/*
 * jdapimin.c
 *
 * This file was part of the Independent JPEG Group's software:
 * Copyright (C) 1994-1998, Thomas G. Lane.
 * libjpeg-turbo Modifications:
 * Copyright (C) 2016, D. R. Commander.
 * For conditions of distribution and use, see the accompanying README.ijg
 * 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"
#include "jdmaster.h"


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

GLOBAL(void)
jpeg_CreateDecompress(j_decompress_ptr cinfo, int version, size_t structsize) {
	int i;

	/* Guard against version mismatches between library and caller. */
	cinfo->mem = NULL;            /* so jpeg_destroy knows mem mgr not called */
	if (version != JPEG_LIB_VERSION)
		ERREXIT2(cinfo, JERR_BAD_LIB_VERSION, JPEG_LIB_VERSION, version);
	if (structsize != sizeof(struct jpeg_decompress_struct))
		ERREXIT2(cinfo, JERR_BAD_STRUCT_SIZE,
		         (int) sizeof(struct jpeg_decompress_struct), (int) structsize);

	/* For debugging purposes, we zero the whole master structure.
	 * But the application has already set the err pointer, and may have set
	 * client_data, so we have to save and restore those fields.
	 * Note: if application hasn't set client_data, tools like Purify may
	 * complain here.
	 */
	{
		struct jpeg_error_mgr *err = cinfo->err;
		void *client_data = cinfo->client_data; /* ignore Purify complaint here */
		MEMZERO(cinfo, sizeof(struct jpeg_decompress_struct));
		cinfo->err = err;
		cinfo->client_data = client_data;
	}
	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.
	 */
	cinfo->marker_list = NULL;
	jinit_marker_reader(cinfo);

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

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

	/* The master struct is used to store extension parameters, so we allocate it
	 * here.
	 */
	cinfo->master = (struct jpeg_decomp_master *)
			(*cinfo->mem->alloc_small)((j_common_ptr) cinfo, JPOOL_PERMANENT,
			                           sizeof(my_decomp_master));
	MEMZERO(cinfo->master, sizeof(my_decomp_master));
}


/*
 * 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 */
}


/*
 * 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;
}
