/*
 * jdmaster.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 master control logic for the JPEG decompressor.
 * These routines are concerned with selecting the modules to be executed
 * and with determining the number of passes and the work to be done in each
 * pass.
 */

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


/* Private state */

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

	int pass_number;    /* # of passes completed */

	boolean using_merged_upsample; /* TRUE if using merged upsample/cconvert */

	/* Saved references to initialized quantizer modules,
	 * in case we need to switch modes.
	 */
	struct jpeg_color_quantizer * quantizer_1pass;
	struct jpeg_color_quantizer * quantizer_2pass;
} my_decomp_master;

typedef my_decomp_master * my_master_ptr;


/*
 * Determine whether merged upsample/color conversion should be used.
 * CRUCIAL: this must match the actual capabilities of jdmerge.c!
 */

LOCAL boolean
use_merged_upsample( j_decompress_ptr cinfo ) {
#ifdef UPSAMPLE_MERGING_SUPPORTED
	/* Merging is the equivalent of plain box-filter upsampling */
	if ( cinfo->do_fancy_upsampling || cinfo->CCIR601_sampling ) {
		return FALSE;
	}
	/* jdmerge.c only supports YCC=>RGB color conversion */
	if ( cinfo->jpeg_color_space != JCS_YCbCr || cinfo->num_components != 3 ||
		 cinfo->out_color_space != JCS_RGB ||
		 cinfo->out_color_components != RGB_PIXELSIZE ) {
		return FALSE;
	}
	/* and it only handles 2h1v or 2h2v sampling ratios */
	if ( cinfo->comp_info[0].h_samp_factor != 2 ||
		 cinfo->comp_info[1].h_samp_factor != 1 ||
		 cinfo->comp_info[2].h_samp_factor != 1 ||
		 cinfo->comp_info[0].v_samp_factor >  2 ||
		 cinfo->comp_info[1].v_samp_factor != 1 ||
		 cinfo->comp_info[2].v_samp_factor != 1 ) {
		return FALSE;
	}
	/* furthermore, it doesn't work if we've scaled the IDCTs differently */
	if ( cinfo->comp_info[0].DCT_scaled_size != cinfo->min_DCT_scaled_size ||
		 cinfo->comp_info[1].DCT_scaled_size != cinfo->min_DCT_scaled_size ||
		 cinfo->comp_info[2].DCT_scaled_size != cinfo->min_DCT_scaled_size ) {
		return FALSE;
	}
	/* ??? also need to test for upsample-time rescaling, when & if supported */
	return TRUE;        /* by golly, it'll work... */
#else
	return FALSE;
#endif
}


/*
 * Compute output image dimensions and related values.
 * NOTE: this is exported for possible use by application.
 * Hence it mustn't do anything that can't be done twice.
 * Also note that it may be called before the master module is initialized!
 */

GLOBAL void
jpeg_calc_output_dimensions( j_decompress_ptr cinfo ) {
/* Do computations that are needed before master selection phase */
#if 0   // JDC: commented out to remove warning
	int ci;
	jpeg_component_info *compptr;
#endif

	/* Prevent application from calling me at wrong times */
	if ( cinfo->global_state != DSTATE_READY ) {
		ERREXIT1( cinfo, JERR_BAD_STATE, cinfo->global_state );
	}

#ifdef IDCT_SCALING_SUPPORTED

	/* Compute actual output image dimensions and DCT scaling choices. */
	if ( cinfo->scale_num * 8 <= cinfo->scale_denom ) {
		/* Provide 1/8 scaling */
		cinfo->output_width = (JDIMENSION)
							  jdiv_round_up( (long) cinfo->image_width, 8L );
		cinfo->output_height = (JDIMENSION)
							   jdiv_round_up( (long) cinfo->image_height, 8L );
		cinfo->min_DCT_scaled_size = 1;
	} else if ( cinfo->scale_num * 4 <= cinfo->scale_denom ) {
		/* Provide 1/4 scaling */
		cinfo->output_width = (JDIMENSION)
							  jdiv_round_up( (long) cinfo->image_width, 4L );
		cinfo->output_height = (JDIMENSION)
							   jdiv_round_up( (long) cinfo->image_height, 4L );
		cinfo->min_DCT_scaled_size = 2;
	} else if ( cinfo->scale_num * 2 <= cinfo->scale_denom ) {
		/* Provide 1/2 scaling */
		cinfo->output_width = (JDIMENSION)
							  jdiv_round_up( (long) cinfo->image_width, 2L );
		cinfo->output_height = (JDIMENSION)
							   jdiv_round_up( (long) cinfo->image_height, 2L );
		cinfo->min_DCT_scaled_size = 4;
	} else {
		/* Provide 1/1 scaling */
		cinfo->output_width = cinfo->image_width;
		cinfo->output_height = cinfo->image_height;
		cinfo->min_DCT_scaled_size = DCTSIZE;
	}
	/* In selecting the actual DCT scaling for each component, we try to
	 * scale up the chroma components via IDCT scaling rather than upsampling.
	 * This saves time if the upsampler gets to use 1:1 scaling.
	 * Note this code assumes that the supported DCT scalings are powers of 2.
	 */
	for ( ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
		  ci++, compptr++ ) {
		int ssize = cinfo->min_DCT_scaled_size;
		while ( ssize < DCTSIZE &&
				( compptr->h_samp_factor * ssize * 2 <=
				  cinfo->max_h_samp_factor * cinfo->min_DCT_scaled_size ) &&
				( compptr->v_samp_factor * ssize * 2 <=
				  cinfo->max_v_samp_factor * cinfo->min_DCT_scaled_size ) ) {
			ssize = ssize * 2;
		}
		compptr->DCT_scaled_size = ssize;
	}

	/* Recompute downsampled dimensions of components;
	 * application needs to know these if using raw downsampled data.
	 */
	for ( ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
		  ci++, compptr++ ) {
		/* Size in samples, after IDCT scaling */
		compptr->downsampled_width = (JDIMENSION)
									 jdiv_round_up( (long) cinfo->image_width *
													(long) ( compptr->h_samp_factor * compptr->DCT_scaled_size ),
													(long) ( cinfo->max_h_samp_factor * DCTSIZE ) );
		compptr->downsampled_height = (JDIMENSION)
									  jdiv_round_up( (long) cinfo->image_height *
													 (long) ( compptr->v_samp_factor * compptr->DCT_scaled_size ),
													 (long) ( cinfo->max_v_samp_factor * DCTSIZE ) );
	}

#else /* !IDCT_SCALING_SUPPORTED */

	/* Hardwire it to "no scaling" */
	cinfo->output_width = cinfo->image_width;
	cinfo->output_height = cinfo->image_height;
	/* jdinput.c has already initialized DCT_scaled_size to DCTSIZE,
	 * and has computed unscaled downsampled_width and downsampled_height.
	 */

#endif /* IDCT_SCALING_SUPPORTED */

	/* Report number of components in selected colorspace. */
	/* Probably this should be in the color conversion module... */
	switch ( cinfo->out_color_space ) {
	case JCS_GRAYSCALE:
		cinfo->out_color_components = 1;
		break;
	case JCS_RGB:
#if RGB_PIXELSIZE != 3
		cinfo->out_color_components = RGB_PIXELSIZE;
		break;
#endif /* else share code with YCbCr */
	case JCS_YCbCr:
		cinfo->out_color_components = 3;
		break;
	case JCS_CMYK:
	case JCS_YCCK:
		cinfo->out_color_components = 4;
		break;
	default:        /* else must be same colorspace as in file */
		cinfo->out_color_components = cinfo->num_components;
		break;
	}
	cinfo->output_components = ( cinfo->quantize_colors ? 1 :
								 cinfo->out_color_components );

	/* See if upsampler will want to emit more than one row at a time */
	if ( use_merged_upsample( cinfo ) ) {
		cinfo->rec_outbuf_height = cinfo->max_v_samp_factor;
	} else {
		cinfo->rec_outbuf_height = 1;
	}
}


/*
 * Several decompression processes need to range-limit values to the range
 * 0..MAXJSAMPLE; the input value may fall somewhat outside this range
 * due to noise introduced by quantization, roundoff error, etc.  These
 * processes are inner loops and need to be as fast as possible.  On most
 * machines, particularly CPUs with pipelines or instruction prefetch,
 * a (subscript-check-less) C table lookup
 *		x = sample_range_limit[x];
 * is faster than explicit tests
 *		if (x < 0)  x = 0;
 *		else if (x > MAXJSAMPLE)  x = MAXJSAMPLE;
 * These processes all use a common table prepared by the routine below.
 *
 * For most steps we can mathematically guarantee that the initial value
 * of x is within MAXJSAMPLE+1 of the legal range, so a table running from
 * -(MAXJSAMPLE+1) to 2*MAXJSAMPLE+1 is sufficient.  But for the initial
 * limiting step (just after the IDCT), a wildly out-of-range value is
 * possible if the input data is corrupt.  To avoid any chance of indexing
 * off the end of memory and getting a bad-pointer trap, we perform the
 * post-IDCT limiting thus:
 *		x = range_limit[x & MASK];
 * where MASK is 2 bits wider than legal sample data, ie 10 bits for 8-bit
 * samples.  Under normal circumstances this is more than enough range and
 * a correct output will be generated; with bogus input data the mask will
 * cause wraparound, and we will safely generate a bogus-but-in-range output.
 * For the post-IDCT step, we want to convert the data from signed to unsigned
 * representation by adding CENTERJSAMPLE at the same time that we limit it.
 * So the post-IDCT limiting table ends up looking like this:
 *   CENTERJSAMPLE,CENTERJSAMPLE+1,...,MAXJSAMPLE,
 *   MAXJSAMPLE (repeat 2*(MAXJSAMPLE+1)-CENTERJSAMPLE times),
 *   0          (repeat 2*(MAXJSAMPLE+1)-CENTERJSAMPLE times),
 *   0,1,...,CENTERJSAMPLE-1
 * Negative inputs select values from the upper half of the table after
 * masking.
 *
 * We can save some space by overlapping the start of the post-IDCT table
 * with the simpler range limiting table.  The post-IDCT table begins at
 * sample_range_limit + CENTERJSAMPLE.
 *
 * Note that the table is allocated in near data space on PCs; it's small
 * enough and used often enough to justify this.
 */

LOCAL void
prepare_range_limit_table( j_decompress_ptr cinfo ) {
/* Allocate and fill in the sample_range_limit table */
	JSAMPLE * table;
	int i;

	table = ( JSAMPLE * )
			( *cinfo->mem->alloc_small )( (j_common_ptr) cinfo, JPOOL_IMAGE,
										  ( 5 * ( MAXJSAMPLE + 1 ) + CENTERJSAMPLE ) * SIZEOF( JSAMPLE ) );
	table += ( MAXJSAMPLE + 1 ); /* allow negative subscripts of simple table */
	cinfo->sample_range_limit = table;
	/* First segment of "simple" table: limit[x] = 0 for x < 0 */
	MEMZERO( table - ( MAXJSAMPLE + 1 ), ( MAXJSAMPLE + 1 ) * SIZEOF( JSAMPLE ) );
	/* Main part of "simple" table: limit[x] = x */
	for ( i = 0; i <= MAXJSAMPLE; i++ )
		table[i] = (JSAMPLE) i;
	table += CENTERJSAMPLE; /* Point to where post-IDCT table starts */
	/* End of simple table, rest of first half of post-IDCT table */
	for ( i = CENTERJSAMPLE; i < 2 * ( MAXJSAMPLE + 1 ); i++ )
		table[i] = MAXJSAMPLE;
	/* Second half of post-IDCT table */
	MEMZERO( table + ( 2 * ( MAXJSAMPLE + 1 ) ),
			 ( 2 * ( MAXJSAMPLE + 1 ) - CENTERJSAMPLE ) * SIZEOF( JSAMPLE ) );
	MEMCOPY( table + ( 4 * ( MAXJSAMPLE + 1 ) - CENTERJSAMPLE ),
			 cinfo->sample_range_limit, CENTERJSAMPLE * SIZEOF( JSAMPLE ) );
}


/*
 * Master selection of decompression modules.
 * This is done once at jpeg_start_decompress time.  We determine
 * which modules will be used and give them appropriate initialization calls.
 * We also initialize the decompressor input side to begin consuming data.
 *
 * Since jpeg_read_header has finished, we know what is in the SOF
 * and (first) SOS markers.  We also have all the application parameter
 * settings.
 */

LOCAL void
master_selection( j_decompress_ptr cinfo ) {
	my_master_ptr master = (my_master_ptr) cinfo->master;
	boolean use_c_buffer;
	long samplesperrow;
	JDIMENSION jd_samplesperrow;

	/* Initialize dimensions and other stuff */
	jpeg_calc_output_dimensions( cinfo );
	prepare_range_limit_table( cinfo );

	/* Width of an output scanline must be representable as JDIMENSION. */
	samplesperrow = (long) cinfo->output_width * (long) cinfo->out_color_components;
	jd_samplesperrow = (JDIMENSION) samplesperrow;
	if ( (long) jd_samplesperrow != samplesperrow ) {
		ERREXIT( cinfo, JERR_WIDTH_OVERFLOW );
	}

	/* Initialize my private state */
	master->pass_number = 0;
	master->using_merged_upsample = use_merged_upsample( cinfo );

	/* Color quantizer selection */
	master->quantizer_1pass = NULL;
	master->quantizer_2pass = NULL;
	/* No mode changes if not using buffered-image mode. */
	if ( !cinfo->quantize_colors || !cinfo->buffered_image ) {
		cinfo->enable_1pass_quant = FALSE;
		cinfo->enable_external_quant = FALSE;
		cinfo->enable_2pass_quant = FALSE;
	}
	if ( cinfo->quantize_colors ) {
		if ( cinfo->raw_data_out ) {
			ERREXIT( cinfo, JERR_NOTIMPL );
		}
		/* 2-pass quantizer only works in 3-component color space. */
		if ( cinfo->out_color_components != 3 ) {
			cinfo->enable_1pass_quant = TRUE;
			cinfo->enable_external_quant = FALSE;
			cinfo->enable_2pass_quant = FALSE;
			cinfo->colormap = NULL;
		} else if ( cinfo->colormap != NULL ) {
			cinfo->enable_external_quant = TRUE;
		} else if ( cinfo->two_pass_quantize ) {
			cinfo->enable_2pass_quant = TRUE;
		} else {
			cinfo->enable_1pass_quant = TRUE;
		}

		if ( cinfo->enable_1pass_quant ) {
#ifdef QUANT_1PASS_SUPPORTED
			jinit_1pass_quantizer( cinfo );
			master->quantizer_1pass = cinfo->cquantize;
#else
			ERREXIT( cinfo, JERR_NOT_COMPILED );
#endif
		}

		/* We use the 2-pass code to map to external colormaps. */
		if ( cinfo->enable_2pass_quant || cinfo->enable_external_quant ) {
#ifdef QUANT_2PASS_SUPPORTED
			jinit_2pass_quantizer( cinfo );
			master->quantizer_2pass = cinfo->cquantize;
#else
			ERREXIT( cinfo, JERR_NOT_COMPILED );
#endif
		}
		/* If both quantizers are initialized, the 2-pass one is left active;
		 * this is necessary for starting with quantization to an external map.
		 */
	}

	/* Post-processing: in particular, color conversion first */
	if ( !cinfo->raw_data_out ) {
		if ( master->using_merged_upsample ) {
#ifdef UPSAMPLE_MERGING_SUPPORTED
			jinit_merged_upsampler( cinfo ); /* does color conversion too */
#else
			ERREXIT( cinfo, JERR_NOT_COMPILED );
#endif
		} else {
			jinit_color_deconverter( cinfo );
			jinit_upsampler( cinfo );
		}
		jinit_d_post_controller( cinfo, cinfo->enable_2pass_quant );
	}
	/* Inverse DCT */
	jinit_inverse_dct( cinfo );
	/* Entropy decoding: either Huffman or arithmetic coding. */
	if ( cinfo->arith_code ) {
		ERREXIT( cinfo, JERR_ARITH_NOTIMPL );
	} else {
		if ( cinfo->progressive_mode ) {
#ifdef D_PROGRESSIVE_SUPPORTED
			jinit_phuff_decoder( cinfo );
#else
			ERREXIT( cinfo, JERR_NOT_COMPILED );
#endif
		} else {
			jinit_huff_decoder( cinfo );
		}
	}

	/* Initialize principal buffer controllers. */
	use_c_buffer = cinfo->inputctl->has_multiple_scans || cinfo->buffered_image;
	jinit_d_coef_controller( cinfo, use_c_buffer );

	if ( !cinfo->raw_data_out ) {
		jinit_d_main_controller( cinfo, FALSE /* never need full buffer here */ );
	}

	/* We can now tell the memory manager to allocate virtual arrays. */
	( *cinfo->mem->realize_virt_arrays )( (j_common_ptr) cinfo );

	/* Initialize input side of decompressor to consume first scan. */
	( *cinfo->inputctl->start_input_pass )( cinfo );

#ifdef D_MULTISCAN_FILES_SUPPORTED
	/* If jpeg_start_decompress will read the whole file, initialize
	 * progress monitoring appropriately.  The input step is counted
	 * as one pass.
	 */
	if ( cinfo->progress != NULL && !cinfo->buffered_image &&
		 cinfo->inputctl->has_multiple_scans ) {
		int nscans;
		/* Estimate number of scans to set pass_limit. */
		if ( cinfo->progressive_mode ) {
			/* Arbitrarily estimate 2 interleaved DC scans + 3 AC scans/component. */
			nscans = 2 + 3 * cinfo->num_components;
		} else {
			/* For a nonprogressive multiscan file, estimate 1 scan per component. */
			nscans = cinfo->num_components;
		}
		cinfo->progress->pass_counter = 0L;
		cinfo->progress->pass_limit = (long) cinfo->total_iMCU_rows * nscans;
		cinfo->progress->completed_passes = 0;
		cinfo->progress->total_passes = ( cinfo->enable_2pass_quant ? 3 : 2 );
		/* Count the input pass as done */
		master->pass_number++;
	}
#endif /* D_MULTISCAN_FILES_SUPPORTED */
}


/*
 * Per-pass setup.
 * This is called at the beginning of each output pass.  We determine which
 * modules will be active during this pass and give them appropriate
 * start_pass calls.  We also set is_dummy_pass to indicate whether this
 * is a "real" output pass or a dummy pass for color quantization.
 * (In the latter case, jdapi.c will crank the pass to completion.)
 */

METHODDEF void
prepare_for_output_pass( j_decompress_ptr cinfo ) {
	my_master_ptr master = (my_master_ptr) cinfo->master;

	if ( master->pub.is_dummy_pass ) {
#ifdef QUANT_2PASS_SUPPORTED
		/* Final pass of 2-pass quantization */
		master->pub.is_dummy_pass = FALSE;
		( *cinfo->cquantize->start_pass )( cinfo, FALSE );
		( *cinfo->post->start_pass )( cinfo, JBUF_CRANK_DEST );
		( *cinfo->main->start_pass )( cinfo, JBUF_CRANK_DEST );
#else
		ERREXIT( cinfo, JERR_NOT_COMPILED );
#endif /* QUANT_2PASS_SUPPORTED */
	} else {
		if ( cinfo->quantize_colors && cinfo->colormap == NULL ) {
			/* Select new quantization method */
			if ( cinfo->two_pass_quantize && cinfo->enable_2pass_quant ) {
				cinfo->cquantize = master->quantizer_2pass;
				master->pub.is_dummy_pass = TRUE;
			} else if ( cinfo->enable_1pass_quant ) {
				cinfo->cquantize = master->quantizer_1pass;
			} else {
				ERREXIT( cinfo, JERR_MODE_CHANGE );
			}
		}
		( *cinfo->idct->start_pass )( cinfo );
		( *cinfo->coef->start_output_pass )( cinfo );
		if ( !cinfo->raw_data_out ) {
			if ( !master->using_merged_upsample ) {
				( *cinfo->cconvert->start_pass )( cinfo );
			}
			( *cinfo->upsample->start_pass )( cinfo );
			if ( cinfo->quantize_colors ) {
				( *cinfo->cquantize->start_pass )( cinfo, master->pub.is_dummy_pass );
			}
			( *cinfo->post->start_pass )( cinfo,
										  ( master->pub.is_dummy_pass ? JBUF_SAVE_AND_PASS : JBUF_PASS_THRU ) );
			( *cinfo->main->start_pass )( cinfo, JBUF_PASS_THRU );
		}
	}

	/* Set up progress monitor's pass info if present */
	if ( cinfo->progress != NULL ) {
		cinfo->progress->completed_passes = master->pass_number;
		cinfo->progress->total_passes = master->pass_number +
										( master->pub.is_dummy_pass ? 2 : 1 );
		/* In buffered-image mode, we assume one more output pass if EOI not
		 * yet reached, but no more passes if EOI has been reached.
		 */
		if ( cinfo->buffered_image && !cinfo->inputctl->eoi_reached ) {
			cinfo->progress->total_passes += ( cinfo->enable_2pass_quant ? 2 : 1 );
		}
	}
}


/*
 * Finish up at end of an output pass.
 */

METHODDEF void
finish_output_pass( j_decompress_ptr cinfo ) {
	my_master_ptr master = (my_master_ptr) cinfo->master;

	if ( cinfo->quantize_colors ) {
		( *cinfo->cquantize->finish_pass )( cinfo );
	}
	master->pass_number++;
}


#ifdef D_MULTISCAN_FILES_SUPPORTED

/*
 * Switch to a new external colormap between output passes.
 */

GLOBAL void
jpeg_new_colormap( j_decompress_ptr cinfo ) {
	my_master_ptr master = (my_master_ptr) cinfo->master;

	/* Prevent application from calling me at wrong times */
	if ( cinfo->global_state != DSTATE_BUFIMAGE ) {
		ERREXIT1( cinfo, JERR_BAD_STATE, cinfo->global_state );
	}

	if ( cinfo->quantize_colors && cinfo->enable_external_quant &&
		 cinfo->colormap != NULL ) {
		/* Select 2-pass quantizer for external colormap use */
		cinfo->cquantize = master->quantizer_2pass;
		/* Notify quantizer of colormap change */
		( *cinfo->cquantize->new_color_map )( cinfo );
		master->pub.is_dummy_pass = FALSE; /* just in case */
	} else {
		ERREXIT( cinfo, JERR_MODE_CHANGE );
	}
}

#endif /* D_MULTISCAN_FILES_SUPPORTED */


/*
 * Initialize master decompression control and select active modules.
 * This is performed at the start of jpeg_start_decompress.
 */

GLOBAL void
jinit_master_decompress( j_decompress_ptr cinfo ) {
	my_master_ptr master;

	master = (my_master_ptr)
				  ( *cinfo->mem->alloc_small ) ( (j_common_ptr) cinfo, JPOOL_IMAGE,
												 SIZEOF( my_decomp_master ) );
	cinfo->master = (struct jpeg_decomp_master *) master;
	master->pub.prepare_for_output_pass = prepare_for_output_pass;
	master->pub.finish_output_pass = finish_output_pass;

	master->pub.is_dummy_pass = FALSE;

	master_selection( cinfo );
}
