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/*
* jddiffct.c
*
* This file was part of the Independent JPEG Group's software:
* Copyright (C) 1994-1997, Thomas G. Lane.
* Lossless JPEG Modifications:
* Copyright (C) 1999, Ken Murchison.
* libjpeg-turbo Modifications:
* Copyright (C) 2022, D. R. Commander.
* For conditions of distribution and use, see the accompanying README.ijg
* file.
*
* This file contains the [un]difference buffer controller for decompression.
* This controller is the top level of the lossless JPEG decompressor proper.
* The difference buffer lies between the entropy decoding and
* prediction/undifferencing steps. The undifference buffer lies between the
* prediction/undifferencing and scaling steps.
*
* In buffered-image mode, this controller is the interface between
* input-oriented processing and output-oriented processing.
*/
#define JPEG_INTERNALS
#include "jinclude.h"
#include "jpeglib.h"
#include "jlossls.h" /* Private declarations for lossless codec */
#ifdef D_LOSSLESS_SUPPORTED
/* 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 */
unsigned int restart_rows_to_go; /* MCU rows left in this restart
interval */
unsigned int MCU_vert_offset; /* counts MCU rows within iMCU row */
unsigned int MCU_rows_per_iMCU_row; /* number of such rows needed */
/* The output side's location is represented by cinfo->output_iMCU_row. */
JDIFFARRAY diff_buf[MAX_COMPONENTS]; /* iMCU row of differences */
JDIFFARRAY undiff_buf[MAX_COMPONENTS]; /* iMCU row of undiff'd samples */
#ifdef D_MULTISCAN_FILES_SUPPORTED
/* In multi-pass modes, we need a virtual sample array for each component. */
jvirt_sarray_ptr whole_image[MAX_COMPONENTS];
#endif
} my_diff_controller;
typedef my_diff_controller *my_diff_ptr;
/* Forward declarations */
METHODDEF(int) decompress_data(j_decompress_ptr cinfo, _JSAMPIMAGE output_buf);
#ifdef D_MULTISCAN_FILES_SUPPORTED
METHODDEF(int) output_data(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_diff_ptr diff = (my_diff_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) {
diff->MCU_rows_per_iMCU_row = 1;
} else {
if (cinfo->input_iMCU_row < (cinfo->total_iMCU_rows-1))
diff->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->v_samp_factor;
else
diff->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->last_row_height;
}
diff->MCU_ctr = 0;
diff->MCU_vert_offset = 0;
}
/*
* Initialize for an input processing pass.
*/
METHODDEF(void)
start_input_pass(j_decompress_ptr cinfo)
{
my_diff_ptr diff = (my_diff_ptr)cinfo->coef;
/* Because it is hitching a ride on the jpeg_inverse_dct struct,
* start_pass_lossless() will be called at the start of the output pass.
* This ensures that it will be called at the start of the input pass as
* well.
*/
(*cinfo->idct->start_pass) (cinfo);
/* Check that the restart interval is an integer multiple of the number
* of MCUs in an MCU row.
*/
if (cinfo->restart_interval % cinfo->MCUs_per_row != 0)
ERREXIT2(cinfo, JERR_BAD_RESTART,
cinfo->restart_interval, cinfo->MCUs_per_row);
/* Initialize restart counter */
diff->restart_rows_to_go = cinfo->restart_interval / cinfo->MCUs_per_row;
cinfo->input_iMCU_row = 0;
start_iMCU_row(cinfo);
}
/*
* Check for a restart marker & resynchronize decoder, undifferencer.
* Returns FALSE if must suspend.
*/
METHODDEF(boolean)
process_restart(j_decompress_ptr cinfo)
{
my_diff_ptr diff = (my_diff_ptr)cinfo->coef;
if (!(*cinfo->entropy->process_restart) (cinfo))
return FALSE;
(*cinfo->idct->start_pass) (cinfo);
/* Reset restart counter */
diff->restart_rows_to_go = cinfo->restart_interval / cinfo->MCUs_per_row;
return TRUE;
}
/*
* Initialize for an output processing pass.
*/
METHODDEF(void)
start_output_pass(j_decompress_ptr cinfo)
{
cinfo->output_iMCU_row = 0;
}
/*
* Decompress and return some data in the supplied buffer.
* 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_data(j_decompress_ptr cinfo, _JSAMPIMAGE output_buf)
{
my_diff_ptr diff = (my_diff_ptr)cinfo->coef;
lossless_decomp_ptr losslessd = (lossless_decomp_ptr)cinfo->idct;
JDIMENSION MCU_col_num; /* index of current MCU within row */
JDIMENSION MCU_count; /* number of MCUs decoded */
JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
int ci, compi, row, prev_row;
unsigned int yoffset;
jpeg_component_info *compptr;
/* Loop to process as much as one whole iMCU row */
for (yoffset = diff->MCU_vert_offset; yoffset < diff->MCU_rows_per_iMCU_row;
yoffset++) {
/* Process restart marker if needed; may have to suspend */
if (cinfo->restart_interval) {
if (diff->restart_rows_to_go == 0)
if (!process_restart(cinfo))
return JPEG_SUSPENDED;
}
MCU_col_num = diff->MCU_ctr;
/* Try to fetch an MCU row (or remaining portion of suspended MCU row). */
MCU_count =
(*cinfo->entropy->decode_mcus) (cinfo,
diff->diff_buf, yoffset, MCU_col_num,
cinfo->MCUs_per_row - MCU_col_num);
if (MCU_count != cinfo->MCUs_per_row - MCU_col_num) {
/* Suspension forced; update state counters and exit */
diff->MCU_vert_offset = yoffset;
diff->MCU_ctr += MCU_count;
return JPEG_SUSPENDED;
}
/* Account for restart interval (no-op if not using restarts) */
if (cinfo->restart_interval)
diff->restart_rows_to_go--;
/* Completed an MCU row, but perhaps not an iMCU row */
diff->MCU_ctr = 0;
}
/*
* Undifference and scale each scanline of the disassembled MCU row
* separately. We do not process dummy samples at the end of a scanline
* or dummy rows at the end of the image.
*/
for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
compptr = cinfo->cur_comp_info[ci];
compi = compptr->component_index;
for (row = 0, prev_row = compptr->v_samp_factor - 1;
row < (cinfo->input_iMCU_row == last_iMCU_row ?
compptr->last_row_height : compptr->v_samp_factor);
prev_row = row, row++) {
(*losslessd->predict_undifference[compi])
(cinfo, compi, diff->diff_buf[compi][row],
diff->undiff_buf[compi][prev_row], diff->undiff_buf[compi][row],
compptr->width_in_blocks);
(*losslessd->scaler_scale) (cinfo, diff->undiff_buf[compi][row],
output_buf[compi][row],
compptr->width_in_blocks);
}
}
/* Completed the iMCU row, advance counters for next one.
*
* NB: output_data will increment output_iMCU_row.
* This counter is not needed for the single-pass case
* or the input side of the multi-pass case.
*/
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 sample buffer.
* We read as much as one fully interleaved MCU row ("iMCU" row) per call,
* ie, v_samp_factor 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_diff_ptr diff = (my_diff_ptr)cinfo->coef;
int ci, compi;
_JSAMPARRAY buffer[MAX_COMPS_IN_SCAN];
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];
compi = compptr->component_index;
buffer[compi] = (_JSAMPARRAY)(*cinfo->mem->access_virt_sarray)
((j_common_ptr)cinfo, diff->whole_image[compi],
cinfo->input_iMCU_row * compptr->v_samp_factor,
(JDIMENSION)compptr->v_samp_factor, TRUE);
}
return decompress_data(cinfo, buffer);
}
/*
* Output some data from the full-image sample buffer 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)
output_data(j_decompress_ptr cinfo, _JSAMPIMAGE output_buf)
{
my_diff_ptr diff = (my_diff_ptr)cinfo->coef;
JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
int ci, samp_rows, row;
_JSAMPARRAY buffer;
jpeg_component_info *compptr;
/* 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++) {
/* Align the virtual buffer for this component. */
buffer = (_JSAMPARRAY)(*cinfo->mem->access_virt_sarray)
((j_common_ptr)cinfo, diff->whole_image[ci],
cinfo->output_iMCU_row * compptr->v_samp_factor,
(JDIMENSION)compptr->v_samp_factor, FALSE);
if (cinfo->output_iMCU_row < last_iMCU_row)
samp_rows = compptr->v_samp_factor;
else {
/* NB: can't use last_row_height here; it is input-side-dependent! */
samp_rows = (int)(compptr->height_in_blocks % compptr->v_samp_factor);
if (samp_rows == 0) samp_rows = compptr->v_samp_factor;
}
for (row = 0; row < samp_rows; row++) {
memcpy(output_buf[ci][row], buffer[row],
compptr->width_in_blocks * sizeof(_JSAMPLE));
}
}
if (++(cinfo->output_iMCU_row) < cinfo->total_iMCU_rows)
return JPEG_ROW_COMPLETED;
return JPEG_SCAN_COMPLETED;
}
#endif /* D_MULTISCAN_FILES_SUPPORTED */
/*
* Initialize difference buffer controller.
*/
GLOBAL(void)
_jinit_d_diff_controller(j_decompress_ptr cinfo, boolean need_full_buffer)
{
my_diff_ptr diff;
int ci;
jpeg_component_info *compptr;
diff = (my_diff_ptr)
(*cinfo->mem->alloc_small) ((j_common_ptr)cinfo, JPOOL_IMAGE,
sizeof(my_diff_controller));
cinfo->coef = (struct jpeg_d_coef_controller *)diff;
diff->pub.start_input_pass = start_input_pass;
diff->pub.start_output_pass = start_output_pass;
/* Create the [un]difference buffers. */
for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
ci++, compptr++) {
diff->diff_buf[ci] =
ALLOC_DARRAY(JPOOL_IMAGE,
(JDIMENSION)jround_up((long)compptr->width_in_blocks,
(long)compptr->h_samp_factor),
(JDIMENSION)compptr->v_samp_factor);
diff->undiff_buf[ci] =
ALLOC_DARRAY(JPOOL_IMAGE,
(JDIMENSION)jround_up((long)compptr->width_in_blocks,
(long)compptr->h_samp_factor),
(JDIMENSION)compptr->v_samp_factor);
}
if (need_full_buffer) {
#ifdef D_MULTISCAN_FILES_SUPPORTED
/* Allocate a full-image virtual array for each component. */
int access_rows;
for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
ci++, compptr++) {
access_rows = compptr->v_samp_factor;
diff->whole_image[ci] = (*cinfo->mem->request_virt_sarray)
((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)access_rows);
}
diff->pub.consume_data = consume_data;
diff->pub._decompress_data = output_data;
#else
ERREXIT(cinfo, JERR_NOT_COMPILED);
#endif
} else {
diff->pub.consume_data = dummy_consume_data;
diff->pub._decompress_data = decompress_data;
diff->whole_image[0] = NULL; /* flag for no virtual arrays */
}
}
#endif /* D_LOSSLESS_SUPPORTED */