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1
/*
2
 * jcmaster.c
3
 *
4
 * Copyright (C) 1991-1997, Thomas G. Lane.
5
 * This file is part of the Independent JPEG Group's software.
6
 * For conditions of distribution and use, see the accompanying README file.
7
 *
8
 * This file contains master control logic for the JPEG compressor.
9
 * These routines are concerned with parameter validation, initial setup,
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 * and inter-pass control (determining the number of passes and the work 
11
 * to be done in each pass).
12
 */
13

14
#define JPEG_INTERNALS
15
#include "jinclude.h"
16
#include "jpeglib.h"
17

18

19
/* Private state */
20

21
typedef enum {
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	main_pass,		/* input data, also do first output step */
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	huff_opt_pass,		/* Huffman code optimization pass */
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	output_pass		/* data output pass */
25
} c_pass_type;
26

27
typedef struct {
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  struct jpeg_comp_master pub;	/* public fields */
29

30
  c_pass_type pass_type;	/* the type of the current pass */
31

32
  int pass_number;		/* # of passes completed */
33
  int total_passes;		/* total # of passes needed */
34

35
  int scan_number;		/* current index in scan_info[] */
36
} my_comp_master;
37

38
typedef my_comp_master * my_master_ptr;
39

40

41
/*
42
 * Support routines that do various essential calculations.
43
 */
44

45
LOCAL(void)
46
initial_setup (j_compress_ptr cinfo)
47
/* Do computations that are needed before master selection phase */
48
{
49
  int ci;
50
  jpeg_component_info *compptr;
51
  long samplesperrow;
52
  JDIMENSION jd_samplesperrow;
53

54
  /* Sanity check on image dimensions */
55
  if (cinfo->image_height <= 0 || cinfo->image_width <= 0
56
      || cinfo->num_components <= 0 || cinfo->input_components <= 0)
57
    ERREXIT(cinfo, JERR_EMPTY_IMAGE);
58

59
  /* Make sure image isn't bigger than I can handle */
60
  if ((long) cinfo->image_height > (long) JPEG_MAX_DIMENSION ||
61
      (long) cinfo->image_width > (long) JPEG_MAX_DIMENSION)
62
    ERREXIT1(cinfo, JERR_IMAGE_TOO_BIG, (unsigned int) JPEG_MAX_DIMENSION);
63

64
  /* Width of an input scanline must be representable as JDIMENSION. */
65
  samplesperrow = (long) cinfo->image_width * (long) cinfo->input_components;
66
  jd_samplesperrow = (JDIMENSION) samplesperrow;
67
  if ((long) jd_samplesperrow != samplesperrow)
68
    ERREXIT(cinfo, JERR_WIDTH_OVERFLOW);
69

70
  /* For now, precision must match compiled-in value... */
71
  if (cinfo->data_precision != BITS_IN_JSAMPLE)
72
    ERREXIT1(cinfo, JERR_BAD_PRECISION, cinfo->data_precision);
73

74
  /* Check that number of components won't exceed internal array sizes */
75
  if (cinfo->num_components > MAX_COMPONENTS)
76
    ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->num_components,
77
	     MAX_COMPONENTS);
78

79
  /* Compute maximum sampling factors; check factor validity */
80
  cinfo->max_h_samp_factor = 1;
81
  cinfo->max_v_samp_factor = 1;
82
  for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
83
       ci++, compptr++) {
84
    if (compptr->h_samp_factor<=0 || compptr->h_samp_factor>MAX_SAMP_FACTOR ||
85
	compptr->v_samp_factor<=0 || compptr->v_samp_factor>MAX_SAMP_FACTOR)
86
      ERREXIT(cinfo, JERR_BAD_SAMPLING);
87
    cinfo->max_h_samp_factor = MAX(cinfo->max_h_samp_factor,
88
				   compptr->h_samp_factor);
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    cinfo->max_v_samp_factor = MAX(cinfo->max_v_samp_factor,
90
				   compptr->v_samp_factor);
91
  }
92

93
  /* Compute dimensions of components */
94
  for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
95
       ci++, compptr++) {
96
    /* Fill in the correct component_index value; don't rely on application */
97
    compptr->component_index = ci;
98
    /* For compression, we never do DCT scaling. */
99
    compptr->DCT_scaled_size = DCTSIZE;
100
    /* Size in DCT blocks */
101
    compptr->width_in_blocks = (JDIMENSION)
102
      jdiv_round_up((long) cinfo->image_width * (long) compptr->h_samp_factor,
103
		    (long) (cinfo->max_h_samp_factor * DCTSIZE));
104
    compptr->height_in_blocks = (JDIMENSION)
105
      jdiv_round_up((long) cinfo->image_height * (long) compptr->v_samp_factor,
106
		    (long) (cinfo->max_v_samp_factor * DCTSIZE));
107
    /* Size in samples */
108
    compptr->downsampled_width = (JDIMENSION)
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      jdiv_round_up((long) cinfo->image_width * (long) compptr->h_samp_factor,
110
		    (long) cinfo->max_h_samp_factor);
111
    compptr->downsampled_height = (JDIMENSION)
112
      jdiv_round_up((long) cinfo->image_height * (long) compptr->v_samp_factor,
113
		    (long) cinfo->max_v_samp_factor);
114
    /* Mark component needed (this flag isn't actually used for compression) */
115
    compptr->component_needed = TRUE;
116
  }
117

118
  /* Compute number of fully interleaved MCU rows (number of times that
119
   * main controller will call coefficient controller).
120
   */
121
  cinfo->total_iMCU_rows = (JDIMENSION)
122
    jdiv_round_up((long) cinfo->image_height,
123
		  (long) (cinfo->max_v_samp_factor*DCTSIZE));
124
}
125

126

127
#ifdef C_MULTISCAN_FILES_SUPPORTED
128

129
LOCAL(void)
130
validate_script (j_compress_ptr cinfo)
131
/* Verify that the scan script in cinfo->scan_info[] is valid; also
132
 * determine whether it uses progressive JPEG, and set cinfo->progressive_mode.
133
 */
134
{
135
  const jpeg_scan_info * scanptr;
136
  int scanno, ncomps, ci, coefi, thisi;
137
  int Ss, Se, Ah, Al;
138
  boolean component_sent[MAX_COMPONENTS];
139
#ifdef C_PROGRESSIVE_SUPPORTED
140
  int * last_bitpos_ptr;
141
  int last_bitpos[MAX_COMPONENTS][DCTSIZE2];
142
  /* -1 until that coefficient has been seen; then last Al for it */
143
#endif
144

145
  if (cinfo->num_scans <= 0)
146
    ERREXIT1(cinfo, JERR_BAD_SCAN_SCRIPT, 0);
147

148
  /* For sequential JPEG, all scans must have Ss=0, Se=DCTSIZE2-1;
149
   * for progressive JPEG, no scan can have this.
150
   */
151
  scanptr = cinfo->scan_info;
152
  if (scanptr->Ss != 0 || scanptr->Se != DCTSIZE2-1) {
153
#ifdef C_PROGRESSIVE_SUPPORTED
154
    cinfo->progressive_mode = TRUE;
155
    last_bitpos_ptr = & last_bitpos[0][0];
156
    for (ci = 0; ci < cinfo->num_components; ci++) 
157
      for (coefi = 0; coefi < DCTSIZE2; coefi++)
158
	*last_bitpos_ptr++ = -1;
159
#else
160
    ERREXIT(cinfo, JERR_NOT_COMPILED);
161
#endif
162
  } else {
163
    cinfo->progressive_mode = FALSE;
164
    for (ci = 0; ci < cinfo->num_components; ci++) 
165
      component_sent[ci] = FALSE;
166
  }
167

168
  for (scanno = 1; scanno <= cinfo->num_scans; scanptr++, scanno++) {
169
    /* Validate component indexes */
170
    ncomps = scanptr->comps_in_scan;
171
    if (ncomps <= 0 || ncomps > MAX_COMPS_IN_SCAN)
172
      ERREXIT2(cinfo, JERR_COMPONENT_COUNT, ncomps, MAX_COMPS_IN_SCAN);
173
    for (ci = 0; ci < ncomps; ci++) {
174
      thisi = scanptr->component_index[ci];
175
      if (thisi < 0 || thisi >= cinfo->num_components)
176
	ERREXIT1(cinfo, JERR_BAD_SCAN_SCRIPT, scanno);
177
      /* Components must appear in SOF order within each scan */
178
      if (ci > 0 && thisi <= scanptr->component_index[ci-1])
179
	ERREXIT1(cinfo, JERR_BAD_SCAN_SCRIPT, scanno);
180
    }
181
    /* Validate progression parameters */
182
    Ss = scanptr->Ss;
183
    Se = scanptr->Se;
184
    Ah = scanptr->Ah;
185
    Al = scanptr->Al;
186
    if (cinfo->progressive_mode) {
187
#ifdef C_PROGRESSIVE_SUPPORTED
188
      /* The JPEG spec simply gives the ranges 0..13 for Ah and Al, but that
189
       * seems wrong: the upper bound ought to depend on data precision.
190
       * Perhaps they really meant 0..N+1 for N-bit precision.
191
       * Here we allow 0..10 for 8-bit data; Al larger than 10 results in
192
       * out-of-range reconstructed DC values during the first DC scan,
193
       * which might cause problems for some decoders.
194
       */
195
#if BITS_IN_JSAMPLE == 8
196
#define MAX_AH_AL 10
197
#else
198
#define MAX_AH_AL 13
199
#endif
200
      if (Ss < 0 || Ss >= DCTSIZE2 || Se < Ss || Se >= DCTSIZE2 ||
201
	  Ah < 0 || Ah > MAX_AH_AL || Al < 0 || Al > MAX_AH_AL)
202
	ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
203
      if (Ss == 0) {
204
	if (Se != 0)		/* DC and AC together not OK */
205
	  ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
206
      } else {
207
	if (ncomps != 1)	/* AC scans must be for only one component */
208
	  ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
209
      }
210
      for (ci = 0; ci < ncomps; ci++) {
211
	last_bitpos_ptr = & last_bitpos[scanptr->component_index[ci]][0];
212
	if (Ss != 0 && last_bitpos_ptr[0] < 0) /* AC without prior DC scan */
213
	  ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
214
	for (coefi = Ss; coefi <= Se; coefi++) {
215
	  if (last_bitpos_ptr[coefi] < 0) {
216
	    /* first scan of this coefficient */
217
	    if (Ah != 0)
218
	      ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
219
	  } else {
220
	    /* not first scan */
221
	    if (Ah != last_bitpos_ptr[coefi] || Al != Ah-1)
222
	      ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
223
	  }
224
	  last_bitpos_ptr[coefi] = Al;
225
	}
226
      }
227
#endif
228
    } else {
229
      /* For sequential JPEG, all progression parameters must be these: */
230
      if (Ss != 0 || Se != DCTSIZE2-1 || Ah != 0 || Al != 0)
231
	ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
232
      /* Make sure components are not sent twice */
233
      for (ci = 0; ci < ncomps; ci++) {
234
	thisi = scanptr->component_index[ci];
235
	if (component_sent[thisi])
236
	  ERREXIT1(cinfo, JERR_BAD_SCAN_SCRIPT, scanno);
237
	component_sent[thisi] = TRUE;
238
      }
239
    }
240
  }
241

242
  /* Now verify that everything got sent. */
243
  if (cinfo->progressive_mode) {
244
#ifdef C_PROGRESSIVE_SUPPORTED
245
    /* For progressive mode, we only check that at least some DC data
246
     * got sent for each component; the spec does not require that all bits
247
     * of all coefficients be transmitted.  Would it be wiser to enforce
248
     * transmission of all coefficient bits??
249
     */
250
    for (ci = 0; ci < cinfo->num_components; ci++) {
251
      if (last_bitpos[ci][0] < 0)
252
	ERREXIT(cinfo, JERR_MISSING_DATA);
253
    }
254
#endif
255
  } else {
256
    for (ci = 0; ci < cinfo->num_components; ci++) {
257
      if (! component_sent[ci])
258
	ERREXIT(cinfo, JERR_MISSING_DATA);
259
    }
260
  }
261
}
262

263
#endif /* C_MULTISCAN_FILES_SUPPORTED */
264

265

266
LOCAL(void)
267
select_scan_parameters (j_compress_ptr cinfo)
268
/* Set up the scan parameters for the current scan */
269
{
270
  int ci;
271

272
#ifdef C_MULTISCAN_FILES_SUPPORTED
273
  if (cinfo->scan_info != NULL) {
274
    /* Prepare for current scan --- the script is already validated */
275
    my_master_ptr master = (my_master_ptr) cinfo->master;
276
    const jpeg_scan_info * scanptr = cinfo->scan_info + master->scan_number;
277

278
    cinfo->comps_in_scan = scanptr->comps_in_scan;
279
    for (ci = 0; ci < scanptr->comps_in_scan; ci++) {
280
      cinfo->cur_comp_info[ci] =
281
	&cinfo->comp_info[scanptr->component_index[ci]];
282
    }
283
    cinfo->Ss = scanptr->Ss;
284
    cinfo->Se = scanptr->Se;
285
    cinfo->Ah = scanptr->Ah;
286
    cinfo->Al = scanptr->Al;
287
  }
288
  else
289
#endif
290
  {
291
    /* Prepare for single sequential-JPEG scan containing all components */
292
    if (cinfo->num_components > MAX_COMPS_IN_SCAN)
293
      ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->num_components,
294
	       MAX_COMPS_IN_SCAN);
295
    cinfo->comps_in_scan = cinfo->num_components;
296
    for (ci = 0; ci < cinfo->num_components; ci++) {
297
      cinfo->cur_comp_info[ci] = &cinfo->comp_info[ci];
298
    }
299
    cinfo->Ss = 0;
300
    cinfo->Se = DCTSIZE2-1;
301
    cinfo->Ah = 0;
302
    cinfo->Al = 0;
303
  }
304
}
305

306

307
LOCAL(void)
308
per_scan_setup (j_compress_ptr cinfo)
309
/* Do computations that are needed before processing a JPEG scan */
310
/* cinfo->comps_in_scan and cinfo->cur_comp_info[] are already set */
311
{
312
  int ci, mcublks, tmp;
313
  jpeg_component_info *compptr;
314
  
315
  if (cinfo->comps_in_scan == 1) {
316
    
317
    /* Noninterleaved (single-component) scan */
318
    compptr = cinfo->cur_comp_info[0];
319
    
320
    /* Overall image size in MCUs */
321
    cinfo->MCUs_per_row = compptr->width_in_blocks;
322
    cinfo->MCU_rows_in_scan = compptr->height_in_blocks;
323
    
324
    /* For noninterleaved scan, always one block per MCU */
325
    compptr->MCU_width = 1;
326
    compptr->MCU_height = 1;
327
    compptr->MCU_blocks = 1;
328
    compptr->MCU_sample_width = DCTSIZE;
329
    compptr->last_col_width = 1;
330
    /* For noninterleaved scans, it is convenient to define last_row_height
331
     * as the number of block rows present in the last iMCU row.
332
     */
333
    tmp = (int) (compptr->height_in_blocks % compptr->v_samp_factor);
334
    if (tmp == 0) tmp = compptr->v_samp_factor;
335
    compptr->last_row_height = tmp;
336
    
337
    /* Prepare array describing MCU composition */
338
    cinfo->blocks_in_MCU = 1;
339
    cinfo->MCU_membership[0] = 0;
340
    
341
  } else {
342
    
343
    /* Interleaved (multi-component) scan */
344
    if (cinfo->comps_in_scan <= 0 || cinfo->comps_in_scan > MAX_COMPS_IN_SCAN)
345
      ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->comps_in_scan,
346
	       MAX_COMPS_IN_SCAN);
347
    
348
    /* Overall image size in MCUs */
349
    cinfo->MCUs_per_row = (JDIMENSION)
350
      jdiv_round_up((long) cinfo->image_width,
351
		    (long) (cinfo->max_h_samp_factor*DCTSIZE));
352
    cinfo->MCU_rows_in_scan = (JDIMENSION)
353
      jdiv_round_up((long) cinfo->image_height,
354
		    (long) (cinfo->max_v_samp_factor*DCTSIZE));
355
    
356
    cinfo->blocks_in_MCU = 0;
357
    
358
    for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
359
      compptr = cinfo->cur_comp_info[ci];
360
      /* Sampling factors give # of blocks of component in each MCU */
361
      compptr->MCU_width = compptr->h_samp_factor;
362
      compptr->MCU_height = compptr->v_samp_factor;
363
      compptr->MCU_blocks = compptr->MCU_width * compptr->MCU_height;
364
      compptr->MCU_sample_width = compptr->MCU_width * DCTSIZE;
365
      /* Figure number of non-dummy blocks in last MCU column & row */
366
      tmp = (int) (compptr->width_in_blocks % compptr->MCU_width);
367
      if (tmp == 0) tmp = compptr->MCU_width;
368
      compptr->last_col_width = tmp;
369
      tmp = (int) (compptr->height_in_blocks % compptr->MCU_height);
370
      if (tmp == 0) tmp = compptr->MCU_height;
371
      compptr->last_row_height = tmp;
372
      /* Prepare array describing MCU composition */
373
      mcublks = compptr->MCU_blocks;
374
      if (cinfo->blocks_in_MCU + mcublks > C_MAX_BLOCKS_IN_MCU)
375
	ERREXIT(cinfo, JERR_BAD_MCU_SIZE);
376
      while (mcublks-- > 0) {
377
	cinfo->MCU_membership[cinfo->blocks_in_MCU++] = ci;
378
      }
379
    }
380
    
381
  }
382

383
  /* Convert restart specified in rows to actual MCU count. */
384
  /* Note that count must fit in 16 bits, so we provide limiting. */
385
  if (cinfo->restart_in_rows > 0) {
386
    long nominal = (long) cinfo->restart_in_rows * (long) cinfo->MCUs_per_row;
387
    cinfo->restart_interval = (unsigned int) MIN(nominal, 65535L);
388
  }
389
}
390

391

392
/*
393
 * Per-pass setup.
394
 * This is called at the beginning of each pass.  We determine which modules
395
 * will be active during this pass and give them appropriate start_pass calls.
396
 * We also set is_last_pass to indicate whether any more passes will be
397
 * required.
398
 */
399

400
METHODDEF(void)
401
prepare_for_pass (j_compress_ptr cinfo)
402
{
403
  my_master_ptr master = (my_master_ptr) cinfo->master;
404

405
  switch (master->pass_type) {
406
  case main_pass:
407
    /* Initial pass: will collect input data, and do either Huffman
408
     * optimization or data output for the first scan.
409
     */
410
    select_scan_parameters(cinfo);
411
    per_scan_setup(cinfo);
412
    if (! cinfo->raw_data_in) {
413
      (*cinfo->cconvert->start_pass) (cinfo);
414
      (*cinfo->downsample->start_pass) (cinfo);
415
      (*cinfo->prep->start_pass) (cinfo, JBUF_PASS_THRU);
416
    }
417
    (*cinfo->fdct->start_pass) (cinfo);
418
    (*cinfo->entropy->start_pass) (cinfo, cinfo->optimize_coding);
419
    (*cinfo->coef->start_pass) (cinfo,
420
				(master->total_passes > 1 ?
421
				 JBUF_SAVE_AND_PASS : JBUF_PASS_THRU));
422
    (*cinfo->main->start_pass) (cinfo, JBUF_PASS_THRU);
423
    if (cinfo->optimize_coding) {
424
      /* No immediate data output; postpone writing frame/scan headers */
425
      master->pub.call_pass_startup = FALSE;
426
    } else {
427
      /* Will write frame/scan headers at first jpeg_write_scanlines call */
428
      master->pub.call_pass_startup = TRUE;
429
    }
430
    break;
431
#ifdef ENTROPY_OPT_SUPPORTED
432
  case huff_opt_pass:
433
    /* Do Huffman optimization for a scan after the first one. */
434
    select_scan_parameters(cinfo);
435
    per_scan_setup(cinfo);
436
    if (cinfo->Ss != 0 || cinfo->Ah == 0 || cinfo->arith_code) {
437
      (*cinfo->entropy->start_pass) (cinfo, TRUE);
438
      (*cinfo->coef->start_pass) (cinfo, JBUF_CRANK_DEST);
439
      master->pub.call_pass_startup = FALSE;
440
      break;
441
    }
442
    /* Special case: Huffman DC refinement scans need no Huffman table
443
     * and therefore we can skip the optimization pass for them.
444
     */
445
    master->pass_type = output_pass;
446
    master->pass_number++;
447
    /*FALLTHROUGH*/
448
#endif
449
  case output_pass:
450
    /* Do a data-output pass. */
451
    /* We need not repeat per-scan setup if prior optimization pass did it. */
452
    if (! cinfo->optimize_coding) {
453
      select_scan_parameters(cinfo);
454
      per_scan_setup(cinfo);
455
    }
456
    (*cinfo->entropy->start_pass) (cinfo, FALSE);
457
    (*cinfo->coef->start_pass) (cinfo, JBUF_CRANK_DEST);
458
    /* We emit frame/scan headers now */
459
    if (master->scan_number == 0)
460
      (*cinfo->marker->write_frame_header) (cinfo);
461
    (*cinfo->marker->write_scan_header) (cinfo);
462
    master->pub.call_pass_startup = FALSE;
463
    break;
464
  default:
465
    ERREXIT(cinfo, JERR_NOT_COMPILED);
466
  }
467

468
  master->pub.is_last_pass = (master->pass_number == master->total_passes-1);
469

470
  /* Set up progress monitor's pass info if present */
471
  if (cinfo->progress != NULL) {
472
    cinfo->progress->completed_passes = master->pass_number;
473
    cinfo->progress->total_passes = master->total_passes;
474
  }
475
}
476

477

478
/*
479
 * Special start-of-pass hook.
480
 * This is called by jpeg_write_scanlines if call_pass_startup is TRUE.
481
 * In single-pass processing, we need this hook because we don't want to
482
 * write frame/scan headers during jpeg_start_compress; we want to let the
483
 * application write COM markers etc. between jpeg_start_compress and the
484
 * jpeg_write_scanlines loop.
485
 * In multi-pass processing, this routine is not used.
486
 */
487

488
METHODDEF(void)
489
pass_startup (j_compress_ptr cinfo)
490
{
491
  cinfo->master->call_pass_startup = FALSE; /* reset flag so call only once */
492

493
  (*cinfo->marker->write_frame_header) (cinfo);
494
  (*cinfo->marker->write_scan_header) (cinfo);
495
}
496

497

498
/*
499
 * Finish up at end of pass.
500
 */
501

502
METHODDEF(void)
503
finish_pass_master (j_compress_ptr cinfo)
504
{
505
  my_master_ptr master = (my_master_ptr) cinfo->master;
506

507
  /* The entropy coder always needs an end-of-pass call,
508
   * either to analyze statistics or to flush its output buffer.
509
   */
510
  (*cinfo->entropy->finish_pass) (cinfo);
511

512
  /* Update state for next pass */
513
  switch (master->pass_type) {
514
  case main_pass:
515
    /* next pass is either output of scan 0 (after optimization)
516
     * or output of scan 1 (if no optimization).
517
     */
518
    master->pass_type = output_pass;
519
    if (! cinfo->optimize_coding)
520
      master->scan_number++;
521
    break;
522
  case huff_opt_pass:
523
    /* next pass is always output of current scan */
524
    master->pass_type = output_pass;
525
    break;
526
  case output_pass:
527
    /* next pass is either optimization or output of next scan */
528
    if (cinfo->optimize_coding)
529
      master->pass_type = huff_opt_pass;
530
    master->scan_number++;
531
    break;
532
  }
533

534
  master->pass_number++;
535
}
536

537

538
/*
539
 * Initialize master compression control.
540
 */
541

542
GLOBAL(void)
543
jinit_c_master_control (j_compress_ptr cinfo, boolean transcode_only)
544
{
545
  my_master_ptr master;
546

547
  master = (my_master_ptr)
548
      (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
549
				  SIZEOF(my_comp_master));
550
  cinfo->master = (struct jpeg_comp_master *) master;
551
  master->pub.prepare_for_pass = prepare_for_pass;
552
  master->pub.pass_startup = pass_startup;
553
  master->pub.finish_pass = finish_pass_master;
554
  master->pub.is_last_pass = FALSE;
555

556
  /* Validate parameters, determine derived values */
557
  initial_setup(cinfo);
558

559
  if (cinfo->scan_info != NULL) {
560
#ifdef C_MULTISCAN_FILES_SUPPORTED
561
    validate_script(cinfo);
562
#else
563
    ERREXIT(cinfo, JERR_NOT_COMPILED);
564
#endif
565
  } else {
566
    cinfo->progressive_mode = FALSE;
567
    cinfo->num_scans = 1;
568
  }
569

570
  if (cinfo->progressive_mode)	/*  TEMPORARY HACK ??? */
571
    cinfo->optimize_coding = TRUE; /* assume default tables no good for progressive mode */
572

573
  /* Initialize my private state */
574
  if (transcode_only) {
575
    /* no main pass in transcoding */
576
    if (cinfo->optimize_coding)
577
      master->pass_type = huff_opt_pass;
578
    else
579
      master->pass_type = output_pass;
580
  } else {
581
    /* for normal compression, first pass is always this type: */
582
    master->pass_type = main_pass;
583
  }
584
  master->scan_number = 0;
585
  master->pass_number = 0;
586
  if (cinfo->optimize_coding)
587
    master->total_passes = cinfo->num_scans * 2;
588
  else
589
    master->total_passes = cinfo->num_scans;
590
}
591

592