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1 /*
2  * jcmaster.c
3  *
4  * Copyright (C) 1991-1997, Thomas G. Lane.
5  * Modified 2003-2010 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 master control logic for the JPEG compressor.
10  * These routines are concerned with parameter validation, initial setup,
11  * and inter-pass control (determining the number of passes and the work 
12  * to be done in each pass).
13  */
14
15 #define JPEG_INTERNALS
16 #include "jinclude.h"
17 #include "jpeglib.h"
18
19
20 /* Private state */
21
22 typedef enum {
23         main_pass,              /* input data, also do first output step */
24         huff_opt_pass,          /* Huffman code optimization pass */
25         output_pass             /* data output pass */
26 } c_pass_type;
27
28 typedef struct {
29   struct jpeg_comp_master pub;  /* public fields */
30
31   c_pass_type pass_type;        /* the type of the current pass */
32
33   int pass_number;              /* # of passes completed */
34   int total_passes;             /* total # of passes needed */
35
36   int scan_number;              /* current index in scan_info[] */
37 } my_comp_master;
38
39 typedef my_comp_master * my_master_ptr;
40
41
42 /*
43  * Support routines that do various essential calculations.
44  */
45
46 /*
47  * Compute JPEG image dimensions and related values.
48  * NOTE: this is exported for possible use by application.
49  * Hence it mustn't do anything that can't be done twice.
50  */
51
52 GLOBAL(void)
53 jpeg_calc_jpeg_dimensions (j_compress_ptr cinfo)
54 /* Do computations that are needed before master selection phase */
55 {
56 #ifdef DCT_SCALING_SUPPORTED
57
58   /* Compute actual JPEG image dimensions and DCT scaling choices. */
59   if (cinfo->scale_num >= cinfo->scale_denom * 8) {
60     /* Provide 8/1 scaling */
61     cinfo->jpeg_width = cinfo->image_width << 3;
62     cinfo->jpeg_height = cinfo->image_height << 3;
63     cinfo->min_DCT_h_scaled_size = 1;
64     cinfo->min_DCT_v_scaled_size = 1;
65   } else if (cinfo->scale_num >= cinfo->scale_denom * 4) {
66     /* Provide 4/1 scaling */
67     cinfo->jpeg_width = cinfo->image_width << 2;
68     cinfo->jpeg_height = cinfo->image_height << 2;
69     cinfo->min_DCT_h_scaled_size = 2;
70     cinfo->min_DCT_v_scaled_size = 2;
71   } else if (cinfo->scale_num * 3 >= cinfo->scale_denom * 8) {
72     /* Provide 8/3 scaling */
73     cinfo->jpeg_width = (cinfo->image_width << 1) + (JDIMENSION)
74       jdiv_round_up((long) cinfo->image_width * 2, 3L);
75     cinfo->jpeg_height = (cinfo->image_height << 1) + (JDIMENSION)
76       jdiv_round_up((long) cinfo->image_height * 2, 3L);
77     cinfo->min_DCT_h_scaled_size = 3;
78     cinfo->min_DCT_v_scaled_size = 3;
79   } else if (cinfo->scale_num >= cinfo->scale_denom * 2) {
80     /* Provide 2/1 scaling */
81     cinfo->jpeg_width = cinfo->image_width << 1;
82     cinfo->jpeg_height = cinfo->image_height << 1;
83     cinfo->min_DCT_h_scaled_size = 4;
84     cinfo->min_DCT_v_scaled_size = 4;
85   } else if (cinfo->scale_num * 5 >= cinfo->scale_denom * 8) {
86     /* Provide 8/5 scaling */
87     cinfo->jpeg_width = cinfo->image_width + (JDIMENSION)
88       jdiv_round_up((long) cinfo->image_width * 3, 5L);
89     cinfo->jpeg_height = cinfo->image_height + (JDIMENSION)
90       jdiv_round_up((long) cinfo->image_height * 3, 5L);
91     cinfo->min_DCT_h_scaled_size = 5;
92     cinfo->min_DCT_v_scaled_size = 5;
93   } else if (cinfo->scale_num * 3 >= cinfo->scale_denom * 4) {
94     /* Provide 4/3 scaling */
95     cinfo->jpeg_width = cinfo->image_width + (JDIMENSION)
96       jdiv_round_up((long) cinfo->image_width, 3L);
97     cinfo->jpeg_height = cinfo->image_height + (JDIMENSION)
98       jdiv_round_up((long) cinfo->image_height, 3L);
99     cinfo->min_DCT_h_scaled_size = 6;
100     cinfo->min_DCT_v_scaled_size = 6;
101   } else if (cinfo->scale_num * 7 >= cinfo->scale_denom * 8) {
102     /* Provide 8/7 scaling */
103     cinfo->jpeg_width = cinfo->image_width + (JDIMENSION)
104       jdiv_round_up((long) cinfo->image_width, 7L);
105     cinfo->jpeg_height = cinfo->image_height + (JDIMENSION)
106       jdiv_round_up((long) cinfo->image_height, 7L);
107     cinfo->min_DCT_h_scaled_size = 7;
108     cinfo->min_DCT_v_scaled_size = 7;
109   } else if (cinfo->scale_num >= cinfo->scale_denom) {
110     /* Provide 1/1 scaling */
111     cinfo->jpeg_width = cinfo->image_width;
112     cinfo->jpeg_height = cinfo->image_height;
113     cinfo->min_DCT_h_scaled_size = 8;
114     cinfo->min_DCT_v_scaled_size = 8;
115   } else if (cinfo->scale_num * 9 >= cinfo->scale_denom * 8) {
116     /* Provide 8/9 scaling */
117     cinfo->jpeg_width = (JDIMENSION)
118       jdiv_round_up((long) cinfo->image_width * 8, 9L);
119     cinfo->jpeg_height = (JDIMENSION)
120       jdiv_round_up((long) cinfo->image_height * 8, 9L);
121     cinfo->min_DCT_h_scaled_size = 9;
122     cinfo->min_DCT_v_scaled_size = 9;
123   } else if (cinfo->scale_num * 5 >= cinfo->scale_denom * 4) {
124     /* Provide 4/5 scaling */
125     cinfo->jpeg_width = (JDIMENSION)
126       jdiv_round_up((long) cinfo->image_width * 4, 5L);
127     cinfo->jpeg_height = (JDIMENSION)
128       jdiv_round_up((long) cinfo->image_height * 4, 5L);
129     cinfo->min_DCT_h_scaled_size = 10;
130     cinfo->min_DCT_v_scaled_size = 10;
131   } else if (cinfo->scale_num * 11 >= cinfo->scale_denom * 8) {
132     /* Provide 8/11 scaling */
133     cinfo->jpeg_width = (JDIMENSION)
134       jdiv_round_up((long) cinfo->image_width * 8, 11L);
135     cinfo->jpeg_height = (JDIMENSION)
136       jdiv_round_up((long) cinfo->image_height * 8, 11L);
137     cinfo->min_DCT_h_scaled_size = 11;
138     cinfo->min_DCT_v_scaled_size = 11;
139   } else if (cinfo->scale_num * 3 >= cinfo->scale_denom * 2) {
140     /* Provide 2/3 scaling */
141     cinfo->jpeg_width = (JDIMENSION)
142       jdiv_round_up((long) cinfo->image_width * 2, 3L);
143     cinfo->jpeg_height = (JDIMENSION)
144       jdiv_round_up((long) cinfo->image_height * 2, 3L);
145     cinfo->min_DCT_h_scaled_size = 12;
146     cinfo->min_DCT_v_scaled_size = 12;
147   } else if (cinfo->scale_num * 13 >= cinfo->scale_denom * 8) {
148     /* Provide 8/13 scaling */
149     cinfo->jpeg_width = (JDIMENSION)
150       jdiv_round_up((long) cinfo->image_width * 8, 13L);
151     cinfo->jpeg_height = (JDIMENSION)
152       jdiv_round_up((long) cinfo->image_height * 8, 13L);
153     cinfo->min_DCT_h_scaled_size = 13;
154     cinfo->min_DCT_v_scaled_size = 13;
155   } else if (cinfo->scale_num * 7 >= cinfo->scale_denom * 4) {
156     /* Provide 4/7 scaling */
157     cinfo->jpeg_width = (JDIMENSION)
158       jdiv_round_up((long) cinfo->image_width * 4, 7L);
159     cinfo->jpeg_height = (JDIMENSION)
160       jdiv_round_up((long) cinfo->image_height * 4, 7L);
161     cinfo->min_DCT_h_scaled_size = 14;
162     cinfo->min_DCT_v_scaled_size = 14;
163   } else if (cinfo->scale_num * 15 >= cinfo->scale_denom * 8) {
164     /* Provide 8/15 scaling */
165     cinfo->jpeg_width = (JDIMENSION)
166       jdiv_round_up((long) cinfo->image_width * 8, 15L);
167     cinfo->jpeg_height = (JDIMENSION)
168       jdiv_round_up((long) cinfo->image_height * 8, 15L);
169     cinfo->min_DCT_h_scaled_size = 15;
170     cinfo->min_DCT_v_scaled_size = 15;
171   } else {
172     /* Provide 1/2 scaling */
173     cinfo->jpeg_width = (JDIMENSION)
174       jdiv_round_up((long) cinfo->image_width, 2L);
175     cinfo->jpeg_height = (JDIMENSION)
176       jdiv_round_up((long) cinfo->image_height, 2L);
177     cinfo->min_DCT_h_scaled_size = 16;
178     cinfo->min_DCT_v_scaled_size = 16;
179   }
180
181 #else /* !DCT_SCALING_SUPPORTED */
182
183   /* Hardwire it to "no scaling" */
184   cinfo->jpeg_width = cinfo->image_width;
185   cinfo->jpeg_height = cinfo->image_height;
186   cinfo->min_DCT_h_scaled_size = DCTSIZE;
187   cinfo->min_DCT_v_scaled_size = DCTSIZE;
188
189 #endif /* DCT_SCALING_SUPPORTED */
190 }
191
192
193 LOCAL(void)
194 jpeg_calc_trans_dimensions (j_compress_ptr cinfo)
195 {
196   if (cinfo->min_DCT_h_scaled_size < 1 || cinfo->min_DCT_h_scaled_size > 16
197       || cinfo->min_DCT_h_scaled_size != cinfo->min_DCT_v_scaled_size)
198     ERREXIT2(cinfo, JERR_BAD_DCTSIZE,
199              cinfo->min_DCT_h_scaled_size, cinfo->min_DCT_v_scaled_size);
200
201   cinfo->block_size = cinfo->min_DCT_h_scaled_size;
202
203   switch (cinfo->block_size) {
204   case 2: cinfo->natural_order = jpeg_natural_order2; break;
205   case 3: cinfo->natural_order = jpeg_natural_order3; break;
206   case 4: cinfo->natural_order = jpeg_natural_order4; break;
207   case 5: cinfo->natural_order = jpeg_natural_order5; break;
208   case 6: cinfo->natural_order = jpeg_natural_order6; break;
209   case 7: cinfo->natural_order = jpeg_natural_order7; break;
210   default: cinfo->natural_order = jpeg_natural_order; break;
211   }
212
213   cinfo->lim_Se = cinfo->block_size < DCTSIZE ?
214     cinfo->block_size * cinfo->block_size - 1 : DCTSIZE2-1;
215 }
216
217
218 LOCAL(void)
219 initial_setup (j_compress_ptr cinfo, boolean transcode_only)
220 /* Do computations that are needed before master selection phase */
221 {
222   int ci, ssize;
223   jpeg_component_info *compptr;
224   long samplesperrow;
225   JDIMENSION jd_samplesperrow;
226
227   if (transcode_only)
228     jpeg_calc_trans_dimensions(cinfo);
229   else
230     jpeg_calc_jpeg_dimensions(cinfo);
231
232   /* Sanity check on image dimensions */
233   if (cinfo->jpeg_height <= 0 || cinfo->jpeg_width <= 0 ||
234       cinfo->num_components <= 0 || cinfo->input_components <= 0)
235     ERREXIT(cinfo, JERR_EMPTY_IMAGE);
236
237   /* Make sure image isn't bigger than I can handle */
238   if ((long) cinfo->jpeg_height > (long) JPEG_MAX_DIMENSION ||
239       (long) cinfo->jpeg_width > (long) JPEG_MAX_DIMENSION)
240     ERREXIT1(cinfo, JERR_IMAGE_TOO_BIG, (unsigned int) JPEG_MAX_DIMENSION);
241
242   /* Width of an input scanline must be representable as JDIMENSION. */
243   samplesperrow = (long) cinfo->image_width * (long) cinfo->input_components;
244   jd_samplesperrow = (JDIMENSION) samplesperrow;
245   if ((long) jd_samplesperrow != samplesperrow)
246     ERREXIT(cinfo, JERR_WIDTH_OVERFLOW);
247
248   /* For now, precision must match compiled-in value... */
249   if (cinfo->data_precision != BITS_IN_JSAMPLE)
250     ERREXIT1(cinfo, JERR_BAD_PRECISION, cinfo->data_precision);
251
252   /* Check that number of components won't exceed internal array sizes */
253   if (cinfo->num_components > MAX_COMPONENTS)
254     ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->num_components,
255              MAX_COMPONENTS);
256
257   /* Compute maximum sampling factors; check factor validity */
258   cinfo->max_h_samp_factor = 1;
259   cinfo->max_v_samp_factor = 1;
260   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
261        ci++, compptr++) {
262     if (compptr->h_samp_factor<=0 || compptr->h_samp_factor>MAX_SAMP_FACTOR ||
263         compptr->v_samp_factor<=0 || compptr->v_samp_factor>MAX_SAMP_FACTOR)
264       ERREXIT(cinfo, JERR_BAD_SAMPLING);
265     cinfo->max_h_samp_factor = MAX(cinfo->max_h_samp_factor,
266                                    compptr->h_samp_factor);
267     cinfo->max_v_samp_factor = MAX(cinfo->max_v_samp_factor,
268                                    compptr->v_samp_factor);
269   }
270
271   /* Compute dimensions of components */
272   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
273        ci++, compptr++) {
274     /* Fill in the correct component_index value; don't rely on application */
275     compptr->component_index = ci;
276     /* In selecting the actual DCT scaling for each component, we try to
277      * scale down the chroma components via DCT scaling rather than downsampling.
278      * This saves time if the downsampler gets to use 1:1 scaling.
279      * Note this code adapts subsampling ratios which are powers of 2.
280      */
281     ssize = 1;
282 #ifdef DCT_SCALING_SUPPORTED
283     while (cinfo->min_DCT_h_scaled_size * ssize <=
284            (cinfo->do_fancy_downsampling ? DCTSIZE : DCTSIZE / 2) &&
285            (cinfo->max_h_samp_factor % (compptr->h_samp_factor * ssize * 2)) == 0) {
286       ssize = ssize * 2;
287     }
288 #endif
289     compptr->DCT_h_scaled_size = cinfo->min_DCT_h_scaled_size * ssize;
290     ssize = 1;
291 #ifdef DCT_SCALING_SUPPORTED
292     while (cinfo->min_DCT_v_scaled_size * ssize <=
293            (cinfo->do_fancy_downsampling ? DCTSIZE : DCTSIZE / 2) &&
294            (cinfo->max_v_samp_factor % (compptr->v_samp_factor * ssize * 2)) == 0) {
295       ssize = ssize * 2;
296     }
297 #endif
298     compptr->DCT_v_scaled_size = cinfo->min_DCT_v_scaled_size * ssize;
299
300     /* We don't support DCT ratios larger than 2. */
301     if (compptr->DCT_h_scaled_size > compptr->DCT_v_scaled_size * 2)
302         compptr->DCT_h_scaled_size = compptr->DCT_v_scaled_size * 2;
303     else if (compptr->DCT_v_scaled_size > compptr->DCT_h_scaled_size * 2)
304         compptr->DCT_v_scaled_size = compptr->DCT_h_scaled_size * 2;
305
306     /* Size in DCT blocks */
307     compptr->width_in_blocks = (JDIMENSION)
308       jdiv_round_up((long) cinfo->jpeg_width * (long) compptr->h_samp_factor,
309                     (long) (cinfo->max_h_samp_factor * cinfo->block_size));
310     compptr->height_in_blocks = (JDIMENSION)
311       jdiv_round_up((long) cinfo->jpeg_height * (long) compptr->v_samp_factor,
312                     (long) (cinfo->max_v_samp_factor * cinfo->block_size));
313     /* Size in samples */
314     compptr->downsampled_width = (JDIMENSION)
315       jdiv_round_up((long) cinfo->jpeg_width *
316                     (long) (compptr->h_samp_factor * compptr->DCT_h_scaled_size),
317                     (long) (cinfo->max_h_samp_factor * cinfo->block_size));
318     compptr->downsampled_height = (JDIMENSION)
319       jdiv_round_up((long) cinfo->jpeg_height *
320                     (long) (compptr->v_samp_factor * compptr->DCT_v_scaled_size),
321                     (long) (cinfo->max_v_samp_factor * cinfo->block_size));
322     /* Mark component needed (this flag isn't actually used for compression) */
323     compptr->component_needed = TRUE;
324   }
325
326   /* Compute number of fully interleaved MCU rows (number of times that
327    * main controller will call coefficient controller).
328    */
329   cinfo->total_iMCU_rows = (JDIMENSION)
330     jdiv_round_up((long) cinfo->jpeg_height,
331                   (long) (cinfo->max_v_samp_factor * cinfo->block_size));
332 }
333
334
335 #ifdef C_MULTISCAN_FILES_SUPPORTED
336
337 LOCAL(void)
338 validate_script (j_compress_ptr cinfo)
339 /* Verify that the scan script in cinfo->scan_info[] is valid; also
340  * determine whether it uses progressive JPEG, and set cinfo->progressive_mode.
341  */
342 {
343   const jpeg_scan_info * scanptr;
344   int scanno, ncomps, ci, coefi, thisi;
345   int Ss, Se, Ah, Al;
346   boolean component_sent[MAX_COMPONENTS];
347 #ifdef C_PROGRESSIVE_SUPPORTED
348   int * last_bitpos_ptr;
349   int last_bitpos[MAX_COMPONENTS][DCTSIZE2];
350   /* -1 until that coefficient has been seen; then last Al for it */
351 #endif
352
353   if (cinfo->num_scans <= 0)
354     ERREXIT1(cinfo, JERR_BAD_SCAN_SCRIPT, 0);
355
356   /* For sequential JPEG, all scans must have Ss=0, Se=DCTSIZE2-1;
357    * for progressive JPEG, no scan can have this.
358    */
359   scanptr = cinfo->scan_info;
360   if (scanptr->Ss != 0 || scanptr->Se != DCTSIZE2-1) {
361 #ifdef C_PROGRESSIVE_SUPPORTED
362     cinfo->progressive_mode = TRUE;
363     last_bitpos_ptr = & last_bitpos[0][0];
364     for (ci = 0; ci < cinfo->num_components; ci++) 
365       for (coefi = 0; coefi < DCTSIZE2; coefi++)
366         *last_bitpos_ptr++ = -1;
367 #else
368     ERREXIT(cinfo, JERR_NOT_COMPILED);
369 #endif
370   } else {
371     cinfo->progressive_mode = FALSE;
372     for (ci = 0; ci < cinfo->num_components; ci++) 
373       component_sent[ci] = FALSE;
374   }
375
376   for (scanno = 1; scanno <= cinfo->num_scans; scanptr++, scanno++) {
377     /* Validate component indexes */
378     ncomps = scanptr->comps_in_scan;
379     if (ncomps <= 0 || ncomps > MAX_COMPS_IN_SCAN)
380       ERREXIT2(cinfo, JERR_COMPONENT_COUNT, ncomps, MAX_COMPS_IN_SCAN);
381     for (ci = 0; ci < ncomps; ci++) {
382       thisi = scanptr->component_index[ci];
383       if (thisi < 0 || thisi >= cinfo->num_components)
384         ERREXIT1(cinfo, JERR_BAD_SCAN_SCRIPT, scanno);
385       /* Components must appear in SOF order within each scan */
386       if (ci > 0 && thisi <= scanptr->component_index[ci-1])
387         ERREXIT1(cinfo, JERR_BAD_SCAN_SCRIPT, scanno);
388     }
389     /* Validate progression parameters */
390     Ss = scanptr->Ss;
391     Se = scanptr->Se;
392     Ah = scanptr->Ah;
393     Al = scanptr->Al;
394     if (cinfo->progressive_mode) {
395 #ifdef C_PROGRESSIVE_SUPPORTED
396       /* The JPEG spec simply gives the ranges 0..13 for Ah and Al, but that
397        * seems wrong: the upper bound ought to depend on data precision.
398        * Perhaps they really meant 0..N+1 for N-bit precision.
399        * Here we allow 0..10 for 8-bit data; Al larger than 10 results in
400        * out-of-range reconstructed DC values during the first DC scan,
401        * which might cause problems for some decoders.
402        */
403 #if BITS_IN_JSAMPLE == 8
404 #define MAX_AH_AL 10
405 #else
406 #define MAX_AH_AL 13
407 #endif
408       if (Ss < 0 || Ss >= DCTSIZE2 || Se < Ss || Se >= DCTSIZE2 ||
409           Ah < 0 || Ah > MAX_AH_AL || Al < 0 || Al > MAX_AH_AL)
410         ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
411       if (Ss == 0) {
412         if (Se != 0)            /* DC and AC together not OK */
413           ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
414       } else {
415         if (ncomps != 1)        /* AC scans must be for only one component */
416           ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
417       }
418       for (ci = 0; ci < ncomps; ci++) {
419         last_bitpos_ptr = & last_bitpos[scanptr->component_index[ci]][0];
420         if (Ss != 0 && last_bitpos_ptr[0] < 0) /* AC without prior DC scan */
421           ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
422         for (coefi = Ss; coefi <= Se; coefi++) {
423           if (last_bitpos_ptr[coefi] < 0) {
424             /* first scan of this coefficient */
425             if (Ah != 0)
426               ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
427           } else {
428             /* not first scan */
429             if (Ah != last_bitpos_ptr[coefi] || Al != Ah-1)
430               ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
431           }
432           last_bitpos_ptr[coefi] = Al;
433         }
434       }
435 #endif
436     } else {
437       /* For sequential JPEG, all progression parameters must be these: */
438       if (Ss != 0 || Se != DCTSIZE2-1 || Ah != 0 || Al != 0)
439         ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
440       /* Make sure components are not sent twice */
441       for (ci = 0; ci < ncomps; ci++) {
442         thisi = scanptr->component_index[ci];
443         if (component_sent[thisi])
444           ERREXIT1(cinfo, JERR_BAD_SCAN_SCRIPT, scanno);
445         component_sent[thisi] = TRUE;
446       }
447     }
448   }
449
450   /* Now verify that everything got sent. */
451   if (cinfo->progressive_mode) {
452 #ifdef C_PROGRESSIVE_SUPPORTED
453     /* For progressive mode, we only check that at least some DC data
454      * got sent for each component; the spec does not require that all bits
455      * of all coefficients be transmitted.  Would it be wiser to enforce
456      * transmission of all coefficient bits??
457      */
458     for (ci = 0; ci < cinfo->num_components; ci++) {
459       if (last_bitpos[ci][0] < 0)
460         ERREXIT(cinfo, JERR_MISSING_DATA);
461     }
462 #endif
463   } else {
464     for (ci = 0; ci < cinfo->num_components; ci++) {
465       if (! component_sent[ci])
466         ERREXIT(cinfo, JERR_MISSING_DATA);
467     }
468   }
469 }
470
471
472 LOCAL(void)
473 reduce_script (j_compress_ptr cinfo)
474 /* Adapt scan script for use with reduced block size;
475  * assume that script has been validated before.
476  */
477 {
478   jpeg_scan_info * scanptr;
479   int idxout, idxin;
480
481   /* Circumvent const declaration for this function */
482   scanptr = (jpeg_scan_info *) cinfo->scan_info;
483   idxout = 0;
484
485   for (idxin = 0; idxin < cinfo->num_scans; idxin++) {
486     /* After skipping, idxout becomes smaller than idxin */
487     if (idxin != idxout)
488       /* Copy rest of data;
489        * note we stay in given chunk of allocated memory.
490        */
491       scanptr[idxout] = scanptr[idxin];
492     if (scanptr[idxout].Ss > cinfo->lim_Se)
493       /* Entire scan out of range - skip this entry */
494       continue;
495     if (scanptr[idxout].Se > cinfo->lim_Se)
496       /* Limit scan to end of block */
497       scanptr[idxout].Se = cinfo->lim_Se;
498     idxout++;
499   }
500
501   cinfo->num_scans = idxout;
502 }
503
504 #endif /* C_MULTISCAN_FILES_SUPPORTED */
505
506
507 LOCAL(void)
508 select_scan_parameters (j_compress_ptr cinfo)
509 /* Set up the scan parameters for the current scan */
510 {
511   int ci;
512
513 #ifdef C_MULTISCAN_FILES_SUPPORTED
514   if (cinfo->scan_info != NULL) {
515     /* Prepare for current scan --- the script is already validated */
516     my_master_ptr master = (my_master_ptr) cinfo->master;
517     const jpeg_scan_info * scanptr = cinfo->scan_info + master->scan_number;
518
519     cinfo->comps_in_scan = scanptr->comps_in_scan;
520     for (ci = 0; ci < scanptr->comps_in_scan; ci++) {
521       cinfo->cur_comp_info[ci] =
522         &cinfo->comp_info[scanptr->component_index[ci]];
523     }
524     if (cinfo->progressive_mode) {
525       cinfo->Ss = scanptr->Ss;
526       cinfo->Se = scanptr->Se;
527       cinfo->Ah = scanptr->Ah;
528       cinfo->Al = scanptr->Al;
529       return;
530     }
531   }
532   else
533 #endif
534   {
535     /* Prepare for single sequential-JPEG scan containing all components */
536     if (cinfo->num_components > MAX_COMPS_IN_SCAN)
537       ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->num_components,
538                MAX_COMPS_IN_SCAN);
539     cinfo->comps_in_scan = cinfo->num_components;
540     for (ci = 0; ci < cinfo->num_components; ci++) {
541       cinfo->cur_comp_info[ci] = &cinfo->comp_info[ci];
542     }
543   }
544   cinfo->Ss = 0;
545   cinfo->Se = cinfo->block_size * cinfo->block_size - 1;
546   cinfo->Ah = 0;
547   cinfo->Al = 0;
548 }
549
550
551 LOCAL(void)
552 per_scan_setup (j_compress_ptr cinfo)
553 /* Do computations that are needed before processing a JPEG scan */
554 /* cinfo->comps_in_scan and cinfo->cur_comp_info[] are already set */
555 {
556   int ci, mcublks, tmp;
557   jpeg_component_info *compptr;
558   
559   if (cinfo->comps_in_scan == 1) {
560     
561     /* Noninterleaved (single-component) scan */
562     compptr = cinfo->cur_comp_info[0];
563     
564     /* Overall image size in MCUs */
565     cinfo->MCUs_per_row = compptr->width_in_blocks;
566     cinfo->MCU_rows_in_scan = compptr->height_in_blocks;
567     
568     /* For noninterleaved scan, always one block per MCU */
569     compptr->MCU_width = 1;
570     compptr->MCU_height = 1;
571     compptr->MCU_blocks = 1;
572     compptr->MCU_sample_width = compptr->DCT_h_scaled_size;
573     compptr->last_col_width = 1;
574     /* For noninterleaved scans, it is convenient to define last_row_height
575      * as the number of block rows present in the last iMCU row.
576      */
577     tmp = (int) (compptr->height_in_blocks % compptr->v_samp_factor);
578     if (tmp == 0) tmp = compptr->v_samp_factor;
579     compptr->last_row_height = tmp;
580     
581     /* Prepare array describing MCU composition */
582     cinfo->blocks_in_MCU = 1;
583     cinfo->MCU_membership[0] = 0;
584     
585   } else {
586     
587     /* Interleaved (multi-component) scan */
588     if (cinfo->comps_in_scan <= 0 || cinfo->comps_in_scan > MAX_COMPS_IN_SCAN)
589       ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->comps_in_scan,
590                MAX_COMPS_IN_SCAN);
591     
592     /* Overall image size in MCUs */
593     cinfo->MCUs_per_row = (JDIMENSION)
594       jdiv_round_up((long) cinfo->jpeg_width,
595                     (long) (cinfo->max_h_samp_factor * cinfo->block_size));
596     cinfo->MCU_rows_in_scan = (JDIMENSION)
597       jdiv_round_up((long) cinfo->jpeg_height,
598                     (long) (cinfo->max_v_samp_factor * cinfo->block_size));
599     
600     cinfo->blocks_in_MCU = 0;
601     
602     for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
603       compptr = cinfo->cur_comp_info[ci];
604       /* Sampling factors give # of blocks of component in each MCU */
605       compptr->MCU_width = compptr->h_samp_factor;
606       compptr->MCU_height = compptr->v_samp_factor;
607       compptr->MCU_blocks = compptr->MCU_width * compptr->MCU_height;
608       compptr->MCU_sample_width = compptr->MCU_width * compptr->DCT_h_scaled_size;
609       /* Figure number of non-dummy blocks in last MCU column & row */
610       tmp = (int) (compptr->width_in_blocks % compptr->MCU_width);
611       if (tmp == 0) tmp = compptr->MCU_width;
612       compptr->last_col_width = tmp;
613       tmp = (int) (compptr->height_in_blocks % compptr->MCU_height);
614       if (tmp == 0) tmp = compptr->MCU_height;
615       compptr->last_row_height = tmp;
616       /* Prepare array describing MCU composition */
617       mcublks = compptr->MCU_blocks;
618       if (cinfo->blocks_in_MCU + mcublks > C_MAX_BLOCKS_IN_MCU)
619         ERREXIT(cinfo, JERR_BAD_MCU_SIZE);
620       while (mcublks-- > 0) {
621         cinfo->MCU_membership[cinfo->blocks_in_MCU++] = ci;
622       }
623     }
624     
625   }
626
627   /* Convert restart specified in rows to actual MCU count. */
628   /* Note that count must fit in 16 bits, so we provide limiting. */
629   if (cinfo->restart_in_rows > 0) {
630     long nominal = (long) cinfo->restart_in_rows * (long) cinfo->MCUs_per_row;
631     cinfo->restart_interval = (unsigned int) MIN(nominal, 65535L);
632   }
633 }
634
635
636 /*
637  * Per-pass setup.
638  * This is called at the beginning of each pass.  We determine which modules
639  * will be active during this pass and give them appropriate start_pass calls.
640  * We also set is_last_pass to indicate whether any more passes will be
641  * required.
642  */
643
644 METHODDEF(void)
645 prepare_for_pass (j_compress_ptr cinfo)
646 {
647   my_master_ptr master = (my_master_ptr) cinfo->master;
648
649   switch (master->pass_type) {
650   case main_pass:
651     /* Initial pass: will collect input data, and do either Huffman
652      * optimization or data output for the first scan.
653      */
654     select_scan_parameters(cinfo);
655     per_scan_setup(cinfo);
656     if (! cinfo->raw_data_in) {
657       (*cinfo->cconvert->start_pass) (cinfo);
658       (*cinfo->downsample->start_pass) (cinfo);
659       (*cinfo->prep->start_pass) (cinfo, JBUF_PASS_THRU);
660     }
661     (*cinfo->fdct->start_pass) (cinfo);
662     (*cinfo->entropy->start_pass) (cinfo, cinfo->optimize_coding);
663     (*cinfo->coef->start_pass) (cinfo,
664                                 (master->total_passes > 1 ?
665                                  JBUF_SAVE_AND_PASS : JBUF_PASS_THRU));
666     (*cinfo->main->start_pass) (cinfo, JBUF_PASS_THRU);
667     if (cinfo->optimize_coding) {
668       /* No immediate data output; postpone writing frame/scan headers */
669       master->pub.call_pass_startup = FALSE;
670     } else {
671       /* Will write frame/scan headers at first jpeg_write_scanlines call */
672       master->pub.call_pass_startup = TRUE;
673     }
674     break;
675 #ifdef ENTROPY_OPT_SUPPORTED
676   case huff_opt_pass:
677     /* Do Huffman optimization for a scan after the first one. */
678     select_scan_parameters(cinfo);
679     per_scan_setup(cinfo);
680     if (cinfo->Ss != 0 || cinfo->Ah == 0) {
681       (*cinfo->entropy->start_pass) (cinfo, TRUE);
682       (*cinfo->coef->start_pass) (cinfo, JBUF_CRANK_DEST);
683       master->pub.call_pass_startup = FALSE;
684       break;
685     }
686     /* Special case: Huffman DC refinement scans need no Huffman table
687      * and therefore we can skip the optimization pass for them.
688      */
689     master->pass_type = output_pass;
690     master->pass_number++;
691     /*FALLTHROUGH*/
692 #endif
693   case output_pass:
694     /* Do a data-output pass. */
695     /* We need not repeat per-scan setup if prior optimization pass did it. */
696     if (! cinfo->optimize_coding) {
697       select_scan_parameters(cinfo);
698       per_scan_setup(cinfo);
699     }
700     (*cinfo->entropy->start_pass) (cinfo, FALSE);
701     (*cinfo->coef->start_pass) (cinfo, JBUF_CRANK_DEST);
702     /* We emit frame/scan headers now */
703     if (master->scan_number == 0)
704       (*cinfo->marker->write_frame_header) (cinfo);
705     (*cinfo->marker->write_scan_header) (cinfo);
706     master->pub.call_pass_startup = FALSE;
707     break;
708   default:
709     ERREXIT(cinfo, JERR_NOT_COMPILED);
710   }
711
712   master->pub.is_last_pass = (master->pass_number == master->total_passes-1);
713
714   /* Set up progress monitor's pass info if present */
715   if (cinfo->progress != NULL) {
716     cinfo->progress->completed_passes = master->pass_number;
717     cinfo->progress->total_passes = master->total_passes;
718   }
719 }
720
721
722 /*
723  * Special start-of-pass hook.
724  * This is called by jpeg_write_scanlines if call_pass_startup is TRUE.
725  * In single-pass processing, we need this hook because we don't want to
726  * write frame/scan headers during jpeg_start_compress; we want to let the
727  * application write COM markers etc. between jpeg_start_compress and the
728  * jpeg_write_scanlines loop.
729  * In multi-pass processing, this routine is not used.
730  */
731
732 METHODDEF(void)
733 pass_startup (j_compress_ptr cinfo)
734 {
735   cinfo->master->call_pass_startup = FALSE; /* reset flag so call only once */
736
737   (*cinfo->marker->write_frame_header) (cinfo);
738   (*cinfo->marker->write_scan_header) (cinfo);
739 }
740
741
742 /*
743  * Finish up at end of pass.
744  */
745
746 METHODDEF(void)
747 finish_pass_master (j_compress_ptr cinfo)
748 {
749   my_master_ptr master = (my_master_ptr) cinfo->master;
750
751   /* The entropy coder always needs an end-of-pass call,
752    * either to analyze statistics or to flush its output buffer.
753    */
754   (*cinfo->entropy->finish_pass) (cinfo);
755
756   /* Update state for next pass */
757   switch (master->pass_type) {
758   case main_pass:
759     /* next pass is either output of scan 0 (after optimization)
760      * or output of scan 1 (if no optimization).
761      */
762     master->pass_type = output_pass;
763     if (! cinfo->optimize_coding)
764       master->scan_number++;
765     break;
766   case huff_opt_pass:
767     /* next pass is always output of current scan */
768     master->pass_type = output_pass;
769     break;
770   case output_pass:
771     /* next pass is either optimization or output of next scan */
772     if (cinfo->optimize_coding)
773       master->pass_type = huff_opt_pass;
774     master->scan_number++;
775     break;
776   }
777
778   master->pass_number++;
779 }
780
781
782 /*
783  * Initialize master compression control.
784  */
785
786 GLOBAL(void)
787 jinit_c_master_control (j_compress_ptr cinfo, boolean transcode_only)
788 {
789   my_master_ptr master;
790
791   master = (my_master_ptr)
792       (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
793                                   SIZEOF(my_comp_master));
794   cinfo->master = (struct jpeg_comp_master *) master;
795   master->pub.prepare_for_pass = prepare_for_pass;
796   master->pub.pass_startup = pass_startup;
797   master->pub.finish_pass = finish_pass_master;
798   master->pub.is_last_pass = FALSE;
799
800   /* Validate parameters, determine derived values */
801   initial_setup(cinfo, transcode_only);
802
803   if (cinfo->scan_info != NULL) {
804 #ifdef C_MULTISCAN_FILES_SUPPORTED
805     validate_script(cinfo);
806     if (cinfo->block_size < DCTSIZE)
807       reduce_script(cinfo);
808 #else
809     ERREXIT(cinfo, JERR_NOT_COMPILED);
810 #endif
811   } else {
812     cinfo->progressive_mode = FALSE;
813     cinfo->num_scans = 1;
814   }
815
816   if ((cinfo->progressive_mode || cinfo->block_size < DCTSIZE) &&
817       !cinfo->arith_code)                       /*  TEMPORARY HACK ??? */
818     /* assume default tables no good for progressive or downscale mode */
819     cinfo->optimize_coding = TRUE;
820
821   /* Initialize my private state */
822   if (transcode_only) {
823     /* no main pass in transcoding */
824     if (cinfo->optimize_coding)
825       master->pass_type = huff_opt_pass;
826     else
827       master->pass_type = output_pass;
828   } else {
829     /* for normal compression, first pass is always this type: */
830     master->pass_type = main_pass;
831   }
832   master->scan_number = 0;
833   master->pass_number = 0;
834   if (cinfo->optimize_coding)
835     master->total_passes = cinfo->num_scans * 2;
836   else
837     master->total_passes = cinfo->num_scans;
838 }