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* Copyright (C) 1995-1998, Thomas G. Lane.
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* Modified 2000-2011 by Guido Vollbeding.
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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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* This file contains library routines for transcoding compression,
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* that is, writing raw DCT coefficient arrays to an output JPEG file.
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* The routines in jcapimin.c will also be needed by a transcoder.
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#define JPEG_INTERNALS
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/* Forward declarations */
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LOCAL(void) transencode_master_selection
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JPP((j_compress_ptr cinfo, jvirt_barray_ptr * coef_arrays));
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LOCAL(void) transencode_coef_controller
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JPP((j_compress_ptr cinfo, jvirt_barray_ptr * coef_arrays));
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* Compression initialization for writing raw-coefficient data.
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* Before calling this, all parameters and a data destination must be set up.
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* Call jpeg_finish_compress() to actually write the data.
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* The number of passed virtual arrays must match cinfo->num_components.
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* Note that the virtual arrays need not be filled or even realized at
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* the time write_coefficients is called; indeed, if the virtual arrays
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* were requested from this compression object's memory manager, they
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* typically will be realized during this routine and filled afterwards.
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jpeg_write_coefficients (j_compress_ptr cinfo, jvirt_barray_ptr * coef_arrays)
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if (cinfo->global_state != CSTATE_START)
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ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
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/* Mark all tables to be written */
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jpeg_suppress_tables(cinfo, FALSE);
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/* (Re)initialize error mgr and destination modules */
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(*cinfo->err->reset_error_mgr) ((j_common_ptr) cinfo);
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(*cinfo->dest->init_destination) (cinfo);
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/* Perform master selection of active modules */
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transencode_master_selection(cinfo, coef_arrays);
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/* Wait for jpeg_finish_compress() call */
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cinfo->next_scanline = 0; /* so jpeg_write_marker works */
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cinfo->global_state = CSTATE_WRCOEFS;
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* Initialize the compression object with default parameters,
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* then copy from the source object all parameters needed for lossless
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* transcoding. Parameters that can be varied without loss (such as
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* scan script and Huffman optimization) are left in their default states.
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jpeg_copy_critical_parameters (j_decompress_ptr srcinfo,
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j_compress_ptr dstinfo)
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JQUANT_TBL ** qtblptr;
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jpeg_component_info *incomp, *outcomp;
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JQUANT_TBL *c_quant, *slot_quant;
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/* Safety check to ensure start_compress not called yet. */
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if (dstinfo->global_state != CSTATE_START)
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ERREXIT1(dstinfo, JERR_BAD_STATE, dstinfo->global_state);
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/* Copy fundamental image dimensions */
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dstinfo->image_width = srcinfo->image_width;
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dstinfo->image_height = srcinfo->image_height;
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dstinfo->input_components = srcinfo->num_components;
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dstinfo->in_color_space = srcinfo->jpeg_color_space;
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dstinfo->jpeg_width = srcinfo->output_width;
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dstinfo->jpeg_height = srcinfo->output_height;
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dstinfo->min_DCT_h_scaled_size = srcinfo->min_DCT_h_scaled_size;
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dstinfo->min_DCT_v_scaled_size = srcinfo->min_DCT_v_scaled_size;
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/* Initialize all parameters to default values */
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jpeg_set_defaults(dstinfo);
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/* jpeg_set_defaults may choose wrong colorspace, eg YCbCr if input is RGB.
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* Fix it to get the right header markers for the image colorspace.
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jpeg_set_colorspace(dstinfo, srcinfo->jpeg_color_space);
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dstinfo->data_precision = srcinfo->data_precision;
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dstinfo->CCIR601_sampling = srcinfo->CCIR601_sampling;
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/* Copy the source's quantization tables. */
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for (tblno = 0; tblno < NUM_QUANT_TBLS; tblno++) {
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if (srcinfo->quant_tbl_ptrs[tblno] != NULL) {
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qtblptr = & dstinfo->quant_tbl_ptrs[tblno];
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*qtblptr = jpeg_alloc_quant_table((j_common_ptr) dstinfo);
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MEMCOPY((*qtblptr)->quantval,
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srcinfo->quant_tbl_ptrs[tblno]->quantval,
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SIZEOF((*qtblptr)->quantval));
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(*qtblptr)->sent_table = FALSE;
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/* Copy the source's per-component info.
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* Note we assume jpeg_set_defaults has allocated the dest comp_info array.
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dstinfo->num_components = srcinfo->num_components;
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if (dstinfo->num_components < 1 || dstinfo->num_components > MAX_COMPONENTS)
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ERREXIT2(dstinfo, JERR_COMPONENT_COUNT, dstinfo->num_components,
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for (ci = 0, incomp = srcinfo->comp_info, outcomp = dstinfo->comp_info;
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ci < dstinfo->num_components; ci++, incomp++, outcomp++) {
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outcomp->component_id = incomp->component_id;
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outcomp->h_samp_factor = incomp->h_samp_factor;
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outcomp->v_samp_factor = incomp->v_samp_factor;
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outcomp->quant_tbl_no = incomp->quant_tbl_no;
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/* Make sure saved quantization table for component matches the qtable
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* slot. If not, the input file re-used this qtable slot.
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* IJG encoder currently cannot duplicate this.
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tblno = outcomp->quant_tbl_no;
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if (tblno < 0 || tblno >= NUM_QUANT_TBLS ||
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srcinfo->quant_tbl_ptrs[tblno] == NULL)
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ERREXIT1(dstinfo, JERR_NO_QUANT_TABLE, tblno);
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slot_quant = srcinfo->quant_tbl_ptrs[tblno];
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c_quant = incomp->quant_table;
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if (c_quant != NULL) {
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for (coefi = 0; coefi < DCTSIZE2; coefi++) {
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if (c_quant->quantval[coefi] != slot_quant->quantval[coefi])
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ERREXIT1(dstinfo, JERR_MISMATCHED_QUANT_TABLE, tblno);
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/* Note: we do not copy the source's Huffman table assignments;
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* instead we rely on jpeg_set_colorspace to have made a suitable choice.
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/* Also copy JFIF version and resolution information, if available.
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* Strictly speaking this isn't "critical" info, but it's nearly
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* always appropriate to copy it if available. In particular,
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* if the application chooses to copy JFIF 1.02 extension markers from
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* the source file, we need to copy the version to make sure we don't
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* emit a file that has 1.02 extensions but a claimed version of 1.01.
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* We will *not*, however, copy version info from mislabeled "2.01" files.
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if (srcinfo->saw_JFIF_marker) {
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if (srcinfo->JFIF_major_version == 1) {
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dstinfo->JFIF_major_version = srcinfo->JFIF_major_version;
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dstinfo->JFIF_minor_version = srcinfo->JFIF_minor_version;
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dstinfo->density_unit = srcinfo->density_unit;
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dstinfo->X_density = srcinfo->X_density;
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dstinfo->Y_density = srcinfo->Y_density;
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* Master selection of compression modules for transcoding.
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* This substitutes for jcinit.c's initialization of the full compressor.
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transencode_master_selection (j_compress_ptr cinfo,
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jvirt_barray_ptr * coef_arrays)
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/* Initialize master control (includes parameter checking/processing) */
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jinit_c_master_control(cinfo, TRUE /* transcode only */);
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/* Entropy encoding: either Huffman or arithmetic coding. */
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if (cinfo->arith_code)
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jinit_arith_encoder(cinfo);
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jinit_huff_encoder(cinfo);
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/* We need a special coefficient buffer controller. */
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transencode_coef_controller(cinfo, coef_arrays);
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jinit_marker_writer(cinfo);
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/* We can now tell the memory manager to allocate virtual arrays. */
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(*cinfo->mem->realize_virt_arrays) ((j_common_ptr) cinfo);
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/* Write the datastream header (SOI, JFIF) immediately.
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* Frame and scan headers are postponed till later.
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* This lets application insert special markers after the SOI.
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(*cinfo->marker->write_file_header) (cinfo);
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* The rest of this file is a special implementation of the coefficient
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* buffer controller. This is similar to jccoefct.c, but it handles only
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* output from presupplied virtual arrays. Furthermore, we generate any
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* dummy padding blocks on-the-fly rather than expecting them to be present
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/* Private buffer controller object */
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struct jpeg_c_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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/* Virtual block array for each component. */
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jvirt_barray_ptr * whole_image;
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/* Workspace for constructing dummy blocks at right/bottom edges. */
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JBLOCKROW dummy_buffer[C_MAX_BLOCKS_IN_MCU];
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} my_coef_controller;
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typedef my_coef_controller * my_coef_ptr;
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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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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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if (cinfo->comps_in_scan > 1) {
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coef->MCU_rows_per_iMCU_row = 1;
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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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coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->last_row_height;
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coef->MCU_vert_offset = 0;
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* Initialize for a processing pass.
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start_pass_coef (j_compress_ptr cinfo, J_BUF_MODE pass_mode)
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my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
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if (pass_mode != JBUF_CRANK_DEST)
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ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
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coef->iMCU_row_num = 0;
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start_iMCU_row(cinfo);
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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 block rows for each component in the scan.
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* The data is obtained from the virtual arrays and fed to the entropy coder.
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* Returns TRUE if the iMCU row is completed, FALSE if suspended.
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* NB: input_buf is ignored; it is likely to be a NULL pointer.
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compress_output (j_compress_ptr cinfo, JSAMPIMAGE input_buf)
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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, blockcnt;
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JDIMENSION start_col;
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JBLOCKARRAY buffer[MAX_COMPS_IN_SCAN];
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JBLOCKROW MCU_buffer[C_MAX_BLOCKS_IN_MCU];
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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,
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(JDIMENSION) compptr->v_samp_factor, FALSE);
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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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for (MCU_col_num = coef->mcu_ctr; MCU_col_num < cinfo->MCUs_per_row;
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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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blockcnt = (MCU_col_num < last_MCU_col) ? compptr->MCU_width
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: compptr->last_col_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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yindex+yoffset < compptr->last_row_height) {
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/* Fill in pointers to real blocks in this row */
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buffer_ptr = buffer[ci][yindex+yoffset] + start_col;
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for (xindex = 0; xindex < blockcnt; xindex++)
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MCU_buffer[blkn++] = buffer_ptr++;
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/* At bottom of image, need a whole row of dummy blocks */
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/* Fill in any dummy blocks needed in this row.
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* Dummy blocks are filled in the same way as in jccoefct.c:
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* all zeroes in the AC entries, DC entries equal to previous
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* block's DC value. The init routine has already zeroed the
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* AC entries, so we need only set the DC entries correctly.
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for (; xindex < compptr->MCU_width; xindex++) {
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MCU_buffer[blkn] = coef->dummy_buffer[blkn];
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MCU_buffer[blkn][0][0] = MCU_buffer[blkn-1][0][0];
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/* Try to write the MCU. */
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if (! (*cinfo->entropy->encode_mcu) (cinfo, 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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/* Completed an MCU row, but perhaps not an iMCU row */
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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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* Initialize coefficient buffer controller.
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* Each passed coefficient array must be the right size for that
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* coefficient: width_in_blocks wide and height_in_blocks high,
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* with unitheight at least v_samp_factor.
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transencode_coef_controller (j_compress_ptr cinfo,
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jvirt_barray_ptr * coef_arrays)
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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_c_coef_controller *) coef;
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coef->pub.start_pass = start_pass_coef;
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coef->pub.compress_data = compress_output;
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/* Save pointer to virtual arrays */
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coef->whole_image = coef_arrays;
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/* Allocate and pre-zero space for dummy DCT blocks. */
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(*cinfo->mem->alloc_large) ((j_common_ptr) cinfo, JPOOL_IMAGE,
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C_MAX_BLOCKS_IN_MCU * SIZEOF(JBLOCK));
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FMEMZERO((void FAR *) buffer, C_MAX_BLOCKS_IN_MCU * SIZEOF(JBLOCK));
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for (i = 0; i < C_MAX_BLOCKS_IN_MCU; i++) {
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coef->dummy_buffer[i] = buffer + i;
added
removed
jpg/jctrans.c
