/*
 * jdinput.c
 *
 * Copyright (C) 1991-1995, 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 input control logic for the JPEG decompressor.
 * These routines are concerned with controlling the decompressor's input
 * processing (marker reading and coefficient decoding).  The actual input
 * reading is done in jdmarker.c, jdhuff.c, and jdphuff.c.
 */

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


/* Private state */

typedef struct {
	struct jpeg_input_controller pub; /* public fields */

	boolean inheaders;      /* TRUE until first SOS is reached */
} my_input_controller;

typedef my_input_controller * my_inputctl_ptr;


/* Forward declarations */
METHODDEF int consume_markers JPP( (j_decompress_ptr cinfo) );


/*
 * Routines to calculate various quantities related to the size of the image.
 */

LOCAL void
initial_setup( j_decompress_ptr cinfo ) {
/* Called once, when first SOS marker is reached */
	int ci;
	jpeg_component_info *compptr;

	/* Make sure image isn't bigger than I can handle */
	if ( (long) cinfo->image_height > (long) JPEG_MAX_DIMENSION ||
		 (long) cinfo->image_width > (long) JPEG_MAX_DIMENSION ) {
		ERREXIT1( cinfo, JERR_IMAGE_TOO_BIG, (unsigned int) JPEG_MAX_DIMENSION );
	}

	/* For now, precision must match compiled-in value... */
	if ( cinfo->data_precision != BITS_IN_JSAMPLE ) {
		ERREXIT1( cinfo, JERR_BAD_PRECISION, cinfo->data_precision );
	}

	/* Check that number of components won't exceed internal array sizes */
	if ( cinfo->num_components > MAX_COMPONENTS ) {
		ERREXIT2( cinfo, JERR_COMPONENT_COUNT, cinfo->num_components,
				  MAX_COMPONENTS );
	}

	/* Compute maximum sampling factors; check factor validity */
	cinfo->max_h_samp_factor = 1;
	cinfo->max_v_samp_factor = 1;
	for ( ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
		  ci++, compptr++ ) {
		if ( compptr->h_samp_factor <= 0 || compptr->h_samp_factor > MAX_SAMP_FACTOR ||
			 compptr->v_samp_factor <= 0 || compptr->v_samp_factor > MAX_SAMP_FACTOR ) {
			ERREXIT( cinfo, JERR_BAD_SAMPLING );
		}
		cinfo->max_h_samp_factor = MAX( cinfo->max_h_samp_factor,
										compptr->h_samp_factor );
		cinfo->max_v_samp_factor = MAX( cinfo->max_v_samp_factor,
										compptr->v_samp_factor );
	}

	/* We initialize DCT_scaled_size and min_DCT_scaled_size to DCTSIZE.
	 * In the full decompressor, this will be overridden by jdmaster.c;
	 * but in the transcoder, jdmaster.c is not used, so we must do it here.
	 */
	cinfo->min_DCT_scaled_size = DCTSIZE;

	/* Compute dimensions of components */
	for ( ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
		  ci++, compptr++ ) {
		compptr->DCT_scaled_size = DCTSIZE;
		/* Size in DCT blocks */
		compptr->width_in_blocks = (JDIMENSION)
								   jdiv_round_up( (long) cinfo->image_width * (long) compptr->h_samp_factor,
												  (long) ( cinfo->max_h_samp_factor * DCTSIZE ) );
		compptr->height_in_blocks = (JDIMENSION)
									jdiv_round_up( (long) cinfo->image_height * (long) compptr->v_samp_factor,
												   (long) ( cinfo->max_v_samp_factor * DCTSIZE ) );
		/* downsampled_width and downsampled_height will also be overridden by
		 * jdmaster.c if we are doing full decompression.  The transcoder library
		 * doesn't use these values, but the calling application might.
		 */
		/* Size in samples */
		compptr->downsampled_width = (JDIMENSION)
									 jdiv_round_up( (long) cinfo->image_width * (long) compptr->h_samp_factor,
													(long) cinfo->max_h_samp_factor );
		compptr->downsampled_height = (JDIMENSION)
									  jdiv_round_up( (long) cinfo->image_height * (long) compptr->v_samp_factor,
													 (long) cinfo->max_v_samp_factor );
		/* Mark component needed, until color conversion says otherwise */
		compptr->component_needed = TRUE;
		/* Mark no quantization table yet saved for component */
		compptr->quant_table = NULL;
	}

	/* Compute number of fully interleaved MCU rows. */
	cinfo->total_iMCU_rows = (JDIMENSION)
							 jdiv_round_up( (long) cinfo->image_height,
											(long) ( cinfo->max_v_samp_factor * DCTSIZE ) );

	/* Decide whether file contains multiple scans */
	if ( cinfo->comps_in_scan < cinfo->num_components || cinfo->progressive_mode ) {
		cinfo->inputctl->has_multiple_scans = TRUE;
	} else {
		cinfo->inputctl->has_multiple_scans = FALSE;
	}
}


LOCAL void
per_scan_setup( j_decompress_ptr cinfo ) {
/* Do computations that are needed before processing a JPEG scan */
/* cinfo->comps_in_scan and cinfo->cur_comp_info[] were set from SOS marker */
	int ci, mcublks, tmp;
	jpeg_component_info *compptr;

	if ( cinfo->comps_in_scan == 1 ) {

		/* Noninterleaved (single-component) scan */
		compptr = cinfo->cur_comp_info[0];

		/* Overall image size in MCUs */
		cinfo->MCUs_per_row = compptr->width_in_blocks;
		cinfo->MCU_rows_in_scan = compptr->height_in_blocks;

		/* For noninterleaved scan, always one block per MCU */
		compptr->MCU_width = 1;
		compptr->MCU_height = 1;
		compptr->MCU_blocks = 1;
		compptr->MCU_sample_width = compptr->DCT_scaled_size;
		compptr->last_col_width = 1;
		/* For noninterleaved scans, it is convenient to define last_row_height
		 * as the number of block rows present in the last iMCU row.
		 */
		tmp = (int) ( compptr->height_in_blocks % compptr->v_samp_factor );
		if ( tmp == 0 ) {
			tmp = compptr->v_samp_factor;
		}
		compptr->last_row_height = tmp;

		/* Prepare array describing MCU composition */
		cinfo->blocks_in_MCU = 1;
		cinfo->MCU_membership[0] = 0;

	} else {

		/* Interleaved (multi-component) scan */
		if ( cinfo->comps_in_scan <= 0 || cinfo->comps_in_scan > MAX_COMPS_IN_SCAN ) {
			ERREXIT2( cinfo, JERR_COMPONENT_COUNT, cinfo->comps_in_scan,
					  MAX_COMPS_IN_SCAN );
		}

		/* Overall image size in MCUs */
		cinfo->MCUs_per_row = (JDIMENSION)
							  jdiv_round_up( (long) cinfo->image_width,
											 (long) ( cinfo->max_h_samp_factor * DCTSIZE ) );
		cinfo->MCU_rows_in_scan = (JDIMENSION)
								  jdiv_round_up( (long) cinfo->image_height,
												 (long) ( cinfo->max_v_samp_factor * DCTSIZE ) );

		cinfo->blocks_in_MCU = 0;

		for ( ci = 0; ci < cinfo->comps_in_scan; ci++ ) {
			compptr = cinfo->cur_comp_info[ci];
			/* Sampling factors give # of blocks of component in each MCU */
			compptr->MCU_width = compptr->h_samp_factor;
			compptr->MCU_height = compptr->v_samp_factor;
			compptr->MCU_blocks = compptr->MCU_width * compptr->MCU_height;
			compptr->MCU_sample_width = compptr->MCU_width * compptr->DCT_scaled_size;
			/* Figure number of non-dummy blocks in last MCU column & row */
			tmp = (int) ( compptr->width_in_blocks % compptr->MCU_width );
			if ( tmp == 0 ) {
				tmp = compptr->MCU_width;
			}
			compptr->last_col_width = tmp;
			tmp = (int) ( compptr->height_in_blocks % compptr->MCU_height );
			if ( tmp == 0 ) {
				tmp = compptr->MCU_height;
			}
			compptr->last_row_height = tmp;
			/* Prepare array describing MCU composition */
			mcublks = compptr->MCU_blocks;
			if ( cinfo->blocks_in_MCU + mcublks > D_MAX_BLOCKS_IN_MCU ) {
				ERREXIT( cinfo, JERR_BAD_MCU_SIZE );
			}
			while ( mcublks-- > 0 ) {
				cinfo->MCU_membership[cinfo->blocks_in_MCU++] = ci;
			}
		}

	}
}


/*
 * Save away a copy of the Q-table referenced by each component present
 * in the current scan, unless already saved during a prior scan.
 *
 * In a multiple-scan JPEG file, the encoder could assign different components
 * the same Q-table slot number, but change table definitions between scans
 * so that each component uses a different Q-table.  (The IJG encoder is not
 * currently capable of doing this, but other encoders might.)  Since we want
 * to be able to dequantize all the components at the end of the file, this
 * means that we have to save away the table actually used for each component.
 * We do this by copying the table at the start of the first scan containing
 * the component.
 * The JPEG spec prohibits the encoder from changing the contents of a Q-table
 * slot between scans of a component using that slot.  If the encoder does so
 * anyway, this decoder will simply use the Q-table values that were current
 * at the start of the first scan for the component.
 *
 * The decompressor output side looks only at the saved quant tables,
 * not at the current Q-table slots.
 */

LOCAL void
latch_quant_tables( j_decompress_ptr cinfo ) {
	int ci, qtblno;
	jpeg_component_info *compptr;
	JQUANT_TBL * qtbl;

	for ( ci = 0; ci < cinfo->comps_in_scan; ci++ ) {
		compptr = cinfo->cur_comp_info[ci];
		/* No work if we already saved Q-table for this component */
		if ( compptr->quant_table != NULL ) {
			continue;
		}
		/* Make sure specified quantization table is present */
		qtblno = compptr->quant_tbl_no;
		if ( qtblno < 0 || qtblno >= NUM_QUANT_TBLS ||
			 cinfo->quant_tbl_ptrs[qtblno] == NULL ) {
			ERREXIT1( cinfo, JERR_NO_QUANT_TABLE, qtblno );
		}
		/* OK, save away the quantization table */
		qtbl = ( JQUANT_TBL * )
			   ( *cinfo->mem->alloc_small )( (j_common_ptr) cinfo, JPOOL_IMAGE,
											 SIZEOF( JQUANT_TBL ) );
		MEMCOPY( qtbl, cinfo->quant_tbl_ptrs[qtblno], SIZEOF( JQUANT_TBL ) );
		compptr->quant_table = qtbl;
	}
}


/*
 * Initialize the input modules to read a scan of compressed data.
 * The first call to this is done by jdmaster.c after initializing
 * the entire decompressor (during jpeg_start_decompress).
 * Subsequent calls come from consume_markers, below.
 */

METHODDEF void
start_input_pass( j_decompress_ptr cinfo ) {
	per_scan_setup( cinfo );
	latch_quant_tables( cinfo );
	( *cinfo->entropy->start_pass )( cinfo );
	( *cinfo->coef->start_input_pass )( cinfo );
	cinfo->inputctl->consume_input = cinfo->coef->consume_data;
}


/*
 * Finish up after inputting a compressed-data scan.
 * This is called by the coefficient controller after it's read all
 * the expected data of the scan.
 */

METHODDEF void
finish_input_pass( j_decompress_ptr cinfo ) {
	cinfo->inputctl->consume_input = consume_markers;
}


/*
 * Read JPEG markers before, between, or after compressed-data scans.
 * Change state as necessary when a new scan is reached.
 * Return value is JPEG_SUSPENDED, JPEG_REACHED_SOS, or JPEG_REACHED_EOI.
 *
 * The consume_input method pointer points either here or to the
 * coefficient controller's consume_data routine, depending on whether
 * we are reading a compressed data segment or inter-segment markers.
 */

METHODDEF int
consume_markers( j_decompress_ptr cinfo ) {
	my_inputctl_ptr inputctl = (my_inputctl_ptr) cinfo->inputctl;
	int val;

	if ( inputctl->pub.eoi_reached ) { /* After hitting EOI, read no further */
		return JPEG_REACHED_EOI;
	}

	val = ( *cinfo->marker->read_markers )( cinfo );

	switch ( val ) {
	case JPEG_REACHED_SOS:  /* Found SOS */
		if ( inputctl->inheaders ) { /* 1st SOS */
			initial_setup( cinfo );
			inputctl->inheaders = FALSE;
			/* Note: start_input_pass must be called by jdmaster.c
			 * before any more input can be consumed.  jdapi.c is
			 * responsible for enforcing this sequencing.
			 */
		} else {        /* 2nd or later SOS marker */
			if ( !inputctl->pub.has_multiple_scans ) {
				ERREXIT( cinfo, JERR_EOI_EXPECTED ); /* Oops, I wasn't expecting this! */
			}
			start_input_pass( cinfo );
		}
		break;
	case JPEG_REACHED_EOI:  /* Found EOI */
		inputctl->pub.eoi_reached = TRUE;
		if ( inputctl->inheaders ) { /* Tables-only datastream, apparently */
			if ( cinfo->marker->saw_SOF ) {
				ERREXIT( cinfo, JERR_SOF_NO_SOS );
			}
		} else {
			/* Prevent infinite loop in coef ctlr's decompress_data routine
			 * if user set output_scan_number larger than number of scans.
			 */
			if ( cinfo->output_scan_number > cinfo->input_scan_number ) {
				cinfo->output_scan_number = cinfo->input_scan_number;
			}
		}
		break;
	case JPEG_SUSPENDED:
		break;
	}

	return val;
}


/*
 * Reset state to begin a fresh datastream.
 */

METHODDEF void
reset_input_controller( j_decompress_ptr cinfo ) {
	my_inputctl_ptr inputctl = (my_inputctl_ptr) cinfo->inputctl;

	inputctl->pub.consume_input = consume_markers;
	inputctl->pub.has_multiple_scans = FALSE; /* "unknown" would be better */
	inputctl->pub.eoi_reached = FALSE;
	inputctl->inheaders = TRUE;
	/* Reset other modules */
	( *cinfo->err->reset_error_mgr )( (j_common_ptr) cinfo );
	( *cinfo->marker->reset_marker_reader )( cinfo );
	/* Reset progression state -- would be cleaner if entropy decoder did this */
	cinfo->coef_bits = NULL;
}


/*
 * Initialize the input controller module.
 * This is called only once, when the decompression object is created.
 */

GLOBAL void
jinit_input_controller( j_decompress_ptr cinfo ) {
	my_inputctl_ptr inputctl;

	/* Create subobject in permanent pool */
	inputctl = (my_inputctl_ptr)
				( *cinfo->mem->alloc_small ) ( (j_common_ptr) cinfo, JPOOL_PERMANENT,
											   SIZEOF( my_input_controller ) );
	cinfo->inputctl = (struct jpeg_input_controller *) inputctl;
	/* Initialize method pointers */
	inputctl->pub.consume_input = consume_markers;
	inputctl->pub.reset_input_controller = reset_input_controller;
	inputctl->pub.start_input_pass = start_input_pass;
	inputctl->pub.finish_input_pass = finish_input_pass;
	/* Initialize state: can't use reset_input_controller since we don't
	 * want to try to reset other modules yet.
	 */
	inputctl->pub.has_multiple_scans = FALSE; /* "unknown" would be better */
	inputctl->pub.eoi_reached = FALSE;
	inputctl->inheaders = TRUE;
}
