revert between 56095 -> 55830 in arch
[AROS.git] / workbench / libs / jpeg / jdmarker.c
blob3fbe5c16578f43e32471b1c37a46a89cc3fd1374
1 /*
2 * jdmarker.c
4 * Copyright (C) 1991-1998, Thomas G. Lane.
5 * Modified 2009-2013 by Guido Vollbeding.
6 * This file is part of the Independent JPEG Group's software.
7 * For conditions of distribution and use, see the accompanying README file.
9 * This file contains routines to decode JPEG datastream markers.
10 * Most of the complexity arises from our desire to support input
11 * suspension: if not all of the data for a marker is available,
12 * we must exit back to the application. On resumption, we reprocess
13 * the marker.
16 #define JPEG_INTERNALS
17 #include "jinclude.h"
18 #include "jpeglib.h"
21 typedef enum { /* JPEG marker codes */
22 M_SOF0 = 0xc0,
23 M_SOF1 = 0xc1,
24 M_SOF2 = 0xc2,
25 M_SOF3 = 0xc3,
27 M_SOF5 = 0xc5,
28 M_SOF6 = 0xc6,
29 M_SOF7 = 0xc7,
31 M_JPG = 0xc8,
32 M_SOF9 = 0xc9,
33 M_SOF10 = 0xca,
34 M_SOF11 = 0xcb,
36 M_SOF13 = 0xcd,
37 M_SOF14 = 0xce,
38 M_SOF15 = 0xcf,
40 M_DHT = 0xc4,
42 M_DAC = 0xcc,
44 M_RST0 = 0xd0,
45 M_RST1 = 0xd1,
46 M_RST2 = 0xd2,
47 M_RST3 = 0xd3,
48 M_RST4 = 0xd4,
49 M_RST5 = 0xd5,
50 M_RST6 = 0xd6,
51 M_RST7 = 0xd7,
53 M_SOI = 0xd8,
54 M_EOI = 0xd9,
55 M_SOS = 0xda,
56 M_DQT = 0xdb,
57 M_DNL = 0xdc,
58 M_DRI = 0xdd,
59 M_DHP = 0xde,
60 M_EXP = 0xdf,
62 M_APP0 = 0xe0,
63 M_APP1 = 0xe1,
64 M_APP2 = 0xe2,
65 M_APP3 = 0xe3,
66 M_APP4 = 0xe4,
67 M_APP5 = 0xe5,
68 M_APP6 = 0xe6,
69 M_APP7 = 0xe7,
70 M_APP8 = 0xe8,
71 M_APP9 = 0xe9,
72 M_APP10 = 0xea,
73 M_APP11 = 0xeb,
74 M_APP12 = 0xec,
75 M_APP13 = 0xed,
76 M_APP14 = 0xee,
77 M_APP15 = 0xef,
79 M_JPG0 = 0xf0,
80 M_JPG8 = 0xf8,
81 M_JPG13 = 0xfd,
82 M_COM = 0xfe,
84 M_TEM = 0x01,
86 M_ERROR = 0x100
87 } JPEG_MARKER;
90 /* Private state */
92 typedef struct {
93 struct jpeg_marker_reader pub; /* public fields */
95 /* Application-overridable marker processing methods */
96 jpeg_marker_parser_method process_COM;
97 jpeg_marker_parser_method process_APPn[16];
99 /* Limit on marker data length to save for each marker type */
100 unsigned int length_limit_COM;
101 unsigned int length_limit_APPn[16];
103 /* Status of COM/APPn marker saving */
104 jpeg_saved_marker_ptr cur_marker; /* NULL if not processing a marker */
105 unsigned int bytes_read; /* data bytes read so far in marker */
106 /* Note: cur_marker is not linked into marker_list until it's all read. */
107 } my_marker_reader;
109 typedef my_marker_reader * my_marker_ptr;
113 * Macros for fetching data from the data source module.
115 * At all times, cinfo->src->next_input_byte and ->bytes_in_buffer reflect
116 * the current restart point; we update them only when we have reached a
117 * suitable place to restart if a suspension occurs.
120 /* Declare and initialize local copies of input pointer/count */
121 #define INPUT_VARS(cinfo) \
122 struct jpeg_source_mgr * datasrc = (cinfo)->src; \
123 const JOCTET * next_input_byte = datasrc->next_input_byte; \
124 size_t bytes_in_buffer = datasrc->bytes_in_buffer
126 /* Unload the local copies --- do this only at a restart boundary */
127 #define INPUT_SYNC(cinfo) \
128 ( datasrc->next_input_byte = next_input_byte, \
129 datasrc->bytes_in_buffer = bytes_in_buffer )
131 /* Reload the local copies --- used only in MAKE_BYTE_AVAIL */
132 #define INPUT_RELOAD(cinfo) \
133 ( next_input_byte = datasrc->next_input_byte, \
134 bytes_in_buffer = datasrc->bytes_in_buffer )
136 /* Internal macro for INPUT_BYTE and INPUT_2BYTES: make a byte available.
137 * Note we do *not* do INPUT_SYNC before calling fill_input_buffer,
138 * but we must reload the local copies after a successful fill.
140 #define MAKE_BYTE_AVAIL(cinfo,action) \
141 if (bytes_in_buffer == 0) { \
142 if (! (*datasrc->fill_input_buffer) (cinfo)) \
143 { action; } \
144 INPUT_RELOAD(cinfo); \
147 /* Read a byte into variable V.
148 * If must suspend, take the specified action (typically "return FALSE").
150 #define INPUT_BYTE(cinfo,V,action) \
151 MAKESTMT( MAKE_BYTE_AVAIL(cinfo,action); \
152 bytes_in_buffer--; \
153 V = GETJOCTET(*next_input_byte++); )
155 /* As above, but read two bytes interpreted as an unsigned 16-bit integer.
156 * V should be declared unsigned int or perhaps INT32.
158 #define INPUT_2BYTES(cinfo,V,action) \
159 MAKESTMT( MAKE_BYTE_AVAIL(cinfo,action); \
160 bytes_in_buffer--; \
161 V = ((unsigned int) GETJOCTET(*next_input_byte++)) << 8; \
162 MAKE_BYTE_AVAIL(cinfo,action); \
163 bytes_in_buffer--; \
164 V += GETJOCTET(*next_input_byte++); )
168 * Routines to process JPEG markers.
170 * Entry condition: JPEG marker itself has been read and its code saved
171 * in cinfo->unread_marker; input restart point is just after the marker.
173 * Exit: if return TRUE, have read and processed any parameters, and have
174 * updated the restart point to point after the parameters.
175 * If return FALSE, was forced to suspend before reaching end of
176 * marker parameters; restart point has not been moved. Same routine
177 * will be called again after application supplies more input data.
179 * This approach to suspension assumes that all of a marker's parameters
180 * can fit into a single input bufferload. This should hold for "normal"
181 * markers. Some COM/APPn markers might have large parameter segments
182 * that might not fit. If we are simply dropping such a marker, we use
183 * skip_input_data to get past it, and thereby put the problem on the
184 * source manager's shoulders. If we are saving the marker's contents
185 * into memory, we use a slightly different convention: when forced to
186 * suspend, the marker processor updates the restart point to the end of
187 * what it's consumed (ie, the end of the buffer) before returning FALSE.
188 * On resumption, cinfo->unread_marker still contains the marker code,
189 * but the data source will point to the next chunk of marker data.
190 * The marker processor must retain internal state to deal with this.
192 * Note that we don't bother to avoid duplicate trace messages if a
193 * suspension occurs within marker parameters. Other side effects
194 * require more care.
198 LOCAL(boolean)
199 get_soi (j_decompress_ptr cinfo)
200 /* Process an SOI marker */
202 int i;
204 TRACEMS(cinfo, 1, JTRC_SOI);
206 if (cinfo->marker->saw_SOI)
207 ERREXIT(cinfo, JERR_SOI_DUPLICATE);
209 /* Reset all parameters that are defined to be reset by SOI */
211 for (i = 0; i < NUM_ARITH_TBLS; i++) {
212 cinfo->arith_dc_L[i] = 0;
213 cinfo->arith_dc_U[i] = 1;
214 cinfo->arith_ac_K[i] = 5;
216 cinfo->restart_interval = 0;
218 /* Set initial assumptions for colorspace etc */
220 cinfo->jpeg_color_space = JCS_UNKNOWN;
221 cinfo->color_transform = JCT_NONE;
222 cinfo->CCIR601_sampling = FALSE; /* Assume non-CCIR sampling??? */
224 cinfo->saw_JFIF_marker = FALSE;
225 cinfo->JFIF_major_version = 1; /* set default JFIF APP0 values */
226 cinfo->JFIF_minor_version = 1;
227 cinfo->density_unit = 0;
228 cinfo->X_density = 1;
229 cinfo->Y_density = 1;
230 cinfo->saw_Adobe_marker = FALSE;
231 cinfo->Adobe_transform = 0;
233 cinfo->marker->saw_SOI = TRUE;
235 return TRUE;
239 LOCAL(boolean)
240 get_sof (j_decompress_ptr cinfo, boolean is_baseline, boolean is_prog,
241 boolean is_arith)
242 /* Process a SOFn marker */
244 INT32 length;
245 int c, ci, i;
246 jpeg_component_info * compptr;
247 INPUT_VARS(cinfo);
249 cinfo->is_baseline = is_baseline;
250 cinfo->progressive_mode = is_prog;
251 cinfo->arith_code = is_arith;
253 INPUT_2BYTES(cinfo, length, return FALSE);
255 INPUT_BYTE(cinfo, cinfo->data_precision, return FALSE);
256 INPUT_2BYTES(cinfo, cinfo->image_height, return FALSE);
257 INPUT_2BYTES(cinfo, cinfo->image_width, return FALSE);
258 INPUT_BYTE(cinfo, cinfo->num_components, return FALSE);
260 length -= 8;
262 TRACEMS4(cinfo, 1, JTRC_SOF, cinfo->unread_marker,
263 (int) cinfo->image_width, (int) cinfo->image_height,
264 cinfo->num_components);
266 if (cinfo->marker->saw_SOF)
267 ERREXIT(cinfo, JERR_SOF_DUPLICATE);
269 /* We don't support files in which the image height is initially specified */
270 /* as 0 and is later redefined by DNL. As long as we have to check that, */
271 /* might as well have a general sanity check. */
272 if (cinfo->image_height <= 0 || cinfo->image_width <= 0 ||
273 cinfo->num_components <= 0)
274 ERREXIT(cinfo, JERR_EMPTY_IMAGE);
276 if (length != (cinfo->num_components * 3))
277 ERREXIT(cinfo, JERR_BAD_LENGTH);
279 if (cinfo->comp_info == NULL) /* do only once, even if suspend */
280 cinfo->comp_info = (jpeg_component_info *) (*cinfo->mem->alloc_small)
281 ((j_common_ptr) cinfo, JPOOL_IMAGE,
282 cinfo->num_components * SIZEOF(jpeg_component_info));
284 for (ci = 0; ci < cinfo->num_components; ci++) {
285 INPUT_BYTE(cinfo, c, return FALSE);
286 /* Check to see whether component id has already been seen */
287 /* (in violation of the spec, but unfortunately seen in some */
288 /* files). If so, create "fake" component id equal to the */
289 /* max id seen so far + 1. */
290 for (i = 0, compptr = cinfo->comp_info; i < ci; i++, compptr++) {
291 if (c == compptr->component_id) {
292 compptr = cinfo->comp_info;
293 c = compptr->component_id;
294 compptr++;
295 for (i = 1; i < ci; i++, compptr++) {
296 if (compptr->component_id > c) c = compptr->component_id;
298 c++;
299 break;
302 compptr->component_id = c;
303 compptr->component_index = ci;
304 INPUT_BYTE(cinfo, c, return FALSE);
305 compptr->h_samp_factor = (c >> 4) & 15;
306 compptr->v_samp_factor = (c ) & 15;
307 INPUT_BYTE(cinfo, compptr->quant_tbl_no, return FALSE);
309 TRACEMS4(cinfo, 1, JTRC_SOF_COMPONENT,
310 compptr->component_id, compptr->h_samp_factor,
311 compptr->v_samp_factor, compptr->quant_tbl_no);
314 cinfo->marker->saw_SOF = TRUE;
316 INPUT_SYNC(cinfo);
317 return TRUE;
321 LOCAL(boolean)
322 get_sos (j_decompress_ptr cinfo)
323 /* Process a SOS marker */
325 INT32 length;
326 int c, ci, i, n;
327 jpeg_component_info * compptr;
328 INPUT_VARS(cinfo);
330 if (! cinfo->marker->saw_SOF)
331 ERREXITS(cinfo, JERR_SOF_BEFORE, "SOS");
333 INPUT_2BYTES(cinfo, length, return FALSE);
335 INPUT_BYTE(cinfo, n, return FALSE); /* Number of components */
337 TRACEMS1(cinfo, 1, JTRC_SOS, n);
339 if (length != (n * 2 + 6) || n > MAX_COMPS_IN_SCAN ||
340 (n == 0 && !cinfo->progressive_mode))
341 /* pseudo SOS marker only allowed in progressive mode */
342 ERREXIT(cinfo, JERR_BAD_LENGTH);
344 cinfo->comps_in_scan = n;
346 /* Collect the component-spec parameters */
348 for (i = 0; i < n; i++) {
349 INPUT_BYTE(cinfo, c, return FALSE);
351 /* Detect the case where component id's are not unique, and, if so, */
352 /* create a fake component id using the same logic as in get_sof. */
353 /* Note: This also ensures that all of the SOF components are */
354 /* referenced in the single scan case, which prevents access to */
355 /* uninitialized memory in later decoding stages. */
356 for (ci = 0; ci < i; ci++) {
357 if (c == cinfo->cur_comp_info[ci]->component_id) {
358 c = cinfo->cur_comp_info[0]->component_id;
359 for (ci = 1; ci < i; ci++) {
360 compptr = cinfo->cur_comp_info[ci];
361 if (compptr->component_id > c) c = compptr->component_id;
363 c++;
364 break;
368 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
369 ci++, compptr++) {
370 if (c == compptr->component_id)
371 goto id_found;
374 ERREXIT1(cinfo, JERR_BAD_COMPONENT_ID, c);
376 id_found:
378 cinfo->cur_comp_info[i] = compptr;
379 INPUT_BYTE(cinfo, c, return FALSE);
380 compptr->dc_tbl_no = (c >> 4) & 15;
381 compptr->ac_tbl_no = (c ) & 15;
383 TRACEMS3(cinfo, 1, JTRC_SOS_COMPONENT, compptr->component_id,
384 compptr->dc_tbl_no, compptr->ac_tbl_no);
387 /* Collect the additional scan parameters Ss, Se, Ah/Al. */
388 INPUT_BYTE(cinfo, c, return FALSE);
389 cinfo->Ss = c;
390 INPUT_BYTE(cinfo, c, return FALSE);
391 cinfo->Se = c;
392 INPUT_BYTE(cinfo, c, return FALSE);
393 cinfo->Ah = (c >> 4) & 15;
394 cinfo->Al = (c ) & 15;
396 TRACEMS4(cinfo, 1, JTRC_SOS_PARAMS, cinfo->Ss, cinfo->Se,
397 cinfo->Ah, cinfo->Al);
399 /* Prepare to scan data & restart markers */
400 cinfo->marker->next_restart_num = 0;
402 /* Count another (non-pseudo) SOS marker */
403 if (n) cinfo->input_scan_number++;
405 INPUT_SYNC(cinfo);
406 return TRUE;
410 #ifdef D_ARITH_CODING_SUPPORTED
412 LOCAL(boolean)
413 get_dac (j_decompress_ptr cinfo)
414 /* Process a DAC marker */
416 INT32 length;
417 int index, val;
418 INPUT_VARS(cinfo);
420 INPUT_2BYTES(cinfo, length, return FALSE);
421 length -= 2;
423 while (length > 0) {
424 INPUT_BYTE(cinfo, index, return FALSE);
425 INPUT_BYTE(cinfo, val, return FALSE);
427 length -= 2;
429 TRACEMS2(cinfo, 1, JTRC_DAC, index, val);
431 if (index < 0 || index >= (2*NUM_ARITH_TBLS))
432 ERREXIT1(cinfo, JERR_DAC_INDEX, index);
434 if (index >= NUM_ARITH_TBLS) { /* define AC table */
435 cinfo->arith_ac_K[index-NUM_ARITH_TBLS] = (UINT8) val;
436 } else { /* define DC table */
437 cinfo->arith_dc_L[index] = (UINT8) (val & 0x0F);
438 cinfo->arith_dc_U[index] = (UINT8) (val >> 4);
439 if (cinfo->arith_dc_L[index] > cinfo->arith_dc_U[index])
440 ERREXIT1(cinfo, JERR_DAC_VALUE, val);
444 if (length != 0)
445 ERREXIT(cinfo, JERR_BAD_LENGTH);
447 INPUT_SYNC(cinfo);
448 return TRUE;
451 #else /* ! D_ARITH_CODING_SUPPORTED */
453 #define get_dac(cinfo) skip_variable(cinfo)
455 #endif /* D_ARITH_CODING_SUPPORTED */
458 LOCAL(boolean)
459 get_dht (j_decompress_ptr cinfo)
460 /* Process a DHT marker */
462 INT32 length;
463 UINT8 bits[17];
464 UINT8 huffval[256];
465 int i, index, count;
466 JHUFF_TBL **htblptr;
467 INPUT_VARS(cinfo);
469 INPUT_2BYTES(cinfo, length, return FALSE);
470 length -= 2;
472 while (length > 16) {
473 INPUT_BYTE(cinfo, index, return FALSE);
475 TRACEMS1(cinfo, 1, JTRC_DHT, index);
477 bits[0] = 0;
478 count = 0;
479 for (i = 1; i <= 16; i++) {
480 INPUT_BYTE(cinfo, bits[i], return FALSE);
481 count += bits[i];
484 length -= 1 + 16;
486 TRACEMS8(cinfo, 2, JTRC_HUFFBITS,
487 bits[1], bits[2], bits[3], bits[4],
488 bits[5], bits[6], bits[7], bits[8]);
489 TRACEMS8(cinfo, 2, JTRC_HUFFBITS,
490 bits[9], bits[10], bits[11], bits[12],
491 bits[13], bits[14], bits[15], bits[16]);
493 /* Here we just do minimal validation of the counts to avoid walking
494 * off the end of our table space. jdhuff.c will check more carefully.
496 if (count > 256 || ((INT32) count) > length)
497 ERREXIT(cinfo, JERR_BAD_HUFF_TABLE);
499 MEMZERO(huffval, SIZEOF(huffval)); /* pre-zero array for later copy */
501 for (i = 0; i < count; i++)
502 INPUT_BYTE(cinfo, huffval[i], return FALSE);
504 length -= count;
506 if (index & 0x10) { /* AC table definition */
507 index -= 0x10;
508 htblptr = &cinfo->ac_huff_tbl_ptrs[index];
509 } else { /* DC table definition */
510 htblptr = &cinfo->dc_huff_tbl_ptrs[index];
513 if (index < 0 || index >= NUM_HUFF_TBLS)
514 ERREXIT1(cinfo, JERR_DHT_INDEX, index);
516 if (*htblptr == NULL)
517 *htblptr = jpeg_alloc_huff_table((j_common_ptr) cinfo);
519 MEMCOPY((*htblptr)->bits, bits, SIZEOF((*htblptr)->bits));
520 MEMCOPY((*htblptr)->huffval, huffval, SIZEOF((*htblptr)->huffval));
523 if (length != 0)
524 ERREXIT(cinfo, JERR_BAD_LENGTH);
526 INPUT_SYNC(cinfo);
527 return TRUE;
531 LOCAL(boolean)
532 get_dqt (j_decompress_ptr cinfo)
533 /* Process a DQT marker */
535 INT32 length, count, i;
536 int n, prec;
537 unsigned int tmp;
538 JQUANT_TBL *quant_ptr;
539 const int *natural_order;
540 INPUT_VARS(cinfo);
542 INPUT_2BYTES(cinfo, length, return FALSE);
543 length -= 2;
545 while (length > 0) {
546 length--;
547 INPUT_BYTE(cinfo, n, return FALSE);
548 prec = n >> 4;
549 n &= 0x0F;
551 TRACEMS2(cinfo, 1, JTRC_DQT, n, prec);
553 if (n >= NUM_QUANT_TBLS)
554 ERREXIT1(cinfo, JERR_DQT_INDEX, n);
556 if (cinfo->quant_tbl_ptrs[n] == NULL)
557 cinfo->quant_tbl_ptrs[n] = jpeg_alloc_quant_table((j_common_ptr) cinfo);
558 quant_ptr = cinfo->quant_tbl_ptrs[n];
560 if (prec) {
561 if (length < DCTSIZE2 * 2) {
562 /* Initialize full table for safety. */
563 for (i = 0; i < DCTSIZE2; i++) {
564 quant_ptr->quantval[i] = 1;
566 count = length >> 1;
567 } else
568 count = DCTSIZE2;
569 } else {
570 if (length < DCTSIZE2) {
571 /* Initialize full table for safety. */
572 for (i = 0; i < DCTSIZE2; i++) {
573 quant_ptr->quantval[i] = 1;
575 count = length;
576 } else
577 count = DCTSIZE2;
580 switch (count) {
581 case (2*2): natural_order = jpeg_natural_order2; break;
582 case (3*3): natural_order = jpeg_natural_order3; break;
583 case (4*4): natural_order = jpeg_natural_order4; break;
584 case (5*5): natural_order = jpeg_natural_order5; break;
585 case (6*6): natural_order = jpeg_natural_order6; break;
586 case (7*7): natural_order = jpeg_natural_order7; break;
587 default: natural_order = jpeg_natural_order; break;
590 for (i = 0; i < count; i++) {
591 if (prec)
592 INPUT_2BYTES(cinfo, tmp, return FALSE);
593 else
594 INPUT_BYTE(cinfo, tmp, return FALSE);
595 /* We convert the zigzag-order table to natural array order. */
596 quant_ptr->quantval[natural_order[i]] = (UINT16) tmp;
599 if (cinfo->err->trace_level >= 2) {
600 for (i = 0; i < DCTSIZE2; i += 8) {
601 TRACEMS8(cinfo, 2, JTRC_QUANTVALS,
602 quant_ptr->quantval[i], quant_ptr->quantval[i+1],
603 quant_ptr->quantval[i+2], quant_ptr->quantval[i+3],
604 quant_ptr->quantval[i+4], quant_ptr->quantval[i+5],
605 quant_ptr->quantval[i+6], quant_ptr->quantval[i+7]);
609 length -= count;
610 if (prec) length -= count;
613 if (length != 0)
614 ERREXIT(cinfo, JERR_BAD_LENGTH);
616 INPUT_SYNC(cinfo);
617 return TRUE;
621 LOCAL(boolean)
622 get_dri (j_decompress_ptr cinfo)
623 /* Process a DRI marker */
625 INT32 length;
626 unsigned int tmp;
627 INPUT_VARS(cinfo);
629 INPUT_2BYTES(cinfo, length, return FALSE);
631 if (length != 4)
632 ERREXIT(cinfo, JERR_BAD_LENGTH);
634 INPUT_2BYTES(cinfo, tmp, return FALSE);
636 TRACEMS1(cinfo, 1, JTRC_DRI, tmp);
638 cinfo->restart_interval = tmp;
640 INPUT_SYNC(cinfo);
641 return TRUE;
645 LOCAL(boolean)
646 get_lse (j_decompress_ptr cinfo)
647 /* Process an LSE marker */
649 INT32 length;
650 unsigned int tmp;
651 int cid;
652 INPUT_VARS(cinfo);
654 if (! cinfo->marker->saw_SOF)
655 ERREXITS(cinfo, JERR_SOF_BEFORE, "LSE");
657 if (cinfo->num_components < 3) goto bad;
659 INPUT_2BYTES(cinfo, length, return FALSE);
661 if (length != 24)
662 ERREXIT(cinfo, JERR_BAD_LENGTH);
664 INPUT_BYTE(cinfo, tmp, return FALSE);
665 if (tmp != 0x0D) /* ID inverse transform specification */
666 ERREXIT1(cinfo, JERR_UNKNOWN_MARKER, cinfo->unread_marker);
667 INPUT_2BYTES(cinfo, tmp, return FALSE);
668 if (tmp != MAXJSAMPLE) goto bad; /* MAXTRANS */
669 INPUT_BYTE(cinfo, tmp, return FALSE);
670 if (tmp != 3) goto bad; /* Nt=3 */
671 INPUT_BYTE(cinfo, cid, return FALSE);
672 if (cid != cinfo->comp_info[1].component_id) goto bad;
673 INPUT_BYTE(cinfo, cid, return FALSE);
674 if (cid != cinfo->comp_info[0].component_id) goto bad;
675 INPUT_BYTE(cinfo, cid, return FALSE);
676 if (cid != cinfo->comp_info[2].component_id) goto bad;
677 INPUT_BYTE(cinfo, tmp, return FALSE);
678 if (tmp != 0x80) goto bad; /* F1: CENTER1=1, NORM1=0 */
679 INPUT_2BYTES(cinfo, tmp, return FALSE);
680 if (tmp != 0) goto bad; /* A(1,1)=0 */
681 INPUT_2BYTES(cinfo, tmp, return FALSE);
682 if (tmp != 0) goto bad; /* A(1,2)=0 */
683 INPUT_BYTE(cinfo, tmp, return FALSE);
684 if (tmp != 0) goto bad; /* F2: CENTER2=0, NORM2=0 */
685 INPUT_2BYTES(cinfo, tmp, return FALSE);
686 if (tmp != 1) goto bad; /* A(2,1)=1 */
687 INPUT_2BYTES(cinfo, tmp, return FALSE);
688 if (tmp != 0) goto bad; /* A(2,2)=0 */
689 INPUT_BYTE(cinfo, tmp, return FALSE);
690 if (tmp != 0) goto bad; /* F3: CENTER3=0, NORM3=0 */
691 INPUT_2BYTES(cinfo, tmp, return FALSE);
692 if (tmp != 1) goto bad; /* A(3,1)=1 */
693 INPUT_2BYTES(cinfo, tmp, return FALSE);
694 if (tmp != 0) { /* A(3,2)=0 */
695 bad:
696 ERREXIT(cinfo, JERR_CONVERSION_NOTIMPL);
699 /* OK, valid transform that we can handle. */
700 cinfo->color_transform = JCT_SUBTRACT_GREEN;
702 INPUT_SYNC(cinfo);
703 return TRUE;
708 * Routines for processing APPn and COM markers.
709 * These are either saved in memory or discarded, per application request.
710 * APP0 and APP14 are specially checked to see if they are
711 * JFIF and Adobe markers, respectively.
714 #define APP0_DATA_LEN 14 /* Length of interesting data in APP0 */
715 #define APP14_DATA_LEN 12 /* Length of interesting data in APP14 */
716 #define APPN_DATA_LEN 14 /* Must be the largest of the above!! */
719 LOCAL(void)
720 examine_app0 (j_decompress_ptr cinfo, JOCTET FAR * data,
721 unsigned int datalen, INT32 remaining)
722 /* Examine first few bytes from an APP0.
723 * Take appropriate action if it is a JFIF marker.
724 * datalen is # of bytes at data[], remaining is length of rest of marker data.
727 INT32 totallen = (INT32) datalen + remaining;
729 if (datalen >= APP0_DATA_LEN &&
730 GETJOCTET(data[0]) == 0x4A &&
731 GETJOCTET(data[1]) == 0x46 &&
732 GETJOCTET(data[2]) == 0x49 &&
733 GETJOCTET(data[3]) == 0x46 &&
734 GETJOCTET(data[4]) == 0) {
735 /* Found JFIF APP0 marker: save info */
736 cinfo->saw_JFIF_marker = TRUE;
737 cinfo->JFIF_major_version = GETJOCTET(data[5]);
738 cinfo->JFIF_minor_version = GETJOCTET(data[6]);
739 cinfo->density_unit = GETJOCTET(data[7]);
740 cinfo->X_density = (GETJOCTET(data[8]) << 8) + GETJOCTET(data[9]);
741 cinfo->Y_density = (GETJOCTET(data[10]) << 8) + GETJOCTET(data[11]);
742 /* Check version.
743 * Major version must be 1 or 2, anything else signals an incompatible
744 * change.
745 * (We used to treat this as an error, but now it's a nonfatal warning,
746 * because some bozo at Hijaak couldn't read the spec.)
747 * Minor version should be 0..2, but process anyway if newer.
749 if (cinfo->JFIF_major_version != 1 && cinfo->JFIF_major_version != 2)
750 WARNMS2(cinfo, JWRN_JFIF_MAJOR,
751 cinfo->JFIF_major_version, cinfo->JFIF_minor_version);
752 /* Generate trace messages */
753 TRACEMS5(cinfo, 1, JTRC_JFIF,
754 cinfo->JFIF_major_version, cinfo->JFIF_minor_version,
755 cinfo->X_density, cinfo->Y_density, cinfo->density_unit);
756 /* Validate thumbnail dimensions and issue appropriate messages */
757 if (GETJOCTET(data[12]) | GETJOCTET(data[13]))
758 TRACEMS2(cinfo, 1, JTRC_JFIF_THUMBNAIL,
759 GETJOCTET(data[12]), GETJOCTET(data[13]));
760 totallen -= APP0_DATA_LEN;
761 if (totallen !=
762 ((INT32)GETJOCTET(data[12]) * (INT32)GETJOCTET(data[13]) * (INT32) 3))
763 TRACEMS1(cinfo, 1, JTRC_JFIF_BADTHUMBNAILSIZE, (int) totallen);
764 } else if (datalen >= 6 &&
765 GETJOCTET(data[0]) == 0x4A &&
766 GETJOCTET(data[1]) == 0x46 &&
767 GETJOCTET(data[2]) == 0x58 &&
768 GETJOCTET(data[3]) == 0x58 &&
769 GETJOCTET(data[4]) == 0) {
770 /* Found JFIF "JFXX" extension APP0 marker */
771 /* The library doesn't actually do anything with these,
772 * but we try to produce a helpful trace message.
774 switch (GETJOCTET(data[5])) {
775 case 0x10:
776 TRACEMS1(cinfo, 1, JTRC_THUMB_JPEG, (int) totallen);
777 break;
778 case 0x11:
779 TRACEMS1(cinfo, 1, JTRC_THUMB_PALETTE, (int) totallen);
780 break;
781 case 0x13:
782 TRACEMS1(cinfo, 1, JTRC_THUMB_RGB, (int) totallen);
783 break;
784 default:
785 TRACEMS2(cinfo, 1, JTRC_JFIF_EXTENSION,
786 GETJOCTET(data[5]), (int) totallen);
787 break;
789 } else {
790 /* Start of APP0 does not match "JFIF" or "JFXX", or too short */
791 TRACEMS1(cinfo, 1, JTRC_APP0, (int) totallen);
796 LOCAL(void)
797 examine_app14 (j_decompress_ptr cinfo, JOCTET FAR * data,
798 unsigned int datalen, INT32 remaining)
799 /* Examine first few bytes from an APP14.
800 * Take appropriate action if it is an Adobe marker.
801 * datalen is # of bytes at data[], remaining is length of rest of marker data.
804 unsigned int version, flags0, flags1, transform;
806 if (datalen >= APP14_DATA_LEN &&
807 GETJOCTET(data[0]) == 0x41 &&
808 GETJOCTET(data[1]) == 0x64 &&
809 GETJOCTET(data[2]) == 0x6F &&
810 GETJOCTET(data[3]) == 0x62 &&
811 GETJOCTET(data[4]) == 0x65) {
812 /* Found Adobe APP14 marker */
813 version = (GETJOCTET(data[5]) << 8) + GETJOCTET(data[6]);
814 flags0 = (GETJOCTET(data[7]) << 8) + GETJOCTET(data[8]);
815 flags1 = (GETJOCTET(data[9]) << 8) + GETJOCTET(data[10]);
816 transform = GETJOCTET(data[11]);
817 TRACEMS4(cinfo, 1, JTRC_ADOBE, version, flags0, flags1, transform);
818 cinfo->saw_Adobe_marker = TRUE;
819 cinfo->Adobe_transform = (UINT8) transform;
820 } else {
821 /* Start of APP14 does not match "Adobe", or too short */
822 TRACEMS1(cinfo, 1, JTRC_APP14, (int) (datalen + remaining));
827 METHODDEF(boolean)
828 get_interesting_appn (j_decompress_ptr cinfo)
829 /* Process an APP0 or APP14 marker without saving it */
831 INT32 length;
832 JOCTET b[APPN_DATA_LEN];
833 unsigned int i, numtoread;
834 INPUT_VARS(cinfo);
836 INPUT_2BYTES(cinfo, length, return FALSE);
837 length -= 2;
839 /* get the interesting part of the marker data */
840 if (length >= APPN_DATA_LEN)
841 numtoread = APPN_DATA_LEN;
842 else if (length > 0)
843 numtoread = (unsigned int) length;
844 else
845 numtoread = 0;
846 for (i = 0; i < numtoread; i++)
847 INPUT_BYTE(cinfo, b[i], return FALSE);
848 length -= numtoread;
850 /* process it */
851 switch (cinfo->unread_marker) {
852 case M_APP0:
853 examine_app0(cinfo, (JOCTET FAR *) b, numtoread, length);
854 break;
855 case M_APP14:
856 examine_app14(cinfo, (JOCTET FAR *) b, numtoread, length);
857 break;
858 default:
859 /* can't get here unless jpeg_save_markers chooses wrong processor */
860 ERREXIT1(cinfo, JERR_UNKNOWN_MARKER, cinfo->unread_marker);
861 break;
864 /* skip any remaining data -- could be lots */
865 INPUT_SYNC(cinfo);
866 if (length > 0)
867 (*cinfo->src->skip_input_data) (cinfo, (long) length);
869 return TRUE;
873 #ifdef SAVE_MARKERS_SUPPORTED
875 METHODDEF(boolean)
876 save_marker (j_decompress_ptr cinfo)
877 /* Save an APPn or COM marker into the marker list */
879 my_marker_ptr marker = (my_marker_ptr) cinfo->marker;
880 jpeg_saved_marker_ptr cur_marker = marker->cur_marker;
881 unsigned int bytes_read, data_length;
882 JOCTET FAR * data;
883 INT32 length = 0;
884 INPUT_VARS(cinfo);
886 if (cur_marker == NULL) {
887 /* begin reading a marker */
888 INPUT_2BYTES(cinfo, length, return FALSE);
889 length -= 2;
890 if (length >= 0) { /* watch out for bogus length word */
891 /* figure out how much we want to save */
892 unsigned int limit;
893 if (cinfo->unread_marker == (int) M_COM)
894 limit = marker->length_limit_COM;
895 else
896 limit = marker->length_limit_APPn[cinfo->unread_marker - (int) M_APP0];
897 if ((unsigned int) length < limit)
898 limit = (unsigned int) length;
899 /* allocate and initialize the marker item */
900 cur_marker = (jpeg_saved_marker_ptr)
901 (*cinfo->mem->alloc_large) ((j_common_ptr) cinfo, JPOOL_IMAGE,
902 SIZEOF(struct jpeg_marker_struct) + limit);
903 cur_marker->next = NULL;
904 cur_marker->marker = (UINT8) cinfo->unread_marker;
905 cur_marker->original_length = (unsigned int) length;
906 cur_marker->data_length = limit;
907 /* data area is just beyond the jpeg_marker_struct */
908 data = cur_marker->data = (JOCTET FAR *) (cur_marker + 1);
909 marker->cur_marker = cur_marker;
910 marker->bytes_read = 0;
911 bytes_read = 0;
912 data_length = limit;
913 } else {
914 /* deal with bogus length word */
915 bytes_read = data_length = 0;
916 data = NULL;
918 } else {
919 /* resume reading a marker */
920 bytes_read = marker->bytes_read;
921 data_length = cur_marker->data_length;
922 data = cur_marker->data + bytes_read;
925 while (bytes_read < data_length) {
926 INPUT_SYNC(cinfo); /* move the restart point to here */
927 marker->bytes_read = bytes_read;
928 /* If there's not at least one byte in buffer, suspend */
929 MAKE_BYTE_AVAIL(cinfo, return FALSE);
930 /* Copy bytes with reasonable rapidity */
931 while (bytes_read < data_length && bytes_in_buffer > 0) {
932 *data++ = *next_input_byte++;
933 bytes_in_buffer--;
934 bytes_read++;
938 /* Done reading what we want to read */
939 if (cur_marker != NULL) { /* will be NULL if bogus length word */
940 /* Add new marker to end of list */
941 if (cinfo->marker_list == NULL) {
942 cinfo->marker_list = cur_marker;
943 } else {
944 jpeg_saved_marker_ptr prev = cinfo->marker_list;
945 while (prev->next != NULL)
946 prev = prev->next;
947 prev->next = cur_marker;
949 /* Reset pointer & calc remaining data length */
950 data = cur_marker->data;
951 length = cur_marker->original_length - data_length;
953 /* Reset to initial state for next marker */
954 marker->cur_marker = NULL;
956 /* Process the marker if interesting; else just make a generic trace msg */
957 switch (cinfo->unread_marker) {
958 case M_APP0:
959 examine_app0(cinfo, data, data_length, length);
960 break;
961 case M_APP14:
962 examine_app14(cinfo, data, data_length, length);
963 break;
964 default:
965 TRACEMS2(cinfo, 1, JTRC_MISC_MARKER, cinfo->unread_marker,
966 (int) (data_length + length));
967 break;
970 /* skip any remaining data -- could be lots */
971 INPUT_SYNC(cinfo); /* do before skip_input_data */
972 if (length > 0)
973 (*cinfo->src->skip_input_data) (cinfo, (long) length);
975 return TRUE;
978 #endif /* SAVE_MARKERS_SUPPORTED */
981 METHODDEF(boolean)
982 skip_variable (j_decompress_ptr cinfo)
983 /* Skip over an unknown or uninteresting variable-length marker */
985 INT32 length;
986 INPUT_VARS(cinfo);
988 INPUT_2BYTES(cinfo, length, return FALSE);
989 length -= 2;
991 TRACEMS2(cinfo, 1, JTRC_MISC_MARKER, cinfo->unread_marker, (int) length);
993 INPUT_SYNC(cinfo); /* do before skip_input_data */
994 if (length > 0)
995 (*cinfo->src->skip_input_data) (cinfo, (long) length);
997 return TRUE;
1002 * Find the next JPEG marker, save it in cinfo->unread_marker.
1003 * Returns FALSE if had to suspend before reaching a marker;
1004 * in that case cinfo->unread_marker is unchanged.
1006 * Note that the result might not be a valid marker code,
1007 * but it will never be 0 or FF.
1010 LOCAL(boolean)
1011 next_marker (j_decompress_ptr cinfo)
1013 int c;
1014 INPUT_VARS(cinfo);
1016 for (;;) {
1017 INPUT_BYTE(cinfo, c, return FALSE);
1018 /* Skip any non-FF bytes.
1019 * This may look a bit inefficient, but it will not occur in a valid file.
1020 * We sync after each discarded byte so that a suspending data source
1021 * can discard the byte from its buffer.
1023 while (c != 0xFF) {
1024 cinfo->marker->discarded_bytes++;
1025 INPUT_SYNC(cinfo);
1026 INPUT_BYTE(cinfo, c, return FALSE);
1028 /* This loop swallows any duplicate FF bytes. Extra FFs are legal as
1029 * pad bytes, so don't count them in discarded_bytes. We assume there
1030 * will not be so many consecutive FF bytes as to overflow a suspending
1031 * data source's input buffer.
1033 do {
1034 INPUT_BYTE(cinfo, c, return FALSE);
1035 } while (c == 0xFF);
1036 if (c != 0)
1037 break; /* found a valid marker, exit loop */
1038 /* Reach here if we found a stuffed-zero data sequence (FF/00).
1039 * Discard it and loop back to try again.
1041 cinfo->marker->discarded_bytes += 2;
1042 INPUT_SYNC(cinfo);
1045 if (cinfo->marker->discarded_bytes != 0) {
1046 WARNMS2(cinfo, JWRN_EXTRANEOUS_DATA, cinfo->marker->discarded_bytes, c);
1047 cinfo->marker->discarded_bytes = 0;
1050 cinfo->unread_marker = c;
1052 INPUT_SYNC(cinfo);
1053 return TRUE;
1057 LOCAL(boolean)
1058 first_marker (j_decompress_ptr cinfo)
1059 /* Like next_marker, but used to obtain the initial SOI marker. */
1060 /* For this marker, we do not allow preceding garbage or fill; otherwise,
1061 * we might well scan an entire input file before realizing it ain't JPEG.
1062 * If an application wants to process non-JFIF files, it must seek to the
1063 * SOI before calling the JPEG library.
1066 int c, c2;
1067 INPUT_VARS(cinfo);
1069 INPUT_BYTE(cinfo, c, return FALSE);
1070 INPUT_BYTE(cinfo, c2, return FALSE);
1071 if (c != 0xFF || c2 != (int) M_SOI)
1072 ERREXIT2(cinfo, JERR_NO_SOI, c, c2);
1074 cinfo->unread_marker = c2;
1076 INPUT_SYNC(cinfo);
1077 return TRUE;
1082 * Read markers until SOS or EOI.
1084 * Returns same codes as are defined for jpeg_consume_input:
1085 * JPEG_SUSPENDED, JPEG_REACHED_SOS, or JPEG_REACHED_EOI.
1087 * Note: This function may return a pseudo SOS marker (with zero
1088 * component number) for treat by input controller's consume_input.
1089 * consume_input itself should filter out (skip) the pseudo marker
1090 * after processing for the caller.
1093 METHODDEF(int)
1094 read_markers (j_decompress_ptr cinfo)
1096 /* Outer loop repeats once for each marker. */
1097 for (;;) {
1098 /* Collect the marker proper, unless we already did. */
1099 /* NB: first_marker() enforces the requirement that SOI appear first. */
1100 if (cinfo->unread_marker == 0) {
1101 if (! cinfo->marker->saw_SOI) {
1102 if (! first_marker(cinfo))
1103 return JPEG_SUSPENDED;
1104 } else {
1105 if (! next_marker(cinfo))
1106 return JPEG_SUSPENDED;
1109 /* At this point cinfo->unread_marker contains the marker code and the
1110 * input point is just past the marker proper, but before any parameters.
1111 * A suspension will cause us to return with this state still true.
1113 switch (cinfo->unread_marker) {
1114 case M_SOI:
1115 if (! get_soi(cinfo))
1116 return JPEG_SUSPENDED;
1117 break;
1119 case M_SOF0: /* Baseline */
1120 if (! get_sof(cinfo, TRUE, FALSE, FALSE))
1121 return JPEG_SUSPENDED;
1122 break;
1124 case M_SOF1: /* Extended sequential, Huffman */
1125 if (! get_sof(cinfo, FALSE, FALSE, FALSE))
1126 return JPEG_SUSPENDED;
1127 break;
1129 case M_SOF2: /* Progressive, Huffman */
1130 if (! get_sof(cinfo, FALSE, TRUE, FALSE))
1131 return JPEG_SUSPENDED;
1132 break;
1134 case M_SOF9: /* Extended sequential, arithmetic */
1135 if (! get_sof(cinfo, FALSE, FALSE, TRUE))
1136 return JPEG_SUSPENDED;
1137 break;
1139 case M_SOF10: /* Progressive, arithmetic */
1140 if (! get_sof(cinfo, FALSE, TRUE, TRUE))
1141 return JPEG_SUSPENDED;
1142 break;
1144 /* Currently unsupported SOFn types */
1145 case M_SOF3: /* Lossless, Huffman */
1146 case M_SOF5: /* Differential sequential, Huffman */
1147 case M_SOF6: /* Differential progressive, Huffman */
1148 case M_SOF7: /* Differential lossless, Huffman */
1149 case M_JPG: /* Reserved for JPEG extensions */
1150 case M_SOF11: /* Lossless, arithmetic */
1151 case M_SOF13: /* Differential sequential, arithmetic */
1152 case M_SOF14: /* Differential progressive, arithmetic */
1153 case M_SOF15: /* Differential lossless, arithmetic */
1154 ERREXIT1(cinfo, JERR_SOF_UNSUPPORTED, cinfo->unread_marker);
1155 break;
1157 case M_SOS:
1158 if (! get_sos(cinfo))
1159 return JPEG_SUSPENDED;
1160 cinfo->unread_marker = 0; /* processed the marker */
1161 return JPEG_REACHED_SOS;
1163 case M_EOI:
1164 TRACEMS(cinfo, 1, JTRC_EOI);
1165 cinfo->unread_marker = 0; /* processed the marker */
1166 return JPEG_REACHED_EOI;
1168 case M_DAC:
1169 if (! get_dac(cinfo))
1170 return JPEG_SUSPENDED;
1171 break;
1173 case M_DHT:
1174 if (! get_dht(cinfo))
1175 return JPEG_SUSPENDED;
1176 break;
1178 case M_DQT:
1179 if (! get_dqt(cinfo))
1180 return JPEG_SUSPENDED;
1181 break;
1183 case M_DRI:
1184 if (! get_dri(cinfo))
1185 return JPEG_SUSPENDED;
1186 break;
1188 case M_JPG8:
1189 if (! get_lse(cinfo))
1190 return JPEG_SUSPENDED;
1191 break;
1193 case M_APP0:
1194 case M_APP1:
1195 case M_APP2:
1196 case M_APP3:
1197 case M_APP4:
1198 case M_APP5:
1199 case M_APP6:
1200 case M_APP7:
1201 case M_APP8:
1202 case M_APP9:
1203 case M_APP10:
1204 case M_APP11:
1205 case M_APP12:
1206 case M_APP13:
1207 case M_APP14:
1208 case M_APP15:
1209 if (! (*((my_marker_ptr) cinfo->marker)->process_APPn[
1210 cinfo->unread_marker - (int) M_APP0]) (cinfo))
1211 return JPEG_SUSPENDED;
1212 break;
1214 case M_COM:
1215 if (! (*((my_marker_ptr) cinfo->marker)->process_COM) (cinfo))
1216 return JPEG_SUSPENDED;
1217 break;
1219 case M_RST0: /* these are all parameterless */
1220 case M_RST1:
1221 case M_RST2:
1222 case M_RST3:
1223 case M_RST4:
1224 case M_RST5:
1225 case M_RST6:
1226 case M_RST7:
1227 case M_TEM:
1228 TRACEMS1(cinfo, 1, JTRC_PARMLESS_MARKER, cinfo->unread_marker);
1229 break;
1231 case M_DNL: /* Ignore DNL ... perhaps the wrong thing */
1232 if (! skip_variable(cinfo))
1233 return JPEG_SUSPENDED;
1234 break;
1236 default: /* must be DHP, EXP, JPGn, or RESn */
1237 /* For now, we treat the reserved markers as fatal errors since they are
1238 * likely to be used to signal incompatible JPEG Part 3 extensions.
1239 * Once the JPEG 3 version-number marker is well defined, this code
1240 * ought to change!
1242 ERREXIT1(cinfo, JERR_UNKNOWN_MARKER, cinfo->unread_marker);
1243 break;
1245 /* Successfully processed marker, so reset state variable */
1246 cinfo->unread_marker = 0;
1247 } /* end loop */
1252 * Read a restart marker, which is expected to appear next in the datastream;
1253 * if the marker is not there, take appropriate recovery action.
1254 * Returns FALSE if suspension is required.
1256 * This is called by the entropy decoder after it has read an appropriate
1257 * number of MCUs. cinfo->unread_marker may be nonzero if the entropy decoder
1258 * has already read a marker from the data source. Under normal conditions
1259 * cinfo->unread_marker will be reset to 0 before returning; if not reset,
1260 * it holds a marker which the decoder will be unable to read past.
1263 METHODDEF(boolean)
1264 read_restart_marker (j_decompress_ptr cinfo)
1266 /* Obtain a marker unless we already did. */
1267 /* Note that next_marker will complain if it skips any data. */
1268 if (cinfo->unread_marker == 0) {
1269 if (! next_marker(cinfo))
1270 return FALSE;
1273 if (cinfo->unread_marker ==
1274 ((int) M_RST0 + cinfo->marker->next_restart_num)) {
1275 /* Normal case --- swallow the marker and let entropy decoder continue */
1276 TRACEMS1(cinfo, 3, JTRC_RST, cinfo->marker->next_restart_num);
1277 cinfo->unread_marker = 0;
1278 } else {
1279 /* Uh-oh, the restart markers have been messed up. */
1280 /* Let the data source manager determine how to resync. */
1281 if (! (*cinfo->src->resync_to_restart) (cinfo,
1282 cinfo->marker->next_restart_num))
1283 return FALSE;
1286 /* Update next-restart state */
1287 cinfo->marker->next_restart_num = (cinfo->marker->next_restart_num + 1) & 7;
1289 return TRUE;
1294 * This is the default resync_to_restart method for data source managers
1295 * to use if they don't have any better approach. Some data source managers
1296 * may be able to back up, or may have additional knowledge about the data
1297 * which permits a more intelligent recovery strategy; such managers would
1298 * presumably supply their own resync method.
1300 * read_restart_marker calls resync_to_restart if it finds a marker other than
1301 * the restart marker it was expecting. (This code is *not* used unless
1302 * a nonzero restart interval has been declared.) cinfo->unread_marker is
1303 * the marker code actually found (might be anything, except 0 or FF).
1304 * The desired restart marker number (0..7) is passed as a parameter.
1305 * This routine is supposed to apply whatever error recovery strategy seems
1306 * appropriate in order to position the input stream to the next data segment.
1307 * Note that cinfo->unread_marker is treated as a marker appearing before
1308 * the current data-source input point; usually it should be reset to zero
1309 * before returning.
1310 * Returns FALSE if suspension is required.
1312 * This implementation is substantially constrained by wanting to treat the
1313 * input as a data stream; this means we can't back up. Therefore, we have
1314 * only the following actions to work with:
1315 * 1. Simply discard the marker and let the entropy decoder resume at next
1316 * byte of file.
1317 * 2. Read forward until we find another marker, discarding intervening
1318 * data. (In theory we could look ahead within the current bufferload,
1319 * without having to discard data if we don't find the desired marker.
1320 * This idea is not implemented here, in part because it makes behavior
1321 * dependent on buffer size and chance buffer-boundary positions.)
1322 * 3. Leave the marker unread (by failing to zero cinfo->unread_marker).
1323 * This will cause the entropy decoder to process an empty data segment,
1324 * inserting dummy zeroes, and then we will reprocess the marker.
1326 * #2 is appropriate if we think the desired marker lies ahead, while #3 is
1327 * appropriate if the found marker is a future restart marker (indicating
1328 * that we have missed the desired restart marker, probably because it got
1329 * corrupted).
1330 * We apply #2 or #3 if the found marker is a restart marker no more than
1331 * two counts behind or ahead of the expected one. We also apply #2 if the
1332 * found marker is not a legal JPEG marker code (it's certainly bogus data).
1333 * If the found marker is a restart marker more than 2 counts away, we do #1
1334 * (too much risk that the marker is erroneous; with luck we will be able to
1335 * resync at some future point).
1336 * For any valid non-restart JPEG marker, we apply #3. This keeps us from
1337 * overrunning the end of a scan. An implementation limited to single-scan
1338 * files might find it better to apply #2 for markers other than EOI, since
1339 * any other marker would have to be bogus data in that case.
1342 GLOBAL(boolean)
1343 jpeg_resync_to_restart (j_decompress_ptr cinfo, int desired)
1345 int marker = cinfo->unread_marker;
1346 int action = 1;
1348 /* Always put up a warning. */
1349 WARNMS2(cinfo, JWRN_MUST_RESYNC, marker, desired);
1351 /* Outer loop handles repeated decision after scanning forward. */
1352 for (;;) {
1353 if (marker < (int) M_SOF0)
1354 action = 2; /* invalid marker */
1355 else if (marker < (int) M_RST0 || marker > (int) M_RST7)
1356 action = 3; /* valid non-restart marker */
1357 else {
1358 if (marker == ((int) M_RST0 + ((desired+1) & 7)) ||
1359 marker == ((int) M_RST0 + ((desired+2) & 7)))
1360 action = 3; /* one of the next two expected restarts */
1361 else if (marker == ((int) M_RST0 + ((desired-1) & 7)) ||
1362 marker == ((int) M_RST0 + ((desired-2) & 7)))
1363 action = 2; /* a prior restart, so advance */
1364 else
1365 action = 1; /* desired restart or too far away */
1367 TRACEMS2(cinfo, 4, JTRC_RECOVERY_ACTION, marker, action);
1368 switch (action) {
1369 case 1:
1370 /* Discard marker and let entropy decoder resume processing. */
1371 cinfo->unread_marker = 0;
1372 return TRUE;
1373 case 2:
1374 /* Scan to the next marker, and repeat the decision loop. */
1375 if (! next_marker(cinfo))
1376 return FALSE;
1377 marker = cinfo->unread_marker;
1378 break;
1379 case 3:
1380 /* Return without advancing past this marker. */
1381 /* Entropy decoder will be forced to process an empty segment. */
1382 return TRUE;
1384 } /* end loop */
1389 * Reset marker processing state to begin a fresh datastream.
1392 METHODDEF(void)
1393 reset_marker_reader (j_decompress_ptr cinfo)
1395 my_marker_ptr marker = (my_marker_ptr) cinfo->marker;
1397 cinfo->comp_info = NULL; /* until allocated by get_sof */
1398 cinfo->input_scan_number = 0; /* no SOS seen yet */
1399 cinfo->unread_marker = 0; /* no pending marker */
1400 marker->pub.saw_SOI = FALSE; /* set internal state too */
1401 marker->pub.saw_SOF = FALSE;
1402 marker->pub.discarded_bytes = 0;
1403 marker->cur_marker = NULL;
1408 * Initialize the marker reader module.
1409 * This is called only once, when the decompression object is created.
1412 GLOBAL(void)
1413 jinit_marker_reader (j_decompress_ptr cinfo)
1415 my_marker_ptr marker;
1416 int i;
1418 /* Create subobject in permanent pool */
1419 marker = (my_marker_ptr)
1420 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
1421 SIZEOF(my_marker_reader));
1422 cinfo->marker = &marker->pub;
1423 /* Initialize public method pointers */
1424 marker->pub.reset_marker_reader = reset_marker_reader;
1425 marker->pub.read_markers = read_markers;
1426 marker->pub.read_restart_marker = read_restart_marker;
1427 /* Initialize COM/APPn processing.
1428 * By default, we examine and then discard APP0 and APP14,
1429 * but simply discard COM and all other APPn.
1431 marker->process_COM = skip_variable;
1432 marker->length_limit_COM = 0;
1433 for (i = 0; i < 16; i++) {
1434 marker->process_APPn[i] = skip_variable;
1435 marker->length_limit_APPn[i] = 0;
1437 marker->process_APPn[0] = get_interesting_appn;
1438 marker->process_APPn[14] = get_interesting_appn;
1439 /* Reset marker processing state */
1440 reset_marker_reader(cinfo);
1445 * Control saving of COM and APPn markers into marker_list.
1448 #ifdef SAVE_MARKERS_SUPPORTED
1450 GLOBAL(void)
1451 jpeg_save_markers (j_decompress_ptr cinfo, int marker_code,
1452 unsigned int length_limit)
1454 my_marker_ptr marker = (my_marker_ptr) cinfo->marker;
1455 long maxlength;
1456 jpeg_marker_parser_method processor;
1458 /* Length limit mustn't be larger than what we can allocate
1459 * (should only be a concern in a 16-bit environment).
1461 maxlength = cinfo->mem->max_alloc_chunk - SIZEOF(struct jpeg_marker_struct);
1462 if (((long) length_limit) > maxlength)
1463 length_limit = (unsigned int) maxlength;
1465 /* Choose processor routine to use.
1466 * APP0/APP14 have special requirements.
1468 if (length_limit) {
1469 processor = save_marker;
1470 /* If saving APP0/APP14, save at least enough for our internal use. */
1471 if (marker_code == (int) M_APP0 && length_limit < APP0_DATA_LEN)
1472 length_limit = APP0_DATA_LEN;
1473 else if (marker_code == (int) M_APP14 && length_limit < APP14_DATA_LEN)
1474 length_limit = APP14_DATA_LEN;
1475 } else {
1476 processor = skip_variable;
1477 /* If discarding APP0/APP14, use our regular on-the-fly processor. */
1478 if (marker_code == (int) M_APP0 || marker_code == (int) M_APP14)
1479 processor = get_interesting_appn;
1482 if (marker_code == (int) M_COM) {
1483 marker->process_COM = processor;
1484 marker->length_limit_COM = length_limit;
1485 } else if (marker_code >= (int) M_APP0 && marker_code <= (int) M_APP15) {
1486 marker->process_APPn[marker_code - (int) M_APP0] = processor;
1487 marker->length_limit_APPn[marker_code - (int) M_APP0] = length_limit;
1488 } else
1489 ERREXIT1(cinfo, JERR_UNKNOWN_MARKER, marker_code);
1492 #endif /* SAVE_MARKERS_SUPPORTED */
1496 * Install a special processing method for COM or APPn markers.
1499 GLOBAL(void)
1500 jpeg_set_marker_processor (j_decompress_ptr cinfo, int marker_code,
1501 jpeg_marker_parser_method routine)
1503 my_marker_ptr marker = (my_marker_ptr) cinfo->marker;
1505 if (marker_code == (int) M_COM)
1506 marker->process_COM = routine;
1507 else if (marker_code >= (int) M_APP0 && marker_code <= (int) M_APP15)
1508 marker->process_APPn[marker_code - (int) M_APP0] = routine;
1509 else
1510 ERREXIT1(cinfo, JERR_UNKNOWN_MARKER, marker_code);