text: /*
   * jdinput.c
   *
   * Copyright (C) 1991-1995, 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.
   */
  
  #include "all.h"
  
  #define JPEG_INTERNALS
  #include "jinclude.h"
  #include "jpeglib.h"
  
  
  /* Private state */
  
  typedef struct {
    struct jpeg_input_controller pub; /* public fields */
  
    boolean 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.  jdapi.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;
  }
  