/*
 * jccoefct.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 compression.
 * This controller is the top level of the JPEG compressor proper.
 * The coefficient buffer lies between forward-DCT and entropy encoding steps.
 */

#define JPEG_INTERNALS
#include "jinclude.h"
#include "jpeglib.h"


/* We use a full-image coefficient buffer when doing Huffman optimization,
 * and also for writing multiple-scan JPEG files.  In all cases, the DCT
 * step is run during the first pass, and subsequent passes need only read
 * the buffered coefficients.
 */
#ifdef ENTROPY_OPT_SUPPORTED
#define FULL_COEF_BUFFER_SUPPORTED
#else
#ifdef C_MULTISCAN_FILES_SUPPORTED
#define FULL_COEF_BUFFER_SUPPORTED
#endif
#endif


/* Private buffer controller object */

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

	JDIMENSION iMCU_row_num; /* iMCU row # within image */
	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 */

	/* For single-pass compression, it's sufficient to buffer just one MCU
	 * (although this may prove a bit slow in practice).  We allocate a
	 * workspace of C_MAX_BLOCKS_IN_MCU coefficient blocks, and reuse it for each
	 * MCU constructed and sent.  (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.
	 */
	JBLOCKROW MCU_buffer[C_MAX_BLOCKS_IN_MCU];

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

typedef my_coef_controller * my_coef_ptr;


/* Forward declarations */
METHODDEF boolean compress_data
JPP( ( j_compress_ptr cinfo, JSAMPIMAGE input_buf ) );
#ifdef FULL_COEF_BUFFER_SUPPORTED
METHODDEF boolean compress_first_pass
JPP( ( j_compress_ptr cinfo, JSAMPIMAGE input_buf ) );
METHODDEF boolean compress_output
JPP( ( j_compress_ptr cinfo, JSAMPIMAGE input_buf ) );
#endif


LOCAL void
start_iMCU_row( j_compress_ptr cinfo ) {
/* Reset within-iMCU-row counters for a new row */
	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 ( coef->iMCU_row_num < ( 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 a processing pass.
 */

METHODDEF void
start_pass_coef( j_compress_ptr cinfo, J_BUF_MODE pass_mode ) {
	my_coef_ptr coef = (my_coef_ptr) cinfo->coef;

	coef->iMCU_row_num = 0;
	start_iMCU_row( cinfo );

	switch ( pass_mode ) {
	case JBUF_PASS_THRU:
		if ( coef->whole_image[0] != NULL ) {
			ERREXIT( cinfo, JERR_BAD_BUFFER_MODE );
		}
		coef->pub.compress_data = compress_data;
		break;
#ifdef FULL_COEF_BUFFER_SUPPORTED
	case JBUF_SAVE_AND_PASS:
		if ( coef->whole_image[0] == NULL ) {
			ERREXIT( cinfo, JERR_BAD_BUFFER_MODE );
		}
		coef->pub.compress_data = compress_first_pass;
		break;
	case JBUF_CRANK_DEST:
		if ( coef->whole_image[0] == NULL ) {
			ERREXIT( cinfo, JERR_BAD_BUFFER_MODE );
		}
		coef->pub.compress_data = compress_output;
		break;
#endif
	default:
		ERREXIT( cinfo, JERR_BAD_BUFFER_MODE );
		break;
	}
}


/*
 * Process some data in the single-pass case.
 * We process the equivalent of one fully interleaved MCU row ("iMCU" row)
 * per call, ie, v_samp_factor block rows for each component in the image.
 * Returns TRUE if the iMCU row is completed, FALSE if suspended.
 *
 * NB: input_buf contains a plane for each component in image.
 * For single pass, this is the same as the components in the scan.
 */

METHODDEF boolean
compress_data( j_compress_ptr cinfo, JSAMPIMAGE input_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, bi, ci, yindex, yoffset, blockcnt;
	JDIMENSION ypos, xpos;
	jpeg_component_info *compptr;

	/* Loop to write 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++ ) {
			/* Determine where data comes from in input_buf and do the DCT thing.
			 * Each call on forward_DCT processes a horizontal row of DCT blocks
			 * as wide as an MCU; we rely on having allocated the MCU_buffer[] blocks
			 * sequentially.  Dummy blocks at the right or bottom edge are filled in
			 * specially.  The data in them does not matter for image reconstruction,
			 * so we fill them with values that will encode to the smallest amount of
			 * data, viz: all zeroes in the AC entries, DC entries equal to previous
			 * block's DC value.  (Thanks to Thomas Kinsman for this idea.)
			 */
			blkn = 0;
			for ( ci = 0; ci < cinfo->comps_in_scan; ci++ ) {
				compptr = cinfo->cur_comp_info[ci];
				blockcnt = ( MCU_col_num < last_MCU_col ) ? compptr->MCU_width
						   : compptr->last_col_width;
				xpos = MCU_col_num * compptr->MCU_sample_width;
				ypos = yoffset * DCTSIZE; /* ypos == (yoffset+yindex) * DCTSIZE */
				for ( yindex = 0; yindex < compptr->MCU_height; yindex++ ) {
					if ( coef->iMCU_row_num < last_iMCU_row ||
						 yoffset + yindex < compptr->last_row_height ) {
						( *cinfo->fdct->forward_DCT )( cinfo, compptr,
													   input_buf[ci], coef->MCU_buffer[blkn],
													   ypos, xpos, (JDIMENSION) blockcnt );
						if ( blockcnt < compptr->MCU_width ) {
							/* Create some dummy blocks at the right edge of the image. */
							jzero_far( (void FAR *) coef->MCU_buffer[blkn + blockcnt],
									   ( compptr->MCU_width - blockcnt ) * SIZEOF( JBLOCK ) );
							for ( bi = blockcnt; bi < compptr->MCU_width; bi++ ) {
								coef->MCU_buffer[blkn + bi][0][0] = coef->MCU_buffer[blkn + bi - 1][0][0];
							}
						}
					} else {
						/* Create a row of dummy blocks at the bottom of the image. */
						jzero_far( (void FAR *) coef->MCU_buffer[blkn],
								   compptr->MCU_width * SIZEOF( JBLOCK ) );
						for ( bi = 0; bi < compptr->MCU_width; bi++ ) {
							coef->MCU_buffer[blkn + bi][0][0] = coef->MCU_buffer[blkn - 1][0][0];
						}
					}
					blkn += compptr->MCU_width;
					ypos += DCTSIZE;
				}
			}
			/* Try to write the MCU.  In event of a suspension failure, we will
			 * re-DCT the MCU on restart (a bit inefficient, could be fixed...)
			 */
			if ( !( *cinfo->entropy->encode_mcu )( cinfo, coef->MCU_buffer ) ) {
				/* Suspension forced; update state counters and exit */
				coef->MCU_vert_offset = yoffset;
				coef->mcu_ctr = MCU_col_num;
				return FALSE;
			}
		}
		/* Completed an MCU row, but perhaps not an iMCU row */
		coef->mcu_ctr = 0;
	}
	/* Completed the iMCU row, advance counters for next one */
	coef->iMCU_row_num++;
	start_iMCU_row( cinfo );
	return TRUE;
}


#ifdef FULL_COEF_BUFFER_SUPPORTED

/*
 * Process some data in the first pass of a multi-pass case.
 * We process the equivalent of one fully interleaved MCU row ("iMCU" row)
 * per call, ie, v_samp_factor block rows for each component in the image.
 * This amount of data is read from the source buffer, DCT'd and quantized,
 * and saved into the virtual arrays.  We also generate suitable dummy blocks
 * as needed at the right and lower edges.  (The dummy blocks are constructed
 * in the virtual arrays, which have been padded appropriately.)  This makes
 * it possible for subsequent passes not to worry about real vs. dummy blocks.
 *
 * We must also emit the data to the entropy encoder.  This is conveniently
 * done by calling compress_output() after we've loaded the current strip
 * of the virtual arrays.
 *
 * NB: input_buf contains a plane for each component in image.  All
 * components are DCT'd and loaded into the virtual arrays in this pass.
 * However, it may be that only a subset of the components are emitted to
 * the entropy encoder during this first pass; be careful about looking
 * at the scan-dependent variables (MCU dimensions, etc).
 */

METHODDEF boolean
compress_first_pass( j_compress_ptr cinfo, JSAMPIMAGE input_buf ) {
	my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
	JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
	JDIMENSION blocks_across, MCUs_across, MCUindex;
	int bi, ci, h_samp_factor, block_row, block_rows, ndummy;
	JCOEF lastDC;
	jpeg_component_info *compptr;
	JBLOCKARRAY buffer;
	JBLOCKROW thisblockrow, lastblockrow;

	for ( ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
		  ci++, compptr++ ) {
		/* Align the virtual buffer for this component. */
		buffer = ( *cinfo->mem->access_virt_barray )
				  ( (j_common_ptr) cinfo, coef->whole_image[ci],
				  coef->iMCU_row_num * compptr->v_samp_factor,
				  (JDIMENSION) compptr->v_samp_factor, TRUE );
		/* Count non-dummy DCT block rows in this iMCU row. */
		if ( coef->iMCU_row_num < last_iMCU_row ) {
			block_rows = compptr->v_samp_factor;
		} else {
			/* NB: can't use last_row_height here, since may not be set! */
			block_rows = (int) ( compptr->height_in_blocks % compptr->v_samp_factor );
			if ( block_rows == 0 ) {
				block_rows = compptr->v_samp_factor;
			}
		}
		blocks_across = compptr->width_in_blocks;
		h_samp_factor = compptr->h_samp_factor;
		/* Count number of dummy blocks to be added at the right margin. */
		ndummy = (int) ( blocks_across % h_samp_factor );
		if ( ndummy > 0 ) {
			ndummy = h_samp_factor - ndummy;
		}
		/* Perform DCT for all non-dummy blocks in this iMCU row.  Each call
		 * on forward_DCT processes a complete horizontal row of DCT blocks.
		 */
		for ( block_row = 0; block_row < block_rows; block_row++ ) {
			thisblockrow = buffer[block_row];
			( *cinfo->fdct->forward_DCT )( cinfo, compptr,
										   input_buf[ci], thisblockrow,
										   (JDIMENSION) ( block_row * DCTSIZE ),
										   (JDIMENSION) 0, blocks_across );
			if ( ndummy > 0 ) {
				/* Create dummy blocks at the right edge of the image. */
				thisblockrow += blocks_across; /* => first dummy block */
				jzero_far( (void FAR *) thisblockrow, ndummy * SIZEOF( JBLOCK ) );
				lastDC = thisblockrow[-1][0];
				for ( bi = 0; bi < ndummy; bi++ ) {
					thisblockrow[bi][0] = lastDC;
				}
			}
		}
		/* If at end of image, create dummy block rows as needed.
		 * The tricky part here is that within each MCU, we want the DC values
		 * of the dummy blocks to match the last real block's DC value.
		 * This squeezes a few more bytes out of the resulting file...
		 */
		if ( coef->iMCU_row_num == last_iMCU_row ) {
			blocks_across += ndummy; /* include lower right corner */
			MCUs_across = blocks_across / h_samp_factor;
			for ( block_row = block_rows; block_row < compptr->v_samp_factor;
				  block_row++ ) {
				thisblockrow = buffer[block_row];
				lastblockrow = buffer[block_row - 1];
				jzero_far( (void FAR *) thisblockrow,
						   (size_t) ( blocks_across * SIZEOF( JBLOCK ) ) );
				for ( MCUindex = 0; MCUindex < MCUs_across; MCUindex++ ) {
					lastDC = lastblockrow[h_samp_factor - 1][0];
					for ( bi = 0; bi < h_samp_factor; bi++ ) {
						thisblockrow[bi][0] = lastDC;
					}
					thisblockrow += h_samp_factor; /* advance to next MCU in row */
					lastblockrow += h_samp_factor;
				}
			}
		}
	}
	/* NB: compress_output will increment iMCU_row_num if successful.
	 * A suspension return will result in redoing all the work above next time.
	 */

	/* Emit data to the entropy encoder, sharing code with subsequent passes */
	return compress_output( cinfo, input_buf );
}


/*
 * Process some data in subsequent passes of a multi-pass case.
 * We process the equivalent of one fully interleaved MCU row ("iMCU" row)
 * per call, ie, v_samp_factor block rows for each component in the scan.
 * The data is obtained from the virtual arrays and fed to the entropy coder.
 * Returns TRUE if the iMCU row is completed, FALSE if suspended.
 *
 * NB: input_buf is ignored; it is likely to be a NULL pointer.
 */

METHODDEF boolean
compress_output( j_compress_ptr cinfo, JSAMPIMAGE input_buf ) {
	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.
	 * NB: during first pass, this is safe only because the buffers will
	 * already be aligned properly, so jmemmgr.c won't need to do any I/O.
	 */
	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],
				  coef->iMCU_row_num * compptr->v_samp_factor,
				  (JDIMENSION) compptr->v_samp_factor, FALSE );
	}

	/* 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 write the MCU. */
			if ( !( *cinfo->entropy->encode_mcu )( cinfo, coef->MCU_buffer ) ) {
				/* Suspension forced; update state counters and exit */
				coef->MCU_vert_offset = yoffset;
				coef->mcu_ctr = MCU_col_num;
				return FALSE;
			}
		}
		/* Completed an MCU row, but perhaps not an iMCU row */
		coef->mcu_ctr = 0;
	}
	/* Completed the iMCU row, advance counters for next one */
	coef->iMCU_row_num++;
	start_iMCU_row( cinfo );
	return TRUE;
}

#endif /* FULL_COEF_BUFFER_SUPPORTED */


/*
 * Initialize coefficient buffer controller.
 */

GLOBAL void
jinit_c_coef_controller( j_compress_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_c_coef_controller *) coef;
	coef->pub.start_pass = start_pass_coef;

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

		for ( ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
			  ci++, compptr++ ) {
			coef->whole_image[ci] = ( *cinfo->mem->request_virt_barray )
				( (j_common_ptr) cinfo, JPOOL_IMAGE, FALSE,
				(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) compptr->v_samp_factor );
		}
#else
		ERREXIT( cinfo, JERR_BAD_BUFFER_MODE );
#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,
												 C_MAX_BLOCKS_IN_MCU * SIZEOF( JBLOCK ) );
		for ( i = 0; i < C_MAX_BLOCKS_IN_MCU; i++ ) {
			coef->MCU_buffer[i] = buffer + i;
		}
		coef->whole_image[0] = NULL; /* flag for no virtual arrays */
	}
}
