379 lines
13 KiB
C
379 lines
13 KiB
C
/*
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* jdcoefct.c
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*
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* Copyright (C) 1994-1995, 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 coefficient buffer controller for decompression.
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* This controller is the top level of the JPEG decompressor proper.
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* The coefficient buffer lies between entropy decoding and inverse-DCT steps.
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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_d_coef_controller pub; /* public fields */
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JDIMENSION iMCU_row_num; /* iMCU row # within image */
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JDIMENSION mcu_ctr; /* counts MCUs processed in current row */
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int MCU_vert_offset; /* counts MCU rows within iMCU row */
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int MCU_rows_per_iMCU_row; /* number of such rows needed */
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/* In single-pass modes without block smoothing, it's sufficient to buffer
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* just one MCU (although this may prove a bit slow in practice).
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* We allocate a workspace of MAX_BLOCKS_IN_MCU coefficient blocks,
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* and let the entropy decoder write into that workspace each time.
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* (On 80x86, the workspace is FAR even though it's not really very big;
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* this is to keep the module interfaces unchanged when a large coefficient
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* buffer is necessary.)
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* In multi-pass modes, this array points to the current MCU's blocks
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* within the virtual arrays.
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*/
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JBLOCKROW MCU_buffer[MAX_BLOCKS_IN_MCU];
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/* In multi-pass modes, we need a virtual block array for each component. */
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jvirt_barray_ptr whole_image[MAX_COMPONENTS];
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} my_coef_controller;
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typedef my_coef_controller * my_coef_ptr;
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/* Forward declarations */
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METHODDEF boolean decompress_data
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JPP((j_decompress_ptr cinfo, JSAMPIMAGE output_buf));
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#ifdef D_MULTISCAN_FILES_SUPPORTED
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METHODDEF boolean decompress_read
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JPP((j_decompress_ptr cinfo, JSAMPIMAGE output_buf));
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METHODDEF boolean decompress_output
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JPP((j_decompress_ptr cinfo, JSAMPIMAGE output_buf));
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#endif
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LOCAL void
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start_iMCU_row (j_decompress_ptr cinfo)
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/* Reset within-iMCU-row counters for a new row */
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{
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my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
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/* In an interleaved scan, an MCU row is the same as an iMCU row.
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* In a noninterleaved scan, an iMCU row has v_samp_factor MCU rows.
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* But at the bottom of the image, process only what's left.
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*/
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if (cinfo->comps_in_scan > 1) {
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coef->MCU_rows_per_iMCU_row = 1;
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} else {
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if (coef->iMCU_row_num < (cinfo->total_iMCU_rows-1))
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coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->v_samp_factor;
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else
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coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->last_row_height;
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}
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coef->mcu_ctr = 0;
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coef->MCU_vert_offset = 0;
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}
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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_coef (j_decompress_ptr cinfo, J_BUF_MODE pass_mode)
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{
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my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
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coef->iMCU_row_num = 0;
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start_iMCU_row(cinfo);
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switch (pass_mode) {
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case JBUF_PASS_THRU:
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if (coef->whole_image[0] != NULL)
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ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
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coef->pub.decompress_data = decompress_data;
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break;
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#ifdef D_MULTISCAN_FILES_SUPPORTED
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case JBUF_SAVE_SOURCE:
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if (coef->whole_image[0] == NULL)
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ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
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coef->pub.decompress_data = decompress_read;
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break;
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case JBUF_CRANK_DEST:
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if (coef->whole_image[0] == NULL)
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ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
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coef->pub.decompress_data = decompress_output;
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break;
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#endif
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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 in the single-pass case.
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* Always attempts to emit one fully interleaved MCU row ("iMCU" row).
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* Returns TRUE if it completed a row, FALSE if not (suspension).
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*
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* NB: output_buf contains a plane for each component in image.
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* For single pass, this is the same as the components in the scan.
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*/
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METHODDEF boolean
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decompress_data (j_decompress_ptr cinfo, JSAMPIMAGE output_buf)
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{
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my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
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JDIMENSION MCU_col_num; /* index of current MCU within row */
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JDIMENSION last_MCU_col = cinfo->MCUs_per_row - 1;
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JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
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int blkn, ci, xindex, yindex, yoffset, useful_width;
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JSAMPARRAY output_ptr;
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JDIMENSION start_col, output_col;
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jpeg_component_info *compptr;
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inverse_DCT_method_ptr inverse_DCT;
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/* Loop to process as much as one whole iMCU row */
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for (yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row;
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yoffset++) {
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for (MCU_col_num = coef->mcu_ctr; MCU_col_num <= last_MCU_col;
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MCU_col_num++) {
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/* Try to fetch an MCU. Entropy decoder expects buffer to be zeroed. */
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jzero_far((void FAR *) coef->MCU_buffer[0],
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(size_t) (cinfo->blocks_in_MCU * SIZEOF(JBLOCK)));
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if (! (*cinfo->entropy->decode_mcu) (cinfo, coef->MCU_buffer)) {
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/* Suspension forced; update state counters and exit */
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coef->MCU_vert_offset = yoffset;
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coef->mcu_ctr = MCU_col_num;
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return FALSE;
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}
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/* Determine where data should go in output_buf and do the IDCT thing.
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* We skip dummy blocks at the right and bottom edges (but blkn gets
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* incremented past them!). Note the inner loop relies on having
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* allocated the MCU_buffer[] blocks sequentially.
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*/
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blkn = 0; /* index of current DCT block within MCU */
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for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
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compptr = cinfo->cur_comp_info[ci];
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/* Don't bother to IDCT an uninteresting component. */
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if (! compptr->component_needed) {
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blkn += compptr->MCU_blocks;
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continue;
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}
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inverse_DCT = cinfo->idct->inverse_DCT[compptr->component_index];
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useful_width = (MCU_col_num < last_MCU_col) ? compptr->MCU_width
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: compptr->last_col_width;
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output_ptr = output_buf[ci] + yoffset * compptr->DCT_scaled_size;
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start_col = MCU_col_num * compptr->MCU_sample_width;
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for (yindex = 0; yindex < compptr->MCU_height; yindex++) {
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if (coef->iMCU_row_num < last_iMCU_row ||
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yoffset+yindex < compptr->last_row_height) {
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output_col = start_col;
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for (xindex = 0; xindex < useful_width; xindex++) {
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(*inverse_DCT) (cinfo, compptr,
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(JCOEFPTR) coef->MCU_buffer[blkn+xindex],
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output_ptr, output_col);
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output_col += compptr->DCT_scaled_size;
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}
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}
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blkn += compptr->MCU_width;
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output_ptr += compptr->DCT_scaled_size;
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}
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}
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}
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/* Completed an MCU row, but perhaps not an iMCU row */
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coef->mcu_ctr = 0;
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}
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/* Completed the iMCU row, advance counters for next one */
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coef->iMCU_row_num++;
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start_iMCU_row(cinfo);
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return TRUE;
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}
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#ifdef D_MULTISCAN_FILES_SUPPORTED
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/*
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* Process some data: handle an input pass for a multiple-scan file.
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* We read the equivalent of one fully interleaved MCU row ("iMCU" row)
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* per call, ie, v_samp_factor block rows for each component in the scan.
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* No data is returned; we just stash it in the virtual arrays.
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* Returns TRUE if it completed a row, FALSE if not (suspension).
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*/
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METHODDEF boolean
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decompress_read (j_decompress_ptr cinfo, JSAMPIMAGE output_buf)
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{
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my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
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JDIMENSION MCU_col_num; /* index of current MCU within row */
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int blkn, ci, xindex, yindex, yoffset;
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JDIMENSION total_width, start_col;
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JBLOCKARRAY buffer[MAX_COMPS_IN_SCAN];
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JBLOCKROW buffer_ptr;
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jpeg_component_info *compptr;
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/* Align the virtual buffers for the components used in this scan. */
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for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
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compptr = cinfo->cur_comp_info[ci];
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buffer[ci] = (*cinfo->mem->access_virt_barray)
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((j_common_ptr) cinfo, coef->whole_image[compptr->component_index],
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coef->iMCU_row_num * compptr->v_samp_factor, TRUE);
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/* Entropy decoder expects buffer to be zeroed. */
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total_width = (JDIMENSION) jround_up((long) compptr->width_in_blocks,
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(long) compptr->h_samp_factor);
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for (yindex = 0; yindex < compptr->v_samp_factor; yindex++) {
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jzero_far((void FAR *) buffer[ci][yindex],
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(size_t) (total_width * SIZEOF(JBLOCK)));
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}
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}
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/* Loop to process one whole iMCU row */
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for (yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row;
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yoffset++) {
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for (MCU_col_num = coef->mcu_ctr; MCU_col_num < cinfo->MCUs_per_row;
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MCU_col_num++) {
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/* Construct list of pointers to DCT blocks belonging to this MCU */
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blkn = 0; /* index of current DCT block within MCU */
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for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
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compptr = cinfo->cur_comp_info[ci];
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start_col = MCU_col_num * compptr->MCU_width;
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for (yindex = 0; yindex < compptr->MCU_height; yindex++) {
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buffer_ptr = buffer[ci][yindex+yoffset] + start_col;
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for (xindex = 0; xindex < compptr->MCU_width; xindex++) {
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coef->MCU_buffer[blkn++] = buffer_ptr++;
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}
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}
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}
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/* Try to fetch the MCU. */
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if (! (*cinfo->entropy->decode_mcu) (cinfo, coef->MCU_buffer)) {
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/* Suspension forced; update state counters and exit */
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coef->MCU_vert_offset = yoffset;
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coef->mcu_ctr = MCU_col_num;
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return FALSE;
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}
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}
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/* Completed an MCU row, but perhaps not an iMCU row */
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coef->mcu_ctr = 0;
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}
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/* Completed the iMCU row, advance counters for next one */
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coef->iMCU_row_num++;
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start_iMCU_row(cinfo);
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return TRUE;
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}
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/*
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* Process some data: output from the virtual arrays after reading is done.
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* Always emits one fully interleaved MCU row ("iMCU" row).
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* Always returns TRUE --- suspension is not possible.
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*
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* NB: output_buf contains a plane for each component in image.
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*/
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METHODDEF boolean
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decompress_output (j_decompress_ptr cinfo, JSAMPIMAGE output_buf)
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{
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my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
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JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
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JDIMENSION block_num;
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int ci, block_row, block_rows;
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JBLOCKARRAY buffer;
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JBLOCKROW buffer_ptr;
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JSAMPARRAY output_ptr;
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JDIMENSION output_col;
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jpeg_component_info *compptr;
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inverse_DCT_method_ptr inverse_DCT;
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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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/* Don't bother to IDCT an uninteresting component. */
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if (! compptr->component_needed)
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continue;
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/* Align the virtual buffer for this component. */
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buffer = (*cinfo->mem->access_virt_barray)
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((j_common_ptr) cinfo, coef->whole_image[ci],
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coef->iMCU_row_num * compptr->v_samp_factor, FALSE);
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/* Count non-dummy DCT block rows in this iMCU row. */
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if (coef->iMCU_row_num < last_iMCU_row)
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block_rows = compptr->v_samp_factor;
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else {
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/* NB: can't use last_row_height here, since may not be set! */
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block_rows = (int) (compptr->height_in_blocks % compptr->v_samp_factor);
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if (block_rows == 0) block_rows = compptr->v_samp_factor;
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}
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inverse_DCT = cinfo->idct->inverse_DCT[ci];
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output_ptr = output_buf[ci];
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/* Loop over all DCT blocks to be processed. */
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for (block_row = 0; block_row < block_rows; block_row++) {
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buffer_ptr = buffer[block_row];
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output_col = 0;
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for (block_num = 0; block_num < compptr->width_in_blocks; block_num++) {
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(*inverse_DCT) (cinfo, compptr, (JCOEFPTR) buffer_ptr,
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output_ptr, output_col);
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buffer_ptr++;
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output_col += compptr->DCT_scaled_size;
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}
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output_ptr += compptr->DCT_scaled_size;
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}
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}
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coef->iMCU_row_num++;
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return TRUE;
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}
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#endif /* D_MULTISCAN_FILES_SUPPORTED */
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/*
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* Initialize coefficient buffer controller.
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*/
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GLOBAL void
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jinit_d_coef_controller (j_decompress_ptr cinfo, boolean need_full_buffer)
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{
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my_coef_ptr coef;
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int ci, i;
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jpeg_component_info *compptr;
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JBLOCKROW buffer;
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coef = (my_coef_ptr)
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(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
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SIZEOF(my_coef_controller));
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cinfo->coef = (struct jpeg_d_coef_controller *) coef;
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coef->pub.start_pass = start_pass_coef;
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/* Create the coefficient buffer. */
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if (need_full_buffer) {
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#ifdef D_MULTISCAN_FILES_SUPPORTED
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/* Allocate a full-image virtual array for each component, */
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/* padded to a multiple of samp_factor DCT blocks in each direction. */
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/* Note memmgr implicitly pads the vertical direction. */
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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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coef->whole_image[ci] = (*cinfo->mem->request_virt_barray)
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((j_common_ptr) cinfo, JPOOL_IMAGE,
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(JDIMENSION) jround_up((long) compptr->width_in_blocks,
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(long) compptr->h_samp_factor),
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compptr->height_in_blocks,
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(JDIMENSION) compptr->v_samp_factor);
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}
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#else
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ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
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#endif
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} else {
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/* We only need a single-MCU buffer. */
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buffer = (JBLOCKROW)
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(*cinfo->mem->alloc_large) ((j_common_ptr) cinfo, JPOOL_IMAGE,
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MAX_BLOCKS_IN_MCU * SIZEOF(JBLOCK));
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for (i = 0; i < MAX_BLOCKS_IN_MCU; i++) {
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coef->MCU_buffer[i] = buffer + i;
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}
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coef->whole_image[0] = NULL; /* flag for no virtual arrays */
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}
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}
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