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/*
* jcmainct.c
*
* This file was part of the Independent JPEG Group's software:
* Copyright (C) 1994-1996, Thomas G. Lane.
* It was modified by The libjpeg-turbo Project to include only code relevant
* to libjpeg-turbo.
* For conditions of distribution and use, see the accompanying README.ijg
* file.
*
* This file contains the main buffer controller for compression.
* The main buffer lies between the pre-processor and the JPEG
* compressor proper; it holds downsampled data in the JPEG colorspace.
*/
#define JPEG_INTERNALS
#include "jinclude.h"
#include "jpeglib.h"
/* Private buffer controller object */
typedef struct {
struct jpeg_c_main_controller pub; /* public fields */
JDIMENSION cur_iMCU_row; /* number of current iMCU row */
JDIMENSION rowgroup_ctr; /* counts row groups received in iMCU row */
boolean suspended; /* remember if we suspended output */
J_BUF_MODE pass_mode; /* current operating mode */
/* If using just a strip buffer, this points to the entire set of buffers
* (we allocate one for each component). In the full-image case, this
* points to the currently accessible strips of the virtual arrays.
*/
JSAMPARRAY buffer[MAX_COMPONENTS];
} my_main_controller;
typedef my_main_controller *my_main_ptr;
/* Forward declarations */
METHODDEF(void) process_data_simple_main
(j_compress_ptr cinfo, JSAMPARRAY input_buf, JDIMENSION *in_row_ctr,
JDIMENSION in_rows_avail);
/*
* Initialize for a processing pass.
*/
METHODDEF(void)
start_pass_main (j_compress_ptr cinfo, J_BUF_MODE pass_mode)
{
my_main_ptr main_ptr = (my_main_ptr) cinfo->main;
/* Do nothing in raw-data mode. */
if (cinfo->raw_data_in)
return;
if (pass_mode != JBUF_PASS_THRU)
ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
main_ptr->cur_iMCU_row = 0; /* initialize counters */
main_ptr->rowgroup_ctr = 0;
main_ptr->suspended = FALSE;
main_ptr->pass_mode = pass_mode; /* save mode for use by process_data */
main_ptr->pub.process_data = process_data_simple_main;
}
/*
* Process some data.
* This routine handles the simple pass-through mode,
* where we have only a strip buffer.
*/
METHODDEF(void)
process_data_simple_main (j_compress_ptr cinfo,
JSAMPARRAY input_buf, JDIMENSION *in_row_ctr,
JDIMENSION in_rows_avail)
{
my_main_ptr main_ptr = (my_main_ptr) cinfo->main;
while (main_ptr->cur_iMCU_row < cinfo->total_iMCU_rows) {
/* Read input data if we haven't filled the main buffer yet */
if (main_ptr->rowgroup_ctr < DCTSIZE)
(*cinfo->prep->pre_process_data) (cinfo,
input_buf, in_row_ctr, in_rows_avail,
main_ptr->buffer, &main_ptr->rowgroup_ctr,
(JDIMENSION) DCTSIZE);
/* If we don't have a full iMCU row buffered, return to application for
* more data. Note that preprocessor will always pad to fill the iMCU row
* at the bottom of the image.
*/
if (main_ptr->rowgroup_ctr != DCTSIZE)
return;
/* Send the completed row to the compressor */
if (! (*cinfo->coef->compress_data) (cinfo, main_ptr->buffer)) {
/* If compressor did not consume the whole row, then we must need to
* suspend processing and return to the application. In this situation
* we pretend we didn't yet consume the last input row; otherwise, if
* it happened to be the last row of the image, the application would
* think we were done.
*/
if (! main_ptr->suspended) {
(*in_row_ctr)--;
main_ptr->suspended = TRUE;
}
return;
}
/* We did finish the row. Undo our little suspension hack if a previous
* call suspended; then mark the main buffer empty.
*/
if (main_ptr->suspended) {
(*in_row_ctr)++;
main_ptr->suspended = FALSE;
}
main_ptr->rowgroup_ctr = 0;
main_ptr->cur_iMCU_row++;
}
}
/*
* Initialize main buffer controller.
*/
GLOBAL(void)
jinit_c_main_controller (j_compress_ptr cinfo, boolean need_full_buffer)
{
my_main_ptr main_ptr;
int ci;
jpeg_component_info *compptr;
main_ptr = (my_main_ptr)
(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
sizeof(my_main_controller));
cinfo->main = (struct jpeg_c_main_controller *) main_ptr;
main_ptr->pub.start_pass = start_pass_main;
/* We don't need to create a buffer in raw-data mode. */
if (cinfo->raw_data_in)
return;
/* Create the buffer. It holds downsampled data, so each component
* may be of a different size.
*/
if (need_full_buffer) {
ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
} else {
/* Allocate a strip buffer for each component */
for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
ci++, compptr++) {
main_ptr->buffer[ci] = (*cinfo->mem->alloc_sarray)
((j_common_ptr) cinfo, JPOOL_IMAGE,
compptr->width_in_blocks * DCTSIZE,
(JDIMENSION) (compptr->v_samp_factor * DCTSIZE));
}
}
}
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