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doom3-bfg/neo/renderer/jpeg-6/jccoefct.cpp
Brian Harris 5016f605b8 Initial commit
2012-11-26 12:58:24 -06:00

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/*
* 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 */
}
}
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