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409 lines
14 KiB
C
409 lines
14 KiB
C
/*
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* jcdiffct.c
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*
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* Copyright (C) 1994-1998, 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 difference buffer controller for compression.
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* This controller is the top level of the lossless JPEG compressor proper.
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* The difference buffer lies between prediction/differencing and entropy
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* encoding.
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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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#include "jlossls.h" /* Private declarations for lossless codec */
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#ifdef C_LOSSLESS_SUPPORTED
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/* We use a full-image sample buffer when doing Huffman optimization,
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* and also for writing multiple-scan JPEG files. In all cases, the
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* full-image buffer is filled during the first pass, and the scaling,
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* prediction and differencing steps are run during subsequent passes.
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*/
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#ifdef ENTROPY_OPT_SUPPORTED
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#define FULL_SAMP_BUFFER_SUPPORTED
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#else
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#ifdef C_MULTISCAN_FILES_SUPPORTED
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#define FULL_SAMP_BUFFER_SUPPORTED
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#endif
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#endif
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/* Private buffer controller object */
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typedef struct {
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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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JSAMPROW cur_row[MAX_COMPONENTS]; /* row of point transformed samples */
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JSAMPROW prev_row[MAX_COMPONENTS]; /* previous row of Pt'd samples */
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JDIFFARRAY diff_buf[MAX_COMPONENTS]; /* iMCU row of differences */
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/* In multi-pass modes, we need a virtual sample array for each component. */
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jvirt_sarray_ptr whole_image[MAX_COMPONENTS];
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} c_diff_controller;
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typedef c_diff_controller * c_diff_ptr;
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/* Forward declarations */
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METHODDEF(boolean) compress_data
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JPP((j_compress_ptr cinfo, JSAMPIMAGE input_buf));
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#ifdef FULL_SAMP_BUFFER_SUPPORTED
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METHODDEF(boolean) compress_first_pass
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JPP((j_compress_ptr cinfo, JSAMPIMAGE input_buf));
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METHODDEF(boolean) compress_output
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JPP((j_compress_ptr cinfo, JSAMPIMAGE input_buf));
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#endif
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LOCAL(void)
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start_iMCU_row (j_compress_ptr cinfo)
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/* Reset within-iMCU-row counters for a new row */
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{
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j_lossless_c_ptr losslsc = (j_lossless_c_ptr) cinfo->codec;
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c_diff_ptr diff = (c_diff_ptr) losslsc->diff_private;
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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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diff->MCU_rows_per_iMCU_row = 1;
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} else {
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if (diff->iMCU_row_num < (cinfo->total_iMCU_rows-1))
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diff->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->v_samp_factor;
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else
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diff->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->last_row_height;
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}
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diff->mcu_ctr = 0;
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diff->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_diff (j_compress_ptr cinfo, J_BUF_MODE pass_mode)
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{
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j_lossless_c_ptr losslsc = (j_lossless_c_ptr) cinfo->codec;
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c_diff_ptr diff = (c_diff_ptr) losslsc->diff_private;
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diff->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 (diff->whole_image[0] != NULL)
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ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
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losslsc->pub.compress_data = compress_data;
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break;
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#ifdef FULL_SAMP_BUFFER_SUPPORTED
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case JBUF_SAVE_AND_PASS:
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if (diff->whole_image[0] == NULL)
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ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
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losslsc->pub.compress_data = compress_first_pass;
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break;
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case JBUF_CRANK_DEST:
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if (diff->whole_image[0] == NULL)
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ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
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losslsc->pub.compress_data = compress_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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#define SWAP_ROWS(rowa,rowb) {JSAMPROW temp; temp=rowa; rowa=rowb; rowb=temp;}
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/*
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* Process some data in the single-pass case.
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* We process the equivalent of one fully interleaved MCU row ("iMCU" row)
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* per call, ie, v_samp_factor rows for each component in the image.
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* Returns TRUE if the iMCU row is completed, FALSE if suspended.
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*
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* NB: input_buf contains a plane for each component in image,
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* which we index according to the component's SOF position.
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*/
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METHODDEF(boolean)
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compress_data (j_compress_ptr cinfo, JSAMPIMAGE input_buf)
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{
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j_lossless_c_ptr losslsc = (j_lossless_c_ptr) cinfo->codec;
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c_diff_ptr diff = (c_diff_ptr) losslsc->diff_private;
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JDIMENSION MCU_col_num; /* index of current MCU within row */
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JDIMENSION MCU_count; /* number of MCUs encoded */
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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 comp, ci, yoffset, samp_row, samp_rows, samps_across;
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jpeg_component_info *compptr;
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/* Loop to write as much as one whole iMCU row */
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for (yoffset = diff->MCU_vert_offset; yoffset < diff->MCU_rows_per_iMCU_row;
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yoffset++) {
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MCU_col_num = diff->mcu_ctr;
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/* Scale and predict each scanline of the MCU-row separately.
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*
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* Note: We only do this if we are at the start of a MCU-row, ie,
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* we don't want to reprocess a row suspended by the output.
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*/
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if (MCU_col_num == 0) {
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for (comp = 0; comp < cinfo->comps_in_scan; comp++) {
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compptr = cinfo->cur_comp_info[comp];
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ci = compptr->component_index;
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if (diff->iMCU_row_num < last_iMCU_row)
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samp_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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samp_rows = (int) (compptr->height_in_data_units % compptr->v_samp_factor);
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if (samp_rows == 0) samp_rows = compptr->v_samp_factor;
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else {
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/* Fill dummy difference rows at the bottom edge with zeros, which
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* will encode to the smallest amount of data.
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*/
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for (samp_row = samp_rows; samp_row < compptr->v_samp_factor;
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samp_row++)
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MEMZERO(diff->diff_buf[ci][samp_row],
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jround_up((long) compptr->width_in_data_units,
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(long) compptr->h_samp_factor) * SIZEOF(JDIFF));
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}
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}
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samps_across = compptr->width_in_data_units;
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for (samp_row = 0; samp_row < samp_rows; samp_row++) {
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(*losslsc->scaler_scale) (cinfo,
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input_buf[ci][samp_row],
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diff->cur_row[ci], samps_across);
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(*losslsc->predict_difference[ci]) (cinfo, ci,
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diff->cur_row[ci],
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diff->prev_row[ci],
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diff->diff_buf[ci][samp_row],
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samps_across);
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SWAP_ROWS(diff->cur_row[ci], diff->prev_row[ci]);
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}
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}
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}
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/* Try to write the MCU-row (or remaining portion of suspended MCU-row). */
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MCU_count =
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(*losslsc->entropy_encode_mcus) (cinfo,
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diff->diff_buf, yoffset, MCU_col_num,
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cinfo->MCUs_per_row - MCU_col_num);
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if (MCU_count != cinfo->MCUs_per_row - MCU_col_num) {
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/* Suspension forced; update state counters and exit */
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diff->MCU_vert_offset = yoffset;
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diff->mcu_ctr += MCU_col_num;
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return FALSE;
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}
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/* Completed an MCU row, but perhaps not an iMCU row */
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diff->mcu_ctr = 0;
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}
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/* Completed the iMCU row, advance counters for next one */
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diff->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 FULL_SAMP_BUFFER_SUPPORTED
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/*
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* Process some data in the first pass of a multi-pass case.
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* We process the equivalent of one fully interleaved MCU row ("iMCU" row)
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* per call, ie, v_samp_factor rows for each component in the image.
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* This amount of data is read from the source buffer and saved into the
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* virtual arrays.
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*
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* We must also emit the data to the compressor. This is conveniently
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* done by calling compress_output() after we've loaded the current strip
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* of the virtual arrays.
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*
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* NB: input_buf contains a plane for each component in image. All components
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* are loaded into the virtual arrays in this pass. However, it may be that
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* only a subset of the components are emitted to the compressor during
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* this first pass; be careful about looking at the scan-dependent variables
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* (MCU dimensions, etc).
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*/
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METHODDEF(boolean)
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compress_first_pass (j_compress_ptr cinfo, JSAMPIMAGE input_buf)
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{
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j_lossless_c_ptr losslsc = (j_lossless_c_ptr) cinfo->codec;
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c_diff_ptr diff = (c_diff_ptr) losslsc->diff_private;
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JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
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JDIMENSION samps_across;
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int ci, samp_row, samp_rows;
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JSAMPARRAY buffer[MAX_COMPONENTS];
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jpeg_component_info *compptr;
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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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/* Align the virtual buffers for this component. */
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buffer[ci] = (*cinfo->mem->access_virt_sarray)
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((j_common_ptr) cinfo, diff->whole_image[ci],
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diff->iMCU_row_num * compptr->v_samp_factor,
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(JDIMENSION) compptr->v_samp_factor, TRUE);
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/* Count non-dummy sample rows in this iMCU row. */
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if (diff->iMCU_row_num < last_iMCU_row)
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samp_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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samp_rows = (int) (compptr->height_in_data_units % compptr->v_samp_factor);
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if (samp_rows == 0) samp_rows = compptr->v_samp_factor;
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}
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samps_across = compptr->width_in_data_units;
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/* Perform point transform scaling and prediction/differencing for all
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* non-dummy rows in this iMCU row. Each call on these functions
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* process a complete row of samples.
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*/
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for (samp_row = 0; samp_row < samp_rows; samp_row++) {
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MEMCOPY(buffer[ci][samp_row], input_buf[ci][samp_row],
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samps_across * SIZEOF(JSAMPLE));
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}
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}
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/* NB: compress_output will increment iMCU_row_num if successful.
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* A suspension return will result in redoing all the work above next time.
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*/
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/* Emit data to the compressor, sharing code with subsequent passes */
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return compress_output(cinfo, input_buf);
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}
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/*
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* Process some data in subsequent passes of a multi-pass case.
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* We process the equivalent of one fully interleaved MCU row ("iMCU" row)
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* per call, ie, v_samp_factor rows for each component in the scan.
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* The data is obtained from the virtual arrays and fed to the compressor.
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* Returns TRUE if the iMCU row is completed, FALSE if suspended.
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*
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* NB: input_buf is ignored; it is likely to be a NULL pointer.
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*/
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METHODDEF(boolean)
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compress_output (j_compress_ptr cinfo, JSAMPIMAGE input_buf)
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{
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j_lossless_c_ptr losslsc = (j_lossless_c_ptr) cinfo->codec;
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c_diff_ptr diff = (c_diff_ptr) losslsc->diff_private;
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// JDIMENSION MCU_col_num; /* index of current MCU within row */
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// JDIMENSION MCU_count; /* number of MCUs encoded */
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int comp, ci; //, yoffset;
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JSAMPARRAY buffer[MAX_COMPONENTS];
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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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* NB: during first pass, this is safe only because the buffers will
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* already be aligned properly, so jmemmgr.c won't need to do any I/O.
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*/
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for (comp = 0; comp < cinfo->comps_in_scan; comp++) {
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compptr = cinfo->cur_comp_info[comp];
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ci = compptr->component_index;
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buffer[ci] = (*cinfo->mem->access_virt_sarray)
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((j_common_ptr) cinfo, diff->whole_image[ci],
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diff->iMCU_row_num * compptr->v_samp_factor,
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(JDIMENSION) compptr->v_samp_factor, FALSE);
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}
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return compress_data(cinfo, buffer);
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}
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#endif /* FULL_SAMP_BUFFER_SUPPORTED */
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/*
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* Initialize difference buffer controller.
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*/
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GLOBAL(void)
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jinit_c_diff_controller (j_compress_ptr cinfo, boolean need_full_buffer)
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{
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j_lossless_c_ptr losslsc = (j_lossless_c_ptr) cinfo->codec;
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c_diff_ptr diff;
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int ci, row;
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jpeg_component_info *compptr;
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diff = (c_diff_ptr)
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(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
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SIZEOF(c_diff_controller));
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losslsc->diff_private = (void *) diff;
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losslsc->diff_start_pass = start_pass_diff;
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/* Create the prediction row buffers. */
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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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diff->cur_row[ci] = *(*cinfo->mem->alloc_sarray)
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((j_common_ptr) cinfo, JPOOL_IMAGE,
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(JDIMENSION) jround_up((long) compptr->width_in_data_units,
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(long) compptr->h_samp_factor),
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(JDIMENSION) 1);
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diff->prev_row[ci] = *(*cinfo->mem->alloc_sarray)
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((j_common_ptr) cinfo, JPOOL_IMAGE,
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(JDIMENSION) jround_up((long) compptr->width_in_data_units,
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(long) compptr->h_samp_factor),
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(JDIMENSION) 1);
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}
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/* Create the difference buffer. */
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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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diff->diff_buf[ci] = (*cinfo->mem->alloc_darray)
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((j_common_ptr) cinfo, JPOOL_IMAGE,
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(JDIMENSION) jround_up((long) compptr->width_in_data_units,
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(long) compptr->h_samp_factor),
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(JDIMENSION) compptr->v_samp_factor);
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/* Prefill difference rows with zeros. We do this because only actual
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* data is placed in the buffers during prediction/differencing, leaving
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* any dummy differences at the right edge as zeros, which will encode
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* to the smallest amount of data.
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*/
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for (row = 0; row < compptr->v_samp_factor; row++)
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MEMZERO(diff->diff_buf[ci][row],
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jround_up((long) compptr->width_in_data_units,
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(long) compptr->h_samp_factor) * SIZEOF(JDIFF));
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}
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/* Create the sample buffer. */
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if (need_full_buffer) {
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#ifdef FULL_SAMP_BUFFER_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 differences in each direction. */
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int ci;
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jpeg_component_info *compptr;
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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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diff->whole_image[ci] = (*cinfo->mem->request_virt_sarray)
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((j_common_ptr) cinfo, JPOOL_IMAGE, FALSE,
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(JDIMENSION) jround_up((long) compptr->width_in_data_units,
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(long) compptr->h_samp_factor),
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(JDIMENSION) jround_up((long) compptr->height_in_data_units,
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(long) compptr->v_samp_factor),
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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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diff->whole_image[0] = NULL; /* flag for no virtual arrays */
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}
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#endif /* C_LOSSLESS_SUPPORTED */
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