/*
 * jdapistd.c
 *
 * Copyright (C) 1994-1995, 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 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 */
