    /*
     * jdmaster.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 decompressor.
     * These routines are concerned with selecting the modules to be executed
     * and with 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 struct {
      struct jpeg_decomp_master pub; /* public fields */

      int pass_number;		/* # of passes completed */

      int using_merged_upsample; /* TRUE if using merged upsample/cconvert */

      /* Saved references to initialized quantizer modules,
       * in case we need to switch modes.
       */
      struct jpeg_color_quantizer * quantizer_1pass;
      struct jpeg_color_quantizer * quantizer_2pass;
    } my_decomp_master;

    typedef my_decomp_master * my_master_ptr;

    /*
     * Determine whether merged upsample/color conversion should be used.
     * CRUCIAL: this must match the actual capabilities of jdmerge.c!
     */

    LOCAL(int)
    use_merged_upsample (j_decompress_ptr cinfo)
    {
    #ifdef UPSAMPLE_MERGING_SUPPORTED
      /* Merging is the equivalent of plain box-filter upsampling */
      if (cinfo->do_fancy_upsampling || cinfo->CCIR601_sampling)
        return FALSE;
      /* jdmerge.c only supports YCC=>RGB color conversion */
      if (cinfo->jpeg_color_space != JCS_YCbCr || cinfo->num_components != 3 ||
          cinfo->out_color_space != JCS_RGB ||
          cinfo->out_color_components != RGB_PIXELSIZE)
        return FALSE;
      /* and it only handles 2h1v or 2h2v sampling ratios */
      if (cinfo->comp_info[0].h_samp_factor != 2 ||
          cinfo->comp_info[1].h_samp_factor != 1 ||
          cinfo->comp_info[2].h_samp_factor != 1 ||
          cinfo->comp_info[0].v_samp_factor >  2 ||
          cinfo->comp_info[1].v_samp_factor != 1 ||
          cinfo->comp_info[2].v_samp_factor != 1)
        return FALSE;
      /* furthermore, it doesn't work if we've scaled the IDCTs differently */
      if (cinfo->comp_info[0].DCT_scaled_size != cinfo->min_DCT_scaled_size ||
          cinfo->comp_info[1].DCT_scaled_size != cinfo->min_DCT_scaled_size ||
          cinfo->comp_info[2].DCT_scaled_size != cinfo->min_DCT_scaled_size)
        return FALSE;
      /* ??? also need to test for upsample-time rescaling, when & if supported */
      return TRUE;			/* by golly, it'll work... */
    #else
      return FALSE;
    #endif
    }

    /*
     * Compute output 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.
     * Also note that it may be called before the master module is initialized!
     */

    GLOBAL(void)
    jpeg_calc_output_dimensions (j_decompress_ptr cinfo)
    /* Do computations that are needed before master selection phase */
    {
    #ifdef IDCT_SCALING_SUPPORTED
      int ci;
      jpeg_component_info *compptr;
    #endif

      /* Prevent application from calling me at wrong times */
      if (cinfo->global_state != DSTATE_READY)
        ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);

    #ifdef IDCT_SCALING_SUPPORTED

      /* Compute actual output image dimensions and DCT scaling choices. */
      if (cinfo->scale_num * 8 <= cinfo->scale_denom) {
        /* Provide 1/8 scaling */
        cinfo->output_width = (JDIMENSION)
          jdiv_round_up((long) cinfo->image_width, 8L);
        cinfo->output_height = (JDIMENSION)
          jdiv_round_up((long) cinfo->image_height, 8L);
        cinfo->min_DCT_scaled_size = 1;
      } else if (cinfo->scale_num * 4 <= cinfo->scale_denom) {
        /* Provide 1/4 scaling */
        cinfo->output_width = (JDIMENSION)
          jdiv_round_up((long) cinfo->image_width, 4L);
        cinfo->output_height = (JDIMENSION)
          jdiv_round_up((long) cinfo->image_height, 4L);
        cinfo->min_DCT_scaled_size = 2;
      } else if (cinfo->scale_num * 2 <= cinfo->scale_denom) {
        /* Provide 1/2 scaling */
        cinfo->output_width = (JDIMENSION)
          jdiv_round_up((long) cinfo->image_width, 2L);
        cinfo->output_height = (JDIMENSION)
          jdiv_round_up((long) cinfo->image_height, 2L);
        cinfo->min_DCT_scaled_size = 4;
      } else {
        /* Provide 1/1 scaling */
        cinfo->output_width = cinfo->image_width;
        cinfo->output_height = cinfo->image_height;
        cinfo->min_DCT_scaled_size = DCTSIZE;
      }
      /* In selecting the actual DCT scaling for each component, we try to
       * scale up the chroma components via IDCT scaling rather than upsampling.
       * This saves time if the upsampler gets to use 1:1 scaling.
       * Note this code assumes that the supported DCT scalings are powers of 2.
       */
      for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
           ci++, compptr++) {
        int ssize = cinfo->min_DCT_scaled_size;
        while (ssize < DCTSIZE &&
    	   (compptr->h_samp_factor * ssize * 2 <=
    	    cinfo->max_h_samp_factor * cinfo->min_DCT_scaled_size) &&
    	   (compptr->v_samp_factor * ssize * 2 <=
    	    cinfo->max_v_samp_factor * cinfo->min_DCT_scaled_size)) {
          ssize = ssize * 2;
        }
        compptr->DCT_scaled_size = ssize;
      }

      /* Recompute downsampled dimensions of components;
       * application needs to know these if using raw downsampled data.
       */
      for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
           ci++, compptr++) {
        /* Size in samples, after IDCT scaling */
        compptr->downsampled_width = (JDIMENSION)
          jdiv_round_up((long) cinfo->image_width *
    		    (long) (compptr->h_samp_factor * compptr->DCT_scaled_size),
    		    (long) (cinfo->max_h_samp_factor * DCTSIZE));
        compptr->downsampled_height = (JDIMENSION)
          jdiv_round_up((long) cinfo->image_height *
    		    (long) (compptr->v_samp_factor * compptr->DCT_scaled_size),
    		    (long) (cinfo->max_v_samp_factor * DCTSIZE));
      }

    #else /* !IDCT_SCALING_SUPPORTED */

      /* Hardwire it to "no scaling" */
      cinfo->output_width = cinfo->image_width;
      cinfo->output_height = cinfo->image_height;
      /* jdinput.c has already initialized DCT_scaled_size to DCTSIZE,
       * and has computed unscaled downsampled_width and downsampled_height.
       */

    #endif /* IDCT_SCALING_SUPPORTED */

      /* Report number of components in selected colorspace. */
      /* Probably this should be in the color conversion module... */
      switch (cinfo->out_color_space) {
      case JCS_GRAYSCALE:
        cinfo->out_color_components = 1;
        break;
      case JCS_RGB:
    #if RGB_PIXELSIZE != 3
        cinfo->out_color_components = RGB_PIXELSIZE;
        break;
    #endif /* else share code with YCbCr */
      case JCS_YCbCr:
        cinfo->out_color_components = 3;
        break;
      case JCS_CMYK:
      case JCS_YCCK:
        cinfo->out_color_components = 4;
        break;
      default:			/* else must be same colorspace as in file */
        cinfo->out_color_components = cinfo->num_components;
        break;
      }
      cinfo->output_components = (cinfo->quantize_colors ? 1 :
    			      cinfo->out_color_components);

      /* See if upsampler will want to emit more than one row at a time */
      if (use_merged_upsample(cinfo))
        cinfo->rec_outbuf_height = cinfo->max_v_samp_factor;
      else
        cinfo->rec_outbuf_height = 1;
    }

    /*
     * Several decompression processes need to range-limit values to the range
     * 0..MAXJSAMPLE; the input value may fall somewhat outside this range
     * due to noise introduced by quantization, roundoff error, etc.  These
     * processes are inner loops and need to be as fast as possible.  On most
     * machines, particularly CPUs with pipelines or instruction prefetch,
     * a (subscript-check-less) C table lookup
     *		x = sample_range_limit[x];
     * is faster than explicit tests
     *		if (x < 0)  x = 0;
     *		else if (x > MAXJSAMPLE)  x = MAXJSAMPLE;
     * These processes all use a common table prepared by the routine below.
     *
     * For most steps we can mathematically guarantee that the initial value
     * of x is within MAXJSAMPLE+1 of the legal range, so a table running from
     * -(MAXJSAMPLE+1) to 2*MAXJSAMPLE+1 is sufficient.  But for the initial
     * limiting step (just after the IDCT), a wildly out-of-range value is
     * possible if the input data is corrupt.  To avoid any chance of indexing
     * off the end of memory and getting a bad-pointer trap, we perform the
     * post-IDCT limiting thus:
     *		x = range_limit[x & MASK];
     * where MASK is 2 bits wider than legal sample data, ie 10 bits for 8-bit
     * samples.  Under normal circumstances this is more than enough range and
     * a correct output will be generated; with bogus input data the mask will
     * cause wraparound, and we will safely generate a bogus-but-in-range output.
     * For the post-IDCT step, we want to convert the data from signed to unsigned
     * representation by adding CENTERJSAMPLE at the same time that we limit it.
     * So the post-IDCT limiting table ends up looking like this:
     *   CENTERJSAMPLE,CENTERJSAMPLE+1,...,MAXJSAMPLE,
     *   MAXJSAMPLE (repeat 2*(MAXJSAMPLE+1)-CENTERJSAMPLE times),
     *   0          (repeat 2*(MAXJSAMPLE+1)-CENTERJSAMPLE times),
     *   0,1,...,CENTERJSAMPLE-1
     * Negative inputs select values from the upper half of the table after
     * masking.
     *
     * We can save some space by overlapping the start of the post-IDCT table
     * with the simpler range limiting table.  The post-IDCT table begins at
     * sample_range_limit + CENTERJSAMPLE.
     *
     * Note that the table is allocated in near data space on PCs; it's small
     * enough and used often enough to justify this.
     */

    LOCAL(void)
    prepare_range_limit_table (j_decompress_ptr cinfo)
    /* Allocate and fill in the sample_range_limit table */
    {
      JSAMPLE * table;
      int i;

      table = (JSAMPLE *)
        (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
    		(5 * (MAXJSAMPLE+1) + CENTERJSAMPLE) * SIZEOF(JSAMPLE));
      table += (MAXJSAMPLE+1);	/* allow negative subscripts of simple table */
      cinfo->sample_range_limit = table;
      /* First segment of "simple" table: limit[x] = 0 for x < 0 */
      MEMZERO(table - (MAXJSAMPLE+1), (MAXJSAMPLE+1) * SIZEOF(JSAMPLE));
      /* Main part of "simple" table: limit[x] = x */
      for (i = 0; i <= MAXJSAMPLE; i++)
        table[i] = (JSAMPLE) i;
      table += CENTERJSAMPLE;	/* Point to where post-IDCT table starts */
      /* End of simple table, rest of first half of post-IDCT table */
      for (i = CENTERJSAMPLE; i < 2*(MAXJSAMPLE+1); i++)
        table[i] = MAXJSAMPLE;
      /* Second half of post-IDCT table */
      MEMZERO(table + (2 * (MAXJSAMPLE+1)),
    	  (2 * (MAXJSAMPLE+1) - CENTERJSAMPLE) * SIZEOF(JSAMPLE));
      MEMCOPY(table + (4 * (MAXJSAMPLE+1) - CENTERJSAMPLE),
    	  cinfo->sample_range_limit, CENTERJSAMPLE * SIZEOF(JSAMPLE));
    }

    /*
     * Master selection of decompression modules.
     * This is done once at jpeg_start_decompress time.  We determine
     * which modules will be used and give them appropriate initialization calls.
     * We also initialize the decompressor input side to begin consuming data.
     *
     * Since jpeg_read_header has finished, we know what is in the SOF
     * and (first) SOS markers.  We also have all the application parameter
     * settings.
     */

    LOCAL(void)
    master_selection (j_decompress_ptr cinfo)
    {
      my_master_ptr master = (my_master_ptr) cinfo->master;
      int use_c_buffer;
      long samplesperrow;
      JDIMENSION jd_samplesperrow;

      /* Initialize dimensions and other stuff */
      jpeg_calc_output_dimensions(cinfo);
      prepare_range_limit_table(cinfo);

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

      /* Initialize my private state */
      master->pass_number = 0;
      master->using_merged_upsample = use_merged_upsample(cinfo);

      /* Color quantizer selection */
      master->quantizer_1pass = NULL;
      master->quantizer_2pass = NULL;
      /* No mode changes if not using buffered-image mode. */
      if (! cinfo->quantize_colors || ! cinfo->buffered_image) {
        cinfo->enable_1pass_quant = FALSE;
        cinfo->enable_external_quant = FALSE;
        cinfo->enable_2pass_quant = FALSE;
      }
      if (cinfo->quantize_colors) {
        if (cinfo->raw_data_out)
          ERREXIT(cinfo, JERR_NOTIMPL);
        /* 2-pass quantizer only works in 3-component color space. */
        if (cinfo->out_color_components != 3) {
          cinfo->enable_1pass_quant = TRUE;
          cinfo->enable_external_quant = FALSE;
          cinfo->enable_2pass_quant = FALSE;
          cinfo->colormap = NULL;
        } else if (cinfo->colormap != NULL) {
          cinfo->enable_external_quant = TRUE;
        } else if (cinfo->two_pass_quantize) {
          cinfo->enable_2pass_quant = TRUE;
        } else {
          cinfo->enable_1pass_quant = TRUE;
        }

        if (cinfo->enable_1pass_quant) {
    #ifdef QUANT_1PASS_SUPPORTED
          jinit_1pass_quantizer(cinfo);
          master->quantizer_1pass = cinfo->cquantize;
    #else
          ERREXIT(cinfo, JERR_NOT_COMPILED);
    #endif
        }

        /* We use the 2-pass code to map to external colormaps. */
        if (cinfo->enable_2pass_quant || cinfo->enable_external_quant) {
    #ifdef QUANT_2PASS_SUPPORTED
          jinit_2pass_quantizer(cinfo);
          master->quantizer_2pass = cinfo->cquantize;
    #else
          ERREXIT(cinfo, JERR_NOT_COMPILED);
    #endif
        }
        /* If both quantizers are initialized, the 2-pass one is left active;
         * this is necessary for starting with quantization to an external map.
         */
      }

      /* Post-processing: in particular, color conversion first */
      if (! cinfo->raw_data_out) {
        if (master->using_merged_upsample) {
    #ifdef UPSAMPLE_MERGING_SUPPORTED
          jinit_merged_upsampler(cinfo); /* does color conversion too */
    #else
          ERREXIT(cinfo, JERR_NOT_COMPILED);
    #endif
        } else {
          jinit_color_deconverter(cinfo);
          jinit_upsampler(cinfo);
        }
        jinit_d_post_controller(cinfo, cinfo->enable_2pass_quant);
      }
      /* Inverse DCT */
      jinit_inverse_dct(cinfo);
      /* Entropy decoding: either Huffman or arithmetic coding. */
      if (cinfo->arith_code) {
        ERREXIT(cinfo, JERR_ARITH_NOTIMPL);
      } else {
        if (cinfo->progressive_mode) {
    #ifdef D_PROGRESSIVE_SUPPORTED
          jinit_phuff_decoder(cinfo);
    #else
          ERREXIT(cinfo, JERR_NOT_COMPILED);
    #endif
        } else
          jinit_huff_decoder(cinfo);
      }

      /* Initialize principal buffer controllers. */
      use_c_buffer = cinfo->inputctl->has_multiple_scans || cinfo->buffered_image;
      jinit_d_coef_controller(cinfo, use_c_buffer);

      if (! cinfo->raw_data_out)
        jinit_d_main_controller(cinfo, FALSE /* never need full buffer here */);

      /* We can now tell the memory manager to allocate virtual arrays. */
      (*cinfo->mem->realize_virt_arrays) ((j_common_ptr) cinfo);

      /* Initialize input side of decompressor to consume first scan. */
      (*cinfo->inputctl->start_input_pass) (cinfo);

    #ifdef D_MULTISCAN_FILES_SUPPORTED
      /* If jpeg_start_decompress will read the whole file, initialize
       * progress monitoring appropriately.  The input step is counted
       * as one pass.
       */
      if (cinfo->progress != NULL && ! cinfo->buffered_image &&
          cinfo->inputctl->has_multiple_scans) {
        int nscans;
        /* Estimate number of scans to set pass_limit. */
        if (cinfo->progressive_mode) {
          /* Arbitrarily estimate 2 interleaved DC scans + 3 AC scans/component. */
          nscans = 2 + 3 * cinfo->num_components;
        } else {
          /* For a nonprogressive multiscan file, estimate 1 scan per component. */
          nscans = cinfo->num_components;
        }
        cinfo->progress->pass_counter = 0L;
        cinfo->progress->pass_limit = (long) cinfo->total_iMCU_rows * nscans;
        cinfo->progress->completed_passes = 0;
        cinfo->progress->total_passes = (cinfo->enable_2pass_quant ? 3 : 2);
        /* Count the input pass as done */
        master->pass_number++;
      }
    #endif /* D_MULTISCAN_FILES_SUPPORTED */
    }

    /*
     * Per-pass setup.
     * This is called at the beginning of each output pass.  We determine which
     * modules will be active during this pass and give them appropriate
     * start_pass calls.  We also set is_dummy_pass to indicate whether this
     * is a "real" output pass or a dummy pass for color quantization.
     * (In the latter case, jdapistd.c will crank the pass to completion.)
     */

    METHODDEF(void)
    prepare_for_output_pass (j_decompress_ptr cinfo)
    {
      my_master_ptr master = (my_master_ptr) cinfo->master;

      if (master->pub.is_dummy_pass) {
    #ifdef QUANT_2PASS_SUPPORTED
        /* Final pass of 2-pass quantization */
        master->pub.is_dummy_pass = FALSE;
        (*cinfo->cquantize->start_pass) (cinfo, FALSE);
        (*cinfo->post->start_pass) (cinfo, JBUF_CRANK_DEST);
        (*cinfo->main->start_pass) (cinfo, JBUF_CRANK_DEST);
    #else
        ERREXIT(cinfo, JERR_NOT_COMPILED);
    #endif /* QUANT_2PASS_SUPPORTED */
      } else {
        if (cinfo->quantize_colors && cinfo->colormap == NULL) {
          /* Select new quantization method */
          if (cinfo->two_pass_quantize && cinfo->enable_2pass_quant) {
    	cinfo->cquantize = master->quantizer_2pass;
    	master->pub.is_dummy_pass = TRUE;
          } else if (cinfo->enable_1pass_quant) {
    	cinfo->cquantize = master->quantizer_1pass;
          } else {
    	ERREXIT(cinfo, JERR_MODE_CHANGE);
          }
        }
        (*cinfo->idct->start_pass) (cinfo);
        (*cinfo->coef->start_output_pass) (cinfo);
        if (! cinfo->raw_data_out) {
          if (! master->using_merged_upsample)
    	(*cinfo->cconvert->start_pass) (cinfo);
          (*cinfo->upsample->start_pass) (cinfo);
          if (cinfo->quantize_colors)
    	(*cinfo->cquantize->start_pass) (cinfo, master->pub.is_dummy_pass);
          (*cinfo->post->start_pass) (cinfo,
    	    (master->pub.is_dummy_pass ? JBUF_SAVE_AND_PASS : JBUF_PASS_THRU));
          (*cinfo->main->start_pass) (cinfo, JBUF_PASS_THRU);
        }
      }

      /* 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->pass_number +
    				    (master->pub.is_dummy_pass ? 2 : 1);
        /* In buffered-image mode, we assume one more output pass if EOI not
         * yet reached, but no more passes if EOI has been reached.
         */
        if (cinfo->buffered_image && ! cinfo->inputctl->eoi_reached) {
          cinfo->progress->total_passes += (cinfo->enable_2pass_quant ? 2 : 1);
        }
      }
    }

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

    METHODDEF(void)
    finish_output_pass (j_decompress_ptr cinfo)
    {
      my_master_ptr master = (my_master_ptr) cinfo->master;

      if (cinfo->quantize_colors)
        (*cinfo->cquantize->finish_pass) (cinfo);
      master->pass_number++;
    }

    #ifdef D_MULTISCAN_FILES_SUPPORTED

    /*
     * Switch to a new external colormap between output passes.
     */

    GLOBAL(void)
    jpeg_new_colormap (j_decompress_ptr cinfo)
    {
      my_master_ptr master = (my_master_ptr) cinfo->master;

      /* Prevent application from calling me at wrong times */
      if (cinfo->global_state != DSTATE_BUFIMAGE)
        ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);

      if (cinfo->quantize_colors && cinfo->enable_external_quant &&
          cinfo->colormap != NULL) {
        /* Select 2-pass quantizer for external colormap use */
        cinfo->cquantize = master->quantizer_2pass;
        /* Notify quantizer of colormap change */
        (*cinfo->cquantize->new_color_map) (cinfo);
        master->pub.is_dummy_pass = FALSE; /* just in case */
      } else
        ERREXIT(cinfo, JERR_MODE_CHANGE);
    }

    #endif /* D_MULTISCAN_FILES_SUPPORTED */

    /*
     * Initialize master decompression control and select active modules.
     * This is performed at the start of jpeg_start_decompress.
     */

    GLOBAL(void)
    jinit_master_decompress (j_decompress_ptr cinfo)
    {
      my_master_ptr master;

      master = (my_master_ptr)
          (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
    				  SIZEOF(my_decomp_master));
      cinfo->master = (struct jpeg_decomp_master *) master;
      master->pub.prepare_for_output_pass = prepare_for_output_pass;
      master->pub.finish_output_pass = finish_output_pass;

      master->pub.is_dummy_pass = FALSE;

      master_selection(cinfo);
    }