/*
 * jdapimin.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 "minimum" API routines that may be
 * needed in either the normal full-decompression case or the
 * transcoding-only case.
 *
 * Most of the routines intended to be called directly by an application
 * are in this file or in jdapistd.c.  But also see jcomapi.c for routines
 * shared by compression and decompression, and jdtrans.c for the transcoding
 * case.
 */

#define JPEG_INTERNALS
#include "jinclude.h"
#include "jpeglib.h"


/*
 * Initialization of a JPEG decompression object.
 * The error manager must already be set up (in case memory manager fails).
 */

GLOBAL void
jpeg_create_decompress( j_decompress_ptr cinfo ) {
	int i;

	/* For debugging purposes, zero the whole master structure.
	 * But error manager pointer is already there, so save and restore it.
	 */
	{
		struct jpeg_error_mgr * err = cinfo->err;
		MEMZERO( cinfo, SIZEOF( struct jpeg_decompress_struct ) );
		cinfo->err = err;
	}
	cinfo->is_decompressor = TRUE;

	/* Initialize a memory manager instance for this object */
	jinit_memory_mgr( (j_common_ptr) cinfo );

	/* Zero out pointers to permanent structures. */
	cinfo->progress = NULL;
	cinfo->src = NULL;

	for ( i = 0; i < NUM_QUANT_TBLS; i++ )
		cinfo->quant_tbl_ptrs[i] = NULL;

	for ( i = 0; i < NUM_HUFF_TBLS; i++ ) {
		cinfo->dc_huff_tbl_ptrs[i] = NULL;
		cinfo->ac_huff_tbl_ptrs[i] = NULL;
	}

	/* Initialize marker processor so application can override methods
	 * for COM, APPn markers before calling jpeg_read_header.
	 */
	jinit_marker_reader( cinfo );

	/* And initialize the overall input controller. */
	jinit_input_controller( cinfo );

	/* OK, I'm ready */
	cinfo->global_state = DSTATE_START;
}


/*
 * Destruction of a JPEG decompression object
 */

GLOBAL void
jpeg_destroy_decompress( j_decompress_ptr cinfo ) {
	jpeg_destroy( (j_common_ptr) cinfo ); /* use common routine */
}


/*
 * Abort processing of a JPEG decompression operation,
 * but don't destroy the object itself.
 */

GLOBAL void
jpeg_abort_decompress( j_decompress_ptr cinfo ) {
	jpeg_abort( (j_common_ptr) cinfo ); /* use common routine */
}


/*
 * Install a special processing method for COM or APPn markers.
 */

GLOBAL void
jpeg_set_marker_processor( j_decompress_ptr cinfo, int marker_code,
						   jpeg_marker_parser_method routine ) {
	if ( marker_code == JPEG_COM ) {
		cinfo->marker->process_COM = routine;
	} else if ( marker_code >= JPEG_APP0 && marker_code <= JPEG_APP0 + 15 )    {
		cinfo->marker->process_APPn[marker_code - JPEG_APP0] = routine;
	} else {
		ERREXIT1( cinfo, JERR_UNKNOWN_MARKER, marker_code );
	}
}


/*
 * Set default decompression parameters.
 */

LOCAL void
default_decompress_parms( j_decompress_ptr cinfo ) {
	/* Guess the input colorspace, and set output colorspace accordingly. */
	/* (Wish JPEG committee had provided a real way to specify this...) */
	/* Note application may override our guesses. */
	switch ( cinfo->num_components ) {
	case 1:
		cinfo->jpeg_color_space = JCS_GRAYSCALE;
		cinfo->out_color_space = JCS_GRAYSCALE;
		break;

	case 3:
		if ( cinfo->saw_JFIF_marker ) {
			cinfo->jpeg_color_space = JCS_YCbCr; /* JFIF implies YCbCr */
		} else if ( cinfo->saw_Adobe_marker ) {
			switch ( cinfo->Adobe_transform ) {
			case 0:
				cinfo->jpeg_color_space = JCS_RGB;
				break;
			case 1:
				cinfo->jpeg_color_space = JCS_YCbCr;
				break;
			default:
				WARNMS1( cinfo, JWRN_ADOBE_XFORM, cinfo->Adobe_transform );
				cinfo->jpeg_color_space = JCS_YCbCr; /* assume it's YCbCr */
				break;
			}
		} else {
			/* Saw no special markers, try to guess from the component IDs */
			int cid0 = cinfo->comp_info[0].component_id;
			int cid1 = cinfo->comp_info[1].component_id;
			int cid2 = cinfo->comp_info[2].component_id;

			if ( cid0 == 1 && cid1 == 2 && cid2 == 3 ) {
				cinfo->jpeg_color_space = JCS_YCbCr; /* assume JFIF w/out marker */
			} else if ( cid0 == 82 && cid1 == 71 && cid2 == 66 )                                                                      {
				cinfo->jpeg_color_space = JCS_RGB; /* ASCII 'R', 'G', 'B' */
			} else {
				TRACEMS3( cinfo, 1, JTRC_UNKNOWN_IDS, cid0, cid1, cid2 );
				cinfo->jpeg_color_space = JCS_YCbCr; /* assume it's YCbCr */
			}
		}
		/* Always guess RGB is proper output colorspace. */
		cinfo->out_color_space = JCS_RGB;
		break;

	case 4:
		if ( cinfo->saw_Adobe_marker ) {
			switch ( cinfo->Adobe_transform ) {
			case 0:
				cinfo->jpeg_color_space = JCS_CMYK;
				break;
			case 2:
				cinfo->jpeg_color_space = JCS_YCCK;
				break;
			default:
				WARNMS1( cinfo, JWRN_ADOBE_XFORM, cinfo->Adobe_transform );
				cinfo->jpeg_color_space = JCS_YCCK; /* assume it's YCCK */
				break;
			}
		} else {
			/* No special markers, assume straight CMYK. */
			cinfo->jpeg_color_space = JCS_CMYK;
		}
		cinfo->out_color_space = JCS_CMYK;
		break;

	default:
		cinfo->jpeg_color_space = JCS_UNKNOWN;
		cinfo->out_color_space = JCS_UNKNOWN;
		break;
	}

	/* Set defaults for other decompression parameters. */
	cinfo->scale_num = 1;   /* 1:1 scaling */
	cinfo->scale_denom = 1;
	cinfo->output_gamma = 1.0;
	cinfo->buffered_image = FALSE;
	cinfo->raw_data_out = FALSE;
	cinfo->dct_method = JDCT_DEFAULT;
	cinfo->do_fancy_upsampling = TRUE;
	cinfo->do_block_smoothing = TRUE;
	cinfo->quantize_colors = FALSE;
	/* We set these in case application only sets quantize_colors. */
	cinfo->dither_mode = JDITHER_FS;
#ifdef QUANT_2PASS_SUPPORTED
	cinfo->two_pass_quantize = TRUE;
#else
	cinfo->two_pass_quantize = FALSE;
#endif
	cinfo->desired_number_of_colors = 256;
	cinfo->colormap = NULL;
	/* Initialize for no mode change in buffered-image mode. */
	cinfo->enable_1pass_quant = FALSE;
	cinfo->enable_external_quant = FALSE;
	cinfo->enable_2pass_quant = FALSE;
}


/*
 * Decompression startup: read start of JPEG datastream to see what's there.
 * Need only initialize JPEG object and supply a data source before calling.
 *
 * This routine will read as far as the first SOS marker (ie, actual start of
 * compressed data), and will save all tables and parameters in the JPEG
 * object.  It will also initialize the decompression parameters to default
 * values, and finally return JPEG_HEADER_OK.  On return, the application may
 * adjust the decompression parameters and then call jpeg_start_decompress.
 * (Or, if the application only wanted to determine the image parameters,
 * the data need not be decompressed.  In that case, call jpeg_abort or
 * jpeg_destroy to release any temporary space.)
 * If an abbreviated (tables only) datastream is presented, the routine will
 * return JPEG_HEADER_TABLES_ONLY upon reaching EOI.  The application may then
 * re-use the JPEG object to read the abbreviated image datastream(s).
 * It is unnecessary (but OK) to call jpeg_abort in this case.
 * The JPEG_SUSPENDED return code only occurs if the data source module
 * requests suspension of the decompressor.  In this case the application
 * should load more source data and then re-call jpeg_read_header to resume
 * processing.
 * If a non-suspending data source is used and require_image is TRUE, then the
 * return code need not be inspected since only JPEG_HEADER_OK is possible.
 *
 * This routine is now just a front end to jpeg_consume_input, with some
 * extra error checking.
 */

GLOBAL int
jpeg_read_header( j_decompress_ptr cinfo, boolean require_image ) {
	int retcode;

	if ( cinfo->global_state != DSTATE_START &&
		 cinfo->global_state != DSTATE_INHEADER ) {
		ERREXIT1( cinfo, JERR_BAD_STATE, cinfo->global_state );
	}

	retcode = jpeg_consume_input( cinfo );

	switch ( retcode ) {
	case JPEG_REACHED_SOS:
		retcode = JPEG_HEADER_OK;
		break;
	case JPEG_REACHED_EOI:
		if ( require_image ) { /* Complain if application wanted an image */
			ERREXIT( cinfo, JERR_NO_IMAGE );
		}
		/* Reset to start state; it would be safer to require the application to
		 * call jpeg_abort, but we can't change it now for compatibility reasons.
		 * A side effect is to free any temporary memory (there shouldn't be any).
		 */
		jpeg_abort( (j_common_ptr) cinfo ); /* sets state = DSTATE_START */
		retcode = JPEG_HEADER_TABLES_ONLY;
		break;
	case JPEG_SUSPENDED:
		/* no work */
		break;
	}

	return retcode;
}


/*
 * Consume data in advance of what the decompressor requires.
 * This can be called at any time once the decompressor object has
 * been created and a data source has been set up.
 *
 * This routine is essentially a state machine that handles a couple
 * of critical state-transition actions, namely initial setup and
 * transition from header scanning to ready-for-start_decompress.
 * All the actual input is done via the input controller's consume_input
 * method.
 */

GLOBAL int
jpeg_consume_input( j_decompress_ptr cinfo ) {
	int retcode = JPEG_SUSPENDED;

	/* NB: every possible DSTATE value should be listed in this switch */
	switch ( cinfo->global_state ) {
	case DSTATE_START:
		/* Start-of-datastream actions: reset appropriate modules */
		( *cinfo->inputctl->reset_input_controller )( cinfo );
		/* Initialize application's data source module */
		( *cinfo->src->init_source )( cinfo );
		cinfo->global_state = DSTATE_INHEADER;
		/*FALLTHROUGH*/
	case DSTATE_INHEADER:
		retcode = ( *cinfo->inputctl->consume_input )( cinfo );
		if ( retcode == JPEG_REACHED_SOS ) { /* Found SOS, prepare to decompress */
			/* Set up default parameters based on header data */
			default_decompress_parms( cinfo );
			/* Set global state: ready for start_decompress */
			cinfo->global_state = DSTATE_READY;
		}
		break;
	case DSTATE_READY:
		/* Can't advance past first SOS until start_decompress is called */
		retcode = JPEG_REACHED_SOS;
		break;
	case DSTATE_PRELOAD:
	case DSTATE_PRESCAN:
	case DSTATE_SCANNING:
	case DSTATE_RAW_OK:
	case DSTATE_BUFIMAGE:
	case DSTATE_BUFPOST:
	case DSTATE_STOPPING:
		retcode = ( *cinfo->inputctl->consume_input )( cinfo );
		break;
	default:
		ERREXIT1( cinfo, JERR_BAD_STATE, cinfo->global_state );
	}
	return retcode;
}


/*
 * Have we finished reading the input file?
 */

GLOBAL boolean
jpeg_input_complete( j_decompress_ptr cinfo ) {
	/* Check for valid jpeg object */
	if ( cinfo->global_state < DSTATE_START ||
		 cinfo->global_state > DSTATE_STOPPING ) {
		ERREXIT1( cinfo, JERR_BAD_STATE, cinfo->global_state );
	}
	return cinfo->inputctl->eoi_reached;
}


/*
 * Is there more than one scan?
 */

GLOBAL boolean
jpeg_has_multiple_scans( j_decompress_ptr cinfo ) {
	/* Only valid after jpeg_read_header completes */
	if ( cinfo->global_state < DSTATE_READY ||
		 cinfo->global_state > DSTATE_STOPPING ) {
		ERREXIT1( cinfo, JERR_BAD_STATE, cinfo->global_state );
	}
	return cinfo->inputctl->has_multiple_scans;
}


/*
 * Finish JPEG decompression.
 *
 * This will normally just verify the file trailer and release temp storage.
 *
 * Returns FALSE if suspended.  The return value need be inspected only if
 * a suspending data source is used.
 */

GLOBAL boolean
jpeg_finish_decompress( j_decompress_ptr cinfo ) {
	if ( ( cinfo->global_state == DSTATE_SCANNING ||
		   cinfo->global_state == DSTATE_RAW_OK ) && !cinfo->buffered_image ) {
		/* Terminate final pass of non-buffered mode */
		if ( cinfo->output_scanline < cinfo->output_height ) {
			ERREXIT( cinfo, JERR_TOO_LITTLE_DATA );
		}
		( *cinfo->master->finish_output_pass )( cinfo );
		cinfo->global_state = DSTATE_STOPPING;
	} else if ( cinfo->global_state == DSTATE_BUFIMAGE ) {
		/* Finishing after a buffered-image operation */
		cinfo->global_state = DSTATE_STOPPING;
	} else if ( cinfo->global_state != DSTATE_STOPPING ) {
		/* STOPPING = repeat call after a suspension, anything else is error */
		ERREXIT1( cinfo, JERR_BAD_STATE, cinfo->global_state );
	}
	/* Read until EOI */
	while ( !cinfo->inputctl->eoi_reached ) {
		if ( ( *cinfo->inputctl->consume_input )( cinfo ) == JPEG_SUSPENDED ) {
			return FALSE; /* Suspend, come back later */
		}
	}
	/* Do final cleanup */
	( *cinfo->src->term_source )( cinfo );
	/* We can use jpeg_abort to release memory and reset global_state */
	jpeg_abort( (j_common_ptr) cinfo );
	return TRUE;
}
