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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,
10  * 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 {
22 	main_pass,		/* input data, also do first output step */
23 	huff_opt_pass,		/* Huffman code optimization pass */
24 	output_pass		/* data output pass */
25 } c_pass_type;
26 
27 typedef struct {
28   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)
initial_setup(j_compress_ptr cinfo)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);
89     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)
109       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)
validate_script(j_compress_ptr cinfo)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)
select_scan_parameters(j_compress_ptr cinfo)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)
per_scan_setup(j_compress_ptr cinfo)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)
prepare_for_pass(j_compress_ptr cinfo)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)
pass_startup(j_compress_ptr cinfo)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)
finish_pass_master(j_compress_ptr cinfo)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)
jinit_c_master_control(j_compress_ptr cinfo,boolean transcode_only)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