Home | History | Annotate | Download | only in libjpeg
      1 #if !defined(_FX_JPEG_TURBO_)
      2 /*
      3  * jcmaster.c
      4  *
      5  * Copyright (C) 1991-1997, Thomas G. Lane.
      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 LOCAL(void)
     47 initial_setup (j_compress_ptr cinfo)
     48 /* Do computations that are needed before master selection phase */
     49 {
     50   int ci;
     51   jpeg_component_info *compptr;
     52   long samplesperrow;
     53   JDIMENSION jd_samplesperrow;
     54 
     55   /* Sanity check on image dimensions */
     56   if (cinfo->image_height <= 0 || cinfo->image_width <= 0
     57       || cinfo->num_components <= 0 || cinfo->input_components <= 0)
     58     ERREXIT(cinfo, JERR_EMPTY_IMAGE);
     59 
     60   /* Make sure image isn't bigger than I can handle */
     61   if ((long) cinfo->image_height > (long) JPEG_MAX_DIMENSION ||
     62       (long) cinfo->image_width > (long) JPEG_MAX_DIMENSION)
     63     ERREXIT1(cinfo, JERR_IMAGE_TOO_BIG, (unsigned int) JPEG_MAX_DIMENSION);
     64 
     65   /* Width of an input scanline must be representable as JDIMENSION. */
     66   samplesperrow = (long) cinfo->image_width * (long) cinfo->input_components;
     67   jd_samplesperrow = (JDIMENSION) samplesperrow;
     68   if ((long) jd_samplesperrow != samplesperrow)
     69     ERREXIT(cinfo, JERR_WIDTH_OVERFLOW);
     70 
     71   /* For now, precision must match compiled-in value... */
     72   if (cinfo->data_precision != BITS_IN_JSAMPLE)
     73     ERREXIT1(cinfo, JERR_BAD_PRECISION, cinfo->data_precision);
     74 
     75   /* Check that number of components won't exceed internal array sizes */
     76   if (cinfo->num_components > MAX_COMPONENTS)
     77     ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->num_components,
     78 	     MAX_COMPONENTS);
     79 
     80   /* Compute maximum sampling factors; check factor validity */
     81   cinfo->max_h_samp_factor = 1;
     82   cinfo->max_v_samp_factor = 1;
     83   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
     84        ci++, compptr++) {
     85     if (compptr->h_samp_factor<=0 || compptr->h_samp_factor>MAX_SAMP_FACTOR ||
     86 	compptr->v_samp_factor<=0 || compptr->v_samp_factor>MAX_SAMP_FACTOR)
     87       ERREXIT(cinfo, JERR_BAD_SAMPLING);
     88     cinfo->max_h_samp_factor = MAX(cinfo->max_h_samp_factor,
     89 				   compptr->h_samp_factor);
     90     cinfo->max_v_samp_factor = MAX(cinfo->max_v_samp_factor,
     91 				   compptr->v_samp_factor);
     92   }
     93 
     94   /* Compute dimensions of components */
     95   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
     96        ci++, compptr++) {
     97     /* Fill in the correct component_index value; don't rely on application */
     98     compptr->component_index = ci;
     99     /* For compression, we never do DCT scaling. */
    100     compptr->DCT_scaled_size = DCTSIZE;
    101     /* Size in DCT blocks */
    102     compptr->width_in_blocks = (JDIMENSION)
    103       jdiv_round_up((long) cinfo->image_width * (long) compptr->h_samp_factor,
    104 		    (long) (cinfo->max_h_samp_factor * DCTSIZE));
    105     compptr->height_in_blocks = (JDIMENSION)
    106       jdiv_round_up((long) cinfo->image_height * (long) compptr->v_samp_factor,
    107 		    (long) (cinfo->max_v_samp_factor * DCTSIZE));
    108     /* Size in samples */
    109     compptr->downsampled_width = (JDIMENSION)
    110       jdiv_round_up((long) cinfo->image_width * (long) compptr->h_samp_factor,
    111 		    (long) cinfo->max_h_samp_factor);
    112     compptr->downsampled_height = (JDIMENSION)
    113       jdiv_round_up((long) cinfo->image_height * (long) compptr->v_samp_factor,
    114 		    (long) cinfo->max_v_samp_factor);
    115     /* Mark component needed (this flag isn't actually used for compression) */
    116     compptr->component_needed = TRUE;
    117   }
    118 
    119   /* Compute number of fully interleaved MCU rows (number of times that
    120    * main controller will call coefficient controller).
    121    */
    122   cinfo->total_iMCU_rows = (JDIMENSION)
    123     jdiv_round_up((long) cinfo->image_height,
    124 		  (long) (cinfo->max_v_samp_factor*DCTSIZE));
    125 }
    126 
    127 
    128 #ifdef C_MULTISCAN_FILES_SUPPORTED
    129 
    130 LOCAL(void)
    131 validate_script (j_compress_ptr cinfo)
    132 /* Verify that the scan script in cinfo->scan_info[] is valid; also
    133  * determine whether it uses progressive JPEG, and set cinfo->progressive_mode.
    134  */
    135 {
    136   const jpeg_scan_info * scanptr;
    137   int scanno, ncomps, ci, coefi, thisi;
    138   int Ss, Se, Ah, Al;
    139   boolean component_sent[MAX_COMPONENTS];
    140 #ifdef C_PROGRESSIVE_SUPPORTED
    141   int * last_bitpos_ptr;
    142   int last_bitpos[MAX_COMPONENTS][DCTSIZE2];
    143   /* -1 until that coefficient has been seen; then last Al for it */
    144 #endif
    145 
    146   if (cinfo->num_scans <= 0)
    147     ERREXIT1(cinfo, JERR_BAD_SCAN_SCRIPT, 0);
    148 
    149   /* For sequential JPEG, all scans must have Ss=0, Se=DCTSIZE2-1;
    150    * for progressive JPEG, no scan can have this.
    151    */
    152   scanptr = cinfo->scan_info;
    153   if (scanptr->Ss != 0 || scanptr->Se != DCTSIZE2-1) {
    154 #ifdef C_PROGRESSIVE_SUPPORTED
    155     cinfo->progressive_mode = TRUE;
    156     last_bitpos_ptr = & last_bitpos[0][0];
    157     for (ci = 0; ci < cinfo->num_components; ci++)
    158       for (coefi = 0; coefi < DCTSIZE2; coefi++)
    159 	*last_bitpos_ptr++ = -1;
    160 #else
    161     ERREXIT(cinfo, JERR_NOT_COMPILED);
    162 #endif
    163   } else {
    164     cinfo->progressive_mode = FALSE;
    165     for (ci = 0; ci < cinfo->num_components; ci++)
    166       component_sent[ci] = FALSE;
    167   }
    168 
    169   for (scanno = 1; scanno <= cinfo->num_scans; scanptr++, scanno++) {
    170     /* Validate component indexes */
    171     ncomps = scanptr->comps_in_scan;
    172     if (ncomps <= 0 || ncomps > MAX_COMPS_IN_SCAN)
    173       ERREXIT2(cinfo, JERR_COMPONENT_COUNT, ncomps, MAX_COMPS_IN_SCAN);
    174     for (ci = 0; ci < ncomps; ci++) {
    175       thisi = scanptr->component_index[ci];
    176       if (thisi < 0 || thisi >= cinfo->num_components)
    177 	ERREXIT1(cinfo, JERR_BAD_SCAN_SCRIPT, scanno);
    178       /* Components must appear in SOF order within each scan */
    179       if (ci > 0 && thisi <= scanptr->component_index[ci-1])
    180 	ERREXIT1(cinfo, JERR_BAD_SCAN_SCRIPT, scanno);
    181     }
    182     /* Validate progression parameters */
    183     Ss = scanptr->Ss;
    184     Se = scanptr->Se;
    185     Ah = scanptr->Ah;
    186     Al = scanptr->Al;
    187     if (cinfo->progressive_mode) {
    188 #ifdef C_PROGRESSIVE_SUPPORTED
    189       /* The JPEG spec simply gives the ranges 0..13 for Ah and Al, but that
    190        * seems wrong: the upper bound ought to depend on data precision.
    191        * Perhaps they really meant 0..N+1 for N-bit precision.
    192        * Here we allow 0..10 for 8-bit data; Al larger than 10 results in
    193        * out-of-range reconstructed DC values during the first DC scan,
    194        * which might cause problems for some decoders.
    195        */
    196 #if BITS_IN_JSAMPLE == 8
    197 #define MAX_AH_AL 10
    198 #else
    199 #define MAX_AH_AL 13
    200 #endif
    201       if (Ss < 0 || Ss >= DCTSIZE2 || Se < Ss || Se >= DCTSIZE2 ||
    202 	  Ah < 0 || Ah > MAX_AH_AL || Al < 0 || Al > MAX_AH_AL)
    203 	ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
    204       if (Ss == 0) {
    205 	if (Se != 0)		/* DC and AC together not OK */
    206 	  ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
    207       } else {
    208 	if (ncomps != 1)	/* AC scans must be for only one component */
    209 	  ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
    210       }
    211       for (ci = 0; ci < ncomps; ci++) {
    212 	last_bitpos_ptr = & last_bitpos[scanptr->component_index[ci]][0];
    213 	if (Ss != 0 && last_bitpos_ptr[0] < 0) /* AC without prior DC scan */
    214 	  ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
    215 	for (coefi = Ss; coefi <= Se; coefi++) {
    216 	  if (last_bitpos_ptr[coefi] < 0) {
    217 	    /* first scan of this coefficient */
    218 	    if (Ah != 0)
    219 	      ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
    220 	  } else {
    221 	    /* not first scan */
    222 	    if (Ah != last_bitpos_ptr[coefi] || Al != Ah-1)
    223 	      ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
    224 	  }
    225 	  last_bitpos_ptr[coefi] = Al;
    226 	}
    227       }
    228 #endif
    229     } else {
    230       /* For sequential JPEG, all progression parameters must be these: */
    231       if (Ss != 0 || Se != DCTSIZE2-1 || Ah != 0 || Al != 0)
    232 	ERREXIT1(cinfo, JERR_BAD_PROG_SCRIPT, scanno);
    233       /* Make sure components are not sent twice */
    234       for (ci = 0; ci < ncomps; ci++) {
    235 	thisi = scanptr->component_index[ci];
    236 	if (component_sent[thisi])
    237 	  ERREXIT1(cinfo, JERR_BAD_SCAN_SCRIPT, scanno);
    238 	component_sent[thisi] = TRUE;
    239       }
    240     }
    241   }
    242 
    243   /* Now verify that everything got sent. */
    244   if (cinfo->progressive_mode) {
    245 #ifdef C_PROGRESSIVE_SUPPORTED
    246     /* For progressive mode, we only check that at least some DC data
    247      * got sent for each component; the spec does not require that all bits
    248      * of all coefficients be transmitted.  Would it be wiser to enforce
    249      * transmission of all coefficient bits??
    250      */
    251     for (ci = 0; ci < cinfo->num_components; ci++) {
    252       if (last_bitpos[ci][0] < 0)
    253 	ERREXIT(cinfo, JERR_MISSING_DATA);
    254     }
    255 #endif
    256   } else {
    257     for (ci = 0; ci < cinfo->num_components; ci++) {
    258       if (! component_sent[ci])
    259 	ERREXIT(cinfo, JERR_MISSING_DATA);
    260     }
    261   }
    262 }
    263 
    264 #endif /* C_MULTISCAN_FILES_SUPPORTED */
    265 
    266 
    267 LOCAL(void)
    268 select_scan_parameters (j_compress_ptr cinfo)
    269 /* Set up the scan parameters for the current scan */
    270 {
    271   int ci;
    272 
    273 #ifdef C_MULTISCAN_FILES_SUPPORTED
    274   if (cinfo->scan_info != NULL) {
    275     /* Prepare for current scan --- the script is already validated */
    276     my_master_ptr master = (my_master_ptr) cinfo->master;
    277     const jpeg_scan_info * scanptr = cinfo->scan_info + master->scan_number;
    278 
    279     cinfo->comps_in_scan = scanptr->comps_in_scan;
    280     for (ci = 0; ci < scanptr->comps_in_scan; ci++) {
    281       cinfo->cur_comp_info[ci] =
    282 	&cinfo->comp_info[scanptr->component_index[ci]];
    283     }
    284     cinfo->Ss = scanptr->Ss;
    285     cinfo->Se = scanptr->Se;
    286     cinfo->Ah = scanptr->Ah;
    287     cinfo->Al = scanptr->Al;
    288   }
    289   else
    290 #endif
    291   {
    292     /* Prepare for single sequential-JPEG scan containing all components */
    293     if (cinfo->num_components > MAX_COMPS_IN_SCAN)
    294       ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->num_components,
    295 	       MAX_COMPS_IN_SCAN);
    296     cinfo->comps_in_scan = cinfo->num_components;
    297     for (ci = 0; ci < cinfo->num_components; ci++) {
    298       cinfo->cur_comp_info[ci] = &cinfo->comp_info[ci];
    299     }
    300     cinfo->Ss = 0;
    301     cinfo->Se = DCTSIZE2-1;
    302     cinfo->Ah = 0;
    303     cinfo->Al = 0;
    304   }
    305 }
    306 
    307 
    308 LOCAL(void)
    309 per_scan_setup (j_compress_ptr cinfo)
    310 /* Do computations that are needed before processing a JPEG scan */
    311 /* cinfo->comps_in_scan and cinfo->cur_comp_info[] are already set */
    312 {
    313   int ci, mcublks, tmp;
    314   jpeg_component_info *compptr;
    315 
    316   if (cinfo->comps_in_scan == 1) {
    317 
    318     /* Noninterleaved (single-component) scan */
    319     compptr = cinfo->cur_comp_info[0];
    320 
    321     /* Overall image size in MCUs */
    322     cinfo->MCUs_per_row = compptr->width_in_blocks;
    323     cinfo->MCU_rows_in_scan = compptr->height_in_blocks;
    324 
    325     /* For noninterleaved scan, always one block per MCU */
    326     compptr->MCU_width = 1;
    327     compptr->MCU_height = 1;
    328     compptr->MCU_blocks = 1;
    329     compptr->MCU_sample_width = DCTSIZE;
    330     compptr->last_col_width = 1;
    331     /* For noninterleaved scans, it is convenient to define last_row_height
    332      * as the number of block rows present in the last iMCU row.
    333      */
    334     tmp = (int) (compptr->height_in_blocks % compptr->v_samp_factor);
    335     if (tmp == 0) tmp = compptr->v_samp_factor;
    336     compptr->last_row_height = tmp;
    337 
    338     /* Prepare array describing MCU composition */
    339     cinfo->blocks_in_MCU = 1;
    340     cinfo->MCU_membership[0] = 0;
    341 
    342   } else {
    343 
    344     /* Interleaved (multi-component) scan */
    345     if (cinfo->comps_in_scan <= 0 || cinfo->comps_in_scan > MAX_COMPS_IN_SCAN)
    346       ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->comps_in_scan,
    347 	       MAX_COMPS_IN_SCAN);
    348 
    349     /* Overall image size in MCUs */
    350     cinfo->MCUs_per_row = (JDIMENSION)
    351       jdiv_round_up((long) cinfo->image_width,
    352 		    (long) (cinfo->max_h_samp_factor*DCTSIZE));
    353     cinfo->MCU_rows_in_scan = (JDIMENSION)
    354       jdiv_round_up((long) cinfo->image_height,
    355 		    (long) (cinfo->max_v_samp_factor*DCTSIZE));
    356 
    357     cinfo->blocks_in_MCU = 0;
    358 
    359     for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
    360       compptr = cinfo->cur_comp_info[ci];
    361       /* Sampling factors give # of blocks of component in each MCU */
    362       compptr->MCU_width = compptr->h_samp_factor;
    363       compptr->MCU_height = compptr->v_samp_factor;
    364       compptr->MCU_blocks = compptr->MCU_width * compptr->MCU_height;
    365       compptr->MCU_sample_width = compptr->MCU_width * DCTSIZE;
    366       /* Figure number of non-dummy blocks in last MCU column & row */
    367       tmp = (int) (compptr->width_in_blocks % compptr->MCU_width);
    368       if (tmp == 0) tmp = compptr->MCU_width;
    369       compptr->last_col_width = tmp;
    370       tmp = (int) (compptr->height_in_blocks % compptr->MCU_height);
    371       if (tmp == 0) tmp = compptr->MCU_height;
    372       compptr->last_row_height = tmp;
    373       /* Prepare array describing MCU composition */
    374       mcublks = compptr->MCU_blocks;
    375       if (cinfo->blocks_in_MCU + mcublks > C_MAX_BLOCKS_IN_MCU)
    376 	ERREXIT(cinfo, JERR_BAD_MCU_SIZE);
    377       while (mcublks-- > 0) {
    378 	cinfo->MCU_membership[cinfo->blocks_in_MCU++] = ci;
    379       }
    380     }
    381 
    382   }
    383 
    384   /* Convert restart specified in rows to actual MCU count. */
    385   /* Note that count must fit in 16 bits, so we provide limiting. */
    386   if (cinfo->restart_in_rows > 0) {
    387     long nominal = (long) cinfo->restart_in_rows * (long) cinfo->MCUs_per_row;
    388     cinfo->restart_interval = (unsigned int) MIN(nominal, 65535L);
    389   }
    390 }
    391 
    392 
    393 /*
    394  * Per-pass setup.
    395  * This is called at the beginning of each pass.  We determine which modules
    396  * will be active during this pass and give them appropriate start_pass calls.
    397  * We also set is_last_pass to indicate whether any more passes will be
    398  * required.
    399  */
    400 
    401 METHODDEF(void)
    402 prepare_for_pass (j_compress_ptr cinfo)
    403 {
    404   my_master_ptr master = (my_master_ptr) cinfo->master;
    405 
    406   switch (master->pass_type) {
    407   case main_pass:
    408     /* Initial pass: will collect input data, and do either Huffman
    409      * optimization or data output for the first scan.
    410      */
    411     select_scan_parameters(cinfo);
    412     per_scan_setup(cinfo);
    413     if (! cinfo->raw_data_in) {
    414       (*cinfo->cconvert->start_pass) (cinfo);
    415       (*cinfo->downsample->start_pass) (cinfo);
    416       (*cinfo->prep->start_pass) (cinfo, JBUF_PASS_THRU);
    417     }
    418     (*cinfo->fdct->start_pass) (cinfo);
    419     (*cinfo->entropy->start_pass) (cinfo, cinfo->optimize_coding);
    420     (*cinfo->coef->start_pass) (cinfo,
    421 				(master->total_passes > 1 ?
    422 				 JBUF_SAVE_AND_PASS : JBUF_PASS_THRU));
    423     (*cinfo->main->start_pass) (cinfo, JBUF_PASS_THRU);
    424     if (cinfo->optimize_coding) {
    425       /* No immediate data output; postpone writing frame/scan headers */
    426       master->pub.call_pass_startup = FALSE;
    427     } else {
    428       /* Will write frame/scan headers at first jpeg_write_scanlines call */
    429       master->pub.call_pass_startup = TRUE;
    430     }
    431     break;
    432 #ifdef ENTROPY_OPT_SUPPORTED
    433   case huff_opt_pass:
    434     /* Do Huffman optimization for a scan after the first one. */
    435     select_scan_parameters(cinfo);
    436     per_scan_setup(cinfo);
    437     if (cinfo->Ss != 0 || cinfo->Ah == 0 || cinfo->arith_code) {
    438       (*cinfo->entropy->start_pass) (cinfo, TRUE);
    439       (*cinfo->coef->start_pass) (cinfo, JBUF_CRANK_DEST);
    440       master->pub.call_pass_startup = FALSE;
    441       break;
    442     }
    443     /* Special case: Huffman DC refinement scans need no Huffman table
    444      * and therefore we can skip the optimization pass for them.
    445      */
    446     master->pass_type = output_pass;
    447     master->pass_number++;
    448     /*FALLTHROUGH*/
    449 #endif
    450   case output_pass:
    451     /* Do a data-output pass. */
    452     /* We need not repeat per-scan setup if prior optimization pass did it. */
    453     if (! cinfo->optimize_coding) {
    454       select_scan_parameters(cinfo);
    455       per_scan_setup(cinfo);
    456     }
    457     (*cinfo->entropy->start_pass) (cinfo, FALSE);
    458     (*cinfo->coef->start_pass) (cinfo, JBUF_CRANK_DEST);
    459     /* We emit frame/scan headers now */
    460     if (master->scan_number == 0)
    461       (*cinfo->marker->write_frame_header) (cinfo);
    462     (*cinfo->marker->write_scan_header) (cinfo);
    463     master->pub.call_pass_startup = FALSE;
    464     break;
    465   default:
    466     ERREXIT(cinfo, JERR_NOT_COMPILED);
    467   }
    468 
    469   master->pub.is_last_pass = (master->pass_number == master->total_passes-1);
    470 
    471   /* Set up progress monitor's pass info if present */
    472   if (cinfo->progress != NULL) {
    473     cinfo->progress->completed_passes = master->pass_number;
    474     cinfo->progress->total_passes = master->total_passes;
    475   }
    476 }
    477 
    478 
    479 /*
    480  * Special start-of-pass hook.
    481  * This is called by jpeg_write_scanlines if call_pass_startup is TRUE.
    482  * In single-pass processing, we need this hook because we don't want to
    483  * write frame/scan headers during jpeg_start_compress; we want to let the
    484  * application write COM markers etc. between jpeg_start_compress and the
    485  * jpeg_write_scanlines loop.
    486  * In multi-pass processing, this routine is not used.
    487  */
    488 
    489 METHODDEF(void)
    490 pass_startup (j_compress_ptr cinfo)
    491 {
    492   cinfo->master->call_pass_startup = FALSE; /* reset flag so call only once */
    493 
    494   (*cinfo->marker->write_frame_header) (cinfo);
    495   (*cinfo->marker->write_scan_header) (cinfo);
    496 }
    497 
    498 
    499 /*
    500  * Finish up at end of pass.
    501  */
    502 
    503 METHODDEF(void)
    504 finish_pass_master (j_compress_ptr cinfo)
    505 {
    506   my_master_ptr master = (my_master_ptr) cinfo->master;
    507 
    508   /* The entropy coder always needs an end-of-pass call,
    509    * either to analyze statistics or to flush its output buffer.
    510    */
    511   (*cinfo->entropy->finish_pass) (cinfo);
    512 
    513   /* Update state for next pass */
    514   switch (master->pass_type) {
    515   case main_pass:
    516     /* next pass is either output of scan 0 (after optimization)
    517      * or output of scan 1 (if no optimization).
    518      */
    519     master->pass_type = output_pass;
    520     if (! cinfo->optimize_coding)
    521       master->scan_number++;
    522     break;
    523   case huff_opt_pass:
    524     /* next pass is always output of current scan */
    525     master->pass_type = output_pass;
    526     break;
    527   case output_pass:
    528     /* next pass is either optimization or output of next scan */
    529     if (cinfo->optimize_coding)
    530       master->pass_type = huff_opt_pass;
    531     master->scan_number++;
    532     break;
    533   }
    534 
    535   master->pass_number++;
    536 }
    537 
    538 
    539 /*
    540  * Initialize master compression control.
    541  */
    542 
    543 GLOBAL(void)
    544 jinit_c_master_control (j_compress_ptr cinfo, boolean transcode_only)
    545 {
    546   my_master_ptr master;
    547 
    548   master = (my_master_ptr)
    549       (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
    550 				  SIZEOF(my_comp_master));
    551   cinfo->master = (struct jpeg_comp_master *) master;
    552   master->pub.prepare_for_pass = prepare_for_pass;
    553   master->pub.pass_startup = pass_startup;
    554   master->pub.finish_pass = finish_pass_master;
    555   master->pub.is_last_pass = FALSE;
    556 
    557   /* Validate parameters, determine derived values */
    558   initial_setup(cinfo);
    559 
    560   if (cinfo->scan_info != NULL) {
    561 #ifdef C_MULTISCAN_FILES_SUPPORTED
    562     validate_script(cinfo);
    563 #else
    564     ERREXIT(cinfo, JERR_NOT_COMPILED);
    565 #endif
    566   } else {
    567     cinfo->progressive_mode = FALSE;
    568     cinfo->num_scans = 1;
    569   }
    570 
    571   if (cinfo->progressive_mode)	/*  TEMPORARY HACK ??? */
    572     cinfo->optimize_coding = TRUE; /* assume default tables no good for progressive mode */
    573 
    574   /* Initialize my private state */
    575   if (transcode_only) {
    576     /* no main pass in transcoding */
    577     if (cinfo->optimize_coding)
    578       master->pass_type = huff_opt_pass;
    579     else
    580       master->pass_type = output_pass;
    581   } else {
    582     /* for normal compression, first pass is always this type: */
    583     master->pass_type = main_pass;
    584   }
    585   master->scan_number = 0;
    586   master->pass_number = 0;
    587   if (cinfo->optimize_coding)
    588     master->total_passes = cinfo->num_scans * 2;
    589   else
    590     master->total_passes = cinfo->num_scans;
    591 }
    592 
    593 #endif //_FX_JPEG_TURBO_
    594