mirror of
https://github.com/id-Software/DOOM-3-BFG.git
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125 lines
4.4 KiB
C++
125 lines
4.4 KiB
C++
/*
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* jdtrans.c
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*
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* Copyright (C) 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 library routines for transcoding decompression,
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* that is, reading raw DCT coefficient arrays from an input JPEG file.
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* The routines in jdapimin.c will also be needed by a transcoder.
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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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/* Forward declarations */
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LOCAL void transdecode_master_selection JPP( (j_decompress_ptr cinfo) );
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/*
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* Read the coefficient arrays from a JPEG file.
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* jpeg_read_header must be completed before calling this.
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*
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* The entire image is read into a set of virtual coefficient-block arrays,
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* one per component. The return value is a pointer to the array of
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* virtual-array descriptors. These can be manipulated directly via the
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* JPEG memory manager, or handed off to jpeg_write_coefficients().
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* To release the memory occupied by the virtual arrays, call
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* jpeg_finish_decompress() when done with the data.
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*
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* Returns NULL if suspended. This case need be checked only if
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* a suspending data source is used.
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*/
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GLOBAL jvirt_barray_ptr *
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jpeg_read_coefficients( j_decompress_ptr cinfo ) {
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if ( cinfo->global_state == DSTATE_READY ) {
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/* First call: initialize active modules */
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transdecode_master_selection( cinfo );
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cinfo->global_state = DSTATE_RDCOEFS;
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} else if ( cinfo->global_state != DSTATE_RDCOEFS ) {
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ERREXIT1( cinfo, JERR_BAD_STATE, cinfo->global_state );
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}
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/* Absorb whole file into the coef buffer */
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for (;; ) {
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int retcode;
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/* Call progress monitor hook if present */
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if ( cinfo->progress != NULL ) {
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( *cinfo->progress->progress_monitor )( (j_common_ptr) cinfo );
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}
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/* Absorb some more input */
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retcode = ( *cinfo->inputctl->consume_input )( cinfo );
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if ( retcode == JPEG_SUSPENDED ) {
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return NULL;
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}
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if ( retcode == JPEG_REACHED_EOI ) {
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break;
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}
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/* Advance progress counter if appropriate */
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if ( ( cinfo->progress != NULL ) &&
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( ( retcode == JPEG_ROW_COMPLETED ) || ( retcode == JPEG_REACHED_SOS ) ) ) {
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if ( ++cinfo->progress->pass_counter >= cinfo->progress->pass_limit ) {
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/* startup underestimated number of scans; ratchet up one scan */
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cinfo->progress->pass_limit += (long) cinfo->total_iMCU_rows;
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}
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}
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}
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/* Set state so that jpeg_finish_decompress does the right thing */
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cinfo->global_state = DSTATE_STOPPING;
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return cinfo->coef->coef_arrays;
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}
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/*
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* Master selection of decompression modules for transcoding.
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* This substitutes for jdmaster.c's initialization of the full decompressor.
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*/
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LOCAL void
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transdecode_master_selection( j_decompress_ptr cinfo ) {
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/* Entropy decoding: either Huffman or arithmetic coding. */
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if ( cinfo->arith_code ) {
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ERREXIT( cinfo, JERR_ARITH_NOTIMPL );
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} else {
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if ( cinfo->progressive_mode ) {
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#ifdef D_PROGRESSIVE_SUPPORTED
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jinit_phuff_decoder( cinfo );
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#else
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ERREXIT( cinfo, JERR_NOT_COMPILED );
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#endif
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} else {
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jinit_huff_decoder( cinfo );
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}
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}
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/* Always get a full-image coefficient buffer. */
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jinit_d_coef_controller( cinfo, TRUE );
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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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/* Initialize input side of decompressor to consume first scan. */
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( *cinfo->inputctl->start_input_pass )( cinfo );
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/* Initialize progress monitoring. */
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if ( cinfo->progress != NULL ) {
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int nscans;
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/* Estimate number of scans to set pass_limit. */
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if ( cinfo->progressive_mode ) {
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/* Arbitrarily estimate 2 interleaved DC scans + 3 AC scans/component. */
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nscans = 2 + 3 * cinfo->num_components;
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} else if ( cinfo->inputctl->has_multiple_scans ) {
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/* For a nonprogressive multiscan file, estimate 1 scan per component. */
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nscans = cinfo->num_components;
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} else {
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nscans = 1;
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}
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cinfo->progress->pass_counter = 0L;
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cinfo->progress->pass_limit = (long) cinfo->total_iMCU_rows * nscans;
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cinfo->progress->completed_passes = 0;
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cinfo->progress->total_passes = 1;
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}
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}
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