    /*
     * jdinput.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 input control logic for the JPEG decompressor.
     * These routines are concerned with controlling the decompressor's input
     * processing (marker reading and coefficient decoding).  The actual input
     * reading is done in jdmarker.c, jdhuff.c, and jdphuff.c.
     */

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

    /* Private state */

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

      int inheaders;		/* TRUE until first SOS is reached */
    } my_input_controller;

    typedef my_input_controller * my_inputctl_ptr;

    /* Forward declarations */
    METHODDEF(int) consume_markers JPP((j_decompress_ptr cinfo));

    /*
     * Routines to calculate various quantities related to the size of the image.
     */

    LOCAL(void)
    initial_setup (j_decompress_ptr cinfo)
    /* Called once, when first SOS marker is reached */
    {
      int ci;
      jpeg_component_info *compptr;

      /* 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);

      /* 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);
      }

      /* We initialize DCT_scaled_size and min_DCT_scaled_size to DCTSIZE.
       * In the full decompressor, this will be overridden by jdmaster.c;
       * but in the transcoder, jdmaster.c is not used, so we must do it here.
       */
      cinfo->min_DCT_scaled_size = DCTSIZE;

      /* Compute dimensions of components */
      for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
           ci++, compptr++) {
        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));
        /* downsampled_width and downsampled_height will also be overridden by
         * jdmaster.c if we are doing full decompression.  The transcoder library
         * doesn't use these values, but the calling application might.
         */
        /* 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, until color conversion says otherwise */
        compptr->component_needed = TRUE;
        /* Mark no quantization table yet saved for component */
        compptr->quant_table = NULL;
      }

      /* Compute number of fully interleaved MCU rows. */
      cinfo->total_iMCU_rows = (JDIMENSION)
        jdiv_round_up((long) cinfo->image_height,
    		  (long) (cinfo->max_v_samp_factor*DCTSIZE));

      /* Decide whether file contains multiple scans */
      if (cinfo->comps_in_scan < cinfo->num_components || cinfo->progressive_mode)
        cinfo->inputctl->has_multiple_scans = TRUE;
      else
        cinfo->inputctl->has_multiple_scans = FALSE;
    }

    LOCAL(void)
    per_scan_setup (j_decompress_ptr cinfo)
    /* Do computations that are needed before processing a JPEG scan */
    /* cinfo->comps_in_scan and cinfo->cur_comp_info[] were set from SOS marker */
    {
      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_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->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 * compptr->DCT_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 > D_MAX_BLOCKS_IN_MCU)
    	ERREXIT(cinfo, JERR_BAD_MCU_SIZE);
          while (mcublks-- > 0) {
    	cinfo->MCU_membership[cinfo->blocks_in_MCU++] = ci;
          }
        }

      }
    }

    /*
     * Save away a copy of the Q-table referenced by each component present
     * in the current scan, unless already saved during a prior scan.
     *
     * In a multiple-scan JPEG file, the encoder could assign different components
     * the same Q-table slot number, but change table definitions between scans
     * so that each component uses a different Q-table.  (The IJG encoder is not
     * currently capable of doing this, but other encoders might.)  Since we want
     * to be able to dequantize all the components at the end of the file, this
     * means that we have to save away the table actually used for each component.
     * We do this by copying the table at the start of the first scan containing
     * the component.
     * The JPEG spec prohibits the encoder from changing the contents of a Q-table
     * slot between scans of a component using that slot.  If the encoder does so
     * anyway, this decoder will simply use the Q-table values that were current
     * at the start of the first scan for the component.
     *
     * The decompressor output side looks only at the saved quant tables,
     * not at the current Q-table slots.
     */

    LOCAL(void)
    latch_quant_tables (j_decompress_ptr cinfo)
    {
      int ci, qtblno;
      jpeg_component_info *compptr;
      JQUANT_TBL * qtbl;

      for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
        compptr = cinfo->cur_comp_info[ci];
        /* No work if we already saved Q-table for this component */
        if (compptr->quant_table != NULL)
          continue;
        /* Make sure specified quantization table is present */
        qtblno = compptr->quant_tbl_no;
        if (qtblno < 0 || qtblno >= NUM_QUANT_TBLS ||
    	cinfo->quant_tbl_ptrs[qtblno] == NULL)
          ERREXIT1(cinfo, JERR_NO_QUANT_TABLE, qtblno);
        /* OK, save away the quantization table */
        qtbl = (JQUANT_TBL *)
          (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
    				  SIZEOF(JQUANT_TBL));
        MEMCOPY(qtbl, cinfo->quant_tbl_ptrs[qtblno], SIZEOF(JQUANT_TBL));
        compptr->quant_table = qtbl;
      }
    }

    /*
     * Initialize the input modules to read a scan of compressed data.
     * The first call to this is done by jdmaster.c after initializing
     * the entire decompressor (during jpeg_start_decompress).
     * Subsequent calls come from consume_markers, below.
     */

    METHODDEF(void)
    start_input_pass (j_decompress_ptr cinfo)
    {
      per_scan_setup(cinfo);
      latch_quant_tables(cinfo);
      (*cinfo->entropy->start_pass) (cinfo);
      (*cinfo->coef->start_input_pass) (cinfo);
      cinfo->inputctl->consume_input = cinfo->coef->consume_data;
    }

    /*
     * Finish up after inputting a compressed-data scan.
     * This is called by the coefficient controller after it's read all
     * the expected data of the scan.
     */

    METHODDEF(void)
    finish_input_pass (j_decompress_ptr cinfo)
    {
      cinfo->inputctl->consume_input = consume_markers;
    }

    /*
     * Read JPEG markers before, between, or after compressed-data scans.
     * Change state as necessary when a new scan is reached.
     * Return value is JPEG_SUSPENDED, JPEG_REACHED_SOS, or JPEG_REACHED_EOI.
     *
     * The consume_input method pointer points either here or to the
     * coefficient controller's consume_data routine, depending on whether
     * we are reading a compressed data segment or inter-segment markers.
     */

    METHODDEF(int)
    consume_markers (j_decompress_ptr cinfo)
    {
      my_inputctl_ptr inputctl = (my_inputctl_ptr) cinfo->inputctl;
      int val;

      if (inputctl->pub.eoi_reached) /* After hitting EOI, read no further */
        return JPEG_REACHED_EOI;

      val = (*cinfo->marker->read_markers) (cinfo);

      switch (val) {
      case JPEG_REACHED_SOS:	/* Found SOS */
        if (inputctl->inheaders) {	/* 1st SOS */
          initial_setup(cinfo);
          inputctl->inheaders = FALSE;
          /* Note: start_input_pass must be called by jdmaster.c
           * before any more input can be consumed.  jdapimin.c is
           * responsible for enforcing this sequencing.
           */
        } else {			/* 2nd or later SOS marker */
          if (! inputctl->pub.has_multiple_scans)
    	ERREXIT(cinfo, JERR_EOI_EXPECTED); /* Oops, I wasn't expecting this! */
          start_input_pass(cinfo);
        }
        break;
      case JPEG_REACHED_EOI:	/* Found EOI */
        inputctl->pub.eoi_reached = TRUE;
        if (inputctl->inheaders) {	/* Tables-only datastream, apparently */
          if (cinfo->marker->saw_SOF)
    	ERREXIT(cinfo, JERR_SOF_NO_SOS);
        } else {
          /* Prevent infinite loop in coef ctlr's decompress_data routine
           * if user set output_scan_number larger than number of scans.
           */
          if (cinfo->output_scan_number > cinfo->input_scan_number)
    	cinfo->output_scan_number = cinfo->input_scan_number;
        }
        break;
      case JPEG_SUSPENDED:
        break;
      }

      return val;
    }

    /*
     * Reset state to begin a fresh datastream.
     */

    METHODDEF(void)
    reset_input_controller (j_decompress_ptr cinfo)
    {
      my_inputctl_ptr inputctl = (my_inputctl_ptr) cinfo->inputctl;

      inputctl->pub.consume_input = consume_markers;
      inputctl->pub.has_multiple_scans = FALSE; /* "unknown" would be better */
      inputctl->pub.eoi_reached = FALSE;
      inputctl->inheaders = TRUE;
      /* Reset other modules */
      (*cinfo->err->reset_error_mgr) ((j_common_ptr) cinfo);
      (*cinfo->marker->reset_marker_reader) (cinfo);
      /* Reset progression state -- would be cleaner if entropy decoder did this */
      cinfo->coef_bits = NULL;
    }

    /*
     * Initialize the input controller module.
     * This is called only once, when the decompression object is created.
     */

    GLOBAL(void)
    jinit_input_controller (j_decompress_ptr cinfo)
    {
      my_inputctl_ptr inputctl;

      /* Create subobject in permanent pool */
      inputctl = (my_inputctl_ptr)
        (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
    				SIZEOF(my_input_controller));
      cinfo->inputctl = (struct jpeg_input_controller *) inputctl;
      /* Initialize method pointers */
      inputctl->pub.consume_input = consume_markers;
      inputctl->pub.reset_input_controller = reset_input_controller;
      inputctl->pub.start_input_pass = start_input_pass;
      inputctl->pub.finish_input_pass = finish_input_pass;
      /* Initialize state: can't use reset_input_controller since we don't
       * want to try to reset other modules yet.
       */
      inputctl->pub.has_multiple_scans = FALSE; /* "unknown" would be better */
      inputctl->pub.eoi_reached = FALSE;
      inputctl->inheaders = TRUE;
    }