text: /*
   * jdapistd.c
   *
   * Copyright (C) 1994-1996, 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 application interface code for the decompression half
   * of the JPEG library.  These are the "standard" API routines that are
   * used in the normal full-decompression case.  They are not used by a
   * transcoding-only application.  Note that if an application links in
   * jpeg_start_decompress, it will end up linking in the entire decompressor.
   * We thus must separate this file from jdapimin.c to avoid linking the
   * whole decompression library into a transcoder.
   */
  
  #define JPEG_INTERNALS
  #include "jinclude.h"
  #include "jpeglib.h"
  
  
  /* Forward declarations */
  LOCAL(boolean) output_pass_setup JPP((j_decompress_ptr cinfo));
  
  /*
   * Decompression initialization.
   * jpeg_read_header must be completed before calling this.
   *
   * If a multipass operating mode was selected, this will do all but the
   * last pass, and thus may take a great deal of time.
   *
   * Returns FALSE if suspended.  The return value need be inspected only if
   * a suspending data source is used.
   */
  
  
  GLOBAL(boolean)
  
  jpeg_start_decompress (j_decompress_ptr cinfo)
  {
    if (cinfo->global_state == DSTATE_READY) {
      /* First call: initialize master control, select active modules */
      jinit_master_decompress(cinfo);
      if (cinfo->buffered_image) {
        /* No more work here; expecting jpeg_start_output next */
        cinfo->global_state = DSTATE_BUFIMAGE;
        return TRUE;
      }
      cinfo->global_state = DSTATE_PRELOAD;
    }
    if (cinfo->global_state == DSTATE_PRELOAD) {
      /* If file has multiple scans, absorb them all into the coef buffer */
      if (cinfo->inputctl->has_multiple_scans) {
  #ifdef D_MULTISCAN_FILES_SUPPORTED
        for (;;) {
  	int retcode;
  	/* Call progress monitor hook if present */
  	if (cinfo->progress != NULL)
  	  (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
  	/* Absorb some more input */
  	retcode = (*cinfo->inputctl->consume_input) (cinfo);
  	if (retcode == JPEG_SUSPENDED)
  	  return FALSE;
  	if (retcode == JPEG_REACHED_EOI)
  	  break;
  	/* Advance progress counter if appropriate */
  	if (cinfo->progress != NULL &&
  	    (retcode == JPEG_ROW_COMPLETED || retcode == JPEG_REACHED_SOS)) {
  	  if (++cinfo->progress->pass_counter >= cinfo->progress->pass_limit) {
  	    /* jdmaster underestimated number of scans; ratchet up one scan */
  	    cinfo->progress->pass_limit += (long) cinfo->total_iMCU_rows;
  	  }
  	}
        }
  #else
        ERREXIT(cinfo, JERR_NOT_COMPILED);
  #endif /* D_MULTISCAN_FILES_SUPPORTED */
      }
      cinfo->output_scan_number = cinfo->input_scan_number;
    } else if (cinfo->global_state != DSTATE_PRESCAN)
      ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
    /* Perform any dummy output passes, and set up for the final pass */
    return output_pass_setup(cinfo);
  }
  
  
  /*
   * Set up for an output pass, and perform any dummy pass(es) needed.
   * Common subroutine for jpeg_start_decompress and jpeg_start_output.
   * Entry: global_state = DSTATE_PRESCAN only if previously suspended.
   * Exit: If done, returns TRUE and sets global_state for proper output mode.
   *       If suspended, returns FALSE and sets global_state = DSTATE_PRESCAN.
   */
  
  LOCAL(boolean)
  output_pass_setup (j_decompress_ptr cinfo)
  {
    if (cinfo->global_state != DSTATE_PRESCAN) {
      /* First call: do pass setup */
      (*cinfo->master->prepare_for_output_pass) (cinfo);
      cinfo->output_scanline = 0;
      cinfo->global_state = DSTATE_PRESCAN;
    }
    /* Loop over any required dummy passes */
    while (cinfo->master->is_dummy_pass) {
  #ifdef QUANT_2PASS_SUPPORTED
      /* Crank through the dummy pass */
      while (cinfo->output_scanline < cinfo->output_height) {
        JDIMENSION last_scanline;
        /* Call progress monitor hook if present */
        if (cinfo->progress != NULL) {
  	cinfo->progress->pass_counter = (long) cinfo->output_scanline;
  	cinfo->progress->pass_limit = (long) cinfo->output_height;
  	(*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
        }
        /* Process some data */
        last_scanline = cinfo->output_scanline;
        (*cinfo->main->process_data) (cinfo, (JSAMPARRAY) NULL,
  				    &cinfo->output_scanline, (JDIMENSION) 0);
        if (cinfo->output_scanline == last_scanline)
  	return FALSE;		/* No progress made, must suspend */
      }
      /* Finish up dummy pass, and set up for another one */
      (*cinfo->master->finish_output_pass) (cinfo);
      (*cinfo->master->prepare_for_output_pass) (cinfo);
      cinfo->output_scanline = 0;
  #else
      ERREXIT(cinfo, JERR_NOT_COMPILED);
  #endif /* QUANT_2PASS_SUPPORTED */
    }
    /* Ready for application to drive output pass through
     * jpeg_read_scanlines or jpeg_read_raw_data.
     */
    cinfo->global_state = cinfo->raw_data_out ? DSTATE_RAW_OK : DSTATE_SCANNING;
    return TRUE;
  }
  
  
  /*
   * Read some scanlines of data from the JPEG decompressor.
   *
   * The return value will be the number of lines actually read.
   * This may be less than the number requested in several cases,
   * including bottom of image, data source suspension, and operating
   * modes that emit multiple scanlines at a time.
   *
   * Note: we warn about excess calls to jpeg_read_scanlines() since
   * this likely signals an application programmer error.  However,
   * an oversize buffer (max_lines > scanlines remaining) is not an error.
   */
  
  GLOBAL(JDIMENSION)
  jpeg_read_scanlines (j_decompress_ptr cinfo, JSAMPARRAY scanlines,
  		     JDIMENSION max_lines)
  {
    JDIMENSION row_ctr;
  
    if (cinfo->global_state != DSTATE_SCANNING)
      ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
    if (cinfo->output_scanline >= cinfo->output_height) {
      WARNMS(cinfo, JWRN_TOO_MUCH_DATA);
      return 0;
    }
  
    /* Call progress monitor hook if present */
    if (cinfo->progress != NULL) {
      cinfo->progress->pass_counter = (long) cinfo->output_scanline;
      cinfo->progress->pass_limit = (long) cinfo->output_height;
      (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
    }
  
    /* Process some data */
    row_ctr = 0;
    (*cinfo->main->process_data) (cinfo, scanlines, &row_ctr, max_lines);
    cinfo->output_scanline += row_ctr;
    return row_ctr;
  }
  
  
  /*
   * Alternate entry point to read raw data.
   * Processes exactly one iMCU row per call, unless suspended.
   */
  
  GLOBAL(JDIMENSION)
  jpeg_read_raw_data (j_decompress_ptr cinfo, JSAMPIMAGE data,
  		    JDIMENSION max_lines)
  {
    JDIMENSION lines_per_iMCU_row;
  
    if (cinfo->global_state != DSTATE_RAW_OK)
      ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
    if (cinfo->output_scanline >= cinfo->output_height) {
      WARNMS(cinfo, JWRN_TOO_MUCH_DATA);
      return 0;
    }
  
    /* Call progress monitor hook if present */
    if (cinfo->progress != NULL) {
      cinfo->progress->pass_counter = (long) cinfo->output_scanline;
      cinfo->progress->pass_limit = (long) cinfo->output_height;
      (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
    }
  
    /* Verify that at least one iMCU row can be returned. */
    lines_per_iMCU_row = (unsigned int) cinfo->max_v_samp_factor * cinfo->min_DCT_scaled_size;
    if (max_lines < lines_per_iMCU_row)
      ERREXIT(cinfo, JERR_BUFFER_SIZE);
  
    /* Decompress directly into user's buffer. */
    if (! (*cinfo->coef->decompress_data) (cinfo, data))
      return 0;			/* suspension forced, can do nothing more */
  
    /* OK, we processed one iMCU row. */
    cinfo->output_scanline += lines_per_iMCU_row;
    return lines_per_iMCU_row;
  }
  
  
  /* Additional entry points for buffered-image mode. */
  
  #ifdef D_MULTISCAN_FILES_SUPPORTED
  
  /*
   * Initialize for an output pass in buffered-image mode.
   */
  
  GLOBAL(boolean)
  jpeg_start_output (j_decompress_ptr cinfo, int scan_number)
  {
    if (cinfo->global_state != DSTATE_BUFIMAGE &&
        cinfo->global_state != DSTATE_PRESCAN)
      ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
    /* Limit scan number to valid range */
    if (scan_number <= 0)
      scan_number = 1;
    if (cinfo->inputctl->eoi_reached &&
        scan_number > cinfo->input_scan_number)
      scan_number = cinfo->input_scan_number;
    cinfo->output_scan_number = scan_number;
    /* Perform any dummy output passes, and set up for the real pass */
    return output_pass_setup(cinfo);
  }
  
  
  /*
   * Finish up after an output pass in buffered-image mode.
   *
   * Returns FALSE if suspended.  The return value need be inspected only if
   * a suspending data source is used.
   */
  
  GLOBAL(boolean)
  jpeg_finish_output (j_decompress_ptr cinfo)
  {
    if ((cinfo->global_state == DSTATE_SCANNING ||
         cinfo->global_state == DSTATE_RAW_OK) && cinfo->buffered_image) {
      /* Terminate this pass. */
      /* We do not require the whole pass to have been completed. */
      (*cinfo->master->finish_output_pass) (cinfo);
      cinfo->global_state = DSTATE_BUFPOST;
    } else if (cinfo->global_state != DSTATE_BUFPOST) {
      /* BUFPOST = repeat call after a suspension, anything else is error */
      ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
    }
    /* Read markers looking for SOS or EOI */
    while (cinfo->input_scan_number <= cinfo->output_scan_number &&
  	 ! cinfo->inputctl->eoi_reached) {
      if ((*cinfo->inputctl->consume_input) (cinfo) == JPEG_SUSPENDED)
        return FALSE;		/* Suspend, come back later */
    }
    cinfo->global_state = DSTATE_BUFIMAGE;
    return TRUE;
  }
  
  #endif /* D_MULTISCAN_FILES_SUPPORTED */
  