aboutsummaryrefslogtreecommitdiffstats
path: root/code/jpeg-6b/jcmaster.c
blob: aab4020b8796ab29492aa1780898f3ccacc45413 (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
/*
 * jcmaster.c
 *
 * Copyright (C) 1991-1997, Thomas G. Lane.
 * This file is part of the Independent JPEG Group's software.
 * For conditions of distribution and use, see the accompanying README file.
 *
 * This file contains master control logic for the JPEG compressor.
 * These routines are concerned with parameter validation, initial setup,
 * and inter-pass control (determining the number of passes and the work 
 * to be done in each pass).
 */

#define JPEG_INTERNALS
#include "jinclude.h"
#include "jpeglib.h"


/* Private state */

typedef enum {
	main_pass,		/* input data, also do first output step */
	huff_opt_pass,		/* Huffman code optimization pass */
	output_pass		/* data output pass */
} c_pass_type;

typedef struct {
  struct jpeg_comp_master pub;	/* public fields */

  c_pass_type pass_type;	/* the type of the current pass */

  int pass_number;		/* # of passes completed */
  int total_passes;		/* total # of passes needed */

  int scan_number;		/* current index in scan_info[] */
} my_comp_master;

typedef my_comp_master * my_master_ptr;


/*
 * Support routines that do various essential calculations.
 */

LOCAL(void)
initial_setup (j_compress_ptr cinfo)
/* Do computations that are needed before master selection phase */
{
  int ci;
  jpeg_component_info *compptr;
  long samplesperrow;
  JDIMENSION jd_samplesperrow;

  /* Sanity check on image dimensions */
  if (cinfo->image_height <= 0 || cinfo->image_width <= 0
      || cinfo->num_components <= 0 || cinfo->input_components <= 0)
    ERREXIT(cinfo, JERR_EMPTY_IMAGE);

  /* Make sure image isn't bigger than I can handle */
  if ((long) cinfo->image_height > (long) JPEG_MAX_DIMENSION ||
      (long) cinfo->image_width > (long) JPEG_MAX_DIMENSION)
    ERREXIT1(cinfo, JERR_IMAGE_TOO_BIG, (unsigned int) JPEG_MAX_DIMENSION);

  /* Width of an input scanline must be representable as JDIMENSION. */
  samplesperrow = (long) cinfo->image_width * (long) cinfo->input_components;
  jd_samplesperrow = (JDIMENSION) samplesperrow;
  if ((long) jd_samplesperrow != samplesperrow)
    ERREXIT(cinfo, JERR_WIDTH_OVERFLOW);

  /* For now, precision must match compiled-in value... */
  if (cinfo->data_precision != BITS_IN_JSAMPLE)
    ERREXIT1(cinfo, JERR_BAD_PRECISION, cinfo->data_precision);

  /* Check that number of components won't exceed internal array sizes */
  if (cinfo->num_components > MAX_COMPONENTS)
    ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->num_components,
	     MAX_COMPONENTS);

  /* Compute maximum sampling factors; check factor validity */
  cinfo->max_h_samp_factor = 1;
  cinfo->max_v_samp_factor = 1;
  for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
       ci++, compptr++) {
    if (compptr->h_samp_factor<=0 || compptr->h_samp_factor>MAX_SAMP_FACTOR ||
	compptr->v_samp_factor<=0 || compptr->v_samp_factor>MAX_SAMP_FACTOR)
      ERREXIT(cinfo, JERR_BAD_SAMPLING);
    cinfo->max_h_samp_factor = MAX(cinfo->max_h_samp_factor,
				   compptr->h_samp_factor);
    cinfo->max_v_samp_factor = MAX(cinfo->max_v_samp_factor,
				   compptr->v_samp_factor);
  }

  /* Compute dimensions of components */
  for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
       ci++, compptr++) {
    /* Fill in the correct component_index value; don't rely on application */
    compptr->component_index = ci;
    /* For compression, we never do DCT scaling. */
    compptr->DCT_scaled_size = DCTSIZE;
    /* Size in DCT blocks */
    compptr->width_in_blocks = (JDIMENSION)
      jdiv_round_up((long) cinfo->image_width * (long) compptr->h_samp_factor,
		    (long) (cinfo->max_h_samp_factor * DCTSIZE));
    compptr->height_in_blocks = (JDIMENSION)
      jdiv_round_up((long) cinfo->image_height * (long) compptr->v_samp_factor,
		    (long) (cinfo->max_v_samp_factor * DCTSIZE));
    /* Size in samples */
    compptr->downsampled_width = (JDIMENSION)
      jdiv_round_up((long) cinfo->image_width * (long) compptr->h_samp_factor,
		    (long) cinfo->max_h_samp_factor);
    compptr->downsampled_height = (JDIMENSION)
      jdiv_round_up((long) cinfo->image_height * (long) compptr->v_samp_factor,
		    (long) cinfo->max_v_samp_factor);
    /* Mark component needed (this flag isn't actually used for compression) */
    compptr->component_needed = TRUE;
  }

  /* Compute number of fully interleaved MCU rows (number of times that
   * main controller will call coefficient controller).
   */
  cinfo->total_iMCU_rows = (JDIMENSION)
    jdiv_round_up((long) cinfo->image_height,
		  (long) (cinfo->max_v_samp_factor*DCTSIZE));
}


#ifdef C_MULTISCAN_FILES_SUPPORTED

LOCAL(void)
validate_script (j_compress_ptr cinfo)
/* Verify that the scan script in cinfo->scan_info[] is valid; also
 * determine whether it uses progressive JPEG, and set cinfo->progressive_mode.
 */
{
  const jpeg_scan_info * scanptr;
  int scanno, ncomps, ci, coefi, thisi;
  int Ss, Se, Ah, Al;
  boolean component_sent[MAX_COMPONENTS];
#ifdef C_PROGRESSIVE_SUPPORTED
  int * last_bitpos_ptr;
  int last_bitpos[MAX_COMPONENTS][DCTSIZE2];
  /* -1 until that coefficient has been seen; then last Al for it */
#endif

  if (cinfo->num_scans <= 0)
    ERREXIT1(cinfo, JERR_BAD_SCAN_SCRIPT, 0);

  /* For sequential JPEG, all scans must have Ss=0, Se=DCTSIZE2-1;
   * for progressive JPEG, no scan can have this.
   */
  scanptr = cinfo->scan_info;
  if (scanptr->Ss != 0 || scanptr->Se != DCTSIZE2-1) {
#ifdef C_PROGRESSIVE_SUPPORTED
    cinfo->progressive_mode = TRUE;
    last_bitpos_ptr = & last_bitpos[0][0];
    for (ci = 0; ci < cinfo->num_components; ci++) 
      for (coefi = 0; coefi < DCTSIZE2; coefi++)
	*last_bitpos_ptr++ = -1;
#else
    ERREXIT(cinfo, JERR_NOT_COMPILED);
#endif
  } else {
    cinfo->progressive_mode = FALSE;
    for (ci = 0; ci < cinfo->num_components; ci++) 
      component_sent[ci] = FALSE;
  }

  for (scanno = 1; scanno <= cinfo->num_scans; scanptr++, scanno++) {
    /* Validate component indexes */
    ncomps = scanptr->comps_in_scan;
    if (ncomps <= 0 || ncomps > MAX_COMPS_IN_SCAN)
      ERREXIT2(cinfo, JERR_COMPONENT_COUNT, ncomps, MAX_COMPS_IN_SCAN);
    for (ci = 0; ci < ncomps; ci++) {
      thisi = scanptr->component_index[ci];
      if (thisi < 0 || thisi >= cinfo->num_components)
	ERREXIT1(cinfo, JERR_BAD_SCAN_SCRIPT, scanno);
      /* Components must appear in SOF order within each scan */
      if (ci > 0 && thisi <= scanptr->component_index[ci-1])
	ERREXIT1(cinfo, JERR_BAD_SCAN_SCRIPT, scanno);
    }
    /* Validate progression parameters */
    Ss = scanptr->Ss;
    Se = scanptr->Se;
    Ah = scanptr->Ah;
    Al = scanptr->Al;
    if (cinfo->progressive_mode) {
#ifdef C_PROGRESSIVE_SUPPORTED
      /* The JPEG spec simply gives the ranges 0..13 for Ah and Al, but that
       * seems wrong: the upper bound ought to depend on data precision.
       * Perhaps they really meant 0..N+1 for N-bit precision.
       * Here we allow 0..10 for 8-bit data; Al larger than 10 results in
       * out-of-range reconstructed DC values during the first DC scan,
       * which might cause problems for some decoders.
       */
#if BITS_IN_JSAMPLE == 8
#define MAX_AH_AL 10
#else
#define MAX_AH_AL 13
#endif
      if (Ss < 0 || Ss >= DCTSIZE2 || Se < Ss || Se >= DCTSIZE2 ||
	  Ah < 0 || Ah > MAX_AH_AL || Al < 0 || Al > MAX_AH_AL)
	ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
      if (Ss == 0) {
	if (Se != 0)		/* DC and AC together not OK */
	  ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
      } else {
	if (ncomps != 1)	/* AC scans must be for only one component */
	  ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
      }
      for (ci = 0; ci < ncomps; ci++) {
	last_bitpos_ptr = & last_bitpos[scanptr->component_index[ci]][0];
	if (Ss != 0 && last_bitpos_ptr[0] < 0) /* AC without prior DC scan */
	  ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
	for (coefi = Ss; coefi <= Se; coefi++) {
	  if (last_bitpos_ptr[coefi] < 0) {
	    /* first scan of this coefficient */
	    if (Ah != 0)
	      ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
	  } else {
	    /* not first scan */
	    if (Ah != last_bitpos_ptr[coefi] || Al != Ah-1)
	      ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
	  }
	  last_bitpos_ptr[coefi] = Al;
	}
      }
#endif
    } else {
      /* For sequential JPEG, all progression parameters must be these: */
      if (Ss != 0 || Se != DCTSIZE2-1 || Ah != 0 || Al != 0)
	ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
      /* Make sure components are not sent twice */
      for (ci = 0; ci < ncomps; ci++) {
	thisi = scanptr->component_index[ci];
	if (component_sent[thisi])
	  ERREXIT1(cinfo, JERR_BAD_SCAN_SCRIPT, scanno);
	component_sent[thisi] = TRUE;
      }
    }
  }

  /* Now verify that everything got sent. */
  if (cinfo->progressive_mode) {
#ifdef C_PROGRESSIVE_SUPPORTED
    /* For progressive mode, we only check that at least some DC data
     * got sent for each component; the spec does not require that all bits
     * of all coefficients be transmitted.  Would it be wiser to enforce
     * transmission of all coefficient bits??
     */
    for (ci = 0; ci < cinfo->num_components; ci++) {
      if (last_bitpos[ci][0] < 0)
	ERREXIT(cinfo, JERR_MISSING_DATA);
    }
#endif
  } else {
    for (ci = 0; ci < cinfo->num_components; ci++) {
      if (! component_sent[ci])
	ERREXIT(cinfo, JERR_MISSING_DATA);
    }
  }
}

#endif /* C_MULTISCAN_FILES_SUPPORTED */


LOCAL(void)
select_scan_parameters (j_compress_ptr cinfo)
/* Set up the scan parameters for the current scan */
{
  int ci;

#ifdef C_MULTISCAN_FILES_SUPPORTED
  if (cinfo->scan_info != NULL) {
    /* Prepare for current scan --- the script is already validated */
    my_master_ptr master = (my_master_ptr) cinfo->master;
    const jpeg_scan_info * scanptr = cinfo->scan_info + master->scan_number;

    cinfo->comps_in_scan = scanptr->comps_in_scan;
    for (ci = 0; ci < scanptr->comps_in_scan; ci++) {
      cinfo->cur_comp_info[ci] =
	&cinfo->comp_info[scanptr->component_index[ci]];
    }
    cinfo->Ss = scanptr->Ss;
    cinfo->Se = scanptr->Se;
    cinfo->Ah = scanptr->Ah;
    cinfo->Al = scanptr->Al;
  }
  else
#endif
  {
    /* Prepare for single sequential-JPEG scan containing all components */
    if (cinfo->num_components > MAX_COMPS_IN_SCAN)
      ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->num_components,
	       MAX_COMPS_IN_SCAN);
    cinfo->comps_in_scan = cinfo->num_components;
    for (ci = 0; ci < cinfo->num_components; ci++) {
      cinfo->cur_comp_info[ci] = &cinfo->comp_info[ci];
    }
    cinfo->Ss = 0;
    cinfo->Se = DCTSIZE2-1;
    cinfo->Ah = 0;
    cinfo->Al = 0;
  }
}


LOCAL(void)
per_scan_setup (j_compress_ptr cinfo)
/* Do computations that are needed before processing a JPEG scan */
/* cinfo->comps_in_scan and cinfo->cur_comp_info[] are already set */
{
  int ci, mcublks, tmp;
  jpeg_component_info *compptr;
  
  if (cinfo->comps_in_scan == 1) {
    
    /* Noninterleaved (single-component) scan */
    compptr = cinfo->cur_comp_info[0];
    
    /* Overall image size in MCUs */
    cinfo->MCUs_per_row = compptr->width_in_blocks;
    cinfo->MCU_rows_in_scan = compptr->height_in_blocks;
    
    /* For noninterleaved scan, always one block per MCU */
    compptr->MCU_width = 1;
    compptr->MCU_height = 1;
    compptr->MCU_blocks = 1;
    compptr->MCU_sample_width = DCTSIZE;
    compptr->last_col_width = 1;
    /* For noninterleaved scans, it is convenient to define last_row_height
     * as the number of block rows present in the last iMCU row.
     */
    tmp = (int) (compptr->height_in_blocks % compptr->v_samp_factor);
    if (tmp == 0) tmp = compptr->v_samp_factor;
    compptr->last_row_height = tmp;
    
    /* Prepare array describing MCU composition */
    cinfo->blocks_in_MCU = 1;
    cinfo->MCU_membership[0] = 0;
    
  } else {
    
    /* Interleaved (multi-component) scan */
    if (cinfo->comps_in_scan <= 0 || cinfo->comps_in_scan > MAX_COMPS_IN_SCAN)
      ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->comps_in_scan,
	       MAX_COMPS_IN_SCAN);
    
    /* Overall image size in MCUs */
    cinfo->MCUs_per_row = (JDIMENSION)
      jdiv_round_up((long) cinfo->image_width,
		    (long) (cinfo->max_h_samp_factor*DCTSIZE));
    cinfo->MCU_rows_in_scan = (JDIMENSION)
      jdiv_round_up((long) cinfo->image_height,
		    (long) (cinfo->max_v_samp_factor*DCTSIZE));
    
    cinfo->blocks_in_MCU = 0;
    
    for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
      compptr = cinfo->cur_comp_info[ci];
      /* Sampling factors give # of blocks of component in each MCU */
      compptr->MCU_width = compptr->h_samp_factor;
      compptr->MCU_height = compptr->v_samp_factor;
      compptr->MCU_blocks = compptr->MCU_width * compptr->MCU_height;
      compptr->MCU_sample_width = compptr->MCU_width * DCTSIZE;
      /* Figure number of non-dummy blocks in last MCU column & row */
      tmp = (int) (compptr->width_in_blocks % compptr->MCU_width);
      if (tmp == 0) tmp = compptr->MCU_width;
      compptr->last_col_width = tmp;
      tmp = (int) (compptr->height_in_blocks % compptr->MCU_height);
      if (tmp == 0) tmp = compptr->MCU_height;
      compptr->last_row_height = tmp;
      /* Prepare array describing MCU composition */
      mcublks = compptr->MCU_blocks;
      if (cinfo->blocks_in_MCU + mcublks > C_MAX_BLOCKS_IN_MCU)
	ERREXIT(cinfo, JERR_BAD_MCU_SIZE);
      while (mcublks-- > 0) {
	cinfo->MCU_membership[cinfo->blocks_in_MCU++] = ci;
      }
    }
    
  }

  /* Convert restart specified in rows to actual MCU count. */
  /* Note that count must fit in 16 bits, so we provide limiting. */
  if (cinfo->restart_in_rows > 0) {
    long nominal = (long) cinfo->restart_in_rows * (long) cinfo->MCUs_per_row;
    cinfo->restart_interval = (unsigned int) MIN(nominal, 65535L);
  }
}


/*
 * Per-pass setup.
 * This is called at the beginning of each pass.  We determine which modules
 * will be active during this pass and give them appropriate start_pass calls.
 * We also set is_last_pass to indicate whether any more passes will be
 * required.
 */

METHODDEF(void)
prepare_for_pass (j_compress_ptr cinfo)
{
  my_master_ptr master = (my_master_ptr) cinfo->master;

  switch (master->pass_type) {
  case main_pass:
    /* Initial pass: will collect input data, and do either Huffman
     * optimization or data output for the first scan.
     */
    select_scan_parameters(cinfo);
    per_scan_setup(cinfo);
    if (! cinfo->raw_data_in) {
      (*cinfo->cconvert->start_pass) (cinfo);
      (*cinfo->downsample->start_pass) (cinfo);
      (*cinfo->prep->start_pass) (cinfo, JBUF_PASS_THRU);
    }
    (*cinfo->fdct->start_pass) (cinfo);
    (*cinfo->entropy->start_pass) (cinfo, cinfo->optimize_coding);
    (*cinfo->coef->start_pass) (cinfo,
				(master->total_passes > 1 ?
				 JBUF_SAVE_AND_PASS : JBUF_PASS_THRU));
    (*cinfo->main->start_pass) (cinfo, JBUF_PASS_THRU);
    if (cinfo->optimize_coding) {
      /* No immediate data output; postpone writing frame/scan headers */
      master->pub.call_pass_startup = FALSE;
    } else {
      /* Will write frame/scan headers at first jpeg_write_scanlines call */
      master->pub.call_pass_startup = TRUE;
    }
    break;
#ifdef ENTROPY_OPT_SUPPORTED
  case huff_opt_pass:
    /* Do Huffman optimization for a scan after the first one. */
    select_scan_parameters(cinfo);
    per_scan_setup(cinfo);
    if (cinfo->Ss != 0 || cinfo->Ah == 0 || cinfo->arith_code) {
      (*cinfo->entropy->start_pass) (cinfo, TRUE);
      (*cinfo->coef->start_pass) (cinfo, JBUF_CRANK_DEST);
      master->pub.call_pass_startup = FALSE;
      break;
    }
    /* Special case: Huffman DC refinement scans need no Huffman table
     * and therefore we can skip the optimization pass for them.
     */
    master->pass_type = output_pass;
    master->pass_number++;
    /*FALLTHROUGH*/
#endif
  case output_pass:
    /* Do a data-output pass. */
    /* We need not repeat per-scan setup if prior optimization pass did it. */
    if (! cinfo->optimize_coding) {
      select_scan_parameters(cinfo);
      per_scan_setup(cinfo);
    }
    (*cinfo->entropy->start_pass) (cinfo, FALSE);
    (*cinfo->coef->start_pass) (cinfo, JBUF_CRANK_DEST);
    /* We emit frame/scan headers now */
    if (master->scan_number == 0)
      (*cinfo->marker->write_frame_header) (cinfo);
    (*cinfo->marker->write_scan_header) (cinfo);
    master->pub.call_pass_startup = FALSE;
    break;
  default:
    ERREXIT(cinfo, JERR_NOT_COMPILED);
  }

  master->pub.is_last_pass = (master->pass_number == master->total_passes-1);

  /* Set up progress monitor's pass info if present */
  if (cinfo->progress != NULL) {
    cinfo->progress->completed_passes = master->pass_number;
    cinfo->progress->total_passes = master->total_passes;
  }
}


/*
 * Special start-of-pass hook.
 * This is called by jpeg_write_scanlines if call_pass_startup is TRUE.
 * In single-pass processing, we need this hook because we don't want to
 * write frame/scan headers during jpeg_start_compress; we want to let the
 * application write COM markers etc. between jpeg_start_compress and the
 * jpeg_write_scanlines loop.
 * In multi-pass processing, this routine is not used.
 */

METHODDEF(void)
pass_startup (j_compress_ptr cinfo)
{
  cinfo->master->call_pass_startup = FALSE; /* reset flag so call only once */

  (*cinfo->marker->write_frame_header) (cinfo);
  (*cinfo->marker->write_scan_header) (cinfo);
}


/*
 * Finish up at end of pass.
 */

METHODDEF(void)
finish_pass_master (j_compress_ptr cinfo)
{
  my_master_ptr master = (my_master_ptr) cinfo->master;

  /* The entropy coder always needs an end-of-pass call,
   * either to analyze statistics or to flush its output buffer.
   */
  (*cinfo->entropy->finish_pass) (cinfo);

  /* Update state for next pass */
  switch (master->pass_type) {
  case main_pass:
    /* next pass is either output of scan 0 (after optimization)
     * or output of scan 1 (if no optimization).
     */
    master->pass_type = output_pass;
    if (! cinfo->optimize_coding)
      master->scan_number++;
    break;
  case huff_opt_pass:
    /* next pass is always output of current scan */
    master->pass_type = output_pass;
    break;
  case output_pass:
    /* next pass is either optimization or output of next scan */
    if (cinfo->optimize_coding)
      master->pass_type = huff_opt_pass;
    master->scan_number++;
    break;
  }

  master->pass_number++;
}


/*
 * Initialize master compression control.
 */

GLOBAL(void)
jinit_c_master_control (j_compress_ptr cinfo, boolean transcode_only)
{
  my_master_ptr master;

  master = (my_master_ptr)
      (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
				  SIZEOF(my_comp_master));
  cinfo->master = (struct jpeg_comp_master *) master;
  master->pub.prepare_for_pass = prepare_for_pass;
  master->pub.pass_startup = pass_startup;
  master->pub.finish_pass = finish_pass_master;
  master->pub.is_last_pass = FALSE;

  /* Validate parameters, determine derived values */
  initial_setup(cinfo);

  if (cinfo->scan_info != NULL) {
#ifdef C_MULTISCAN_FILES_SUPPORTED
    validate_script(cinfo);
#else
    ERREXIT(cinfo, JERR_NOT_COMPILED);
#endif
  } else {
    cinfo->progressive_mode = FALSE;
    cinfo->num_scans = 1;
  }

  if (cinfo->progressive_mode)	/*  TEMPORARY HACK ??? */
    cinfo->optimize_coding = TRUE; /* assume default tables no good for progressive mode */

  /* Initialize my private state */
  if (transcode_only) {
    /* no main pass in transcoding */
    if (cinfo->optimize_coding)
      master->pass_type = huff_opt_pass;
    else
      master->pass_type = output_pass;
  } else {
    /* for normal compression, first pass is always this type: */
    master->pass_type = main_pass;
  }
  master->scan_number = 0;
  master->pass_number = 0;
  if (cinfo->optimize_coding)
    master->total_passes = cinfo->num_scans * 2;
  else
    master->total_passes = cinfo->num_scans;
}