/*
 * jdmaster.c
 *
 * This file was part of the Independent JPEG Group's software:
 * Copyright (C) 1991-1997, Thomas G. Lane.
 * Modified 2002-2009 by Guido Vollbeding.
 * libjpeg-turbo Modifications:
 * Copyright (C) 2009-2011, 2016, D. R. Commander.
 * Copyright (C) 2013, Linaro Limited.
 * Copyright (C) 2015, Google, Inc.
 * For conditions of distribution and use, see the accompanying README.ijg
 * 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"
#include "jpegcomp.h"
#include "jdmaster.h"


/*
 * 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 and YCC=>RGB565 color conversion */
	if (cinfo->jpeg_color_space != JCS_YCbCr || cinfo->num_components != 3 ||
	    (cinfo->out_color_space != JCS_RGB &&
	     cinfo->out_color_space != JCS_RGB565 &&
	     cinfo->out_color_space != JCS_EXT_RGB &&
	     cinfo->out_color_space != JCS_EXT_RGBX &&
	     cinfo->out_color_space != JCS_EXT_BGR &&
	     cinfo->out_color_space != JCS_EXT_BGRX &&
	     cinfo->out_color_space != JCS_EXT_XBGR &&
	     cinfo->out_color_space != JCS_EXT_XRGB &&
	     cinfo->out_color_space != JCS_EXT_RGBA &&
	     cinfo->out_color_space != JCS_EXT_BGRA &&
	     cinfo->out_color_space != JCS_EXT_ABGR &&
	     cinfo->out_color_space != JCS_EXT_ARGB))
		return FALSE;
	if ((cinfo->out_color_space == JCS_RGB565 &&
	     cinfo->out_color_components != 3) ||
	    (cinfo->out_color_space != JCS_RGB565 &&
	     cinfo->out_color_components != rgb_pixelsize[cinfo->out_color_space]))
		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.
 */

#if JPEG_LIB_VERSION >= 80
GLOBAL(void)
#else

LOCAL(void)
#endif
jpeg_core_output_dimensions(j_decompress_ptr cinfo)
/* Do computations that are needed before master selection phase.
 * This function is used for transcoding and full decompression.
 */
{
#ifdef IDCT_SCALING_SUPPORTED
	int ci;
	jpeg_component_info *compptr;

	/* Compute actual output image dimensions and DCT scaling choices. */
	if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom) {
		/* Provide 1/block_size scaling */
		cinfo->output_width = (JDIMENSION)
				jdiv_round_up((long) cinfo->image_width, (long) DCTSIZE);
		cinfo->output_height = (JDIMENSION)
				jdiv_round_up((long) cinfo->image_height, (long) DCTSIZE);
		cinfo->_min_DCT_h_scaled_size = 1;
		cinfo->_min_DCT_v_scaled_size = 1;
	} else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 2) {
		/* Provide 2/block_size scaling */
		cinfo->output_width = (JDIMENSION)
				jdiv_round_up((long) cinfo->image_width * 2L, (long) DCTSIZE);
		cinfo->output_height = (JDIMENSION)
				jdiv_round_up((long) cinfo->image_height * 2L, (long) DCTSIZE);
		cinfo->_min_DCT_h_scaled_size = 2;
		cinfo->_min_DCT_v_scaled_size = 2;
	} else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 3) {
		/* Provide 3/block_size scaling */
		cinfo->output_width = (JDIMENSION)
				jdiv_round_up((long) cinfo->image_width * 3L, (long) DCTSIZE);
		cinfo->output_height = (JDIMENSION)
				jdiv_round_up((long) cinfo->image_height * 3L, (long) DCTSIZE);
		cinfo->_min_DCT_h_scaled_size = 3;
		cinfo->_min_DCT_v_scaled_size = 3;
	} else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 4) {
		/* Provide 4/block_size scaling */
		cinfo->output_width = (JDIMENSION)
				jdiv_round_up((long) cinfo->image_width * 4L, (long) DCTSIZE);
		cinfo->output_height = (JDIMENSION)
				jdiv_round_up((long) cinfo->image_height * 4L, (long) DCTSIZE);
		cinfo->_min_DCT_h_scaled_size = 4;
		cinfo->_min_DCT_v_scaled_size = 4;
	} else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 5) {
		/* Provide 5/block_size scaling */
		cinfo->output_width = (JDIMENSION)
				jdiv_round_up((long) cinfo->image_width * 5L, (long) DCTSIZE);
		cinfo->output_height = (JDIMENSION)
				jdiv_round_up((long) cinfo->image_height * 5L, (long) DCTSIZE);
		cinfo->_min_DCT_h_scaled_size = 5;
		cinfo->_min_DCT_v_scaled_size = 5;
	} else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 6) {
		/* Provide 6/block_size scaling */
		cinfo->output_width = (JDIMENSION)
				jdiv_round_up((long) cinfo->image_width * 6L, (long) DCTSIZE);
		cinfo->output_height = (JDIMENSION)
				jdiv_round_up((long) cinfo->image_height * 6L, (long) DCTSIZE);
		cinfo->_min_DCT_h_scaled_size = 6;
		cinfo->_min_DCT_v_scaled_size = 6;
	} else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 7) {
		/* Provide 7/block_size scaling */
		cinfo->output_width = (JDIMENSION)
				jdiv_round_up((long) cinfo->image_width * 7L, (long) DCTSIZE);
		cinfo->output_height = (JDIMENSION)
				jdiv_round_up((long) cinfo->image_height * 7L, (long) DCTSIZE);
		cinfo->_min_DCT_h_scaled_size = 7;
		cinfo->_min_DCT_v_scaled_size = 7;
	} else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 8) {
		/* Provide 8/block_size scaling */
		cinfo->output_width = (JDIMENSION)
				jdiv_round_up((long) cinfo->image_width * 8L, (long) DCTSIZE);
		cinfo->output_height = (JDIMENSION)
				jdiv_round_up((long) cinfo->image_height * 8L, (long) DCTSIZE);
		cinfo->_min_DCT_h_scaled_size = 8;
		cinfo->_min_DCT_v_scaled_size = 8;
	} else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 9) {
		/* Provide 9/block_size scaling */
		cinfo->output_width = (JDIMENSION)
				jdiv_round_up((long) cinfo->image_width * 9L, (long) DCTSIZE);
		cinfo->output_height = (JDIMENSION)
				jdiv_round_up((long) cinfo->image_height * 9L, (long) DCTSIZE);
		cinfo->_min_DCT_h_scaled_size = 9;
		cinfo->_min_DCT_v_scaled_size = 9;
	} else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 10) {
		/* Provide 10/block_size scaling */
		cinfo->output_width = (JDIMENSION)
				jdiv_round_up((long) cinfo->image_width * 10L, (long) DCTSIZE);
		cinfo->output_height = (JDIMENSION)
				jdiv_round_up((long) cinfo->image_height * 10L, (long) DCTSIZE);
		cinfo->_min_DCT_h_scaled_size = 10;
		cinfo->_min_DCT_v_scaled_size = 10;
	} else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 11) {
		/* Provide 11/block_size scaling */
		cinfo->output_width = (JDIMENSION)
				jdiv_round_up((long) cinfo->image_width * 11L, (long) DCTSIZE);
		cinfo->output_height = (JDIMENSION)
				jdiv_round_up((long) cinfo->image_height * 11L, (long) DCTSIZE);
		cinfo->_min_DCT_h_scaled_size = 11;
		cinfo->_min_DCT_v_scaled_size = 11;
	} else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 12) {
		/* Provide 12/block_size scaling */
		cinfo->output_width = (JDIMENSION)
				jdiv_round_up((long) cinfo->image_width * 12L, (long) DCTSIZE);
		cinfo->output_height = (JDIMENSION)
				jdiv_round_up((long) cinfo->image_height * 12L, (long) DCTSIZE);
		cinfo->_min_DCT_h_scaled_size = 12;
		cinfo->_min_DCT_v_scaled_size = 12;
	} else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 13) {
		/* Provide 13/block_size scaling */
		cinfo->output_width = (JDIMENSION)
				jdiv_round_up((long) cinfo->image_width * 13L, (long) DCTSIZE);
		cinfo->output_height = (JDIMENSION)
				jdiv_round_up((long) cinfo->image_height * 13L, (long) DCTSIZE);
		cinfo->_min_DCT_h_scaled_size = 13;
		cinfo->_min_DCT_v_scaled_size = 13;
	} else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 14) {
		/* Provide 14/block_size scaling */
		cinfo->output_width = (JDIMENSION)
				jdiv_round_up((long) cinfo->image_width * 14L, (long) DCTSIZE);
		cinfo->output_height = (JDIMENSION)
				jdiv_round_up((long) cinfo->image_height * 14L, (long) DCTSIZE);
		cinfo->_min_DCT_h_scaled_size = 14;
		cinfo->_min_DCT_v_scaled_size = 14;
	} else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 15) {
		/* Provide 15/block_size scaling */
		cinfo->output_width = (JDIMENSION)
				jdiv_round_up((long) cinfo->image_width * 15L, (long) DCTSIZE);
		cinfo->output_height = (JDIMENSION)
				jdiv_round_up((long) cinfo->image_height * 15L, (long) DCTSIZE);
		cinfo->_min_DCT_h_scaled_size = 15;
		cinfo->_min_DCT_v_scaled_size = 15;
	} else {
		/* Provide 16/block_size scaling */
		cinfo->output_width = (JDIMENSION)
				jdiv_round_up((long) cinfo->image_width * 16L, (long) DCTSIZE);
		cinfo->output_height = (JDIMENSION)
				jdiv_round_up((long) cinfo->image_height * 16L, (long) DCTSIZE);
		cinfo->_min_DCT_h_scaled_size = 16;
		cinfo->_min_DCT_v_scaled_size = 16;
	}

	/* Recompute dimensions of components */
	for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
	     ci++, compptr++) {
		compptr->_DCT_h_scaled_size = cinfo->_min_DCT_h_scaled_size;
		compptr->_DCT_v_scaled_size = cinfo->_min_DCT_v_scaled_size;
	}

#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,
	 * and has computed unscaled downsampled_width and downsampled_height.
	 */

#endif /* IDCT_SCALING_SUPPORTED */
}


/*
 * 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 */
{
#ifdef IDCT_SCALING_SUPPORTED
	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);

	/* Compute core output image dimensions and DCT scaling choices. */
	jpeg_core_output_dimensions(cinfo);

#ifdef IDCT_SCALING_SUPPORTED

	/* 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 adapts subsampling ratios which 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 &&
		       ((cinfo->max_h_samp_factor * cinfo->_min_DCT_scaled_size) %
		        (compptr->h_samp_factor * ssize * 2) == 0) &&
		       ((cinfo->max_v_samp_factor * cinfo->_min_DCT_scaled_size) %
		        (compptr->v_samp_factor * ssize * 2) == 0)) {
			ssize = ssize * 2;
		}
#if JPEG_LIB_VERSION >= 70
		compptr->DCT_h_scaled_size = compptr->DCT_v_scaled_size = ssize;
#else
		compptr->DCT_scaled_size = ssize;
#endif
	}

	/* 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:
		case JCS_EXT_RGB:
		case JCS_EXT_RGBX:
		case JCS_EXT_BGR:
		case JCS_EXT_BGRX:
		case JCS_EXT_XBGR:
		case JCS_EXT_XRGB:
		case JCS_EXT_RGBA:
		case JCS_EXT_BGRA:
		case JCS_EXT_ABGR:
		case JCS_EXT_ARGB:
			cinfo->out_color_components = rgb_pixelsize[cinfo->out_color_space];
			break;
		case JCS_YCbCr:
		case JCS_RGB565:
			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.
 */

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) {
#ifdef D_ARITH_CODING_SUPPORTED
		jinit_arith_decoder(cinfo);
#else
		ERREXIT(cinfo, JERR_ARITH_NOTIMPL);
#endif
	} 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);

	/* Set the first and last iMCU columns to decompress from single-scan images.
	 * By default, decompress all of the iMCU columns.
	 */
	cinfo->master->first_iMCU_col = 0;
	cinfo->master->last_iMCU_col = cinfo->MCUs_per_row - 1;

#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, jdapistd.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 = (my_master_ptr) cinfo->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->pub.jinit_upsampler_no_alloc = FALSE;

	master_selection(cinfo);
}
