
		#define GIF_LOOPFOREVER		0x02			// Looping is forever
	uint8_t			bgcolor;					// Background Color (global)
	uint16_t		loops;						// Remaining frame loops (if animated)
	uint16_t		palsize;					// Global palette size (global)
	pixel_t			*palette;					// Global palette (global)
	size_t			frame0pos;					// The position of the first frame
	gifimgcache *	cache;						// The list of cached frames
	gifimgcache *	curcache;					// The cache of the current frame (if created)
	gifimgdecode *	decode;						// The decode data for the decode in progress
	gifimgframe		frame;
	gifimgdispose	dispose;
	pixel_t			buf[BLIT_BUFFER_SIZE_GIF];	// Buffer for reading and blitting
	} gdispImagePrivate_GIF;

/**
 * Get ready for decoding a frame.
 *
 * Pre:		Frame info has been read.
 */
static gdispImageError startDecodeGif(gdispImage *img) {
	gdispImagePrivate_GIF *	priv;
	gifimgdecode *			decode;
	uint16_t				cnt;

	priv = (gdispImagePrivate_GIF *)img->priv;

	// We need the decode ram, and possibly a palette
	if (!(decode = (gifimgdecode *)gdispImageAlloc(img, sizeof(gifimgdecode)+priv->frame.palsize*sizeof(color_t))))
		return GDISP_IMAGE_ERR_NOMEMORY;

	// We currently have not read any image data block
	decode->blocksz = 0;

	// Set the palette
	if (priv->frame.palsize) {
		// Local palette
		decode->maxpixel = priv->frame.palsize-1;
		decode->palette = (color_t *)(decode+1);
		gfileSetPos(img->f, priv->frame.pospal);
		for(cnt = 0; cnt < priv->frame.palsize; cnt++) {
			if (gfileRead(img->f, &decode->buf, 3) != 3)
				goto baddatacleanup;
			decode->palette[cnt] = RGB2COLOR(decode->buf[0], decode->buf[1], decode->buf[2]);
		}
	} else if (priv->palette) {
		// Global palette
		decode->maxpixel = priv->palsize-1;
		decode->palette = priv->palette;
	} else {
		// Oops - we must have a palette
		goto baddatacleanup;
	}

	// Get the initial lzw code size and values
	gfileSetPos(img->f, priv->frame.posimg);
	if (gfileRead(img->f, &decode->bitsperpixel, 1) != 1 || decode->bitsperpixel >= GIF_MAX_CODE_BITS)
		goto baddatacleanup;
	decode->code_clear = 1 << decode->bitsperpixel;
	decode->code_eof = decode->code_clear + 1;
	decode->code_max = decode->code_clear + 2;
	decode->code_last = GIF_CODE_NONE;
	decode->bitspercode = decode->bitsperpixel+1;
	decode->maxcodesz = 1 << decode->bitspercode;
	decode->shiftbits = 0;
	decode->shiftdata = 0;
	decode->stackcnt = 0;
	for(cnt = 0; cnt <= GIF_CODE_MAX; cnt++)
		decode->prefix[cnt] = GIF_CODE_NONE;

	// All ready to go
	priv->decode = decode;
	return GDISP_IMAGE_ERR_OK;

baddatacleanup:
	gdispImageFree(img, decode, sizeof(gifimgdecode)+priv->frame.palsize*sizeof(color_t));
	return GDISP_IMAGE_ERR_BADDATA;
}

/**
 * Stop decoding a frame.
 *
 * Pre:		Frame info has been read.
 */
static void stopDecodeGif(gdispImage *img) {
	gdispImagePrivate_GIF *	priv;

	priv = (gdispImagePrivate_GIF *)img->priv;

	// Free the decode data
	if (priv->decode) {
		gdispImageFree(img, (void *)priv->decode, sizeof(gifimgdecode)+priv->frame.palsize*sizeof(color_t));
		priv->decode = 0;
	}
}

static uint16_t getPrefixGif(gifimgdecode *decode, uint16_t code) {
	uint16_t i;

	for(i=0; code > decode->code_clear && i <= GIF_CODE_MAX; i++, code = decode->prefix[code]) {
		if (code > GIF_CODE_MAX)
			return GIF_CODE_NONE;
	}
    return code;
}

/**
 * Decode some pixels from a frame.
 *
 * Pre:		We are ready for decoding.
 *
 * Return:	The number of pixels decoded 0 .. BLIT_BUFFER_SIZE_GIF-1. 0 means EOF
 *
 * Note:	The resulting pixels are stored in decode->buf
 */
static uint16_t getBytesGif(gdispImage *img) {
	gdispImagePrivate_GIF *	priv;
	gifimgdecode *			decode;
	uint16_t				cnt;
	uint16_t				code, prefix;
	uint8_t					bdata;

	priv = (gdispImagePrivate_GIF *)img->priv;
	decode = priv->decode;
	cnt = 0;

	// At EOF
	if (decode->code_last == decode->code_eof)
		return 0;

	while(cnt < sizeof(decode->buf)) {
		// Use the stack up first
		if (decode->stackcnt > 0) {
			decode->buf[cnt++] = decode->stack[--decode->stackcnt];
			continue;
		}

	    // Get another code - a code is made up of decode->bitspercode bits.
	    while (decode->shiftbits < decode->bitspercode) {
	    	// Get a byte - we may have to start a new data block
	    	if ((!decode->blocksz && (gfileRead(img->f, &decode->blocksz, 1) != 1 || !decode->blocksz))
	    			|| gfileRead(img->f, &bdata, 1) != 1) {
	    		// Pretend we got the EOF code - some encoders seem to just end the file
	    		decode->code_last = decode->code_eof;
	    		return cnt;
	    	}
   	    	decode->blocksz--;

	        decode->shiftdata |= ((unsigned long)bdata) << decode->shiftbits;
	        decode->shiftbits += 8;
	    }
	    code = decode->shiftdata & GifBitMask[decode->bitspercode];
	    decode->shiftdata >>= decode->bitspercode;
	    decode->shiftbits -= decode->bitspercode;
	    /**
	     * If code cannot fit into bitspercode bits we must raise its size.
	     * Note that codes above GIF_CODE_MAX are used for special signaling.
	     * If we're using GIF_MAX_CODE_BITS bits already and we're at the max code, just
	     * keep using the table as it is, don't increment decode->bitspercode.
	     */
	    if (decode->code_max < GIF_CODE_MAX + 2 && ++decode->code_max > decode->maxcodesz && decode->bitspercode < GIF_MAX_CODE_BITS) {
	        decode->maxcodesz <<= 1;
	        decode->bitspercode++;
	    }

		// EOF - the appropriate way to stop decoding
		if (code == decode->code_eof) {
			// Skip to the end of the data blocks
			do {
				gfileSetPos(img->f, gfileGetPos(img->f)+decode->blocksz);
			} while (gfileRead(img->f, &decode->blocksz, 1) == 1 && decode->blocksz);

			// Mark the end
			decode->code_last = decode->code_eof;
			break;
		}

		if (code == decode->code_clear) {
			// Start again
			for(prefix = 0; prefix <= GIF_CODE_MAX; prefix++)
				decode->prefix[prefix] = GIF_CODE_NONE;
			decode->code_max = decode->code_eof + 1;
			decode->bitspercode = decode->bitsperpixel + 1;
			decode->maxcodesz = 1 << decode->bitspercode;
			decode->code_last = GIF_CODE_NONE;
			continue;
		}

		if (code < decode->code_clear) {
			// Simple unencoded pixel - add it
			decode->buf[cnt++] = code;

		} else {
			/**
			 * Its a LZW code - trace the linked list until the prefix is a
			 * valid pixel while pushing the suffix pixels on the stack.
			 * If done, pop the stack in reverse order adding the pixels
			 */
			if (decode->prefix[code] != GIF_CODE_NONE)
				prefix = code;

			/**
			 * Only allowed if the code equals the partial code.
			 * In that case code = XXXCode, CrntCode or the
			 * prefix code is last code and the suffix char is
			 * exactly the prefix of last code!
			 */
			else if (code == decode->code_max - 2 && decode->stackcnt < sizeof(decode->stack)) {
				prefix = decode->code_last;
				decode->suffix[decode->code_max - 2] = decode->stack[decode->stackcnt++] = getPrefixGif(decode, decode->code_last);
			} else
				return 0;

			/**
			 * If the image is OK we should not get a GIF_CODE_NONE while tracing.
			 * To prevent looping with a bad image we use StackPtr as loop counter
			 * and stop before overflowing Stack[].
			 */
			while (decode->stackcnt < sizeof(decode->stack) && prefix > decode->code_clear && prefix <= GIF_CODE_MAX) {
				decode->stack[decode->stackcnt++] = decode->suffix[prefix];
				prefix = decode->prefix[prefix];
			}
			if (decode->stackcnt >= sizeof(decode->stack) || prefix > GIF_CODE_MAX)
				return 0;

			/* Push the last character on stack: */
			decode->stack[decode->stackcnt++] = prefix;
		}

		if (decode->code_last != GIF_CODE_NONE && decode->prefix[decode->code_max - 2] == GIF_CODE_NONE) {
			decode->prefix[decode->code_max - 2] = decode->code_last;

			/* Only allowed if code is exactly the running code:
			* In that case code = XXXCode, CrntCode or the
			* prefix code is last code and the suffix char is
			* exactly the prefix of last code! */
			decode->suffix[decode->code_max - 2] = getPrefixGif(decode, code == decode->code_max - 2 ? decode->code_last : code);
		}
		decode->code_last = code;
	}
	return cnt;
}

/**
 * Read the info on a frame.
 *
 * Pre:		The file position is at the start of the frame.
 */
static gdispImageError initFrameGif(gdispImage *img) {
	gdispImagePrivate_GIF *	priv;
	gifimgcache *			cache;
	uint8_t					blocktype;
	uint8_t					blocksz;

	priv = (gdispImagePrivate_GIF *)img->priv;

	// Save the dispose info from the existing frame
	priv->dispose.flags = priv->frame.flags;
	priv->dispose.paltrans = priv->frame.paltrans;
	priv->dispose.x = priv->frame.x;
	priv->dispose.y = priv->frame.y;
	priv->dispose.width = priv->frame.width;
	priv->dispose.height = priv->frame.height;

	// Check for a cached version of this image
	for(cache=priv->cache; cache && cache->frame.posstart <= (size_t)gfileGetPos(img->f); cache=cache->next) {
		if (cache->frame.posstart == (size_t)gfileGetPos(img->f)) {
			priv->frame = cache->frame;
			priv->curcache = cache;
			return GDISP_IMAGE_ERR_OK;
		}
	}

	// Get ready for a new image
	priv->curcache = 0;
	priv->frame.posstart = gfileGetPos(img->f);
	priv->frame.flags = 0;
	priv->frame.delay = 0;
	priv->frame.palsize = 0;

	// Process blocks until we reach the image descriptor
	while(1) {
		if (gfileRead(img->f, &blocktype, 1) != 1)
			return GDISP_IMAGE_ERR_BADDATA;

		switch(blocktype) {
		case 0x2C:			//',' - IMAGE_DESC_RECORD_TYPE;
			// Read the Image Descriptor
			if (gfileRead(img->f, priv->buf, 9) != 9)
				return GDISP_IMAGE_ERR_BADDATA;
			priv->frame.x = gdispImageGetAlignedLE16(priv->buf, 0);
			priv->frame.y = gdispImageGetAlignedLE16(priv->buf, 2);
			priv->frame.width = gdispImageGetAlignedLE16(priv->buf, 4);
			priv->frame.height = gdispImageGetAlignedLE16(priv->buf, 6);
			if (((uint8_t *)priv->buf)[8] & 0x80)				// Local color table?
				priv->frame.palsize = 2 << (((uint8_t *)priv->buf)[8] & 0x07);
			if (((uint8_t *)priv->buf)[8] & 0x40)				// Interlaced?
				priv->frame.flags |= GIFL_INTERLACE;

			// We are ready to go for the actual palette read and image decode
			priv->frame.pospal = gfileGetPos(img->f);
			priv->frame.posimg = priv->frame.pospal+priv->frame.palsize*3;
			priv->frame.posend = 0;

			// Mark this as an animated image if more than 1 frame.
			if (priv->frame.posstart != priv->frame0pos)
				img->flags |= GDISP_IMAGE_FLG_ANIMATED;
			return GDISP_IMAGE_ERR_OK;

		case 0x21:			//'!' - EXTENSION_RECORD_TYPE;
			// Read the extension type
			if (gfileRead(img->f, &blocktype, 1) != 1)
				return GDISP_IMAGE_ERR_BADDATA;

			switch(blocktype) {
			case 0xF9:			// EXTENSION - Graphics Control Block
				// Read the GCB
				if (gfileRead(img->f, priv->buf, 6) != 6)
					return GDISP_IMAGE_ERR_BADDATA;
				// Check we have read a 4 byte data block and a data block terminator (0)
				if (((uint8_t *)priv->buf)[0] != 4 || ((uint8_t *)priv->buf)[5] != 0)
					return GDISP_IMAGE_ERR_BADDATA;
				// Process the flags
				switch(((uint8_t *)priv->buf)[1] & 0x1C) {
				case 0x00: case 0x04:												break;		// Dispose = do nothing
				case 0x08:				priv->frame.flags |= GIFL_DISPOSECLEAR;		break;		// Dispose = clear
				case 0x0C: case 0x10:	priv->frame.flags |= GIFL_DISPOSEREST;		break;		// Dispose = restore. Value 0x10 is a hack for bad encoders
				default:				return GDISP_IMAGE_ERR_UNSUPPORTED;
				}
				if (((uint8_t *)priv->buf)[1] & 0x01) {
					priv->frame.flags |= GIFL_TRANSPARENT;
					img->flags |= GDISP_IMAGE_FLG_TRANSPARENT;		// We set this but never clear it
				}
				if (((uint8_t *)priv->buf)[1] & 0x02)				// Wait for user input?
					img->flags |= GDISP_IMAGE_FLG_MULTIPAGE;
				else
					img->flags &= ~GDISP_IMAGE_FLG_MULTIPAGE;
				// Process frame delay and the transparent color (if any)
				priv->frame.delay = gdispImageGetAlignedLE16(priv->buf, 2);
				priv->frame.paltrans = ((uint8_t *)priv->buf)[4];
				break;

			case 0xFF:			// EXTENSION - Application
				// We only handle this for the special Netscape loop counter for animation
				if (priv->flags & GIF_LOOP)
					goto skipdatablocks;
				// Read the Application header
				if (gfileRead(img->f, priv->buf, 16) != 16)
					return GDISP_IMAGE_ERR_BADDATA;
				// Check we have read a 11 byte data block
				if (((uint8_t *)priv->buf)[0] != 11 && ((uint8_t *)priv->buf)[12] != 3)
					return GDISP_IMAGE_ERR_BADDATA;
				// Check the vendor
				if (((uint8_t *)priv->buf)[1] == 'N' && ((uint8_t *)priv->buf)[2] == 'E' && ((uint8_t *)priv->buf)[3] == 'T'
						&& ((uint8_t *)priv->buf)[4] == 'S' && ((uint8_t *)priv->buf)[5] == 'C' && ((uint8_t *)priv->buf)[6] == 'A'
						&& ((uint8_t *)priv->buf)[7] == 'P' && ((uint8_t *)priv->buf)[8] == 'E' && ((uint8_t *)priv->buf)[9] == '2'
						&& ((uint8_t *)priv->buf)[10] == '.' && ((uint8_t *)priv->buf)[11] == '0') {
					if (((uint8_t *)priv->buf)[13] == 1) {
						priv->loops = gdispImageGetAlignedLE16(priv->buf, 14);
						priv->flags |= GIF_LOOP;
						if (!priv->loops)
							priv->flags |= GIF_LOOPFOREVER;
					}
				}
				goto skipdatablocks;

			case 0x01:			// EXTENSION - Plain Text (Graphics Rendering)
			case 0xFE:			// EXTENSION - Comment
			default:
				// 0x00-0x7F (0-127) are the Graphic Rendering blocks
				if (blocktype <= 0x7F)
					return GDISP_IMAGE_ERR_UNSUPPORTED;
				// 0x80-0xF9 (128-249) are the Control blocks
				// 0xFA-0xFF (250-255) are the Special Purpose blocks
				// We don't understand this extension - just skip it by skipping data blocks
			skipdatablocks:
				while(1) {
					if (gfileRead(img->f, &blocksz, 1) != 1)
						return GDISP_IMAGE_ERR_BADDATA;
					if (!blocksz)
						break;
					gfileSetPos(img->f, gfileGetPos(img->f) + blocksz);
				}
				break;
			}
			break;

		case 0x3B:			//';' - TERMINATE_RECORD_TYPE;
			// Are we an looping animation
			if (!(priv->flags & GIF_LOOP))
				return GDISP_IMAGE_GIF_EOF;
			if (!(priv->flags & GIF_LOOPFOREVER)) {
				if (!priv->loops)
					return GDISP_IMAGE_GIF_EOF;
				priv->loops--;
			}

			// Seek back to frame0
			gfileSetPos(img->f, priv->frame0pos);
			return GDISP_IMAGE_GIF_LOOP;

		default:			// UNDEFINED_RECORD_TYPE;
			return GDISP_IMAGE_ERR_UNSUPPORTED;
		}
	}
}

void gdispImageClose_GIF(gdispImage *img) {
	gdispImagePrivate_GIF *	priv;
	gifimgcache *			cache;
	gifimgcache *			ncache;

	priv = (gdispImagePrivate_GIF *)img->priv;
	if (priv) {
		// Free any stored frames
		cache = priv->cache;
		while(cache) {
			ncache = cache->next;
			gdispImageFree(img, (void *)cache, sizeof(gifimgcache)+cache->frame.width*cache->frame.height+cache->frame.palsize*sizeof(color_t));
			cache = ncache;
		}
		if (priv->palette)
			gdispImageFree(img, (void *)priv->palette, priv->palsize*sizeof(color_t));
		gdispImageFree(img, (void *)priv, sizeof(gdispImagePrivate_GIF));
		img->priv = 0;
	}
}

gdispImageError gdispImageOpen_GIF(gdispImage *img) {
	gdispImagePrivate_GIF *priv;
	uint8_t		hdr[6];
	uint16_t	aword;

	/* Read the file identifier */
	if (gfileRead(img->f, hdr, 6) != 6)
		return GDISP_IMAGE_ERR_BADFORMAT;		// It can't be us

	/* Process the GIFFILEHEADER structure */

	if (hdr[0] != 'G' || hdr[1] != 'I' || hdr[2] != 'F'
			|| hdr[3] != '8' || (hdr[4] != '7' && hdr[4] != '9') || hdr[5] != 'a')
		return GDISP_IMAGE_ERR_BADFORMAT;		// It can't be us

	/* We know we are a GIF format image */
	img->flags = 0;

	/* Allocate our private area */
	if (!(img->priv = gdispImageAlloc(img, sizeof(gdispImagePrivate_GIF))))
		return GDISP_IMAGE_ERR_NOMEMORY;

	/* Initialise the essential bits in the private area */
	priv = (gdispImagePrivate_GIF *)img->priv;
	priv->flags = 0;
	priv->palsize = 0;
	priv->palette = 0;
	priv->frame.flags = 0;
	priv->cache = 0;
	priv->curcache = 0;
	priv->decode = 0;

	/* Process the Screen Descriptor structure */

	// Read the screen descriptor
	if (gfileRead(img->f, priv->buf, 7) != 7)
		goto baddatacleanup;
	// Get the width
	img->width = gdispImageGetAlignedLE16(priv->buf, 0);
	// Get the height
	img->height = gdispImageGetAlignedLE16(priv->buf, 2);
	if (((uint8_t *)priv->buf)[4] & 0x80) {
		// Global color table
		priv->palsize = 2 << (((uint8_t *)priv->buf)[4] & 0x07);
		// Allocate the global palette
		if (!(priv->palette = (color_t *)gdispImageAlloc(img, priv->palsize*sizeof(color_t))))
			goto nomemcleanup;
		// Read the global palette
		for(aword = 0; aword < priv->palsize; aword++) {
			if (gfileRead(img->f, &priv->buf, 3) != 3)
				goto baddatacleanup;
			priv->palette[aword] = RGB2COLOR(((uint8_t *)priv->buf)[0], ((uint8_t *)priv->buf)[1], ((uint8_t *)priv->buf)[2]);
		}
	}
	priv->bgcolor = ((uint8_t *)priv->buf)[5];

	// Save the fram0pos
	priv->frame0pos = gfileGetPos(img->f);

	// Read the first frame descriptor
	switch(initFrameGif(img)) {
	case GDISP_IMAGE_ERR_OK:					// Everything OK
		img->type = GDISP_IMAGE_TYPE_GIF;
		return GDISP_IMAGE_ERR_OK;
	case GDISP_IMAGE_ERR_UNSUPPORTED:			// Unsupported
		gdispImageClose_GIF(img);					// Clean up the private data area
		return GDISP_IMAGE_ERR_UNSUPPORTED;
	case GDISP_IMAGE_ERR_NOMEMORY:				// Out of Memory
	nomemcleanup:
		gdispImageClose_GIF(img);					// Clean up the private data area
		return GDISP_IMAGE_ERR_NOMEMORY;
	case GDISP_IMAGE_GIF_EOF:						// We should have a frame but we don't seem to
	case GDISP_IMAGE_GIF_LOOP:						// We should have a frame but we don't seem to
	case GDISP_IMAGE_ERR_BADDATA:				// Oops - something wrong with the data
	default:
	baddatacleanup:
		gdispImageClose_GIF(img);					// Clean up the private data area
		return GDISP_IMAGE_ERR_BADDATA;
	}
}

gdispImageError gdispImageCache_GIF(gdispImage *img) {
	gdispImagePrivate_GIF *	priv;
	gifimgcache *			cache;
	gifimgdecode *			decode;
	uint8_t *				p;
	uint8_t *				q;
	coord_t					mx, my;
	uint16_t				cnt;

	/* If we are already cached - just return OK */
	priv = (gdispImagePrivate_GIF *)img->priv;
	if (priv->curcache)
		return GDISP_IMAGE_ERR_OK;

	/* We need to allocate the frame, the palette and bits for the image */
	if (!(cache = (gifimgcache *)gdispImageAlloc(img, sizeof(gifimgcache) + priv->frame.palsize*sizeof(color_t) + priv->frame.width*priv->frame.height)))
		return GDISP_IMAGE_ERR_NOMEMORY;

	/* Initialise the cache */
	decode = 0;
	cache->frame = priv->frame;
	cache->imagebits = (uint8_t *)(cache+1) + cache->frame.palsize*sizeof(color_t);
	cache->next = 0;

	/* Start the decode */
	switch(startDecodeGif(img)) {
	case GDISP_IMAGE_ERR_OK:			break;
	case GDISP_IMAGE_ERR_NOMEMORY:		goto nomemcleanup;
	case GDISP_IMAGE_ERR_BADDATA:
	default:							goto baddatacleanup;
	}
	decode = priv->decode;

	// Save the palette
	if (cache->frame.palsize) {
		cache->palette = (color_t *)(cache+1);

		/* Copy the local palette into the cache */
		for(cnt = 0; cnt < cache->frame.palsize; cnt++)
			cache->palette[cnt] = decode->palette[cnt];
	} else
		cache->palette = priv->palette;

	// Check for interlacing
	cnt = 0;
	q = 0;
	if (cache->frame.flags & GIFL_INTERLACE) {
		// Every 8th row starting at row 0
		for(p=cache->imagebits, my=0; my < cache->frame.height; my+=8, p += cache->frame.width*7) {
			for(mx=0; mx < cache->frame.width; mx++) {
				if (!cnt) {
					if (!(cnt = getBytesGif(img))) {
						// Sometimes the image EOF is a bit early - treat the rest as transparent
						if (decode->code_last != decode->code_eof)
							goto baddatacleanup;
						while(cnt < sizeof(decode->buf))
							decode->buf[cnt++] = (cache->frame.flags & GIFL_TRANSPARENT) ? cache->frame.paltrans : 0;
					}
					q = decode->buf;
				}
				*p++ = *q++;
				cnt--;
			}
		}
		// Every 8th row starting at row 4
		for(p=cache->imagebits+cache->frame.width*4, my=4; my < cache->frame.height; my+=8, p += cache->frame.width*7) {
			for(mx=0; mx < cache->frame.width; mx++) {
				if (!cnt) {
					if (!(cnt = getBytesGif(img))) {
						// Sometimes the image EOF is a bit early - treat the rest as transparent
						if (decode->code_last != decode->code_eof)
							goto baddatacleanup;
						while(cnt < sizeof(decode->buf))
							decode->buf[cnt++] = (cache->frame.flags & GIFL_TRANSPARENT) ? cache->frame.paltrans : 0;
					}
					q = decode->buf;
				}
				*p++ = *q++;
				cnt--;
			}
		}
		// Every 4th row starting at row 2
		for(p=cache->imagebits+cache->frame.width*2, my=2; my < cache->frame.height; my+=4, p += cache->frame.width*3) {
			for(mx=0; mx < cache->frame.width; mx++) {
				if (!cnt) {
					if (!(cnt = getBytesGif(img))) {
						// Sometimes the image EOF is a bit early - treat the rest as transparent
						if (decode->code_last != decode->code_eof)
							goto baddatacleanup;
						while(cnt < sizeof(decode->buf))
							decode->buf[cnt++] = (cache->frame.flags & GIFL_TRANSPARENT) ? cache->frame.paltrans : 0;
					}
					q = decode->buf;
				}
				*p++ = *q++;
				cnt--;
			}
		}
		// Every 2nd row starting at row 1
		for(p=cache->imagebits+cache->frame.width, my=1; my < cache->frame.height; my+=2, p += cache->frame.width) {
			for(mx=0; mx < cache->frame.width; mx++) {
				if (!cnt) {
					if (!(cnt = getBytesGif(img))) {
						// Sometimes the image EOF is a bit early - treat the rest as transparent
						if (decode->code_last != decode->code_eof)
							goto baddatacleanup;
						while(cnt < sizeof(decode->buf))
							decode->buf[cnt++] = (cache->frame.flags & GIFL_TRANSPARENT) ? cache->frame.paltrans : 0;
					}
					q = decode->buf;
				}
				*p++ = *q++;
				cnt--;
			}
		}
	} else {
		// Every row in sequence
		p=cache->imagebits;
		for(my=0; my < cache->frame.height; my++) {
			for(mx=0; mx < cache->frame.width; mx++) {
				if (!cnt) {
					if (!(cnt = getBytesGif(img))) {
						// Sometimes the image EOF is a bit early - treat the rest as transparent
						if (decode->code_last != decode->code_eof)
							goto baddatacleanup;
						while(cnt < sizeof(decode->buf))
							decode->buf[cnt++] = (cache->frame.flags & GIFL_TRANSPARENT) ? cache->frame.paltrans : 0;
					}
					q = decode->buf;
				}
				*p++ = *q++;
				cnt--;
			}
		}
	}
	// We could be pedantic here but extra bytes won't hurt us
	while(getBytesGif(img));
	priv->frame.posend = cache->frame.posend = gfileGetPos(img->f);

	// Save everything
	priv->curcache = cache;
	if (!priv->cache)
		priv->cache = cache;
	else if (priv->cache->frame.posstart > cache->frame.posstart) {
		cache->next = priv->cache;
		priv->cache = cache;
	} else {
		gifimgcache	*pc;

		for(pc = priv->cache; pc; pc = pc->next) {
			if (!pc->next || pc->next->frame.posstart > cache->frame.posstart) {
				cache->next = pc->next;
				pc->next = cache;
				break;
			}
		}
	}
	stopDecodeGif(img);
	return GDISP_IMAGE_ERR_OK;

nomemcleanup:
	stopDecodeGif(img);
	gdispImageFree(img, cache, sizeof(gifimgcache) + priv->frame.palsize*sizeof(color_t) + priv->frame.width*priv->frame.height);
	return GDISP_IMAGE_ERR_NOMEMORY;

baddatacleanup:
	stopDecodeGif(img);
	gdispImageFree(img, cache, sizeof(gifimgcache) + priv->frame.palsize*sizeof(color_t) + priv->frame.width*priv->frame.height);
	return GDISP_IMAGE_ERR_BADDATA;
}

gdispImageError gdispGImageDraw_GIF(GDisplay *g, gdispImage *img, coord_t x, coord_t y, coord_t cx, coord_t cy, coord_t sx, coord_t sy) {
	gdispImagePrivate_GIF *	priv;
	gifimgdecode *			decode;
	uint8_t *				q = 0;
	coord_t					mx, my, fx, fy;
	uint16_t				cnt, gcnt;
	uint8_t					col;

	priv = (gdispImagePrivate_GIF *)img->priv;

	/* Handle previous frame disposing */
	if (priv->dispose.flags & (GIFL_DISPOSECLEAR|GIFL_DISPOSEREST)) {
		// Clip to the disposal area - clip area = mx,my -> fx, fy (sx,sy,cx,cy are unchanged)
		mx = priv->dispose.x;
		my = priv->dispose.y;
		fx = priv->dispose.x+priv->dispose.width;
		fy = priv->dispose.y+priv->dispose.height;
		if (sx > mx) mx = sx;
		if (sy > my) my = sy;
		if (sx+cx <= fx) fx = sx+cx;
		if (sy+cy <= fy) fy = sy+cy;
		if (fx > mx && fy > my) {
			// We only support clearing (not restoring). The specification says that we are allowed to do this.
			// Calculate the bgcolor
			// The spec says to restore the backgound color (priv->bgcolor) but in practice if there is transparency
			//	image decoders tend to assume that a restore to the transparent color is required instead
			if (((priv->dispose.flags & GIFL_TRANSPARENT) /*&& priv->dispose.paltrans == priv->bgcolor*/) || priv->bgcolor >= priv->palsize)
				gdispGFillArea(g, x+mx-sx, y+my-sy, fx-mx, fy-my, img->bgcolor);
			else
				gdispGFillArea(g, x+mx-sx, y+my-sy, fx-mx, fy-my, priv->palette[priv->bgcolor]);
		}
	}

	/* Clip to just this frame - clip area = sx,sy -> fx, fy */
	fx = priv->frame.x+priv->frame.width;
	fy = priv->frame.y+priv->frame.height;
	if (sx >= fx || sy >= fy || sx+cx < priv->frame.x || sy+cy < priv->frame.y) return GDISP_IMAGE_ERR_OK;
	if (sx < priv->frame.x) { mx = priv->frame.x - sx; x += mx; cx -= mx; sx = priv->frame.x; }
	if (sy < priv->frame.y) { my = priv->frame.y - sy; y += my; cy -= my; sy = priv->frame.y; }
	if (sx+cx > fx) cx = fx-sx;
	if (sy+cy > fy) cy = fy-sy;

	// Make sx, sy relative to this frame so we are not adding priv->frame.x & priv->frame.y each time
	sx -= priv->frame.x; sy -= priv->frame.y;
	fx = sx + cx;
	fy = sy + cy;

	/* Draw from the image cache - if it exists */
	if (priv->curcache) {
		gifimgcache *	cache;

		cache = priv->curcache;
		q = cache->imagebits+priv->frame.width*sy+sx;

		for(my=sy; my < fy; my++, q += priv->frame.width - cx) {
			for(gcnt=0, mx=sx, cnt=0; mx < fx; mx++) {
				col = *q++;
				if ((priv->frame.flags & GIFL_TRANSPARENT) && col == priv->frame.paltrans) {
					// We have a transparent pixel - dump the buffer to the display
					switch(gcnt) {
					case 0:																							break;
					case 1:		gdispGDrawPixel(g, x+mx-sx-gcnt, y+my-sy, priv->buf[0]); gcnt = 0;					break;
					default:	gdispGBlitArea(g, x+mx-sx-gcnt, y+my-sy, gcnt, 1, 0, 0, gcnt, priv->buf); gcnt = 0;	break;
					}
					continue;
				}
				priv->buf[gcnt++] = cache->palette[col];
				if (gcnt >= BLIT_BUFFER_SIZE_GIF) {
					// We have run out of buffer - dump it to the display
					gdispGBlitArea(g, x+mx-sx-gcnt+1, y+my-sy, gcnt, 1, 0, 0, gcnt, priv->buf);
					gcnt = 0;
				}
			}
			// We have finished the line - dump the buffer to the display
			switch(gcnt) {
			case 0:																					break;
			case 1:		gdispGDrawPixel(g, x+mx-sx-gcnt, y+my-sy, priv->buf[0]);					break;
			default:	gdispGBlitArea(g, x+mx-sx-gcnt, y+my-sy, gcnt, 1, 0, 0, gcnt, priv->buf);	break;
			}
		}

		return GDISP_IMAGE_ERR_OK;
	}

	/* Start the decode */
	switch(startDecodeGif(img)) {
	case GDISP_IMAGE_ERR_OK:			break;
	case GDISP_IMAGE_ERR_NOMEMORY:		return GDISP_IMAGE_ERR_NOMEMORY;
	case GDISP_IMAGE_ERR_BADDATA:
	default:							return GDISP_IMAGE_ERR_BADDATA;
	}
	decode = priv->decode;

	// Check for interlacing
	cnt = 0;
	if (priv->frame.flags & GIFL_INTERLACE) {
		// Every 8th row starting at row 0
		for(my=0; my < priv->frame.height; my+=8) {
			for(gcnt=0, mx=0; mx < priv->frame.width; mx++, q++, cnt--) {
				if (!cnt) {
					if (!(cnt = getBytesGif(img))) {
						// Sometimes the image EOF is a bit early - treat the rest as transparent
						if (decode->code_last != decode->code_eof)
							goto baddatacleanup;
						mx++;
						break;
					}
					q = decode->buf;
				}
				if (my >= sy && my < fy && mx >= sx && mx < fx) {
					col = *q;
					if ((priv->frame.flags & GIFL_TRANSPARENT) && col == priv->frame.paltrans) {
						// We have a transparent pixel - dump the buffer to the display
						switch(gcnt) {
						case 0:																							break;
						case 1:		gdispGDrawPixel(g, x+mx-sx-gcnt, y+my-sy, priv->buf[0]); gcnt = 0;					break;
						default:	gdispGBlitArea(g, x+mx-sx-gcnt, y+my-sy, gcnt, 1, 0, 0, gcnt, priv->buf); gcnt = 0;	break;
						}
						continue;
					}
					priv->buf[gcnt++] = decode->palette[col];
					if (gcnt >= BLIT_BUFFER_SIZE_GIF) {
						// We have run out of buffer - dump it to the display
						gdispGBlitArea(g, x+mx-sx-gcnt+1, y+my-sy, gcnt, 1, 0, 0, gcnt, priv->buf);
						gcnt = 0;
					}
					continue;
				}
				// We have finished the visible area - dump the buffer to the display
				switch(gcnt) {
				case 0:																							break;
				case 1:		gdispGDrawPixel(g, x+mx-sx-gcnt, y+my-sy, priv->buf[0]); gcnt = 0;					break;
				default:	gdispGBlitArea(g, x+mx-sx-gcnt, y+my-sy, gcnt, 1, 0, 0, gcnt, priv->buf); gcnt = 0;	break;
				}
			}
			// We have finished the line - dump the buffer to the display
			switch(gcnt) {
			case 0:																					break;
			case 1:		gdispGDrawPixel(g, x+mx-sx-gcnt, y+my-sy, priv->buf[0]);					break;
			default:	gdispGBlitArea(g, x+mx-sx-gcnt, y+my-sy, gcnt, 1, 0, 0, gcnt, priv->buf);	break;
			}
		}
		// Every 8th row starting at row 4
		for(my=4; my < priv->frame.height; my+=8) {
			for(gcnt=0, mx=0; mx < priv->frame.width; mx++, q++, cnt--) {
				if (!cnt) {
					if (!(cnt = getBytesGif(img))) {
						// Sometimes the image EOF is a bit early - treat the rest as transparent
						if (decode->code_last != decode->code_eof)
							goto baddatacleanup;
						mx++;
						break;
					}
					q = decode->buf;
				}
				if (my >= sy && my < fy && mx >= sx && mx < fx) {
					col = *q;
					if ((priv->frame.flags & GIFL_TRANSPARENT) && col == priv->frame.paltrans) {
						// We have a transparent pixel - dump the buffer to the display
						switch(gcnt) {
						case 0:																							break;
						case 1:		gdispGDrawPixel(g, x+mx-sx-gcnt, y+my-sy, priv->buf[0]); gcnt = 0;					break;
						default:	gdispGBlitArea(g, x+mx-sx-gcnt, y+my-sy, gcnt, 1, 0, 0, gcnt, priv->buf); gcnt = 0;	break;
						}
						continue;
					}
					priv->buf[gcnt++] = decode->palette[col];
					if (gcnt >= BLIT_BUFFER_SIZE_GIF) {
						// We have run out of buffer - dump it to the display
						gdispGBlitArea(g, x+mx-sx-gcnt+1, y+my-sy, gcnt, 1, 0, 0, gcnt, priv->buf);
						gcnt = 0;
					}
					continue;
				}
				// We have finished the visible area - dump the buffer to the display
				switch(gcnt) {
				case 0:																							break;
				case 1:		gdispGDrawPixel(g, x+mx-sx-gcnt, y+my-sy, priv->buf[0]); gcnt = 0;					break;
				default:	gdispGBlitArea(g, x+mx-sx-gcnt, y+my-sy, gcnt, 1, 0, 0, gcnt, priv->buf); gcnt = 0;	break;
				}
			}
			// We have finished the line - dump the buffer to the display
			switch(gcnt) {
			case 0:																					break;
			case 1:		gdispGDrawPixel(g, x+mx-sx-gcnt, y+my-sy, priv->buf[0]);					break;
			default:	gdispGBlitArea(g, x+mx-sx-gcnt, y+my-sy, gcnt, 1, 0, 0, gcnt, priv->buf);	break;
			}
		}
		// Every 4th row starting at row 2
		for(my=2; my < priv->frame.height; my+=4) {
			for(gcnt=0, mx=0; mx < priv->frame.width; mx++, q++, cnt--) {
				if (!cnt) {
					if (!(cnt = getBytesGif(img))) {
						// Sometimes the image EOF is a bit early - treat the rest as transparent
						if (decode->code_last != decode->code_eof)
							goto baddatacleanup;
						mx++;
						break;
					}
					q = decode->buf;
				}
				if (my >= sy && my < fy && mx >= sx && mx < fx) {
					col = *q;
					if ((priv->frame.flags & GIFL_TRANSPARENT) && col == priv->frame.paltrans) {
						// We have a transparent pixel - dump the buffer to the display
						switch(gcnt) {
						case 0:																							break;
						case 1:		gdispGDrawPixel(g, x+mx-sx-gcnt, y+my-sy, priv->buf[0]); gcnt = 0;					break;
						default:	gdispGBlitArea(g, x+mx-sx-gcnt, y+my-sy, gcnt, 1, 0, 0, gcnt, priv->buf); gcnt = 0;	break;
						}
						continue;
					}
					priv->buf[gcnt++] = decode->palette[col];
					if (gcnt >= BLIT_BUFFER_SIZE_GIF) {
						// We have run out of buffer - dump it to the display
						gdispGBlitArea(g, x+mx-sx-gcnt+1, y+my-sy, gcnt, 1, 0, 0, gcnt, priv->buf);
						gcnt = 0;
					}
					continue;
				}
				// We have finished the visible area - dump the buffer to the display
				switch(gcnt) {
				case 0:																							break;
				case 1:		gdispGDrawPixel(g, x+mx-sx-gcnt, y+my-sy, priv->buf[0]); gcnt = 0;					break;
				default:	gdispGBlitArea(g, x+mx-sx-gcnt, y+my-sy, gcnt, 1, 0, 0, gcnt, priv->buf); gcnt = 0;	break;
				}
			}
			// We have finished the line - dump the buffer to the display
			switch(gcnt) {
			case 0:																					break;
			case 1:		gdispGDrawPixel(g, x+mx-sx-gcnt, y+my-sy, priv->buf[0]);					break;
			default:	gdispGBlitArea(g, x+mx-sx-gcnt, y+my-sy, gcnt, 1, 0, 0, gcnt, priv->buf);	break;
			}
		}
		// Every 2nd row starting at row 1
		for(my=1; my < priv->frame.height; my+=2) {
			for(gcnt=0, mx=0; mx < priv->frame.width; mx++, q++, cnt--) {
				if (!cnt) {
					if (!(cnt = getBytesGif(img))) {
						// Sometimes the image EOF is a bit early - treat the rest as transparent
						if (decode->code_last != decode->code_eof)
							goto baddatacleanup;
						mx++;
						break;
					}
					q = decode->buf;
				}
				if (my >= sy && my < fy && mx >= sx && mx < fx) {
					col = *q;
					if ((priv->frame.flags & GIFL_TRANSPARENT) && col == priv->frame.paltrans) {
						// We have a transparent pixel - dump the buffer to the display
						switch(gcnt) {
						case 0:																							break;
						case 1:		gdispGDrawPixel(g, x+mx-sx-gcnt, y+my-sy, priv->buf[0]); gcnt = 0;					break;
						default:	gdispGBlitArea(g, x+mx-sx-gcnt, y+my-sy, gcnt, 1, 0, 0, gcnt, priv->buf); gcnt = 0;	break;
						}
						continue;
					}
					priv->buf[gcnt++] = decode->palette[col];
					if (gcnt >= BLIT_BUFFER_SIZE_GIF) {
						// We have run out of buffer - dump it to the display
						gdispGBlitArea(g, x+mx-sx-gcnt+1, y+my-sy, gcnt, 1, 0, 0, gcnt, priv->buf);
						gcnt = 0;
					}
					continue;
				}
				// We have finished the visible area - dump the buffer to the display
				switch(gcnt) {
				case 0:																							break;
				case 1:		gdispGDrawPixel(g, x+mx-sx-gcnt, y+my-sy, priv->buf[0]); gcnt = 0;					break;
				default:	gdispGBlitArea(g, x+mx-sx-gcnt, y+my-sy, gcnt, 1, 0, 0, gcnt, priv->buf); gcnt = 0;	break;
				}
			}
			// We have finished the line - dump the buffer to the display
			switch(gcnt) {
			case 0:																					break;
			case 1:		gdispGDrawPixel(g, x+mx-sx-gcnt, y+my-sy, priv->buf[0]);					break;
			default:	gdispGBlitArea(g, x+mx-sx-gcnt, y+my-sy, gcnt, 1, 0, 0, gcnt, priv->buf);	break;
			}
		}
	} else {
		// Every row in sequence
		for(my=0; my < priv->frame.height; my++) {
			for(gcnt=0, mx=0; mx < priv->frame.width; mx++, q++, cnt--) {
				if (!cnt) {
					if (!(cnt = getBytesGif(img))) {
						// Sometimes the image EOF is a bit early - treat the rest as transparent
						if (decode->code_last != decode->code_eof)
							goto baddatacleanup;
						mx++;
						break;
					}
					q = decode->buf;
				}
				if (my >= sy && my < fy && mx >= sx && mx < fx) {
					col = *q;
					if ((priv->frame.flags & GIFL_TRANSPARENT) && col == priv->frame.paltrans) {
						// We have a transparent pixel - dump the buffer to the display
						switch(gcnt) {
						case 0:																							break;
						case 1:		gdispGDrawPixel(g, x+mx-sx-gcnt, y+my-sy, priv->buf[0]); gcnt = 0;					break;
						default:	gdispGBlitArea(g, x+mx-sx-gcnt, y+my-sy, gcnt, 1, 0, 0, gcnt, priv->buf); gcnt = 0;	break;
						}
						continue;
					}
					priv->buf[gcnt++] = decode->palette[col];
					if (gcnt >= BLIT_BUFFER_SIZE_GIF) {
						// We have run out of buffer - dump it to the display
						gdispGBlitArea(g, x+mx-sx-gcnt+1, y+my-sy, gcnt, 1, 0, 0, gcnt, priv->buf);
						gcnt = 0;
					}
					continue;
				}
				// We have finished the visible area - dump the buffer to the display
				switch(gcnt) {
				case 0:																							break;
				case 1:		gdispGDrawPixel(g, x+mx-sx-gcnt, y+my-sy, priv->buf[0]); gcnt = 0;					break;
				default:	gdispGBlitArea(g, x+mx-sx-gcnt, y+my-sy, gcnt, 1, 0, 0, gcnt, priv->buf); gcnt = 0;	break;
				}
			}
			// We have finished the line - dump the buffer to the display
			switch(gcnt) {
			case 0:																					break;
			case 1:		gdispGDrawPixel(g, x+mx-sx-gcnt, y+my-sy, priv->buf[0]);					break;
			default:	gdispGBlitArea(g, x+mx-sx-gcnt, y+my-sy, gcnt, 1, 0, 0, gcnt, priv->buf);	break;
			}
		}
	}
	// We could be pedantic here but extra bytes won't hurt us
	while (getBytesGif(img));
	priv->frame.posend = gfileGetPos(img->f);

	stopDecodeGif(img);
	return GDISP_IMAGE_ERR_OK;

baddatacleanup:
	stopDecodeGif(img);
	return GDISP_IMAGE_ERR_BADDATA;
}

delaytime_t gdispImageNext_GIF(gdispImage *img) {
	gdispImagePrivate_GIF *	priv;
	delaytime_t				delay;
	uint8_t					blocksz;

	priv = (gdispImagePrivate_GIF *)img->priv;

	// Save the delay and convert to millisecs
	delay = (delaytime_t)priv->frame.delay * 10;

	// We need to get to the end of this frame
	if (!priv->frame.posend) {
		// We don't know where the end of the frame is yet - find it!
		gfileSetPos(img->f, priv->frame.posimg+1);				// Skip the code size byte too
		while(1) {
			if (gfileRead(img->f, &blocksz, 1) != 1)
				return TIME_INFINITE;
			if (!blocksz)
				break;
			gfileSetPos(img->f, gfileGetPos(img->f) + blocksz);
		}
		priv->frame.posend = gfileGetPos(img->f);
	}

	// Seek to the end of this frame
	gfileSetPos(img->f, priv->frame.posend);

	// Read the next frame descriptor
	for(blocksz=0; blocksz < 2; blocksz++) {		// 2 loops max to prevent cycling forever with a bad file
		switch(initFrameGif(img)) {
		case GDISP_IMAGE_ERR_OK:					// Everything OK
			return delay;
		case GDISP_IMAGE_GIF_LOOP:						// Back to the beginning
			break;
		case GDISP_IMAGE_GIF_EOF:						// The real End-Of-File
		case GDISP_IMAGE_ERR_BADDATA:				// Oops - something wrong with the data
		case GDISP_IMAGE_ERR_NOMEMORY:				// Out of Memory
		case GDISP_IMAGE_ERR_UNSUPPORTED:			// Unsupported
		default:
			return TIME_INFINITE;
		}
	}
	return TIME_INFINITE;
}

#endif /* GFX_USE_GDISP && GDISP_NEED_IMAGE && GDISP_NEED_IMAGE_GIF */