nuclear@2: /*
nuclear@2:  * jdapistd.c
nuclear@2:  *
nuclear@2:  * Copyright (C) 1994-1996, Thomas G. Lane.
nuclear@2:  * This file is part of the Independent JPEG Group's software.
nuclear@2:  * For conditions of distribution and use, see the accompanying README file.
nuclear@2:  *
nuclear@2:  * This file contains application interface code for the decompression half
nuclear@2:  * of the JPEG library.  These are the "standard" API routines that are
nuclear@2:  * used in the normal full-decompression case.  They are not used by a
nuclear@2:  * transcoding-only application.  Note that if an application links in
nuclear@2:  * jpeg_start_decompress, it will end up linking in the entire decompressor.
nuclear@2:  * We thus must separate this file from jdapimin.c to avoid linking the
nuclear@2:  * whole decompression library into a transcoder.
nuclear@2:  */
nuclear@2: 
nuclear@2: #define JPEG_INTERNALS
nuclear@2: #include "jinclude.h"
nuclear@2: #include "jpeglib.h"
nuclear@2: 
nuclear@2: 
nuclear@2: /* Forward declarations */
nuclear@2: LOCAL(boolean) output_pass_setup JPP((j_decompress_ptr cinfo));
nuclear@2: 
nuclear@2: 
nuclear@2: /*
nuclear@2:  * Decompression initialization.
nuclear@2:  * jpeg_read_header must be completed before calling this.
nuclear@2:  *
nuclear@2:  * If a multipass operating mode was selected, this will do all but the
nuclear@2:  * last pass, and thus may take a great deal of time.
nuclear@2:  *
nuclear@2:  * Returns FALSE if suspended.  The return value need be inspected only if
nuclear@2:  * a suspending data source is used.
nuclear@2:  */
nuclear@2: 
nuclear@2: GLOBAL(boolean)
nuclear@2: jpeg_start_decompress (j_decompress_ptr cinfo)
nuclear@2: {
nuclear@2:   if (cinfo->global_state == DSTATE_READY) {
nuclear@2:     /* First call: initialize master control, select active modules */
nuclear@2:     jinit_master_decompress(cinfo);
nuclear@2:     if (cinfo->buffered_image) {
nuclear@2:       /* No more work here; expecting jpeg_start_output next */
nuclear@2:       cinfo->global_state = DSTATE_BUFIMAGE;
nuclear@2:       return TRUE;
nuclear@2:     }
nuclear@2:     cinfo->global_state = DSTATE_PRELOAD;
nuclear@2:   }
nuclear@2:   if (cinfo->global_state == DSTATE_PRELOAD) {
nuclear@2:     /* If file has multiple scans, absorb them all into the coef buffer */
nuclear@2:     if (cinfo->inputctl->has_multiple_scans) {
nuclear@2: #ifdef D_MULTISCAN_FILES_SUPPORTED
nuclear@2:       for (;;) {
nuclear@2: 	int retcode;
nuclear@2: 	/* Call progress monitor hook if present */
nuclear@2: 	if (cinfo->progress != NULL)
nuclear@2: 	  (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
nuclear@2: 	/* Absorb some more input */
nuclear@2: 	retcode = (*cinfo->inputctl->consume_input) (cinfo);
nuclear@2: 	if (retcode == JPEG_SUSPENDED)
nuclear@2: 	  return FALSE;
nuclear@2: 	if (retcode == JPEG_REACHED_EOI)
nuclear@2: 	  break;
nuclear@2: 	/* Advance progress counter if appropriate */
nuclear@2: 	if (cinfo->progress != NULL &&
nuclear@2: 	    (retcode == JPEG_ROW_COMPLETED || retcode == JPEG_REACHED_SOS)) {
nuclear@2: 	  if (++cinfo->progress->pass_counter >= cinfo->progress->pass_limit) {
nuclear@2: 	    /* jdmaster underestimated number of scans; ratchet up one scan */
nuclear@2: 	    cinfo->progress->pass_limit += (long) cinfo->total_iMCU_rows;
nuclear@2: 	  }
nuclear@2: 	}
nuclear@2:       }
nuclear@2: #else
nuclear@2:       ERREXIT(cinfo, JERR_NOT_COMPILED);
nuclear@2: #endif /* D_MULTISCAN_FILES_SUPPORTED */
nuclear@2:     }
nuclear@2:     cinfo->output_scan_number = cinfo->input_scan_number;
nuclear@2:   } else if (cinfo->global_state != DSTATE_PRESCAN)
nuclear@2:     ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
nuclear@2:   /* Perform any dummy output passes, and set up for the final pass */
nuclear@2:   return output_pass_setup(cinfo);
nuclear@2: }
nuclear@2: 
nuclear@2: 
nuclear@2: /*
nuclear@2:  * Set up for an output pass, and perform any dummy pass(es) needed.
nuclear@2:  * Common subroutine for jpeg_start_decompress and jpeg_start_output.
nuclear@2:  * Entry: global_state = DSTATE_PRESCAN only if previously suspended.
nuclear@2:  * Exit: If done, returns TRUE and sets global_state for proper output mode.
nuclear@2:  *       If suspended, returns FALSE and sets global_state = DSTATE_PRESCAN.
nuclear@2:  */
nuclear@2: 
nuclear@2: LOCAL(boolean)
nuclear@2: output_pass_setup (j_decompress_ptr cinfo)
nuclear@2: {
nuclear@2:   if (cinfo->global_state != DSTATE_PRESCAN) {
nuclear@2:     /* First call: do pass setup */
nuclear@2:     (*cinfo->master->prepare_for_output_pass) (cinfo);
nuclear@2:     cinfo->output_scanline = 0;
nuclear@2:     cinfo->global_state = DSTATE_PRESCAN;
nuclear@2:   }
nuclear@2:   /* Loop over any required dummy passes */
nuclear@2:   while (cinfo->master->is_dummy_pass) {
nuclear@2: #ifdef QUANT_2PASS_SUPPORTED
nuclear@2:     /* Crank through the dummy pass */
nuclear@2:     while (cinfo->output_scanline < cinfo->output_height) {
nuclear@2:       JDIMENSION last_scanline;
nuclear@2:       /* Call progress monitor hook if present */
nuclear@2:       if (cinfo->progress != NULL) {
nuclear@2: 	cinfo->progress->pass_counter = (long) cinfo->output_scanline;
nuclear@2: 	cinfo->progress->pass_limit = (long) cinfo->output_height;
nuclear@2: 	(*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
nuclear@2:       }
nuclear@2:       /* Process some data */
nuclear@2:       last_scanline = cinfo->output_scanline;
nuclear@2:       (*cinfo->main->process_data) (cinfo, (JSAMPARRAY) NULL,
nuclear@2: 				    &cinfo->output_scanline, (JDIMENSION) 0);
nuclear@2:       if (cinfo->output_scanline == last_scanline)
nuclear@2: 	return FALSE;		/* No progress made, must suspend */
nuclear@2:     }
nuclear@2:     /* Finish up dummy pass, and set up for another one */
nuclear@2:     (*cinfo->master->finish_output_pass) (cinfo);
nuclear@2:     (*cinfo->master->prepare_for_output_pass) (cinfo);
nuclear@2:     cinfo->output_scanline = 0;
nuclear@2: #else
nuclear@2:     ERREXIT(cinfo, JERR_NOT_COMPILED);
nuclear@2: #endif /* QUANT_2PASS_SUPPORTED */
nuclear@2:   }
nuclear@2:   /* Ready for application to drive output pass through
nuclear@2:    * jpeg_read_scanlines or jpeg_read_raw_data.
nuclear@2:    */
nuclear@2:   cinfo->global_state = cinfo->raw_data_out ? DSTATE_RAW_OK : DSTATE_SCANNING;
nuclear@2:   return TRUE;
nuclear@2: }
nuclear@2: 
nuclear@2: 
nuclear@2: /*
nuclear@2:  * Read some scanlines of data from the JPEG decompressor.
nuclear@2:  *
nuclear@2:  * The return value will be the number of lines actually read.
nuclear@2:  * This may be less than the number requested in several cases,
nuclear@2:  * including bottom of image, data source suspension, and operating
nuclear@2:  * modes that emit multiple scanlines at a time.
nuclear@2:  *
nuclear@2:  * Note: we warn about excess calls to jpeg_read_scanlines() since
nuclear@2:  * this likely signals an application programmer error.  However,
nuclear@2:  * an oversize buffer (max_lines > scanlines remaining) is not an error.
nuclear@2:  */
nuclear@2: 
nuclear@2: GLOBAL(JDIMENSION)
nuclear@2: jpeg_read_scanlines (j_decompress_ptr cinfo, JSAMPARRAY scanlines,
nuclear@2: 		     JDIMENSION max_lines)
nuclear@2: {
nuclear@2:   JDIMENSION row_ctr;
nuclear@2: 
nuclear@2:   if (cinfo->global_state != DSTATE_SCANNING)
nuclear@2:     ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
nuclear@2:   if (cinfo->output_scanline >= cinfo->output_height) {
nuclear@2:     WARNMS(cinfo, JWRN_TOO_MUCH_DATA);
nuclear@2:     return 0;
nuclear@2:   }
nuclear@2: 
nuclear@2:   /* Call progress monitor hook if present */
nuclear@2:   if (cinfo->progress != NULL) {
nuclear@2:     cinfo->progress->pass_counter = (long) cinfo->output_scanline;
nuclear@2:     cinfo->progress->pass_limit = (long) cinfo->output_height;
nuclear@2:     (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
nuclear@2:   }
nuclear@2: 
nuclear@2:   /* Process some data */
nuclear@2:   row_ctr = 0;
nuclear@2:   (*cinfo->main->process_data) (cinfo, scanlines, &row_ctr, max_lines);
nuclear@2:   cinfo->output_scanline += row_ctr;
nuclear@2:   return row_ctr;
nuclear@2: }
nuclear@2: 
nuclear@2: 
nuclear@2: /*
nuclear@2:  * Alternate entry point to read raw data.
nuclear@2:  * Processes exactly one iMCU row per call, unless suspended.
nuclear@2:  */
nuclear@2: 
nuclear@2: GLOBAL(JDIMENSION)
nuclear@2: jpeg_read_raw_data (j_decompress_ptr cinfo, JSAMPIMAGE data,
nuclear@2: 		    JDIMENSION max_lines)
nuclear@2: {
nuclear@2:   JDIMENSION lines_per_iMCU_row;
nuclear@2: 
nuclear@2:   if (cinfo->global_state != DSTATE_RAW_OK)
nuclear@2:     ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
nuclear@2:   if (cinfo->output_scanline >= cinfo->output_height) {
nuclear@2:     WARNMS(cinfo, JWRN_TOO_MUCH_DATA);
nuclear@2:     return 0;
nuclear@2:   }
nuclear@2: 
nuclear@2:   /* Call progress monitor hook if present */
nuclear@2:   if (cinfo->progress != NULL) {
nuclear@2:     cinfo->progress->pass_counter = (long) cinfo->output_scanline;
nuclear@2:     cinfo->progress->pass_limit = (long) cinfo->output_height;
nuclear@2:     (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
nuclear@2:   }
nuclear@2: 
nuclear@2:   /* Verify that at least one iMCU row can be returned. */
nuclear@2:   lines_per_iMCU_row = cinfo->max_v_samp_factor * cinfo->min_DCT_scaled_size;
nuclear@2:   if (max_lines < lines_per_iMCU_row)
nuclear@2:     ERREXIT(cinfo, JERR_BUFFER_SIZE);
nuclear@2: 
nuclear@2:   /* Decompress directly into user's buffer. */
nuclear@2:   if (! (*cinfo->coef->decompress_data) (cinfo, data))
nuclear@2:     return 0;			/* suspension forced, can do nothing more */
nuclear@2: 
nuclear@2:   /* OK, we processed one iMCU row. */
nuclear@2:   cinfo->output_scanline += lines_per_iMCU_row;
nuclear@2:   return lines_per_iMCU_row;
nuclear@2: }
nuclear@2: 
nuclear@2: 
nuclear@2: /* Additional entry points for buffered-image mode. */
nuclear@2: 
nuclear@2: #ifdef D_MULTISCAN_FILES_SUPPORTED
nuclear@2: 
nuclear@2: /*
nuclear@2:  * Initialize for an output pass in buffered-image mode.
nuclear@2:  */
nuclear@2: 
nuclear@2: GLOBAL(boolean)
nuclear@2: jpeg_start_output (j_decompress_ptr cinfo, int scan_number)
nuclear@2: {
nuclear@2:   if (cinfo->global_state != DSTATE_BUFIMAGE &&
nuclear@2:       cinfo->global_state != DSTATE_PRESCAN)
nuclear@2:     ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
nuclear@2:   /* Limit scan number to valid range */
nuclear@2:   if (scan_number <= 0)
nuclear@2:     scan_number = 1;
nuclear@2:   if (cinfo->inputctl->eoi_reached &&
nuclear@2:       scan_number > cinfo->input_scan_number)
nuclear@2:     scan_number = cinfo->input_scan_number;
nuclear@2:   cinfo->output_scan_number = scan_number;
nuclear@2:   /* Perform any dummy output passes, and set up for the real pass */
nuclear@2:   return output_pass_setup(cinfo);
nuclear@2: }
nuclear@2: 
nuclear@2: 
nuclear@2: /*
nuclear@2:  * Finish up after an output pass in buffered-image mode.
nuclear@2:  *
nuclear@2:  * Returns FALSE if suspended.  The return value need be inspected only if
nuclear@2:  * a suspending data source is used.
nuclear@2:  */
nuclear@2: 
nuclear@2: GLOBAL(boolean)
nuclear@2: jpeg_finish_output (j_decompress_ptr cinfo)
nuclear@2: {
nuclear@2:   if ((cinfo->global_state == DSTATE_SCANNING ||
nuclear@2:        cinfo->global_state == DSTATE_RAW_OK) && cinfo->buffered_image) {
nuclear@2:     /* Terminate this pass. */
nuclear@2:     /* We do not require the whole pass to have been completed. */
nuclear@2:     (*cinfo->master->finish_output_pass) (cinfo);
nuclear@2:     cinfo->global_state = DSTATE_BUFPOST;
nuclear@2:   } else if (cinfo->global_state != DSTATE_BUFPOST) {
nuclear@2:     /* BUFPOST = repeat call after a suspension, anything else is error */
nuclear@2:     ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
nuclear@2:   }
nuclear@2:   /* Read markers looking for SOS or EOI */
nuclear@2:   while (cinfo->input_scan_number <= cinfo->output_scan_number &&
nuclear@2: 	 ! cinfo->inputctl->eoi_reached) {
nuclear@2:     if ((*cinfo->inputctl->consume_input) (cinfo) == JPEG_SUSPENDED)
nuclear@2:       return FALSE;		/* Suspend, come back later */
nuclear@2:   }
nuclear@2:   cinfo->global_state = DSTATE_BUFIMAGE;
nuclear@2:   return TRUE;
nuclear@2: }
nuclear@2: 
nuclear@2: #endif /* D_MULTISCAN_FILES_SUPPORTED */