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1 /*
2  * jdinput.c
3  *
4  * Copyright (C) 1991-1997, Thomas G. Lane.
5  * Modified 2002-2009 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.
8  *
9  * This file contains input control logic for the JPEG decompressor.
10  * These routines are concerned with controlling the decompressor's input
11  * processing (marker reading and coefficient decoding).  The actual input
12  * reading is done in jdmarker.c, jdhuff.c, and jdarith.c.
13  */
14
15 #define JPEG_INTERNALS
16 #include "jinclude.h"
17 #include "jpeglib.h"
18
19
20 /* Private state */
21
22 typedef struct {
23   struct jpeg_input_controller pub; /* public fields */
24
25   int inheaders;                /* Nonzero until first SOS is reached */
26 } my_input_controller;
27
28 typedef my_input_controller * my_inputctl_ptr;
29
30
31 /* Forward declarations */
32 METHODDEF(int) consume_markers JPP((j_decompress_ptr cinfo));
33
34
35 /*
36  * Routines to calculate various quantities related to the size of the image.
37  */
38
39
40 /*
41  * Compute output image dimensions and related values.
42  * NOTE: this is exported for possible use by application.
43  * Hence it mustn't do anything that can't be done twice.
44  */
45
46 GLOBAL(void)
47 jpeg_core_output_dimensions (j_decompress_ptr cinfo)
48 /* Do computations that are needed before master selection phase.
49  * This function is used for transcoding and full decompression.
50  */
51 {
52 #ifdef IDCT_SCALING_SUPPORTED
53   int ci;
54   jpeg_component_info *compptr;
55
56   /* Compute actual output image dimensions and DCT scaling choices. */
57   if (cinfo->scale_num * cinfo->block_size <= cinfo->scale_denom) {
58     /* Provide 1/block_size scaling */
59     cinfo->output_width = (JDIMENSION)
60       jdiv_round_up((long) cinfo->image_width, (long) cinfo->block_size);
61     cinfo->output_height = (JDIMENSION)
62       jdiv_round_up((long) cinfo->image_height, (long) cinfo->block_size);
63     cinfo->min_DCT_h_scaled_size = 1;
64     cinfo->min_DCT_v_scaled_size = 1;
65   } else if (cinfo->scale_num * cinfo->block_size <= cinfo->scale_denom * 2) {
66     /* Provide 2/block_size scaling */
67     cinfo->output_width = (JDIMENSION)
68       jdiv_round_up((long) cinfo->image_width * 2L, (long) cinfo->block_size);
69     cinfo->output_height = (JDIMENSION)
70       jdiv_round_up((long) cinfo->image_height * 2L, (long) cinfo->block_size);
71     cinfo->min_DCT_h_scaled_size = 2;
72     cinfo->min_DCT_v_scaled_size = 2;
73   } else if (cinfo->scale_num * cinfo->block_size <= cinfo->scale_denom * 3) {
74     /* Provide 3/block_size scaling */
75     cinfo->output_width = (JDIMENSION)
76       jdiv_round_up((long) cinfo->image_width * 3L, (long) cinfo->block_size);
77     cinfo->output_height = (JDIMENSION)
78       jdiv_round_up((long) cinfo->image_height * 3L, (long) cinfo->block_size);
79     cinfo->min_DCT_h_scaled_size = 3;
80     cinfo->min_DCT_v_scaled_size = 3;
81   } else if (cinfo->scale_num * cinfo->block_size <= cinfo->scale_denom * 4) {
82     /* Provide 4/block_size scaling */
83     cinfo->output_width = (JDIMENSION)
84       jdiv_round_up((long) cinfo->image_width * 4L, (long) cinfo->block_size);
85     cinfo->output_height = (JDIMENSION)
86       jdiv_round_up((long) cinfo->image_height * 4L, (long) cinfo->block_size);
87     cinfo->min_DCT_h_scaled_size = 4;
88     cinfo->min_DCT_v_scaled_size = 4;
89   } else if (cinfo->scale_num * cinfo->block_size <= cinfo->scale_denom * 5) {
90     /* Provide 5/block_size scaling */
91     cinfo->output_width = (JDIMENSION)
92       jdiv_round_up((long) cinfo->image_width * 5L, (long) cinfo->block_size);
93     cinfo->output_height = (JDIMENSION)
94       jdiv_round_up((long) cinfo->image_height * 5L, (long) cinfo->block_size);
95     cinfo->min_DCT_h_scaled_size = 5;
96     cinfo->min_DCT_v_scaled_size = 5;
97   } else if (cinfo->scale_num * cinfo->block_size <= cinfo->scale_denom * 6) {
98     /* Provide 6/block_size scaling */
99     cinfo->output_width = (JDIMENSION)
100       jdiv_round_up((long) cinfo->image_width * 6L, (long) cinfo->block_size);
101     cinfo->output_height = (JDIMENSION)
102       jdiv_round_up((long) cinfo->image_height * 6L, (long) cinfo->block_size);
103     cinfo->min_DCT_h_scaled_size = 6;
104     cinfo->min_DCT_v_scaled_size = 6;
105   } else if (cinfo->scale_num * cinfo->block_size <= cinfo->scale_denom * 7) {
106     /* Provide 7/block_size scaling */
107     cinfo->output_width = (JDIMENSION)
108       jdiv_round_up((long) cinfo->image_width * 7L, (long) cinfo->block_size);
109     cinfo->output_height = (JDIMENSION)
110       jdiv_round_up((long) cinfo->image_height * 7L, (long) cinfo->block_size);
111     cinfo->min_DCT_h_scaled_size = 7;
112     cinfo->min_DCT_v_scaled_size = 7;
113   } else if (cinfo->scale_num * cinfo->block_size <= cinfo->scale_denom * 8) {
114     /* Provide 8/block_size scaling */
115     cinfo->output_width = (JDIMENSION)
116       jdiv_round_up((long) cinfo->image_width * 8L, (long) cinfo->block_size);
117     cinfo->output_height = (JDIMENSION)
118       jdiv_round_up((long) cinfo->image_height * 8L, (long) cinfo->block_size);
119     cinfo->min_DCT_h_scaled_size = 8;
120     cinfo->min_DCT_v_scaled_size = 8;
121   } else if (cinfo->scale_num * cinfo->block_size <= cinfo->scale_denom * 9) {
122     /* Provide 9/block_size scaling */
123     cinfo->output_width = (JDIMENSION)
124       jdiv_round_up((long) cinfo->image_width * 9L, (long) cinfo->block_size);
125     cinfo->output_height = (JDIMENSION)
126       jdiv_round_up((long) cinfo->image_height * 9L, (long) cinfo->block_size);
127     cinfo->min_DCT_h_scaled_size = 9;
128     cinfo->min_DCT_v_scaled_size = 9;
129   } else if (cinfo->scale_num * cinfo->block_size <= cinfo->scale_denom * 10) {
130     /* Provide 10/block_size scaling */
131     cinfo->output_width = (JDIMENSION)
132       jdiv_round_up((long) cinfo->image_width * 10L, (long) cinfo->block_size);
133     cinfo->output_height = (JDIMENSION)
134       jdiv_round_up((long) cinfo->image_height * 10L, (long) cinfo->block_size);
135     cinfo->min_DCT_h_scaled_size = 10;
136     cinfo->min_DCT_v_scaled_size = 10;
137   } else if (cinfo->scale_num * cinfo->block_size <= cinfo->scale_denom * 11) {
138     /* Provide 11/block_size scaling */
139     cinfo->output_width = (JDIMENSION)
140       jdiv_round_up((long) cinfo->image_width * 11L, (long) cinfo->block_size);
141     cinfo->output_height = (JDIMENSION)
142       jdiv_round_up((long) cinfo->image_height * 11L, (long) cinfo->block_size);
143     cinfo->min_DCT_h_scaled_size = 11;
144     cinfo->min_DCT_v_scaled_size = 11;
145   } else if (cinfo->scale_num * cinfo->block_size <= cinfo->scale_denom * 12) {
146     /* Provide 12/block_size scaling */
147     cinfo->output_width = (JDIMENSION)
148       jdiv_round_up((long) cinfo->image_width * 12L, (long) cinfo->block_size);
149     cinfo->output_height = (JDIMENSION)
150       jdiv_round_up((long) cinfo->image_height * 12L, (long) cinfo->block_size);
151     cinfo->min_DCT_h_scaled_size = 12;
152     cinfo->min_DCT_v_scaled_size = 12;
153   } else if (cinfo->scale_num * cinfo->block_size <= cinfo->scale_denom * 13) {
154     /* Provide 13/block_size scaling */
155     cinfo->output_width = (JDIMENSION)
156       jdiv_round_up((long) cinfo->image_width * 13L, (long) cinfo->block_size);
157     cinfo->output_height = (JDIMENSION)
158       jdiv_round_up((long) cinfo->image_height * 13L, (long) cinfo->block_size);
159     cinfo->min_DCT_h_scaled_size = 13;
160     cinfo->min_DCT_v_scaled_size = 13;
161   } else if (cinfo->scale_num * cinfo->block_size <= cinfo->scale_denom * 14) {
162     /* Provide 14/block_size scaling */
163     cinfo->output_width = (JDIMENSION)
164       jdiv_round_up((long) cinfo->image_width * 14L, (long) cinfo->block_size);
165     cinfo->output_height = (JDIMENSION)
166       jdiv_round_up((long) cinfo->image_height * 14L, (long) cinfo->block_size);
167     cinfo->min_DCT_h_scaled_size = 14;
168     cinfo->min_DCT_v_scaled_size = 14;
169   } else if (cinfo->scale_num * cinfo->block_size <= cinfo->scale_denom * 15) {
170     /* Provide 15/block_size scaling */
171     cinfo->output_width = (JDIMENSION)
172       jdiv_round_up((long) cinfo->image_width * 15L, (long) cinfo->block_size);
173     cinfo->output_height = (JDIMENSION)
174       jdiv_round_up((long) cinfo->image_height * 15L, (long) cinfo->block_size);
175     cinfo->min_DCT_h_scaled_size = 15;
176     cinfo->min_DCT_v_scaled_size = 15;
177   } else {
178     /* Provide 16/block_size scaling */
179     cinfo->output_width = (JDIMENSION)
180       jdiv_round_up((long) cinfo->image_width * 16L, (long) cinfo->block_size);
181     cinfo->output_height = (JDIMENSION)
182       jdiv_round_up((long) cinfo->image_height * 16L, (long) cinfo->block_size);
183     cinfo->min_DCT_h_scaled_size = 16;
184     cinfo->min_DCT_v_scaled_size = 16;
185   }
186
187   /* Recompute dimensions of components */
188   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
189        ci++, compptr++) {
190     compptr->DCT_h_scaled_size = cinfo->min_DCT_h_scaled_size;
191     compptr->DCT_v_scaled_size = cinfo->min_DCT_v_scaled_size;
192   }
193
194 #else /* !IDCT_SCALING_SUPPORTED */
195
196   /* Hardwire it to "no scaling" */
197   cinfo->output_width = cinfo->image_width;
198   cinfo->output_height = cinfo->image_height;
199   /* jdinput.c has already initialized DCT_scaled_size,
200    * and has computed unscaled downsampled_width and downsampled_height.
201    */
202
203 #endif /* IDCT_SCALING_SUPPORTED */
204 }
205
206
207 LOCAL(void)
208 initial_setup (j_decompress_ptr cinfo)
209 /* Called once, when first SOS marker is reached */
210 {
211   int ci;
212   jpeg_component_info *compptr;
213
214   /* Make sure image isn't bigger than I can handle */
215   if ((long) cinfo->image_height > (long) JPEG_MAX_DIMENSION ||
216       (long) cinfo->image_width > (long) JPEG_MAX_DIMENSION)
217     ERREXIT1(cinfo, JERR_IMAGE_TOO_BIG, (unsigned int) JPEG_MAX_DIMENSION);
218
219   /* For now, precision must match compiled-in value... */
220   if (cinfo->data_precision != BITS_IN_JSAMPLE)
221     ERREXIT1(cinfo, JERR_BAD_PRECISION, cinfo->data_precision);
222
223   /* Check that number of components won't exceed internal array sizes */
224   if (cinfo->num_components > MAX_COMPONENTS)
225     ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->num_components,
226              MAX_COMPONENTS);
227
228   /* Compute maximum sampling factors; check factor validity */
229   cinfo->max_h_samp_factor = 1;
230   cinfo->max_v_samp_factor = 1;
231   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
232        ci++, compptr++) {
233     if (compptr->h_samp_factor<=0 || compptr->h_samp_factor>MAX_SAMP_FACTOR ||
234         compptr->v_samp_factor<=0 || compptr->v_samp_factor>MAX_SAMP_FACTOR)
235       ERREXIT(cinfo, JERR_BAD_SAMPLING);
236     cinfo->max_h_samp_factor = MAX(cinfo->max_h_samp_factor,
237                                    compptr->h_samp_factor);
238     cinfo->max_v_samp_factor = MAX(cinfo->max_v_samp_factor,
239                                    compptr->v_samp_factor);
240   }
241
242   /* Derive block_size, natural_order, and lim_Se */
243   if (cinfo->is_baseline || (cinfo->progressive_mode &&
244       cinfo->comps_in_scan)) { /* no pseudo SOS marker */
245     cinfo->block_size = DCTSIZE;
246     cinfo->natural_order = jpeg_natural_order;
247     cinfo->lim_Se = DCTSIZE2-1;
248   } else
249     switch (cinfo->Se) {
250     case (1*1-1):
251       cinfo->block_size = 1;
252       cinfo->natural_order = jpeg_natural_order; /* not needed */
253       cinfo->lim_Se = cinfo->Se;
254       break;
255     case (2*2-1):
256       cinfo->block_size = 2;
257       cinfo->natural_order = jpeg_natural_order2;
258       cinfo->lim_Se = cinfo->Se;
259       break;
260     case (3*3-1):
261       cinfo->block_size = 3;
262       cinfo->natural_order = jpeg_natural_order3;
263       cinfo->lim_Se = cinfo->Se;
264       break;
265     case (4*4-1):
266       cinfo->block_size = 4;
267       cinfo->natural_order = jpeg_natural_order4;
268       cinfo->lim_Se = cinfo->Se;
269       break;
270     case (5*5-1):
271       cinfo->block_size = 5;
272       cinfo->natural_order = jpeg_natural_order5;
273       cinfo->lim_Se = cinfo->Se;
274       break;
275     case (6*6-1):
276       cinfo->block_size = 6;
277       cinfo->natural_order = jpeg_natural_order6;
278       cinfo->lim_Se = cinfo->Se;
279       break;
280     case (7*7-1):
281       cinfo->block_size = 7;
282       cinfo->natural_order = jpeg_natural_order7;
283       cinfo->lim_Se = cinfo->Se;
284       break;
285     case (8*8-1):
286       cinfo->block_size = 8;
287       cinfo->natural_order = jpeg_natural_order;
288       cinfo->lim_Se = DCTSIZE2-1;
289       break;
290     case (9*9-1):
291       cinfo->block_size = 9;
292       cinfo->natural_order = jpeg_natural_order;
293       cinfo->lim_Se = DCTSIZE2-1;
294       break;
295     case (10*10-1):
296       cinfo->block_size = 10;
297       cinfo->natural_order = jpeg_natural_order;
298       cinfo->lim_Se = DCTSIZE2-1;
299       break;
300     case (11*11-1):
301       cinfo->block_size = 11;
302       cinfo->natural_order = jpeg_natural_order;
303       cinfo->lim_Se = DCTSIZE2-1;
304       break;
305     case (12*12-1):
306       cinfo->block_size = 12;
307       cinfo->natural_order = jpeg_natural_order;
308       cinfo->lim_Se = DCTSIZE2-1;
309       break;
310     case (13*13-1):
311       cinfo->block_size = 13;
312       cinfo->natural_order = jpeg_natural_order;
313       cinfo->lim_Se = DCTSIZE2-1;
314       break;
315     case (14*14-1):
316       cinfo->block_size = 14;
317       cinfo->natural_order = jpeg_natural_order;
318       cinfo->lim_Se = DCTSIZE2-1;
319       break;
320     case (15*15-1):
321       cinfo->block_size = 15;
322       cinfo->natural_order = jpeg_natural_order;
323       cinfo->lim_Se = DCTSIZE2-1;
324       break;
325     case (16*16-1):
326       cinfo->block_size = 16;
327       cinfo->natural_order = jpeg_natural_order;
328       cinfo->lim_Se = DCTSIZE2-1;
329       break;
330     default:
331       ERREXIT4(cinfo, JERR_BAD_PROGRESSION,
332                cinfo->Ss, cinfo->Se, cinfo->Ah, cinfo->Al);
333       break;
334     }
335
336   /* We initialize DCT_scaled_size and min_DCT_scaled_size to block_size.
337    * In the full decompressor,
338    * this will be overridden by jpeg_calc_output_dimensions in jdmaster.c;
339    * but in the transcoder,
340    * jpeg_calc_output_dimensions is not used, so we must do it here.
341    */
342   cinfo->min_DCT_h_scaled_size = cinfo->block_size;
343   cinfo->min_DCT_v_scaled_size = cinfo->block_size;
344
345   /* Compute dimensions of components */
346   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
347        ci++, compptr++) {
348     compptr->DCT_h_scaled_size = cinfo->block_size;
349     compptr->DCT_v_scaled_size = cinfo->block_size;
350     /* Size in DCT blocks */
351     compptr->width_in_blocks = (JDIMENSION)
352       jdiv_round_up((long) cinfo->image_width * (long) compptr->h_samp_factor,
353                     (long) (cinfo->max_h_samp_factor * cinfo->block_size));
354     compptr->height_in_blocks = (JDIMENSION)
355       jdiv_round_up((long) cinfo->image_height * (long) compptr->v_samp_factor,
356                     (long) (cinfo->max_v_samp_factor * cinfo->block_size));
357     /* downsampled_width and downsampled_height will also be overridden by
358      * jdmaster.c if we are doing full decompression.  The transcoder library
359      * doesn't use these values, but the calling application might.
360      */
361     /* Size in samples */
362     compptr->downsampled_width = (JDIMENSION)
363       jdiv_round_up((long) cinfo->image_width * (long) compptr->h_samp_factor,
364                     (long) cinfo->max_h_samp_factor);
365     compptr->downsampled_height = (JDIMENSION)
366       jdiv_round_up((long) cinfo->image_height * (long) compptr->v_samp_factor,
367                     (long) cinfo->max_v_samp_factor);
368     /* Mark component needed, until color conversion says otherwise */
369     compptr->component_needed = TRUE;
370     /* Mark no quantization table yet saved for component */
371     compptr->quant_table = NULL;
372   }
373
374   /* Compute number of fully interleaved MCU rows. */
375   cinfo->total_iMCU_rows = (JDIMENSION)
376     jdiv_round_up((long) cinfo->image_height,
377                   (long) (cinfo->max_v_samp_factor * cinfo->block_size));
378
379   /* Decide whether file contains multiple scans */
380   if (cinfo->comps_in_scan < cinfo->num_components || cinfo->progressive_mode)
381     cinfo->inputctl->has_multiple_scans = TRUE;
382   else
383     cinfo->inputctl->has_multiple_scans = FALSE;
384 }
385
386
387 LOCAL(void)
388 per_scan_setup (j_decompress_ptr cinfo)
389 /* Do computations that are needed before processing a JPEG scan */
390 /* cinfo->comps_in_scan and cinfo->cur_comp_info[] were set from SOS marker */
391 {
392   int ci, mcublks, tmp;
393   jpeg_component_info *compptr;
394   
395   if (cinfo->comps_in_scan == 1) {
396     
397     /* Noninterleaved (single-component) scan */
398     compptr = cinfo->cur_comp_info[0];
399     
400     /* Overall image size in MCUs */
401     cinfo->MCUs_per_row = compptr->width_in_blocks;
402     cinfo->MCU_rows_in_scan = compptr->height_in_blocks;
403     
404     /* For noninterleaved scan, always one block per MCU */
405     compptr->MCU_width = 1;
406     compptr->MCU_height = 1;
407     compptr->MCU_blocks = 1;
408     compptr->MCU_sample_width = compptr->DCT_h_scaled_size;
409     compptr->last_col_width = 1;
410     /* For noninterleaved scans, it is convenient to define last_row_height
411      * as the number of block rows present in the last iMCU row.
412      */
413     tmp = (int) (compptr->height_in_blocks % compptr->v_samp_factor);
414     if (tmp == 0) tmp = compptr->v_samp_factor;
415     compptr->last_row_height = tmp;
416     
417     /* Prepare array describing MCU composition */
418     cinfo->blocks_in_MCU = 1;
419     cinfo->MCU_membership[0] = 0;
420     
421   } else {
422     
423     /* Interleaved (multi-component) scan */
424     if (cinfo->comps_in_scan <= 0 || cinfo->comps_in_scan > MAX_COMPS_IN_SCAN)
425       ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->comps_in_scan,
426                MAX_COMPS_IN_SCAN);
427     
428     /* Overall image size in MCUs */
429     cinfo->MCUs_per_row = (JDIMENSION)
430       jdiv_round_up((long) cinfo->image_width,
431                     (long) (cinfo->max_h_samp_factor * cinfo->block_size));
432     cinfo->MCU_rows_in_scan = (JDIMENSION)
433       jdiv_round_up((long) cinfo->image_height,
434                     (long) (cinfo->max_v_samp_factor * cinfo->block_size));
435     
436     cinfo->blocks_in_MCU = 0;
437     
438     for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
439       compptr = cinfo->cur_comp_info[ci];
440       /* Sampling factors give # of blocks of component in each MCU */
441       compptr->MCU_width = compptr->h_samp_factor;
442       compptr->MCU_height = compptr->v_samp_factor;
443       compptr->MCU_blocks = compptr->MCU_width * compptr->MCU_height;
444       compptr->MCU_sample_width = compptr->MCU_width * compptr->DCT_h_scaled_size;
445       /* Figure number of non-dummy blocks in last MCU column & row */
446       tmp = (int) (compptr->width_in_blocks % compptr->MCU_width);
447       if (tmp == 0) tmp = compptr->MCU_width;
448       compptr->last_col_width = tmp;
449       tmp = (int) (compptr->height_in_blocks % compptr->MCU_height);
450       if (tmp == 0) tmp = compptr->MCU_height;
451       compptr->last_row_height = tmp;
452       /* Prepare array describing MCU composition */
453       mcublks = compptr->MCU_blocks;
454       if (cinfo->blocks_in_MCU + mcublks > D_MAX_BLOCKS_IN_MCU)
455         ERREXIT(cinfo, JERR_BAD_MCU_SIZE);
456       while (mcublks-- > 0) {
457         cinfo->MCU_membership[cinfo->blocks_in_MCU++] = ci;
458       }
459     }
460     
461   }
462 }
463
464
465 /*
466  * Save away a copy of the Q-table referenced by each component present
467  * in the current scan, unless already saved during a prior scan.
468  *
469  * In a multiple-scan JPEG file, the encoder could assign different components
470  * the same Q-table slot number, but change table definitions between scans
471  * so that each component uses a different Q-table.  (The IJG encoder is not
472  * currently capable of doing this, but other encoders might.)  Since we want
473  * to be able to dequantize all the components at the end of the file, this
474  * means that we have to save away the table actually used for each component.
475  * We do this by copying the table at the start of the first scan containing
476  * the component.
477  * The JPEG spec prohibits the encoder from changing the contents of a Q-table
478  * slot between scans of a component using that slot.  If the encoder does so
479  * anyway, this decoder will simply use the Q-table values that were current
480  * at the start of the first scan for the component.
481  *
482  * The decompressor output side looks only at the saved quant tables,
483  * not at the current Q-table slots.
484  */
485
486 LOCAL(void)
487 latch_quant_tables (j_decompress_ptr cinfo)
488 {
489   int ci, qtblno;
490   jpeg_component_info *compptr;
491   JQUANT_TBL * qtbl;
492
493   for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
494     compptr = cinfo->cur_comp_info[ci];
495     /* No work if we already saved Q-table for this component */
496     if (compptr->quant_table != NULL)
497       continue;
498     /* Make sure specified quantization table is present */
499     qtblno = compptr->quant_tbl_no;
500     if (qtblno < 0 || qtblno >= NUM_QUANT_TBLS ||
501         cinfo->quant_tbl_ptrs[qtblno] == NULL)
502       ERREXIT1(cinfo, JERR_NO_QUANT_TABLE, qtblno);
503     /* OK, save away the quantization table */
504     qtbl = (JQUANT_TBL *)
505       (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
506                                   SIZEOF(JQUANT_TBL));
507     MEMCOPY(qtbl, cinfo->quant_tbl_ptrs[qtblno], SIZEOF(JQUANT_TBL));
508     compptr->quant_table = qtbl;
509   }
510 }
511
512
513 /*
514  * Initialize the input modules to read a scan of compressed data.
515  * The first call to this is done by jdmaster.c after initializing
516  * the entire decompressor (during jpeg_start_decompress).
517  * Subsequent calls come from consume_markers, below.
518  */
519
520 METHODDEF(void)
521 start_input_pass (j_decompress_ptr cinfo)
522 {
523   per_scan_setup(cinfo);
524   latch_quant_tables(cinfo);
525   (*cinfo->entropy->start_pass) (cinfo);
526   (*cinfo->coef->start_input_pass) (cinfo);
527   cinfo->inputctl->consume_input = cinfo->coef->consume_data;
528 }
529
530
531 /*
532  * Finish up after inputting a compressed-data scan.
533  * This is called by the coefficient controller after it's read all
534  * the expected data of the scan.
535  */
536
537 METHODDEF(void)
538 finish_input_pass (j_decompress_ptr cinfo)
539 {
540   cinfo->inputctl->consume_input = consume_markers;
541 }
542
543
544 /*
545  * Read JPEG markers before, between, or after compressed-data scans.
546  * Change state as necessary when a new scan is reached.
547  * Return value is JPEG_SUSPENDED, JPEG_REACHED_SOS, or JPEG_REACHED_EOI.
548  *
549  * The consume_input method pointer points either here or to the
550  * coefficient controller's consume_data routine, depending on whether
551  * we are reading a compressed data segment or inter-segment markers.
552  *
553  * Note: This function should NOT return a pseudo SOS marker (with zero
554  * component number) to the caller.  A pseudo marker received by
555  * read_markers is processed and then skipped for other markers.
556  */
557
558 METHODDEF(int)
559 consume_markers (j_decompress_ptr cinfo)
560 {
561   my_inputctl_ptr inputctl = (my_inputctl_ptr) cinfo->inputctl;
562   int val;
563
564   if (inputctl->pub.eoi_reached) /* After hitting EOI, read no further */
565     return JPEG_REACHED_EOI;
566
567   for (;;) {                    /* Loop to pass pseudo SOS marker */
568     val = (*cinfo->marker->read_markers) (cinfo);
569
570     switch (val) {
571     case JPEG_REACHED_SOS:      /* Found SOS */
572       if (inputctl->inheaders) { /* 1st SOS */
573         if (inputctl->inheaders == 1)
574           initial_setup(cinfo);
575         if (cinfo->comps_in_scan == 0) { /* pseudo SOS marker */
576           inputctl->inheaders = 2;
577           break;
578         }
579         inputctl->inheaders = 0;
580         /* Note: start_input_pass must be called by jdmaster.c
581          * before any more input can be consumed.  jdapimin.c is
582          * responsible for enforcing this sequencing.
583          */
584       } else {                  /* 2nd or later SOS marker */
585         if (! inputctl->pub.has_multiple_scans)
586           ERREXIT(cinfo, JERR_EOI_EXPECTED); /* Oops, I wasn't expecting this! */
587         if (cinfo->comps_in_scan == 0) /* unexpected pseudo SOS marker */
588           break;
589         start_input_pass(cinfo);
590       }
591       return val;
592     case JPEG_REACHED_EOI:      /* Found EOI */
593       inputctl->pub.eoi_reached = TRUE;
594       if (inputctl->inheaders) { /* Tables-only datastream, apparently */
595         if (cinfo->marker->saw_SOF)
596           ERREXIT(cinfo, JERR_SOF_NO_SOS);
597       } else {
598         /* Prevent infinite loop in coef ctlr's decompress_data routine
599          * if user set output_scan_number larger than number of scans.
600          */
601         if (cinfo->output_scan_number > cinfo->input_scan_number)
602           cinfo->output_scan_number = cinfo->input_scan_number;
603       }
604       return val;
605     case JPEG_SUSPENDED:
606       return val;
607     default:
608       return val;
609     }
610   }
611 }
612
613
614 /*
615  * Reset state to begin a fresh datastream.
616  */
617
618 METHODDEF(void)
619 reset_input_controller (j_decompress_ptr cinfo)
620 {
621   my_inputctl_ptr inputctl = (my_inputctl_ptr) cinfo->inputctl;
622
623   inputctl->pub.consume_input = consume_markers;
624   inputctl->pub.has_multiple_scans = FALSE; /* "unknown" would be better */
625   inputctl->pub.eoi_reached = FALSE;
626   inputctl->inheaders = 1;
627   /* Reset other modules */
628   (*cinfo->err->reset_error_mgr) ((j_common_ptr) cinfo);
629   (*cinfo->marker->reset_marker_reader) (cinfo);
630   /* Reset progression state -- would be cleaner if entropy decoder did this */
631   cinfo->coef_bits = NULL;
632 }
633
634
635 /*
636  * Initialize the input controller module.
637  * This is called only once, when the decompression object is created.
638  */
639
640 GLOBAL(void)
641 jinit_input_controller (j_decompress_ptr cinfo)
642 {
643   my_inputctl_ptr inputctl;
644
645   /* Create subobject in permanent pool */
646   inputctl = (my_inputctl_ptr)
647     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
648                                 SIZEOF(my_input_controller));
649   cinfo->inputctl = (struct jpeg_input_controller *) inputctl;
650   /* Initialize method pointers */
651   inputctl->pub.consume_input = consume_markers;
652   inputctl->pub.reset_input_controller = reset_input_controller;
653   inputctl->pub.start_input_pass = start_input_pass;
654   inputctl->pub.finish_input_pass = finish_input_pass;
655   /* Initialize state: can't use reset_input_controller since we don't
656    * want to try to reset other modules yet.
657    */
658   inputctl->pub.has_multiple_scans = FALSE; /* "unknown" would be better */
659   inputctl->pub.eoi_reached = FALSE;
660   inputctl->inheaders = 1;
661 }