Source code
Revision control
Copy as Markdown
Other Tools
/*
* jdcoefct.c
*
* 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
* Copyright (C) 2010, 2015-2016, 2019-2020, 2022-2023, D. R. Commander.
* Copyright (C) 2015, 2020, Google, Inc.
* For conditions of distribution and use, see the accompanying README.ijg
* file.
*
* This file contains the coefficient buffer controller for decompression.
* This controller is the top level of the lossy 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.
*/
#include "jinclude.h"
#include "jdcoefct.h"
#include "jpegapicomp.h"
#include "jsamplecomp.h"
/* Forward declarations */
METHODDEF(int) decompress_onepass(j_decompress_ptr cinfo,
_JSAMPIMAGE output_buf);
#ifdef D_MULTISCAN_FILES_SUPPORTED
METHODDEF(int) decompress_data(j_decompress_ptr cinfo, _JSAMPIMAGE output_buf);
#endif
#ifdef BLOCK_SMOOTHING_SUPPORTED
LOCAL(boolean) smoothing_ok(j_decompress_ptr cinfo);
METHODDEF(int) decompress_smooth_data(j_decompress_ptr cinfo,
_JSAMPIMAGE output_buf);
#endif
/*
* 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,
* which we index according to the component's SOF position.
*/
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 *)coef->MCU_buffer[0],
(size_t)(cinfo->blocks_in_MCU * sizeof(JBLOCK)));
if (!cinfo->entropy->insufficient_data)
cinfo->master->last_good_iMCU_row = cinfo->input_iMCU_row;
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;
}
/* Only perform the IDCT on blocks that are contained within the desired
* cropping region.
*/
if (MCU_col_num >= cinfo->master->first_iMCU_col &&
MCU_col_num <= cinfo->master->last_iMCU_col) {
/* 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[compptr->component_index] +
yoffset * compptr->_DCT_scaled_size;
start_col = (MCU_col_num - cinfo->master->first_iMCU_col) *
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++;
}
}
}
if (!cinfo->entropy->insufficient_data)
cinfo->master->last_good_iMCU_row = cinfo->input_iMCU_row;
/* 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] + cinfo->master->first_MCU_col[ci];
output_col = 0;
for (block_num = cinfo->master->first_MCU_col[ci];
block_num <= cinfo->master->last_MCU_col[ci]; 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; the first 9 AC coefficients are
* estimated from the DC values of a DCT block and its 24 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.
*/
/* Natural-order array positions of the first 9 zigzag-order coefficients */
#define Q01_POS 1
#define Q10_POS 8
#define Q20_POS 16
#define Q11_POS 9
#define Q02_POS 2
#define Q03_POS 3
#define Q12_POS 10
#define Q21_POS 17
#define Q30_POS 24
/*
* 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, *prev_coef_bits;
int *coef_bits_latch, *prev_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 * 2 *
(SAVED_COEFS * sizeof(int)));
coef_bits_latch = coef->coef_bits_latch;
prev_coef_bits_latch =
&coef->coef_bits_latch[cinfo->num_components * SAVED_COEFS];
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 9 AC quantizers are nonzero to avoid zero-divide. */
if (qtable->quantval[0] == 0 ||
qtable->quantval[Q01_POS] == 0 ||
qtable->quantval[Q10_POS] == 0 ||
qtable->quantval[Q20_POS] == 0 ||
qtable->quantval[Q11_POS] == 0 ||
qtable->quantval[Q02_POS] == 0 ||
qtable->quantval[Q03_POS] == 0 ||
qtable->quantval[Q12_POS] == 0 ||
qtable->quantval[Q21_POS] == 0 ||
qtable->quantval[Q30_POS] == 0)
return FALSE;
/* DC values must be at least partly known for all components. */
coef_bits = cinfo->coef_bits[ci];
prev_coef_bits = cinfo->coef_bits[ci + cinfo->num_components];
if (coef_bits[0] < 0)
return FALSE;
coef_bits_latch[0] = coef_bits[0];
/* Block smoothing is helpful if some AC coefficients remain inaccurate. */
for (coefi = 1; coefi < SAVED_COEFS; coefi++) {
if (cinfo->input_scan_number > 1)
prev_coef_bits_latch[coefi] = prev_coef_bits[coefi];
else
prev_coef_bits_latch[coefi] = -1;
coef_bits_latch[coefi] = coef_bits[coefi];
if (coef_bits[coefi] != 0)
smoothing_useful = TRUE;
}
coef_bits_latch += SAVED_COEFS;
prev_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, image_block_row,
image_block_rows;
JBLOCKARRAY buffer;
JBLOCKROW buffer_ptr, prev_prev_block_row, prev_block_row;
JBLOCKROW next_block_row, next_next_block_row;
_JSAMPARRAY output_ptr;
JDIMENSION output_col;
jpeg_component_info *compptr;
_inverse_DCT_method_ptr inverse_DCT;
boolean change_dc;
JCOEF *workspace;
int *coef_bits;
JQUANT_TBL *quanttbl;
JLONG Q00, Q01, Q02, Q03 = 0, Q10, Q11, Q12 = 0, Q20, Q21 = 0, Q30 = 0, num;
int DC01, DC02, DC03, DC04, DC05, DC06, DC07, DC08, DC09, DC10, DC11, DC12,
DC13, DC14, DC15, DC16, DC17, DC18, DC19, DC20, DC21, DC22, DC23, DC24,
DC25;
int Al, pred;
/* Keep a local variable to avoid looking it up more than once */
workspace = coef->workspace;
/* 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 two rows ahead so that next two block rows' DC
* values are up to date.
*/
JDIMENSION delta = (cinfo->Ss == 0) ? 2 : 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 + 1 < last_iMCU_row) {
block_rows = compptr->v_samp_factor;
access_rows = block_rows * 3; /* this and next two iMCU rows */
} else if (cinfo->output_iMCU_row < last_iMCU_row) {
block_rows = compptr->v_samp_factor;
access_rows = block_rows * 2; /* this and next iMCU row */
} 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 */
}
/* Align the virtual buffer for this component. */
if (cinfo->output_iMCU_row > 1) {
access_rows += 2 * compptr->v_samp_factor; /* prior two iMCU rows too */
buffer = (*cinfo->mem->access_virt_barray)
((j_common_ptr)cinfo, coef->whole_image[ci],
(cinfo->output_iMCU_row - 2) * compptr->v_samp_factor,
(JDIMENSION)access_rows, FALSE);
buffer += 2 * compptr->v_samp_factor; /* point to current iMCU row */
} else 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 */
} else {
buffer = (*cinfo->mem->access_virt_barray)
((j_common_ptr)cinfo, coef->whole_image[ci],
(JDIMENSION)0, (JDIMENSION)access_rows, FALSE);
}
/* Fetch component-dependent info.
* If the current scan is incomplete, then we use the component-dependent
* info from the previous scan.
*/
if (cinfo->output_iMCU_row > cinfo->master->last_good_iMCU_row)
coef_bits =
coef->coef_bits_latch + ((ci + cinfo->num_components) * SAVED_COEFS);
else
coef_bits = coef->coef_bits_latch + (ci * SAVED_COEFS);
/* We only do DC interpolation if no AC coefficient data is available. */
change_dc =
coef_bits[1] == -1 && coef_bits[2] == -1 && coef_bits[3] == -1 &&
coef_bits[4] == -1 && coef_bits[5] == -1 && coef_bits[6] == -1 &&
coef_bits[7] == -1 && coef_bits[8] == -1 && coef_bits[9] == -1;
quanttbl = compptr->quant_table;
Q00 = quanttbl->quantval[0];
Q01 = quanttbl->quantval[Q01_POS];
Q10 = quanttbl->quantval[Q10_POS];
Q20 = quanttbl->quantval[Q20_POS];
Q11 = quanttbl->quantval[Q11_POS];
Q02 = quanttbl->quantval[Q02_POS];
if (change_dc) {
Q03 = quanttbl->quantval[Q03_POS];
Q12 = quanttbl->quantval[Q12_POS];
Q21 = quanttbl->quantval[Q21_POS];
Q30 = quanttbl->quantval[Q30_POS];
}
inverse_DCT = cinfo->idct->_inverse_DCT[ci];
output_ptr = output_buf[ci];
/* Loop over all DCT blocks to be processed. */
image_block_rows = block_rows * cinfo->total_iMCU_rows;
for (block_row = 0; block_row < block_rows; block_row++) {
image_block_row = cinfo->output_iMCU_row * block_rows + block_row;
buffer_ptr = buffer[block_row] + cinfo->master->first_MCU_col[ci];
if (image_block_row > 0)
prev_block_row =
buffer[block_row - 1] + cinfo->master->first_MCU_col[ci];
else
prev_block_row = buffer_ptr;
if (image_block_row > 1)
prev_prev_block_row =
buffer[block_row - 2] + cinfo->master->first_MCU_col[ci];
else
prev_prev_block_row = prev_block_row;
if (image_block_row < image_block_rows - 1)
next_block_row =
buffer[block_row + 1] + cinfo->master->first_MCU_col[ci];
else
next_block_row = buffer_ptr;
if (image_block_row < image_block_rows - 2)
next_next_block_row =
buffer[block_row + 2] + cinfo->master->first_MCU_col[ci];
else
next_next_block_row = next_block_row;
/* We fetch the surrounding DC values using a sliding-register approach.
* Initialize all 25 here so as to do the right thing on narrow pics.
*/
DC01 = DC02 = DC03 = DC04 = DC05 = (int)prev_prev_block_row[0][0];
DC06 = DC07 = DC08 = DC09 = DC10 = (int)prev_block_row[0][0];
DC11 = DC12 = DC13 = DC14 = DC15 = (int)buffer_ptr[0][0];
DC16 = DC17 = DC18 = DC19 = DC20 = (int)next_block_row[0][0];
DC21 = DC22 = DC23 = DC24 = DC25 = (int)next_next_block_row[0][0];
output_col = 0;
last_block_column = compptr->width_in_blocks - 1;
for (block_num = cinfo->master->first_MCU_col[ci];
block_num <= cinfo->master->last_MCU_col[ci]; 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 == cinfo->master->first_MCU_col[ci] &&
block_num < last_block_column) {
DC04 = DC05 = (int)prev_prev_block_row[1][0];
DC09 = DC10 = (int)prev_block_row[1][0];
DC14 = DC15 = (int)buffer_ptr[1][0];
DC19 = DC20 = (int)next_block_row[1][0];
DC24 = DC25 = (int)next_next_block_row[1][0];
}
if (block_num + 1 < last_block_column) {
DC05 = (int)prev_prev_block_row[2][0];
DC10 = (int)prev_block_row[2][0];
DC15 = (int)buffer_ptr[2][0];
DC20 = (int)next_block_row[2][0];
DC25 = (int)next_next_block_row[2][0];
}
/* If DC interpolation is enabled, compute coefficient estimates using
* a Gaussian-like kernel, keeping the averages of the DC values.
*
* If DC interpolation is disabled, compute coefficient estimates using
* an algorithm similar to the one described in Section K.8 of the JPEG
* standard, except applied to a 5x5 window rather than a 3x3 window.
*
* An estimate is applied only if the coefficient is still zero and is
* not known to be fully accurate.
*/
/* AC01 */
if ((Al = coef_bits[1]) != 0 && workspace[1] == 0) {
num = Q00 * (change_dc ?
(-DC01 - DC02 + DC04 + DC05 - 3 * DC06 + 13 * DC07 -
13 * DC09 + 3 * DC10 - 3 * DC11 + 38 * DC12 - 38 * DC14 +
3 * DC15 - 3 * DC16 + 13 * DC17 - 13 * DC19 + 3 * DC20 -
DC21 - DC22 + DC24 + DC25) :
(-7 * DC11 + 50 * DC12 - 50 * DC14 + 7 * DC15));
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 = Q00 * (change_dc ?
(-DC01 - 3 * DC02 - 3 * DC03 - 3 * DC04 - DC05 - DC06 +
13 * DC07 + 38 * DC08 + 13 * DC09 - DC10 + DC16 -
13 * DC17 - 38 * DC18 - 13 * DC19 + DC20 + DC21 +
3 * DC22 + 3 * DC23 + 3 * DC24 + DC25) :
(-7 * DC03 + 50 * DC08 - 50 * DC18 + 7 * DC23));
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 = Q00 * (change_dc ?
(DC03 + 2 * DC07 + 7 * DC08 + 2 * DC09 - 5 * DC12 - 14 * DC13 -
5 * DC14 + 2 * DC17 + 7 * DC18 + 2 * DC19 + DC23) :
(-DC03 + 13 * DC08 - 24 * DC13 + 13 * DC18 - DC23));
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 = Q00 * (change_dc ?
(-DC01 + DC05 + 9 * DC07 - 9 * DC09 - 9 * DC17 +
9 * DC19 + DC21 - DC25) :
(DC10 + DC16 - 10 * DC17 + 10 * DC19 - DC02 - DC20 + DC22 -
DC24 + DC04 - DC06 + 10 * DC07 - 10 * DC09));
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 = Q00 * (change_dc ?
(2 * DC07 - 5 * DC08 + 2 * DC09 + DC11 + 7 * DC12 - 14 * DC13 +
7 * DC14 + DC15 + 2 * DC17 - 5 * DC18 + 2 * DC19) :
(-DC11 + 13 * DC12 - 24 * DC13 + 13 * DC14 - DC15));
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;
}
if (change_dc) {
/* AC03 */
if ((Al = coef_bits[6]) != 0 && workspace[3] == 0) {
num = Q00 * (DC07 - DC09 + 2 * DC12 - 2 * DC14 + DC17 - DC19);
if (num >= 0) {
pred = (int)(((Q03 << 7) + num) / (Q03 << 8));
if (Al > 0 && pred >= (1 << Al))
pred = (1 << Al) - 1;
} else {
pred = (int)(((Q03 << 7) - num) / (Q03 << 8));
if (Al > 0 && pred >= (1 << Al))
pred = (1 << Al) - 1;
pred = -pred;
}
workspace[3] = (JCOEF)pred;
}
/* AC12 */
if ((Al = coef_bits[7]) != 0 && workspace[10] == 0) {
num = Q00 * (DC07 - 3 * DC08 + DC09 - DC17 + 3 * DC18 - DC19);
if (num >= 0) {
pred = (int)(((Q12 << 7) + num) / (Q12 << 8));
if (Al > 0 && pred >= (1 << Al))
pred = (1 << Al) - 1;
} else {
pred = (int)(((Q12 << 7) - num) / (Q12 << 8));
if (Al > 0 && pred >= (1 << Al))
pred = (1 << Al) - 1;
pred = -pred;
}
workspace[10] = (JCOEF)pred;
}
/* AC21 */
if ((Al = coef_bits[8]) != 0 && workspace[17] == 0) {
num = Q00 * (DC07 - DC09 - 3 * DC12 + 3 * DC14 + DC17 - DC19);
if (num >= 0) {
pred = (int)(((Q21 << 7) + num) / (Q21 << 8));
if (Al > 0 && pred >= (1 << Al))
pred = (1 << Al) - 1;
} else {
pred = (int)(((Q21 << 7) - num) / (Q21 << 8));
if (Al > 0 && pred >= (1 << Al))
pred = (1 << Al) - 1;
pred = -pred;
}
workspace[17] = (JCOEF)pred;
}
/* AC30 */
if ((Al = coef_bits[9]) != 0 && workspace[24] == 0) {
num = Q00 * (DC07 + 2 * DC08 + DC09 - DC17 - 2 * DC18 - DC19);
if (num >= 0) {
pred = (int)(((Q30 << 7) + num) / (Q30 << 8));
if (Al > 0 && pred >= (1 << Al))
pred = (1 << Al) - 1;
} else {
pred = (int)(((Q30 << 7) - num) / (Q30 << 8));
if (Al > 0 && pred >= (1 << Al))
pred = (1 << Al) - 1;
pred = -pred;
}
workspace[24] = (JCOEF)pred;
}
/* coef_bits[0] is non-negative. Otherwise this function would not
* be called.
*/
num = Q00 *
(-2 * DC01 - 6 * DC02 - 8 * DC03 - 6 * DC04 - 2 * DC05 -
6 * DC06 + 6 * DC07 + 42 * DC08 + 6 * DC09 - 6 * DC10 -
8 * DC11 + 42 * DC12 + 152 * DC13 + 42 * DC14 - 8 * DC15 -
6 * DC16 + 6 * DC17 + 42 * DC18 + 6 * DC19 - 6 * DC20 -
2 * DC21 - 6 * DC22 - 8 * DC23 - 6 * DC24 - 2 * DC25);
if (num >= 0) {
pred = (int)(((Q00 << 7) + num) / (Q00 << 8));
} else {
pred = (int)(((Q00 << 7) - num) / (Q00 << 8));
pred = -pred;
}
workspace[0] = (JCOEF)pred;
} /* change_dc */
/* OK, do the IDCT */
(*inverse_DCT) (cinfo, compptr, (JCOEFPTR)workspace, output_ptr,
output_col);
/* Advance for next column */
DC01 = DC02; DC02 = DC03; DC03 = DC04; DC04 = DC05;
DC06 = DC07; DC07 = DC08; DC08 = DC09; DC09 = DC10;
DC11 = DC12; DC12 = DC13; DC13 = DC14; DC14 = DC15;
DC16 = DC17; DC17 = DC18; DC18 = DC19; DC19 = DC20;
DC21 = DC22; DC22 = DC23; DC23 = DC24; DC24 = DC25;
buffer_ptr++, prev_block_row++, next_block_row++,
prev_prev_block_row++, next_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;
if (cinfo->data_precision != BITS_IN_JSAMPLE)
ERREXIT1(cinfo, JERR_BAD_PRECISION, cinfo->data_precision);
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 *= 5;
#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 */
}
/* Allocate the workspace buffer */
coef->workspace = (JCOEF *)
(*cinfo->mem->alloc_small) ((j_common_ptr)cinfo, JPOOL_IMAGE,
sizeof(JCOEF) * DCTSIZE2);
}