/*
 * jdcoefct.h
 *
 * This file was part of the Independent JPEG Group's software:
 * Copyright (C) 1994-1997, Thomas G. Lane.
 * libjpeg-turbo Modifications:
 * Copyright 2009 Pierre Ossman <ossman@cendio.se> for Cendio AB
 * For conditions of distribution and use, see the accompanying README.ijg
 * file.
 */

#define JPEG_INTERNALS

#include "jpeglib.h"


/* Block smoothing is only applicable for progressive JPEG, so: */
#ifndef D_PROGRESSIVE_SUPPORTED
#undef BLOCK_SMOOTHING_SUPPORTED
#endif


/* Private buffer controller object */

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

	/* These variables keep track of the current location of the input side. */
	/* cinfo->input_iMCU_row is also used for this. */
	JDIMENSION MCU_ctr;           /* counts MCUs processed in current row */
	int MCU_vert_offset;          /* counts MCU rows within iMCU row */
	int MCU_rows_per_iMCU_row;    /* number of such rows needed */

	/* The output side's location is represented by cinfo->output_iMCU_row. */

	/* In single-pass modes, it's sufficient to buffer just one MCU.
	 * We allocate a workspace of D_MAX_BLOCKS_IN_MCU coefficient blocks,
	 * and let the entropy decoder write into that workspace each time.
	 * In multi-pass modes, this array points to the current MCU's blocks
	 * within the virtual arrays; it is used only by the input side.
	 */
	JBLOCKROW MCU_buffer[D_MAX_BLOCKS_IN_MCU];

	/* Temporary workspace for one MCU */
	JCOEF *workspace;

#ifdef D_MULTISCAN_FILES_SUPPORTED
	/* In multi-pass modes, we need a virtual block array for each component. */
	jvirt_barray_ptr whole_image[MAX_COMPONENTS];
#endif

#ifdef BLOCK_SMOOTHING_SUPPORTED
	/* When doing block smoothing, we latch coefficient Al values here */
	int *coef_bits_latch;
#define SAVED_COEFS  6          /* we save coef_bits[0..5] */
#endif
} my_coef_controller;

typedef my_coef_controller *my_coef_ptr;


LOCAL(void)
start_iMCU_row(j_decompress_ptr cinfo)
/* Reset within-iMCU-row counters for a new row (input side) */
{
	my_coef_ptr coef = (my_coef_ptr) cinfo->coef;

	/* In an interleaved scan, an MCU row is the same as an iMCU row.
	 * In a noninterleaved scan, an iMCU row has v_samp_factor MCU rows.
	 * But at the bottom of the image, process only what's left.
	 */
	if (cinfo->comps_in_scan > 1) {
		coef->MCU_rows_per_iMCU_row = 1;
	} else {
		if (cinfo->input_iMCU_row < (cinfo->total_iMCU_rows - 1))
			coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->v_samp_factor;
		else
			coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->last_row_height;
	}

	coef->MCU_ctr = 0;
	coef->MCU_vert_offset = 0;
}
