84 lines
2.6 KiB
C
84 lines
2.6 KiB
C
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/*
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* jdcoefct.h
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*
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* This file was part of the Independent JPEG Group's software:
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* Copyright (C) 1994-1997, Thomas G. Lane.
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* libjpeg-turbo Modifications:
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* Copyright 2009 Pierre Ossman <ossman@cendio.se> for Cendio AB
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* Copyright (C) 2020, Google, Inc.
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* For conditions of distribution and use, see the accompanying README.ijg
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* file.
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*/
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#define JPEG_INTERNALS
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#include "jpeglib.h"
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/* Block smoothing is only applicable for progressive JPEG, so: */
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#ifndef D_PROGRESSIVE_SUPPORTED
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#undef BLOCK_SMOOTHING_SUPPORTED
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#endif
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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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/* These variables keep track of the current location of the input side. */
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/* cinfo->input_iMCU_row is also used for this. */
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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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/* The output side's location is represented by cinfo->output_iMCU_row. */
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/* In single-pass modes, it's sufficient to buffer just one MCU.
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* We allocate a workspace of D_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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* In multi-pass modes, this array points to the current MCU's blocks
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* within the virtual arrays; it is used only by the input side.
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*/
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JBLOCKROW MCU_buffer[D_MAX_BLOCKS_IN_MCU];
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/* Temporary workspace for one MCU */
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JCOEF *workspace;
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#ifdef D_MULTISCAN_FILES_SUPPORTED
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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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#endif
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#ifdef BLOCK_SMOOTHING_SUPPORTED
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/* When doing block smoothing, we latch coefficient Al values here */
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int *coef_bits_latch;
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#define SAVED_COEFS 10 /* we save coef_bits[0..9] */
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#endif
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} my_coef_controller;
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typedef my_coef_controller *my_coef_ptr;
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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 (input side) */
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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 (cinfo->input_iMCU_row < (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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