# dlib C++ Library - jcmaster.c

    /*
     * jcmaster.c
     *
     * Copyright (C) 1991-1997, Thomas G. Lane.
     * Modified 2003-2011 by Guido Vollbeding.
     * 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.
     */

    /*
     * Compute JPEG image dimensions and related values.
     * NOTE: this is exported for possible use by application.
     * Hence it mustn't do anything that can't be done twice.
     */

    GLOBAL(void)
    jpeg_calc_jpeg_dimensions (j_compress_ptr cinfo)
    /* Do computations that are needed before master selection phase */
    {
    #ifdef DCT_SCALING_SUPPORTED

      /* Sanity check on input image dimensions to prevent overflow in
       * following calculation.
       * We do check jpeg_width and jpeg_height in initial_setup below,
       * but image_width and image_height can come from arbitrary data,
       * and we need some space for multiplication by block_size.
       */
      if (((long) cinfo->image_width >> 24) || ((long) cinfo->image_height >> 24))
        ERREXIT1(cinfo, JERR_IMAGE_TOO_BIG, (unsigned int) JPEG_MAX_DIMENSION);

      /* Compute actual JPEG image dimensions and DCT scaling choices. */
      if (cinfo->scale_num >= cinfo->scale_denom * cinfo->block_size) {
        /* Provide block_size/1 scaling */
        cinfo->jpeg_width = cinfo->image_width * cinfo->block_size;
        cinfo->jpeg_height = cinfo->image_height * cinfo->block_size;
        cinfo->min_DCT_h_scaled_size = 1;
        cinfo->min_DCT_v_scaled_size = 1;
      } else if (cinfo->scale_num * 2 >= cinfo->scale_denom * cinfo->block_size) {
        /* Provide block_size/2 scaling */
        cinfo->jpeg_width = (JDIMENSION)
          jdiv_round_up((long) cinfo->image_width * cinfo->block_size, 2L);
        cinfo->jpeg_height = (JDIMENSION)
          jdiv_round_up((long) cinfo->image_height * cinfo->block_size, 2L);
        cinfo->min_DCT_h_scaled_size = 2;
        cinfo->min_DCT_v_scaled_size = 2;
      } else if (cinfo->scale_num * 3 >= cinfo->scale_denom * cinfo->block_size) {
        /* Provide block_size/3 scaling */
        cinfo->jpeg_width = (JDIMENSION)
          jdiv_round_up((long) cinfo->image_width * cinfo->block_size, 3L);
        cinfo->jpeg_height = (JDIMENSION)
          jdiv_round_up((long) cinfo->image_height * cinfo->block_size, 3L);
        cinfo->min_DCT_h_scaled_size = 3;
        cinfo->min_DCT_v_scaled_size = 3;
      } else if (cinfo->scale_num * 4 >= cinfo->scale_denom * cinfo->block_size) {
        /* Provide block_size/4 scaling */
        cinfo->jpeg_width = (JDIMENSION)
          jdiv_round_up((long) cinfo->image_width * cinfo->block_size, 4L);
        cinfo->jpeg_height = (JDIMENSION)
          jdiv_round_up((long) cinfo->image_height * cinfo->block_size, 4L);
        cinfo->min_DCT_h_scaled_size = 4;
        cinfo->min_DCT_v_scaled_size = 4;
      } else if (cinfo->scale_num * 5 >= cinfo->scale_denom * cinfo->block_size) {
        /* Provide block_size/5 scaling */
        cinfo->jpeg_width = (JDIMENSION)
          jdiv_round_up((long) cinfo->image_width * cinfo->block_size, 5L);
        cinfo->jpeg_height = (JDIMENSION)
          jdiv_round_up((long) cinfo->image_height * cinfo->block_size, 5L);
        cinfo->min_DCT_h_scaled_size = 5;
        cinfo->min_DCT_v_scaled_size = 5;
      } else if (cinfo->scale_num * 6 >= cinfo->scale_denom * cinfo->block_size) {
        /* Provide block_size/6 scaling */
        cinfo->jpeg_width = (JDIMENSION)
          jdiv_round_up((long) cinfo->image_width * cinfo->block_size, 6L);
        cinfo->jpeg_height = (JDIMENSION)
          jdiv_round_up((long) cinfo->image_height * cinfo->block_size, 6L);
        cinfo->min_DCT_h_scaled_size = 6;
        cinfo->min_DCT_v_scaled_size = 6;
      } else if (cinfo->scale_num * 7 >= cinfo->scale_denom * cinfo->block_size) {
        /* Provide block_size/7 scaling */
        cinfo->jpeg_width = (JDIMENSION)
          jdiv_round_up((long) cinfo->image_width * cinfo->block_size, 7L);
        cinfo->jpeg_height = (JDIMENSION)
          jdiv_round_up((long) cinfo->image_height * cinfo->block_size, 7L);
        cinfo->min_DCT_h_scaled_size = 7;
        cinfo->min_DCT_v_scaled_size = 7;
      } else if (cinfo->scale_num * 8 >= cinfo->scale_denom * cinfo->block_size) {
        /* Provide block_size/8 scaling */
        cinfo->jpeg_width = (JDIMENSION)
          jdiv_round_up((long) cinfo->image_width * cinfo->block_size, 8L);
        cinfo->jpeg_height = (JDIMENSION)
          jdiv_round_up((long) cinfo->image_height * cinfo->block_size, 8L);
        cinfo->min_DCT_h_scaled_size = 8;
        cinfo->min_DCT_v_scaled_size = 8;
      } else if (cinfo->scale_num * 9 >= cinfo->scale_denom * cinfo->block_size) {
        /* Provide block_size/9 scaling */
        cinfo->jpeg_width = (JDIMENSION)
          jdiv_round_up((long) cinfo->image_width * cinfo->block_size, 9L);
        cinfo->jpeg_height = (JDIMENSION)
          jdiv_round_up((long) cinfo->image_height * cinfo->block_size, 9L);
        cinfo->min_DCT_h_scaled_size = 9;
        cinfo->min_DCT_v_scaled_size = 9;
      } else if (cinfo->scale_num * 10 >= cinfo->scale_denom * cinfo->block_size) {
        /* Provide block_size/10 scaling */
        cinfo->jpeg_width = (JDIMENSION)
          jdiv_round_up((long) cinfo->image_width * cinfo->block_size, 10L);
        cinfo->jpeg_height = (JDIMENSION)
          jdiv_round_up((long) cinfo->image_height * cinfo->block_size, 10L);
        cinfo->min_DCT_h_scaled_size = 10;
        cinfo->min_DCT_v_scaled_size = 10;
      } else if (cinfo->scale_num * 11 >= cinfo->scale_denom * cinfo->block_size) {
        /* Provide block_size/11 scaling */
        cinfo->jpeg_width = (JDIMENSION)
          jdiv_round_up((long) cinfo->image_width * cinfo->block_size, 11L);
        cinfo->jpeg_height = (JDIMENSION)
          jdiv_round_up((long) cinfo->image_height * cinfo->block_size, 11L);
        cinfo->min_DCT_h_scaled_size = 11;
        cinfo->min_DCT_v_scaled_size = 11;
      } else if (cinfo->scale_num * 12 >= cinfo->scale_denom * cinfo->block_size) {
        /* Provide block_size/12 scaling */
        cinfo->jpeg_width = (JDIMENSION)
          jdiv_round_up((long) cinfo->image_width * cinfo->block_size, 12L);
        cinfo->jpeg_height = (JDIMENSION)
          jdiv_round_up((long) cinfo->image_height * cinfo->block_size, 12L);
        cinfo->min_DCT_h_scaled_size = 12;
        cinfo->min_DCT_v_scaled_size = 12;
      } else if (cinfo->scale_num * 13 >= cinfo->scale_denom * cinfo->block_size) {
        /* Provide block_size/13 scaling */
        cinfo->jpeg_width = (JDIMENSION)
          jdiv_round_up((long) cinfo->image_width * cinfo->block_size, 13L);
        cinfo->jpeg_height = (JDIMENSION)
          jdiv_round_up((long) cinfo->image_height * cinfo->block_size, 13L);
        cinfo->min_DCT_h_scaled_size = 13;
        cinfo->min_DCT_v_scaled_size = 13;
      } else if (cinfo->scale_num * 14 >= cinfo->scale_denom * cinfo->block_size) {
        /* Provide block_size/14 scaling */
        cinfo->jpeg_width = (JDIMENSION)
          jdiv_round_up((long) cinfo->image_width * cinfo->block_size, 14L);
        cinfo->jpeg_height = (JDIMENSION)
          jdiv_round_up((long) cinfo->image_height * cinfo->block_size, 14L);
        cinfo->min_DCT_h_scaled_size = 14;
        cinfo->min_DCT_v_scaled_size = 14;
      } else if (cinfo->scale_num * 15 >= cinfo->scale_denom * cinfo->block_size) {
        /* Provide block_size/15 scaling */
        cinfo->jpeg_width = (JDIMENSION)
          jdiv_round_up((long) cinfo->image_width * cinfo->block_size, 15L);
        cinfo->jpeg_height = (JDIMENSION)
          jdiv_round_up((long) cinfo->image_height * cinfo->block_size, 15L);
        cinfo->min_DCT_h_scaled_size = 15;
        cinfo->min_DCT_v_scaled_size = 15;
      } else {
        /* Provide block_size/16 scaling */
        cinfo->jpeg_width = (JDIMENSION)
          jdiv_round_up((long) cinfo->image_width * cinfo->block_size, 16L);
        cinfo->jpeg_height = (JDIMENSION)
          jdiv_round_up((long) cinfo->image_height * cinfo->block_size, 16L);
        cinfo->min_DCT_h_scaled_size = 16;
        cinfo->min_DCT_v_scaled_size = 16;
      }

    #else /* !DCT_SCALING_SUPPORTED */

      /* Hardwire it to "no scaling" */
      cinfo->jpeg_width = cinfo->image_width;
      cinfo->jpeg_height = cinfo->image_height;
      cinfo->min_DCT_h_scaled_size = DCTSIZE;
      cinfo->min_DCT_v_scaled_size = DCTSIZE;

    #endif /* DCT_SCALING_SUPPORTED */
    }

    LOCAL(void)
    jpeg_calc_trans_dimensions (j_compress_ptr cinfo)
    {
      if (cinfo->min_DCT_h_scaled_size != cinfo->min_DCT_v_scaled_size)
        ERREXIT2(cinfo, JERR_BAD_DCTSIZE,
    	     cinfo->min_DCT_h_scaled_size, cinfo->min_DCT_v_scaled_size);

      cinfo->block_size = cinfo->min_DCT_h_scaled_size;
    }

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

      if (transcode_only)
        jpeg_calc_trans_dimensions(cinfo);
      else
        jpeg_calc_jpeg_dimensions(cinfo);

      /* Sanity check on block_size */
      if (cinfo->block_size < 1 || cinfo->block_size > 16)
        ERREXIT2(cinfo, JERR_BAD_DCTSIZE, cinfo->block_size, cinfo->block_size);

      /* Derive natural_order from block_size */
      switch (cinfo->block_size) {
      case 2: cinfo->natural_order = jpeg_natural_order2; break;
      case 3: cinfo->natural_order = jpeg_natural_order3; break;
      case 4: cinfo->natural_order = jpeg_natural_order4; break;
      case 5: cinfo->natural_order = jpeg_natural_order5; break;
      case 6: cinfo->natural_order = jpeg_natural_order6; break;
      case 7: cinfo->natural_order = jpeg_natural_order7; break;
      default: cinfo->natural_order = jpeg_natural_order; break;
      }

      /* Derive lim_Se from block_size */
      cinfo->lim_Se = cinfo->block_size < DCTSIZE ?
        cinfo->block_size * cinfo->block_size - 1 : DCTSIZE2-1;

      /* Sanity check on image dimensions */
      if (cinfo->jpeg_height <= 0 || cinfo->jpeg_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->jpeg_height > (long) JPEG_MAX_DIMENSION ||
          (long) cinfo->jpeg_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;
        /* In selecting the actual DCT scaling for each component, we try to
         * scale down the chroma components via DCT scaling rather than downsampling.
         * This saves time if the downsampler gets to use 1:1 scaling.
         * Note this code adapts subsampling ratios which are powers of 2.
         */
        ssize = 1;
    #ifdef DCT_SCALING_SUPPORTED
        while (cinfo->min_DCT_h_scaled_size * ssize <=
    	   (cinfo->do_fancy_downsampling ? DCTSIZE : DCTSIZE / 2) &&
    	   (cinfo->max_h_samp_factor % (compptr->h_samp_factor * ssize * 2)) == 0) {
          ssize = ssize * 2;
        }
    #endif
        compptr->DCT_h_scaled_size = cinfo->min_DCT_h_scaled_size * ssize;
        ssize = 1;
    #ifdef DCT_SCALING_SUPPORTED
        while (cinfo->min_DCT_v_scaled_size * ssize <=
    	   (cinfo->do_fancy_downsampling ? DCTSIZE : DCTSIZE / 2) &&
    	   (cinfo->max_v_samp_factor % (compptr->v_samp_factor * ssize * 2)) == 0) {
          ssize = ssize * 2;
        }
    #endif
        compptr->DCT_v_scaled_size = cinfo->min_DCT_v_scaled_size * ssize;

        /* We don't support DCT ratios larger than 2. */
        if (compptr->DCT_h_scaled_size > compptr->DCT_v_scaled_size * 2)
    	compptr->DCT_h_scaled_size = compptr->DCT_v_scaled_size * 2;
        else if (compptr->DCT_v_scaled_size > compptr->DCT_h_scaled_size * 2)
    	compptr->DCT_v_scaled_size = compptr->DCT_h_scaled_size * 2;

        /* Size in DCT blocks */
        compptr->width_in_blocks = (JDIMENSION)
          jdiv_round_up((long) cinfo->jpeg_width * (long) compptr->h_samp_factor,
    		    (long) (cinfo->max_h_samp_factor * cinfo->block_size));
        compptr->height_in_blocks = (JDIMENSION)
          jdiv_round_up((long) cinfo->jpeg_height * (long) compptr->v_samp_factor,
    		    (long) (cinfo->max_v_samp_factor * cinfo->block_size));
        /* Size in samples */
        compptr->downsampled_width = (JDIMENSION)
          jdiv_round_up((long) cinfo->jpeg_width *
    		    (long) (compptr->h_samp_factor * compptr->DCT_h_scaled_size),
    		    (long) (cinfo->max_h_samp_factor * cinfo->block_size));
        compptr->downsampled_height = (JDIMENSION)
          jdiv_round_up((long) cinfo->jpeg_height *
    		    (long) (compptr->v_samp_factor * compptr->DCT_v_scaled_size),
    		    (long) (cinfo->max_v_samp_factor * cinfo->block_size));
        /* 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->jpeg_height,
    		  (long) (cinfo->max_v_samp_factor * cinfo->block_size));
    }

    #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);
        }
      }
    }

    LOCAL(void)
    reduce_script (j_compress_ptr cinfo)
    /* Adapt scan script for use with reduced block size;
     * assume that script has been validated before.
     */
    {
      jpeg_scan_info * scanptr;
      int idxout, idxin;

      /* Circumvent const declaration for this function */
      scanptr = (jpeg_scan_info *) cinfo->scan_info;
      idxout = 0;

      for (idxin = 0; idxin < cinfo->num_scans; idxin++) {
        /* After skipping, idxout becomes smaller than idxin */
        if (idxin != idxout)
          /* Copy rest of data;
           * note we stay in given chunk of allocated memory.
           */
          scanptr[idxout] = scanptr[idxin];
        if (scanptr[idxout].Ss > cinfo->lim_Se)
          /* Entire scan out of range - skip this entry */
          continue;
        if (scanptr[idxout].Se > cinfo->lim_Se)
          /* Limit scan to end of block */
          scanptr[idxout].Se = cinfo->lim_Se;
        idxout++;
      }

      cinfo->num_scans = idxout;
    }

    #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]];
        }
        if (cinfo->progressive_mode) {
          cinfo->Ss = scanptr->Ss;
          cinfo->Se = scanptr->Se;
          cinfo->Ah = scanptr->Ah;
          cinfo->Al = scanptr->Al;
          return;
        }
      }
      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 = cinfo->block_size * cinfo->block_size - 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 = compptr->DCT_h_scaled_size;
        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->jpeg_width,
    		    (long) (cinfo->max_h_samp_factor * cinfo->block_size));
        cinfo->MCU_rows_in_scan = (JDIMENSION)
          jdiv_round_up((long) cinfo->jpeg_height,
    		    (long) (cinfo->max_v_samp_factor * cinfo->block_size));

        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 * compptr->DCT_h_scaled_size;
          /* 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->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, transcode_only);

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

      if ((cinfo->progressive_mode || cinfo->block_size < DCTSIZE) &&
          !cinfo->arith_code)			/*  TEMPORARY HACK ??? */
        /* assume default tables no good for progressive or downscale mode */
        cinfo->optimize_coding = TRUE;

      /* 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;
    }