/*

 * 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 = 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 */