third_party/libjpeg/jcmaster.c - cobalt - Git at Google

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

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


 /* Private state */

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

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

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

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

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

 typedef my_comp_master * my_master_ptr;


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

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

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

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

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

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

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

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

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

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


 #ifdef C_MULTISCAN_FILES_SUPPORTED

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

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

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

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

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

 #endif /* C_MULTISCAN_FILES_SUPPORTED */


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

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

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


 LOCAL(void)
 per_scan_setup (j_compress_ptr cinfo)
 /* Do computations that are needed before processing a JPEG scan */
 /* cinfo->comps_in_scan and cinfo->cur_comp_info[] are already set */
 {
   int ci, mcublks, tmp;
   jpeg_component_info *compptr;

   if (cinfo->comps_in_scan == 1) {

     /* Noninterleaved (single-component) scan */
     compptr = cinfo->cur_comp_info[0];

     /* Overall image size in MCUs */
     cinfo->MCUs_per_row = compptr->width_in_blocks;
     cinfo->MCU_rows_in_scan = compptr->height_in_blocks;

     /* For noninterleaved scan, always one block per MCU */
     compptr->MCU_width = 1;
     compptr->MCU_height = 1;
     compptr->MCU_blocks = 1;
     compptr->MCU_sample_width = DCTSIZE;
     compptr->last_col_width = 1;
     /* For noninterleaved scans, it is convenient to define last_row_height
      * as the number of block rows present in the last iMCU row.
      */
     tmp = (int) (compptr->height_in_blocks % compptr->v_samp_factor);
     if (tmp == 0) tmp = compptr->v_samp_factor;
     compptr->last_row_height = tmp;

     /* Prepare array describing MCU composition */
     cinfo->blocks_in_MCU = 1;
     cinfo->MCU_membership[0] = 0;

   } else {

     /* Interleaved (multi-component) scan */
     if (cinfo->comps_in_scan <= 0 || cinfo->comps_in_scan > MAX_COMPS_IN_SCAN)
       ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->comps_in_scan,
 	       MAX_COMPS_IN_SCAN);

     /* Overall image size in MCUs */
     cinfo->MCUs_per_row = (JDIMENSION)
       jdiv_round_up((long) cinfo->image_width,
 		    (long) (cinfo->max_h_samp_factor*DCTSIZE));
     cinfo->MCU_rows_in_scan = (JDIMENSION)
       jdiv_round_up((long) cinfo->image_height,
 		    (long) (cinfo->max_v_samp_factor*DCTSIZE));

     cinfo->blocks_in_MCU = 0;

     for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
       compptr = cinfo->cur_comp_info[ci];
       /* Sampling factors give # of blocks of component in each MCU */
       compptr->MCU_width = compptr->h_samp_factor;
       compptr->MCU_height = compptr->v_samp_factor;
       compptr->MCU_blocks = compptr->MCU_width * compptr->MCU_height;
       compptr->MCU_sample_width = compptr->MCU_width * DCTSIZE;
       /* Figure number of non-dummy blocks in last MCU column & row */
       tmp = (int) (compptr->width_in_blocks % compptr->MCU_width);
       if (tmp == 0) tmp = compptr->MCU_width;
       compptr->last_col_width = tmp;
       tmp = (int) (compptr->height_in_blocks % compptr->MCU_height);
       if (tmp == 0) tmp = compptr->MCU_height;
       compptr->last_row_height = tmp;
       /* Prepare array describing MCU composition */
       mcublks = compptr->MCU_blocks;
       if (cinfo->blocks_in_MCU + mcublks > C_MAX_BLOCKS_IN_MCU)
 	ERREXIT(cinfo, JERR_BAD_MCU_SIZE);
       while (mcublks-- > 0) {
 	cinfo->MCU_membership[cinfo->blocks_in_MCU++] = ci;
       }
     }

   }

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


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

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

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

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

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


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

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

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


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

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

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

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

   master->pass_number++;
 }


 /*
  * Initialize master compression control.
  */

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

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

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

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

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

   /* Initialize my private state */
   if (transcode_only) {
     /* no main pass in transcoding */
     if (cinfo->optimize_coding)
       master->pass_type = huff_opt_pass;
     else
       master->pass_type = output_pass;
   } else {
     /* for normal compression, first pass is always this type: */
     master->pass_type = main_pass;
   }
   master->scan_number = 0;
   master->pass_number = 0;
   if (cinfo->optimize_coding)
     master->total_passes = cinfo->num_scans * 2;
   else
     master->total_passes = cinfo->num_scans;
 }
	/*
	* jcmaster.c
	*
	* Copyright (C) 1991-1997, Thomas G. Lane.
	* This file is part of the Independent JPEG Group's software.
	* For conditions of distribution and use, see the accompanying README file.
	*
	* This file contains master control logic for the JPEG compressor.
	* These routines are concerned with parameter validation, initial setup,
	* and inter-pass control (determining the number of passes and the work
	* to be done in each pass).
	*/

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


	/* Private state */

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

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

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

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

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

	typedef my_comp_master * my_master_ptr;


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

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

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

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

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

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

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

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

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

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


	#ifdef C_MULTISCAN_FILES_SUPPORTED

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

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

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

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

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

	#endif /* C_MULTISCAN_FILES_SUPPORTED */


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

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

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


	LOCAL(void)
	per_scan_setup (j_compress_ptr cinfo)
	/* Do computations that are needed before processing a JPEG scan */
	/* cinfo->comps_in_scan and cinfo->cur_comp_info[] are already set */
	{
	int ci, mcublks, tmp;
	jpeg_component_info *compptr;

	if (cinfo->comps_in_scan == 1) {

	/* Noninterleaved (single-component) scan */
	compptr = cinfo->cur_comp_info[0];

	/* Overall image size in MCUs */
	cinfo->MCUs_per_row = compptr->width_in_blocks;
	cinfo->MCU_rows_in_scan = compptr->height_in_blocks;

	/* For noninterleaved scan, always one block per MCU */
	compptr->MCU_width = 1;
	compptr->MCU_height = 1;
	compptr->MCU_blocks = 1;
	compptr->MCU_sample_width = DCTSIZE;
	compptr->last_col_width = 1;
	/* For noninterleaved scans, it is convenient to define last_row_height
	* as the number of block rows present in the last iMCU row.
	*/
	tmp = (int) (compptr->height_in_blocks % compptr->v_samp_factor);
	if (tmp == 0) tmp = compptr->v_samp_factor;
	compptr->last_row_height = tmp;

	/* Prepare array describing MCU composition */
	cinfo->blocks_in_MCU = 1;
	cinfo->MCU_membership[0] = 0;

	} else {

	/* Interleaved (multi-component) scan */
	if (cinfo->comps_in_scan <= 0 \|\| cinfo->comps_in_scan > MAX_COMPS_IN_SCAN)
	ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->comps_in_scan,
	MAX_COMPS_IN_SCAN);

	/* Overall image size in MCUs */
	cinfo->MCUs_per_row = (JDIMENSION)
	jdiv_round_up((long) cinfo->image_width,
	(long) (cinfo->max_h_samp_factor*DCTSIZE));
	cinfo->MCU_rows_in_scan = (JDIMENSION)
	jdiv_round_up((long) cinfo->image_height,
	(long) (cinfo->max_v_samp_factor*DCTSIZE));

	cinfo->blocks_in_MCU = 0;

	for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
	compptr = cinfo->cur_comp_info[ci];
	/* Sampling factors give # of blocks of component in each MCU */
	compptr->MCU_width = compptr->h_samp_factor;
	compptr->MCU_height = compptr->v_samp_factor;
	compptr->MCU_blocks = compptr->MCU_width * compptr->MCU_height;
	compptr->MCU_sample_width = compptr->MCU_width * DCTSIZE;
	/* Figure number of non-dummy blocks in last MCU column & row */
	tmp = (int) (compptr->width_in_blocks % compptr->MCU_width);
	if (tmp == 0) tmp = compptr->MCU_width;
	compptr->last_col_width = tmp;
	tmp = (int) (compptr->height_in_blocks % compptr->MCU_height);
	if (tmp == 0) tmp = compptr->MCU_height;
	compptr->last_row_height = tmp;
	/* Prepare array describing MCU composition */
	mcublks = compptr->MCU_blocks;
	if (cinfo->blocks_in_MCU + mcublks > C_MAX_BLOCKS_IN_MCU)
	ERREXIT(cinfo, JERR_BAD_MCU_SIZE);
	while (mcublks-- > 0) {
	cinfo->MCU_membership[cinfo->blocks_in_MCU++] = ci;
	}
	}

	}

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


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

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

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

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

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


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

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

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


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

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

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

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

	master->pass_number++;
	}


	/*
	* Initialize master compression control.
	*/

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

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

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

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

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

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