/*
 * jdcoefct.c
 *
 * Copyright (C) 1994-1995, 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 the coefficient buffer controller for decompression.
 * This controller is the top level of the JPEG decompressor proper.
 * The coefficient buffer lies between entropy decoding and inverse-DCT steps.
 *
 * In buffered-image mode, this controller is the interface between
 * input-oriented processing and output-oriented processing.
 * Also, the input side (only) is used when reading a file for transcoding.
 */

#define JPEG_INTERNALS
#include "jinclude.h"
#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.
	 * (On 80x86, the workspace is FAR even though it's not really very big;
	 * this is to keep the module interfaces unchanged when a large coefficient
	 * buffer is necessary.)
	 * 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];

#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;

/* Forward declarations */
METHODDEF int decompress_onepass
JPP( ( j_decompress_ptr cinfo, JSAMPIMAGE output_buf ) );
#ifdef D_MULTISCAN_FILES_SUPPORTED
METHODDEF int decompress_data
JPP( ( j_decompress_ptr cinfo, JSAMPIMAGE output_buf ) );
#endif
#ifdef BLOCK_SMOOTHING_SUPPORTED
LOCAL boolean smoothing_ok JPP( (j_decompress_ptr cinfo) );
METHODDEF int decompress_smooth_data
JPP( ( j_decompress_ptr cinfo, JSAMPIMAGE output_buf ) );
#endif


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;
}


/*
 * Initialize for an input processing pass.
 */

METHODDEF void
start_input_pass( j_decompress_ptr cinfo ) {
	cinfo->input_iMCU_row = 0;
	start_iMCU_row( cinfo );
}


/*
 * Initialize for an output processing pass.
 */

METHODDEF void
start_output_pass( j_decompress_ptr cinfo ) {
#ifdef BLOCK_SMOOTHING_SUPPORTED
	my_coef_ptr coef = (my_coef_ptr) cinfo->coef;

	/* If multipass, check to see whether to use block smoothing on this pass */
	if ( coef->pub.coef_arrays != NULL ) {
		if ( cinfo->do_block_smoothing && smoothing_ok( cinfo ) ) {
			coef->pub.decompress_data = decompress_smooth_data;
		} else {
			coef->pub.decompress_data = decompress_data;
		}
	}
#endif
	cinfo->output_iMCU_row = 0;
}


/*
 * Decompress and return some data in the single-pass case.
 * Always attempts to emit one fully interleaved MCU row ("iMCU" row).
 * Input and output must run in lockstep since we have only a one-MCU buffer.
 * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED.
 *
 * NB: output_buf contains a plane for each component in image.
 * For single pass, this is the same as the components in the scan.
 */

METHODDEF int
decompress_onepass( j_decompress_ptr cinfo, JSAMPIMAGE output_buf ) {
	my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
	JDIMENSION MCU_col_num; /* index of current MCU within row */
	JDIMENSION last_MCU_col = cinfo->MCUs_per_row - 1;
	JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
	int blkn, ci, xindex, yindex, yoffset, useful_width;
	JSAMPARRAY output_ptr;
	JDIMENSION start_col, output_col;
	jpeg_component_info *compptr;
	inverse_DCT_method_ptr inverse_DCT;

	/* Loop to process as much as one whole iMCU row */
	for ( yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row;
		  yoffset++ ) {
		for ( MCU_col_num = coef->MCU_ctr; MCU_col_num <= last_MCU_col;
			  MCU_col_num++ ) {
			/* Try to fetch an MCU.  Entropy decoder expects buffer to be zeroed. */
			jzero_far( (void FAR *) coef->MCU_buffer[0],
					   (size_t) ( cinfo->blocks_in_MCU * SIZEOF( JBLOCK ) ) );
			if ( !( *cinfo->entropy->decode_mcu )( cinfo, coef->MCU_buffer ) ) {
				/* Suspension forced; update state counters and exit */
				coef->MCU_vert_offset = yoffset;
				coef->MCU_ctr = MCU_col_num;
				return JPEG_SUSPENDED;
			}
			/* Determine where data should go in output_buf and do the IDCT thing.
			 * We skip dummy blocks at the right and bottom edges (but blkn gets
			 * incremented past them!).  Note the inner loop relies on having
			 * allocated the MCU_buffer[] blocks sequentially.
			 */
			blkn = 0;   /* index of current DCT block within MCU */
			for ( ci = 0; ci < cinfo->comps_in_scan; ci++ ) {
				compptr = cinfo->cur_comp_info[ci];
				/* Don't bother to IDCT an uninteresting component. */
				if ( !compptr->component_needed ) {
					blkn += compptr->MCU_blocks;
					continue;
				}
				inverse_DCT = cinfo->idct->inverse_DCT[compptr->component_index];
				useful_width = ( MCU_col_num < last_MCU_col ) ? compptr->MCU_width
							   : compptr->last_col_width;
				output_ptr = output_buf[ci] + yoffset * compptr->DCT_scaled_size;
				start_col = MCU_col_num * compptr->MCU_sample_width;
				for ( yindex = 0; yindex < compptr->MCU_height; yindex++ ) {
					if ( cinfo->input_iMCU_row < last_iMCU_row ||
						 yoffset + yindex < compptr->last_row_height ) {
						output_col = start_col;
						for ( xindex = 0; xindex < useful_width; xindex++ ) {
							( *inverse_DCT )( cinfo, compptr,
											  (JCOEFPTR) coef->MCU_buffer[blkn + xindex],
											  output_ptr, output_col );
							output_col += compptr->DCT_scaled_size;
						}
					}
					blkn += compptr->MCU_width;
					output_ptr += compptr->DCT_scaled_size;
				}
			}
		}
		/* Completed an MCU row, but perhaps not an iMCU row */
		coef->MCU_ctr = 0;
	}
	/* Completed the iMCU row, advance counters for next one */
	cinfo->output_iMCU_row++;
	if ( ++( cinfo->input_iMCU_row ) < cinfo->total_iMCU_rows ) {
		start_iMCU_row( cinfo );
		return JPEG_ROW_COMPLETED;
	}
	/* Completed the scan */
	( *cinfo->inputctl->finish_input_pass )( cinfo );
	return JPEG_SCAN_COMPLETED;
}


/*
 * Dummy consume-input routine for single-pass operation.
 */

METHODDEF int
dummy_consume_data( j_decompress_ptr cinfo ) {
	return JPEG_SUSPENDED;  /* Always indicate nothing was done */
}


#ifdef D_MULTISCAN_FILES_SUPPORTED

/*
 * Consume input data and store it in the full-image coefficient buffer.
 * We read as much as one fully interleaved MCU row ("iMCU" row) per call,
 * ie, v_samp_factor block rows for each component in the scan.
 * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED.
 */

METHODDEF int
consume_data( j_decompress_ptr cinfo ) {
	my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
	JDIMENSION MCU_col_num; /* index of current MCU within row */
	int blkn, ci, xindex, yindex, yoffset;
	JDIMENSION start_col;
	JBLOCKARRAY buffer[MAX_COMPS_IN_SCAN];
	JBLOCKROW buffer_ptr;
	jpeg_component_info *compptr;

	/* Align the virtual buffers for the components used in this scan. */
	for ( ci = 0; ci < cinfo->comps_in_scan; ci++ ) {
		compptr = cinfo->cur_comp_info[ci];
		buffer[ci] = ( *cinfo->mem->access_virt_barray )
				  ( (j_common_ptr) cinfo, coef->whole_image[compptr->component_index],
				  cinfo->input_iMCU_row * compptr->v_samp_factor,
				  (JDIMENSION) compptr->v_samp_factor, TRUE );
		/* Note: entropy decoder expects buffer to be zeroed,
		 * but this is handled automatically by the memory manager
		 * because we requested a pre-zeroed array.
		 */
	}

	/* Loop to process one whole iMCU row */
	for ( yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row;
		  yoffset++ ) {
		for ( MCU_col_num = coef->MCU_ctr; MCU_col_num < cinfo->MCUs_per_row;
			  MCU_col_num++ ) {
			/* Construct list of pointers to DCT blocks belonging to this MCU */
			blkn = 0;   /* index of current DCT block within MCU */
			for ( ci = 0; ci < cinfo->comps_in_scan; ci++ ) {
				compptr = cinfo->cur_comp_info[ci];
				start_col = MCU_col_num * compptr->MCU_width;
				for ( yindex = 0; yindex < compptr->MCU_height; yindex++ ) {
					buffer_ptr = buffer[ci][yindex + yoffset] + start_col;
					for ( xindex = 0; xindex < compptr->MCU_width; xindex++ ) {
						coef->MCU_buffer[blkn++] = buffer_ptr++;
					}
				}
			}
			/* Try to fetch the MCU. */
			if ( !( *cinfo->entropy->decode_mcu )( cinfo, coef->MCU_buffer ) ) {
				/* Suspension forced; update state counters and exit */
				coef->MCU_vert_offset = yoffset;
				coef->MCU_ctr = MCU_col_num;
				return JPEG_SUSPENDED;
			}
		}
		/* Completed an MCU row, but perhaps not an iMCU row */
		coef->MCU_ctr = 0;
	}
	/* Completed the iMCU row, advance counters for next one */
	if ( ++( cinfo->input_iMCU_row ) < cinfo->total_iMCU_rows ) {
		start_iMCU_row( cinfo );
		return JPEG_ROW_COMPLETED;
	}
	/* Completed the scan */
	( *cinfo->inputctl->finish_input_pass )( cinfo );
	return JPEG_SCAN_COMPLETED;
}


/*
 * Decompress and return some data in the multi-pass case.
 * Always attempts to emit one fully interleaved MCU row ("iMCU" row).
 * Return value is JPEG_ROW_COMPLETED, JPEG_SCAN_COMPLETED, or JPEG_SUSPENDED.
 *
 * NB: output_buf contains a plane for each component in image.
 */

METHODDEF int
decompress_data( j_decompress_ptr cinfo, JSAMPIMAGE output_buf ) {
	my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
	JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
	JDIMENSION block_num;
	int ci, block_row, block_rows;
	JBLOCKARRAY buffer;
	JBLOCKROW buffer_ptr;
	JSAMPARRAY output_ptr;
	JDIMENSION output_col;
	jpeg_component_info *compptr;
	inverse_DCT_method_ptr inverse_DCT;

	/* Force some input to be done if we are getting ahead of the input. */
	while ( cinfo->input_scan_number < cinfo->output_scan_number ||
			( cinfo->input_scan_number == cinfo->output_scan_number &&
			  cinfo->input_iMCU_row <= cinfo->output_iMCU_row ) ) {
		if ( ( *cinfo->inputctl->consume_input )( cinfo ) == JPEG_SUSPENDED ) {
			return JPEG_SUSPENDED;
		}
	}

	/* OK, output from the virtual arrays. */
	for ( ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
		  ci++, compptr++ ) {
		/* Don't bother to IDCT an uninteresting component. */
		if ( !compptr->component_needed ) {
			continue;
		}
		/* Align the virtual buffer for this component. */
		buffer = ( *cinfo->mem->access_virt_barray )
				  ( (j_common_ptr) cinfo, coef->whole_image[ci],
				  cinfo->output_iMCU_row * compptr->v_samp_factor,
				  (JDIMENSION) compptr->v_samp_factor, FALSE );
		/* Count non-dummy DCT block rows in this iMCU row. */
		if ( cinfo->output_iMCU_row < last_iMCU_row ) {
			block_rows = compptr->v_samp_factor;
		} else {
			/* NB: can't use last_row_height here; it is input-side-dependent! */
			block_rows = (int) ( compptr->height_in_blocks % compptr->v_samp_factor );
			if ( block_rows == 0 ) {
				block_rows = compptr->v_samp_factor;
			}
		}
		inverse_DCT = cinfo->idct->inverse_DCT[ci];
		output_ptr = output_buf[ci];
		/* Loop over all DCT blocks to be processed. */
		for ( block_row = 0; block_row < block_rows; block_row++ ) {
			buffer_ptr = buffer[block_row];
			output_col = 0;
			for ( block_num = 0; block_num < compptr->width_in_blocks; block_num++ ) {
				( *inverse_DCT )( cinfo, compptr, (JCOEFPTR) buffer_ptr,
								  output_ptr, output_col );
				buffer_ptr++;
				output_col += compptr->DCT_scaled_size;
			}
			output_ptr += compptr->DCT_scaled_size;
		}
	}

	if ( ++( cinfo->output_iMCU_row ) < cinfo->total_iMCU_rows ) {
		return JPEG_ROW_COMPLETED;
	}
	return JPEG_SCAN_COMPLETED;
}

#endif /* D_MULTISCAN_FILES_SUPPORTED */


#ifdef BLOCK_SMOOTHING_SUPPORTED

/*
 * This code applies interblock smoothing as described by section K.8
 * of the JPEG standard: the first 5 AC coefficients are estimated from
 * the DC values of a DCT block and its 8 neighboring blocks.
 * We apply smoothing only for progressive JPEG decoding, and only if
 * the coefficients it can estimate are not yet known to full precision.
 */

/*
 * Determine whether block smoothing is applicable and safe.
 * We also latch the current states of the coef_bits[] entries for the
 * AC coefficients; otherwise, if the input side of the decompressor
 * advances into a new scan, we might think the coefficients are known
 * more accurately than they really are.
 */

LOCAL boolean
smoothing_ok( j_decompress_ptr cinfo ) {
	my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
	boolean smoothing_useful = FALSE;
	int ci, coefi;
	jpeg_component_info *compptr;
	JQUANT_TBL * qtable;
	int * coef_bits;
	int * coef_bits_latch;

	if ( !cinfo->progressive_mode || cinfo->coef_bits == NULL ) {
		return FALSE;
	}

	/* Allocate latch area if not already done */
	if ( coef->coef_bits_latch == NULL ) {
		coef->coef_bits_latch = ( int * )
								( *cinfo->mem->alloc_small )( (j_common_ptr) cinfo, JPOOL_IMAGE,
															  cinfo->num_components *
															  ( SAVED_COEFS * SIZEOF( int ) ) );
	}
	coef_bits_latch = coef->coef_bits_latch;

	for ( ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
		  ci++, compptr++ ) {
		/* All components' quantization values must already be latched. */
		if ( ( qtable = compptr->quant_table ) == NULL ) {
			return FALSE;
		}
		/* Verify DC & first 5 AC quantizers are nonzero to avoid zero-divide. */
		for ( coefi = 0; coefi <= 5; coefi++ ) {
			if ( qtable->quantval[coefi] == 0 ) {
				return FALSE;
			}
		}
		/* DC values must be at least partly known for all components. */
		coef_bits = cinfo->coef_bits[ci];
		if ( coef_bits[0] < 0 ) {
			return FALSE;
		}
		/* Block smoothing is helpful if some AC coefficients remain inaccurate. */
		for ( coefi = 1; coefi <= 5; coefi++ ) {
			coef_bits_latch[coefi] = coef_bits[coefi];
			if ( coef_bits[coefi] != 0 ) {
				smoothing_useful = TRUE;
			}
		}
		coef_bits_latch += SAVED_COEFS;
	}

	return smoothing_useful;
}


/*
 * Variant of decompress_data for use when doing block smoothing.
 */

METHODDEF int
decompress_smooth_data( j_decompress_ptr cinfo, JSAMPIMAGE output_buf ) {
	my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
	JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
	JDIMENSION block_num, last_block_column;
	int ci, block_row, block_rows, access_rows;
	JBLOCKARRAY buffer;
	JBLOCKROW buffer_ptr, prev_block_row, next_block_row;
	JSAMPARRAY output_ptr;
	JDIMENSION output_col;
	jpeg_component_info *compptr;
	inverse_DCT_method_ptr inverse_DCT;
	boolean first_row, last_row;
	JBLOCK workspace;
	int *coef_bits;
	JQUANT_TBL *quanttbl;
	INT32 Q00,Q01,Q02,Q10,Q11,Q20, num;
	int DC1,DC2,DC3,DC4,DC5,DC6,DC7,DC8,DC9;
	int Al, pred;

	/* Force some input to be done if we are getting ahead of the input. */
	while ( cinfo->input_scan_number <= cinfo->output_scan_number &&
			!cinfo->inputctl->eoi_reached ) {
		if ( cinfo->input_scan_number == cinfo->output_scan_number ) {
			/* If input is working on current scan, we ordinarily want it to
			 * have completed the current row.  But if input scan is DC,
			 * we want it to keep one row ahead so that next block row's DC
			 * values are up to date.
			 */
			JDIMENSION delta = ( cinfo->Ss == 0 ) ? 1 : 0;
			if ( cinfo->input_iMCU_row > cinfo->output_iMCU_row + delta ) {
				break;
			}
		}
		if ( ( *cinfo->inputctl->consume_input )( cinfo ) == JPEG_SUSPENDED ) {
			return JPEG_SUSPENDED;
		}
	}

	/* OK, output from the virtual arrays. */
	for ( ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
		  ci++, compptr++ ) {
		/* Don't bother to IDCT an uninteresting component. */
		if ( !compptr->component_needed ) {
			continue;
		}
		/* Count non-dummy DCT block rows in this iMCU row. */
		if ( cinfo->output_iMCU_row < last_iMCU_row ) {
			block_rows = compptr->v_samp_factor;
			access_rows = block_rows * 2; /* this and next iMCU row */
			last_row = FALSE;
		} else {
			/* NB: can't use last_row_height here; it is input-side-dependent! */
			block_rows = (int) ( compptr->height_in_blocks % compptr->v_samp_factor );
			if ( block_rows == 0 ) {
				block_rows = compptr->v_samp_factor;
			}
			access_rows = block_rows; /* this iMCU row only */
			last_row = TRUE;
		}
		/* Align the virtual buffer for this component. */
		if ( cinfo->output_iMCU_row > 0 ) {
			access_rows += compptr->v_samp_factor; /* prior iMCU row too */
			buffer = ( *cinfo->mem->access_virt_barray )
				( (j_common_ptr) cinfo, coef->whole_image[ci],
				( cinfo->output_iMCU_row - 1 ) * compptr->v_samp_factor,
				(JDIMENSION) access_rows, FALSE );
			buffer += compptr->v_samp_factor; /* point to current iMCU row */
			first_row = FALSE;
		} else {
			buffer = ( *cinfo->mem->access_virt_barray )
				( (j_common_ptr) cinfo, coef->whole_image[ci],
				(JDIMENSION) 0, (JDIMENSION) access_rows, FALSE );
			first_row = TRUE;
		}
		/* Fetch component-dependent info */
		coef_bits = coef->coef_bits_latch + ( ci * SAVED_COEFS );
		quanttbl = compptr->quant_table;
		Q00 = quanttbl->quantval[0];
		Q01 = quanttbl->quantval[1];
		Q10 = quanttbl->quantval[2];
		Q20 = quanttbl->quantval[3];
		Q11 = quanttbl->quantval[4];
		Q02 = quanttbl->quantval[5];
		inverse_DCT = cinfo->idct->inverse_DCT[ci];
		output_ptr = output_buf[ci];
		/* Loop over all DCT blocks to be processed. */
		for ( block_row = 0; block_row < block_rows; block_row++ ) {
			buffer_ptr = buffer[block_row];
			if ( first_row && block_row == 0 ) {
				prev_block_row = buffer_ptr;
			} else {
				prev_block_row = buffer[block_row - 1];
			}
			if ( last_row && block_row == block_rows - 1 ) {
				next_block_row = buffer_ptr;
			} else {
				next_block_row = buffer[block_row + 1];
			}
			/* We fetch the surrounding DC values using a sliding-register approach.
			 * Initialize all nine here so as to do the right thing on narrow pics.
			 */
			DC1 = DC2 = DC3 = (int) prev_block_row[0][0];
			DC4 = DC5 = DC6 = (int) buffer_ptr[0][0];
			DC7 = DC8 = DC9 = (int) next_block_row[0][0];
			output_col = 0;
			last_block_column = compptr->width_in_blocks - 1;
			for ( block_num = 0; block_num <= last_block_column; block_num++ ) {
				/* Fetch current DCT block into workspace so we can modify it. */
				jcopy_block_row( buffer_ptr, (JBLOCKROW) workspace, (JDIMENSION) 1 );
				/* Update DC values */
				if ( block_num < last_block_column ) {
					DC3 = (int) prev_block_row[1][0];
					DC6 = (int) buffer_ptr[1][0];
					DC9 = (int) next_block_row[1][0];
				}
				/* Compute coefficient estimates per K.8.
				 * An estimate is applied only if coefficient is still zero,
				 * and is not known to be fully accurate.
				 */
				/* AC01 */
				if ( ( Al = coef_bits[1] ) != 0 && workspace[1] == 0 ) {
					num = 36 * Q00 * ( DC4 - DC6 );
					if ( num >= 0 ) {
						pred = (int) ( ( ( Q01 << 7 ) + num ) / ( Q01 << 8 ) );
						if ( Al > 0 && pred >= ( 1 << Al ) ) {
							pred = ( 1 << Al ) - 1;
						}
					} else {
						pred = (int) ( ( ( Q01 << 7 ) - num ) / ( Q01 << 8 ) );
						if ( Al > 0 && pred >= ( 1 << Al ) ) {
							pred = ( 1 << Al ) - 1;
						}
						pred = -pred;
					}
					workspace[1] = (JCOEF) pred;
				}
				/* AC10 */
				if ( ( Al = coef_bits[2] ) != 0 && workspace[8] == 0 ) {
					num = 36 * Q00 * ( DC2 - DC8 );
					if ( num >= 0 ) {
						pred = (int) ( ( ( Q10 << 7 ) + num ) / ( Q10 << 8 ) );
						if ( Al > 0 && pred >= ( 1 << Al ) ) {
							pred = ( 1 << Al ) - 1;
						}
					} else {
						pred = (int) ( ( ( Q10 << 7 ) - num ) / ( Q10 << 8 ) );
						if ( Al > 0 && pred >= ( 1 << Al ) ) {
							pred = ( 1 << Al ) - 1;
						}
						pred = -pred;
					}
					workspace[8] = (JCOEF) pred;
				}
				/* AC20 */
				if ( ( Al = coef_bits[3] ) != 0 && workspace[16] == 0 ) {
					num = 9 * Q00 * ( DC2 + DC8 - 2 * DC5 );
					if ( num >= 0 ) {
						pred = (int) ( ( ( Q20 << 7 ) + num ) / ( Q20 << 8 ) );
						if ( Al > 0 && pred >= ( 1 << Al ) ) {
							pred = ( 1 << Al ) - 1;
						}
					} else {
						pred = (int) ( ( ( Q20 << 7 ) - num ) / ( Q20 << 8 ) );
						if ( Al > 0 && pred >= ( 1 << Al ) ) {
							pred = ( 1 << Al ) - 1;
						}
						pred = -pred;
					}
					workspace[16] = (JCOEF) pred;
				}
				/* AC11 */
				if ( ( Al = coef_bits[4] ) != 0 && workspace[9] == 0 ) {
					num = 5 * Q00 * ( DC1 - DC3 - DC7 + DC9 );
					if ( num >= 0 ) {
						pred = (int) ( ( ( Q11 << 7 ) + num ) / ( Q11 << 8 ) );
						if ( Al > 0 && pred >= ( 1 << Al ) ) {
							pred = ( 1 << Al ) - 1;
						}
					} else {
						pred = (int) ( ( ( Q11 << 7 ) - num ) / ( Q11 << 8 ) );
						if ( Al > 0 && pred >= ( 1 << Al ) ) {
							pred = ( 1 << Al ) - 1;
						}
						pred = -pred;
					}
					workspace[9] = (JCOEF) pred;
				}
				/* AC02 */
				if ( ( Al = coef_bits[5] ) != 0 && workspace[2] == 0 ) {
					num = 9 * Q00 * ( DC4 + DC6 - 2 * DC5 );
					if ( num >= 0 ) {
						pred = (int) ( ( ( Q02 << 7 ) + num ) / ( Q02 << 8 ) );
						if ( Al > 0 && pred >= ( 1 << Al ) ) {
							pred = ( 1 << Al ) - 1;
						}
					} else {
						pred = (int) ( ( ( Q02 << 7 ) - num ) / ( Q02 << 8 ) );
						if ( Al > 0 && pred >= ( 1 << Al ) ) {
							pred = ( 1 << Al ) - 1;
						}
						pred = -pred;
					}
					workspace[2] = (JCOEF) pred;
				}
				/* OK, do the IDCT */
				( *inverse_DCT )( cinfo, compptr, (JCOEFPTR) workspace,
								  output_ptr, output_col );
				/* Advance for next column */
				DC1 = DC2; DC2 = DC3;
				DC4 = DC5; DC5 = DC6;
				DC7 = DC8; DC8 = DC9;
				buffer_ptr++, prev_block_row++, next_block_row++;
				output_col += compptr->DCT_scaled_size;
			}
			output_ptr += compptr->DCT_scaled_size;
		}
	}

	if ( ++( cinfo->output_iMCU_row ) < cinfo->total_iMCU_rows ) {
		return JPEG_ROW_COMPLETED;
	}
	return JPEG_SCAN_COMPLETED;
}

#endif /* BLOCK_SMOOTHING_SUPPORTED */


/*
 * Initialize coefficient buffer controller.
 */

GLOBAL void
jinit_d_coef_controller( j_decompress_ptr cinfo, boolean need_full_buffer ) {
	my_coef_ptr coef;

	coef = (my_coef_ptr)
				( *cinfo->mem->alloc_small ) ( (j_common_ptr) cinfo, JPOOL_IMAGE,
											   SIZEOF( my_coef_controller ) );
	cinfo->coef = (struct jpeg_d_coef_controller *) coef;
	coef->pub.start_input_pass = start_input_pass;
	coef->pub.start_output_pass = start_output_pass;
#ifdef BLOCK_SMOOTHING_SUPPORTED
	coef->coef_bits_latch = NULL;
#endif

	/* Create the coefficient buffer. */
	if ( need_full_buffer ) {
#ifdef D_MULTISCAN_FILES_SUPPORTED
		/* Allocate a full-image virtual array for each component, */
		/* padded to a multiple of samp_factor DCT blocks in each direction. */
		/* Note we ask for a pre-zeroed array. */
		int ci, access_rows;
		jpeg_component_info *compptr;

		for ( ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
			  ci++, compptr++ ) {
			access_rows = compptr->v_samp_factor;
#ifdef BLOCK_SMOOTHING_SUPPORTED
			/* If block smoothing could be used, need a bigger window */
			if ( cinfo->progressive_mode ) {
				access_rows *= 3;
			}
#endif
			coef->whole_image[ci] = ( *cinfo->mem->request_virt_barray )
				( (j_common_ptr) cinfo, JPOOL_IMAGE, TRUE,
				(JDIMENSION) jround_up( (long) compptr->width_in_blocks,
										(long) compptr->h_samp_factor ),
				(JDIMENSION) jround_up( (long) compptr->height_in_blocks,
										(long) compptr->v_samp_factor ),
				(JDIMENSION) access_rows );
		}
		coef->pub.consume_data = consume_data;
		coef->pub.decompress_data = decompress_data;
		coef->pub.coef_arrays = coef->whole_image; /* link to virtual arrays */
#else
		ERREXIT( cinfo, JERR_NOT_COMPILED );
#endif
	} else {
		/* We only need a single-MCU buffer. */
		JBLOCKROW buffer;
		int i;

		buffer = (JBLOCKROW)
				  ( *cinfo->mem->alloc_large ) ( (j_common_ptr) cinfo, JPOOL_IMAGE,
												 D_MAX_BLOCKS_IN_MCU * SIZEOF( JBLOCK ) );
		for ( i = 0; i < D_MAX_BLOCKS_IN_MCU; i++ ) {
			coef->MCU_buffer[i] = buffer + i;
		}
		coef->pub.consume_data = dummy_consume_data;
		coef->pub.decompress_data = decompress_onepass;
		coef->pub.coef_arrays = NULL; /* flag for no virtual arrays */
	}
}
