1 line
8.8 KiB
C
1 line
8.8 KiB
C
/*
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* jcmainct.c
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*
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* Copyright (C) 1994, Thomas G. Lane.
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* This file is part of the Independent JPEG Group's software.
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* For conditions of distribution and use, see the accompanying README file.
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*
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* This file contains the main buffer controller for compression.
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* The main buffer lies between the pre-processor and the JPEG
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* compressor proper; it holds downsampled data in the JPEG colorspace.
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*/
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#define JPEG_INTERNALS
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#include "jinclude.h"
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#include "jpeglib.h"
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/* Private buffer controller object */
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typedef struct {
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struct jpeg_c_main_controller pub; /* public fields */
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JDIMENSION cur_mcu_row; /* number of current MCU row */
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JDIMENSION rowgroup_ctr; /* counts row groups received in MCU row */
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JDIMENSION mcu_ctr; /* counts MCUs output from current row */
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boolean suspended; /* remember if we suspended output */
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J_BUF_MODE pass_mode; /* current operating mode */
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/* If using full-image storage, this array holds pointers to virtual-array
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* control blocks for each component. Unused if not full-image storage.
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*/
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jvirt_sarray_ptr virtual[MAX_COMPONENTS];
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/* If using just a strip buffer, this points to the entire set of buffers
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* (we allocate one for each component). In the virtual-array case, this
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* points to the currently accessible strips of the virtual arrays.
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*/
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JSAMPARRAY buffer[MAX_COMPONENTS];
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/* This vector points to the current strips of the components being written
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* during the current scan.
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*/
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JSAMPARRAY cur_buffer[MAX_COMPS_IN_SCAN];
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} my_main_controller;
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typedef my_main_controller * my_main_ptr;
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/* Forward declarations */
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METHODDEF void process_data_simple_main
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JPP((j_compress_ptr cinfo, JSAMPARRAY input_buf,
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JDIMENSION *in_row_ctr, JDIMENSION in_rows_avail));
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METHODDEF void process_data_buffer_main
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JPP((j_compress_ptr cinfo, JSAMPARRAY input_buf,
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JDIMENSION *in_row_ctr, JDIMENSION in_rows_avail));
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/*
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* Initialize for a processing pass.
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*/
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METHODDEF void
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start_pass_main (j_compress_ptr cinfo, J_BUF_MODE pass_mode)
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{
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my_main_ptr main = (my_main_ptr) cinfo->main;
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int ci, cindex;
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main->cur_mcu_row = 0; /* initialize counters */
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main->rowgroup_ctr = 0;
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main->mcu_ctr = 0;
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main->suspended = FALSE;
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main->pass_mode = pass_mode; /* save mode for use by process_data */
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switch (pass_mode) {
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case JBUF_PASS_THRU:
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if (main->virtual[0] != NULL)
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ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
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main->pub.process_data = process_data_simple_main;
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/* The output-strip pointers can be set up once for the whole pass. */
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for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
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cindex = cinfo->cur_comp_info[ci]->component_index;
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main->cur_buffer[ci] = main->buffer[cindex];
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}
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break;
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case JBUF_SAVE_SOURCE:
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case JBUF_CRANK_DEST:
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case JBUF_SAVE_AND_PASS:
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if (main->virtual[0] == NULL)
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ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
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main->pub.process_data = process_data_buffer_main;
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break;
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default:
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ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
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break;
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}
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}
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/*
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* Process some data.
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* This routine handles the simple pass-through mode,
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* where we have only a strip buffer.
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*/
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METHODDEF void
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process_data_simple_main (j_compress_ptr cinfo,
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JSAMPARRAY input_buf, JDIMENSION *in_row_ctr,
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JDIMENSION in_rows_avail)
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{
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my_main_ptr main = (my_main_ptr) cinfo->main;
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while (*in_row_ctr < in_rows_avail) {
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/* Read input data if we haven't filled the main buffer yet */
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if (main->rowgroup_ctr < DCTSIZE)
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(*cinfo->prep->pre_process_data) (cinfo,
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input_buf, in_row_ctr, in_rows_avail,
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main->buffer, &main->rowgroup_ctr,
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(JDIMENSION) DCTSIZE);
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/* If we have a full MCU row buffered, emit data. */
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/* Note that preprocessor ensures this will be true at bottom of image. */
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if (main->rowgroup_ctr == DCTSIZE) {
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(*cinfo->coef->compress_data) (cinfo, main->cur_buffer, &main->mcu_ctr);
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/* If compressor did not consume the whole row, then we must need to
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* suspend processing and return to the application. In this situation
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* we pretend we didn't yet consume the last input row; otherwise, if
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* it happened to be the last row of the image, the application would
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* think we were done.
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*/
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if (main->mcu_ctr < cinfo->MCUs_per_row) {
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if (! main->suspended) {
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(*in_row_ctr)--;
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main->suspended = TRUE;
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}
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return;
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}
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/* We did finish the row. Undo our little suspension hack if a previous
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* call suspended; then mark the main buffer empty.
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*/
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if (main->suspended) {
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(*in_row_ctr)++;
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main->suspended = FALSE;
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}
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main->mcu_ctr = 0;
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main->rowgroup_ctr = 0;
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}
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}
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}
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/*
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* Process some data.
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* This routine handles all of the modes that use a full-size buffer.
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*/
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METHODDEF void
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process_data_buffer_main (j_compress_ptr cinfo,
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JSAMPARRAY input_buf, JDIMENSION *in_row_ctr,
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JDIMENSION in_rows_avail)
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{
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my_main_ptr main = (my_main_ptr) cinfo->main;
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int ci, cindex;
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jpeg_component_info *compptr;
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boolean writing = (main->pass_mode != JBUF_CRANK_DEST);
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/* Realign the virtual buffers if at the start of an MCU row. */
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if (main->rowgroup_ctr == 0) {
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/* Note: during a read pass it is not necessary to reposition the
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* buffers of components not being output. This could save some I/O,
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* but is not currently implemented.
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*/
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for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
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ci++, compptr++) {
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main->buffer[ci] = (*cinfo->mem->access_virt_sarray)
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((j_common_ptr) cinfo, main->virtual[ci],
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main->cur_mcu_row * (compptr->v_samp_factor * DCTSIZE), writing);
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}
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/* Set the output-strip pointers too. */
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for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
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cindex = cinfo->cur_comp_info[ci]->component_index;
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main->cur_buffer[ci] = main->buffer[cindex];
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}
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/* In a read pass, pretend we just read some source data. */
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if (! writing) {
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*in_row_ctr += cinfo->max_v_samp_factor * DCTSIZE;
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main->rowgroup_ctr = DCTSIZE;
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}
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}
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/* If a write pass, read input data until the current MCU strip is full. */
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/* Note: preprocessor will pad if necessary to fill the last MCU strip. */
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if (writing) {
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(*cinfo->prep->pre_process_data) (cinfo,
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input_buf, in_row_ctr, in_rows_avail,
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main->buffer, &main->rowgroup_ctr,
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(JDIMENSION) DCTSIZE);
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/* Quit if we didn't yet fill the MCU strip. */
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if (main->rowgroup_ctr < DCTSIZE)
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return;
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}
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/* Emit data, unless this is a sink-only pass. */
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if (main->pass_mode != JBUF_SAVE_SOURCE) {
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(*cinfo->coef->compress_data) (cinfo, main->cur_buffer, &main->mcu_ctr);
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/* If compressor did not consume the whole row, then we must need to
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* suspend processing and return to the application. In this situation
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* we pretend we didn't yet consume the last input row; otherwise, if
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* it happened to be the last row of the image, the application would
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* think we were done.
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*/
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if (main->mcu_ctr < cinfo->MCUs_per_row) {
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if (! main->suspended) {
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(*in_row_ctr)--;
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main->suspended = TRUE;
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}
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return;
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}
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/* We did finish the row. Undo our little suspension hack if a previous
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* call suspended; then mark the main buffer empty.
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*/
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if (main->suspended) {
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(*in_row_ctr)++;
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main->suspended = FALSE;
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}
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}
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/* If get here, we are done with this MCU strip. Mark buffer empty. */
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main->mcu_ctr = 0;
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main->rowgroup_ctr = 0;
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main->cur_mcu_row++;
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}
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/*
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* Initialize main buffer controller.
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*/
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GLOBAL void
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jinit_c_main_controller (j_compress_ptr cinfo, boolean need_full_buffer)
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{
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my_main_ptr main;
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int ci;
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jpeg_component_info *compptr;
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main = (my_main_ptr)
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(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
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SIZEOF(my_main_controller));
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cinfo->main = (struct jpeg_c_main_controller *) main;
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main->pub.start_pass = start_pass_main;
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/* Create the buffer. It holds downsampled data, so each component
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* may be of a different size.
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*/
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if (need_full_buffer) {
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/* Allocate a full-image virtual array for each component */
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/* Note we implicitly pad the bottom to a multiple of the MCU height */
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for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
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ci++, compptr++) {
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main->virtual[ci] = (*cinfo->mem->request_virt_sarray)
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((j_common_ptr) cinfo, JPOOL_IMAGE,
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compptr->width_in_blocks * DCTSIZE,
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compptr->height_in_blocks * DCTSIZE,
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(JDIMENSION) (compptr->v_samp_factor * DCTSIZE));
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}
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} else {
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main->virtual[0] = NULL; /* flag for no virtual arrays */
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/* Allocate a strip buffer for each component */
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for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
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ci++, compptr++) {
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main->buffer[ci] = (*cinfo->mem->alloc_sarray)
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((j_common_ptr) cinfo, JPOOL_IMAGE,
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compptr->width_in_blocks * DCTSIZE,
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(JDIMENSION) (compptr->v_samp_factor * DCTSIZE));
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}
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}
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}
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