/*
 * jcmainct.c
 *
 * This file was part of the Independent JPEG Group's software:
 * Copyright (C) 1994-1996, Thomas G. Lane.
 * It was modified by The libjpeg-turbo Project to include only code relevant
 * to libjpeg-turbo.
 * For conditions of distribution and use, see the accompanying README.ijg
 * file.
 *
 * This file contains the main buffer controller for compression.
 * The main buffer lies between the pre-processor and the JPEG
 * compressor proper; it holds downsampled data in the JPEG colorspace.
 */

#define JPEG_INTERNALS

#include "jinclude.h"
#include "jpeglib.h"


/* Private buffer controller object */

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

	JDIMENSION cur_iMCU_row;      /* number of current iMCU row */
	JDIMENSION rowgroup_ctr;      /* counts row groups received in iMCU row */
	boolean suspended;            /* remember if we suspended output */
	J_BUF_MODE pass_mode;         /* current operating mode */

	/* If using just a strip buffer, this points to the entire set of buffers
	 * (we allocate one for each component).  In the full-image case, this
	 * points to the currently accessible strips of the virtual arrays.
	 */
	JSAMPARRAY buffer[MAX_COMPONENTS];
} my_main_controller;

typedef my_main_controller *my_main_ptr;


/* Forward declarations */
METHODDEF(void) process_data_simple_main
		(j_compress_ptr cinfo, JSAMPARRAY input_buf, JDIMENSION *in_row_ctr,
		 JDIMENSION in_rows_avail);


/*
 * Initialize for a processing pass.
 */

METHODDEF(void)
start_pass_main(j_compress_ptr cinfo, J_BUF_MODE pass_mode) {
	my_main_ptr main_ptr = (my_main_ptr) cinfo->main;

	/* Do nothing in raw-data mode. */
	if (cinfo->raw_data_in)
		return;

	if (pass_mode != JBUF_PASS_THRU)
		ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);

	main_ptr->cur_iMCU_row = 0;   /* initialize counters */
	main_ptr->rowgroup_ctr = 0;
	main_ptr->suspended = FALSE;
	main_ptr->pass_mode = pass_mode;      /* save mode for use by process_data */
	main_ptr->pub.process_data = process_data_simple_main;
}


/*
 * Process some data.
 * This routine handles the simple pass-through mode,
 * where we have only a strip buffer.
 */

METHODDEF(void)
process_data_simple_main(j_compress_ptr cinfo,
                         JSAMPARRAY input_buf, JDIMENSION *in_row_ctr,
                         JDIMENSION in_rows_avail) {
	my_main_ptr main_ptr = (my_main_ptr) cinfo->main;

	while (main_ptr->cur_iMCU_row < cinfo->total_iMCU_rows) {
		/* Read input data if we haven't filled the main buffer yet */
		if (main_ptr->rowgroup_ctr < DCTSIZE)
			(*cinfo->prep->pre_process_data)(cinfo,
			                                 input_buf, in_row_ctr, in_rows_avail,
			                                 main_ptr->buffer, &main_ptr->rowgroup_ctr,
			                                 (JDIMENSION) DCTSIZE);

		/* If we don't have a full iMCU row buffered, return to application for
		 * more data.  Note that preprocessor will always pad to fill the iMCU row
		 * at the bottom of the image.
		 */
		if (main_ptr->rowgroup_ctr != DCTSIZE)
			return;

		/* Send the completed row to the compressor */
		if (!(*cinfo->coef->compress_data)(cinfo, main_ptr->buffer)) {
			/* If compressor did not consume the whole row, then we must need to
			 * suspend processing and return to the application.  In this situation
			 * we pretend we didn't yet consume the last input row; otherwise, if
			 * it happened to be the last row of the image, the application would
			 * think we were done.
			 */
			if (!main_ptr->suspended) {
				(*in_row_ctr)--;
				main_ptr->suspended = TRUE;
			}
			return;
		}
		/* We did finish the row.  Undo our little suspension hack if a previous
		 * call suspended; then mark the main buffer empty.
		 */
		if (main_ptr->suspended) {
			(*in_row_ctr)++;
			main_ptr->suspended = FALSE;
		}
		main_ptr->rowgroup_ctr = 0;
		main_ptr->cur_iMCU_row++;
	}
}


/*
 * Initialize main buffer controller.
 */

GLOBAL(void)
jinit_c_main_controller(j_compress_ptr cinfo, boolean need_full_buffer) {
	my_main_ptr main_ptr;
	int ci;
	jpeg_component_info *compptr;

	main_ptr = (my_main_ptr)
			(*cinfo->mem->alloc_small)((j_common_ptr) cinfo, JPOOL_IMAGE,
			                           sizeof(my_main_controller));
	cinfo->main = (struct jpeg_c_main_controller *) main_ptr;
	main_ptr->pub.start_pass = start_pass_main;

	/* We don't need to create a buffer in raw-data mode. */
	if (cinfo->raw_data_in)
		return;

	/* Create the buffer.  It holds downsampled data, so each component
	 * may be of a different size.
	 */
	if (need_full_buffer) {
		ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
	} else {
		/* Allocate a strip buffer for each component */
		for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
		     ci++, compptr++) {
			main_ptr->buffer[ci] = (*cinfo->mem->alloc_sarray)
					((j_common_ptr) cinfo, JPOOL_IMAGE,
					 compptr->width_in_blocks * DCTSIZE,
					 (JDIMENSION) (compptr->v_samp_factor * DCTSIZE));
		}
	}
}
