558 lines
20 KiB
C
558 lines
20 KiB
C
/*
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* jdmaster.c
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*
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* Copyright (C) 1991-1997, 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 master control logic for the JPEG decompressor.
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* These routines are concerned with selecting the modules to be executed
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* and with determining the number of passes and the work to be done in each
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* pass.
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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 state */
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typedef struct {
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struct jpeg_decomp_master pub; /* public fields */
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int pass_number; /* # of passes completed */
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boolean using_merged_upsample; /* TRUE if using merged upsample/cconvert */
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/* Saved references to initialized quantizer modules,
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* in case we need to switch modes.
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*/
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struct jpeg_color_quantizer * quantizer_1pass;
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struct jpeg_color_quantizer * quantizer_2pass;
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} my_decomp_master;
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typedef my_decomp_master * my_master_ptr;
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/*
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* Determine whether merged upsample/color conversion should be used.
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* CRUCIAL: this must match the actual capabilities of jdmerge.c!
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*/
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LOCAL(boolean)
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use_merged_upsample (j_decompress_ptr cinfo)
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{
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#ifdef UPSAMPLE_MERGING_SUPPORTED
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/* Merging is the equivalent of plain box-filter upsampling */
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if (cinfo->do_fancy_upsampling || cinfo->CCIR601_sampling)
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return FALSE;
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/* jdmerge.c only supports YCC=>RGB color conversion */
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if (cinfo->jpeg_color_space != JCS_YCbCr || cinfo->num_components != 3 ||
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cinfo->out_color_space != JCS_RGB ||
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cinfo->out_color_components != RGB_PIXELSIZE)
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return FALSE;
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/* and it only handles 2h1v or 2h2v sampling ratios */
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if (cinfo->comp_info[0].h_samp_factor != 2 ||
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cinfo->comp_info[1].h_samp_factor != 1 ||
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cinfo->comp_info[2].h_samp_factor != 1 ||
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cinfo->comp_info[0].v_samp_factor > 2 ||
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cinfo->comp_info[1].v_samp_factor != 1 ||
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cinfo->comp_info[2].v_samp_factor != 1)
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return FALSE;
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/* furthermore, it doesn't work if we've scaled the IDCTs differently */
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if (cinfo->comp_info[0].DCT_scaled_size != cinfo->min_DCT_scaled_size ||
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cinfo->comp_info[1].DCT_scaled_size != cinfo->min_DCT_scaled_size ||
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cinfo->comp_info[2].DCT_scaled_size != cinfo->min_DCT_scaled_size)
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return FALSE;
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/* ??? also need to test for upsample-time rescaling, when & if supported */
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return TRUE; /* by golly, it'll work... */
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#else
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return FALSE;
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#endif
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}
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/*
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* Compute output image dimensions and related values.
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* NOTE: this is exported for possible use by application.
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* Hence it mustn't do anything that can't be done twice.
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* Also note that it may be called before the master module is initialized!
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*/
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GLOBAL(void)
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jpeg_calc_output_dimensions (j_decompress_ptr cinfo)
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/* Do computations that are needed before master selection phase */
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{
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#ifdef IDCT_SCALING_SUPPORTED
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int ci;
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jpeg_component_info *compptr;
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#endif
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/* Prevent application from calling me at wrong times */
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if (cinfo->global_state != DSTATE_READY)
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ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
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#ifdef IDCT_SCALING_SUPPORTED
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/* Compute actual output image dimensions and DCT scaling choices. */
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if (cinfo->scale_num * 8 <= cinfo->scale_denom) {
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/* Provide 1/8 scaling */
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cinfo->output_width = (JDIMENSION)
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jdiv_round_up((long) cinfo->image_width, 8L);
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cinfo->output_height = (JDIMENSION)
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jdiv_round_up((long) cinfo->image_height, 8L);
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cinfo->min_DCT_scaled_size = 1;
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} else if (cinfo->scale_num * 4 <= cinfo->scale_denom) {
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/* Provide 1/4 scaling */
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cinfo->output_width = (JDIMENSION)
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jdiv_round_up((long) cinfo->image_width, 4L);
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cinfo->output_height = (JDIMENSION)
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jdiv_round_up((long) cinfo->image_height, 4L);
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cinfo->min_DCT_scaled_size = 2;
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} else if (cinfo->scale_num * 2 <= cinfo->scale_denom) {
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/* Provide 1/2 scaling */
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cinfo->output_width = (JDIMENSION)
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jdiv_round_up((long) cinfo->image_width, 2L);
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cinfo->output_height = (JDIMENSION)
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jdiv_round_up((long) cinfo->image_height, 2L);
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cinfo->min_DCT_scaled_size = 4;
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} else {
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/* Provide 1/1 scaling */
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cinfo->output_width = cinfo->image_width;
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cinfo->output_height = cinfo->image_height;
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cinfo->min_DCT_scaled_size = DCTSIZE;
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}
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/* In selecting the actual DCT scaling for each component, we try to
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* scale up the chroma components via IDCT scaling rather than upsampling.
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* This saves time if the upsampler gets to use 1:1 scaling.
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* Note this code assumes that the supported DCT scalings are powers of 2.
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*/
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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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int ssize = cinfo->min_DCT_scaled_size;
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while (ssize < DCTSIZE &&
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(compptr->h_samp_factor * ssize * 2 <=
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cinfo->max_h_samp_factor * cinfo->min_DCT_scaled_size) &&
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(compptr->v_samp_factor * ssize * 2 <=
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cinfo->max_v_samp_factor * cinfo->min_DCT_scaled_size)) {
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ssize = ssize * 2;
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}
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compptr->DCT_scaled_size = ssize;
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}
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/* Recompute downsampled dimensions of components;
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* application needs to know these if using raw downsampled data.
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*/
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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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/* Size in samples, after IDCT scaling */
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compptr->downsampled_width = (JDIMENSION)
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jdiv_round_up((long) cinfo->image_width *
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(long) (compptr->h_samp_factor * compptr->DCT_scaled_size),
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(long) (cinfo->max_h_samp_factor * DCTSIZE));
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compptr->downsampled_height = (JDIMENSION)
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jdiv_round_up((long) cinfo->image_height *
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(long) (compptr->v_samp_factor * compptr->DCT_scaled_size),
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(long) (cinfo->max_v_samp_factor * DCTSIZE));
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}
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#else /* !IDCT_SCALING_SUPPORTED */
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/* Hardwire it to "no scaling" */
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cinfo->output_width = cinfo->image_width;
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cinfo->output_height = cinfo->image_height;
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/* jdinput.c has already initialized DCT_scaled_size to DCTSIZE,
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* and has computed unscaled downsampled_width and downsampled_height.
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*/
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#endif /* IDCT_SCALING_SUPPORTED */
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/* Report number of components in selected colorspace. */
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/* Probably this should be in the color conversion module... */
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switch (cinfo->out_color_space) {
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case JCS_GRAYSCALE:
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cinfo->out_color_components = 1;
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break;
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case JCS_RGB:
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#if RGB_PIXELSIZE != 3
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cinfo->out_color_components = RGB_PIXELSIZE;
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break;
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#endif /* else share code with YCbCr */
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case JCS_YCbCr:
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cinfo->out_color_components = 3;
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break;
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case JCS_CMYK:
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case JCS_YCCK:
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cinfo->out_color_components = 4;
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break;
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default: /* else must be same colorspace as in file */
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cinfo->out_color_components = cinfo->num_components;
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break;
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}
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cinfo->output_components = (cinfo->quantize_colors ? 1 :
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cinfo->out_color_components);
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/* See if upsampler will want to emit more than one row at a time */
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if (use_merged_upsample(cinfo))
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cinfo->rec_outbuf_height = cinfo->max_v_samp_factor;
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else
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cinfo->rec_outbuf_height = 1;
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}
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/*
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* Several decompression processes need to range-limit values to the range
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* 0..MAXJSAMPLE; the input value may fall somewhat outside this range
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* due to noise introduced by quantization, roundoff error, etc. These
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* processes are inner loops and need to be as fast as possible. On most
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* machines, particularly CPUs with pipelines or instruction prefetch,
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* a (subscript-check-less) C table lookup
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* x = sample_range_limit[x];
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* is faster than explicit tests
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* if (x < 0) x = 0;
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* else if (x > MAXJSAMPLE) x = MAXJSAMPLE;
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* These processes all use a common table prepared by the routine below.
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*
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* For most steps we can mathematically guarantee that the initial value
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* of x is within MAXJSAMPLE+1 of the legal range, so a table running from
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* -(MAXJSAMPLE+1) to 2*MAXJSAMPLE+1 is sufficient. But for the initial
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* limiting step (just after the IDCT), a wildly out-of-range value is
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* possible if the input data is corrupt. To avoid any chance of indexing
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* off the end of memory and getting a bad-pointer trap, we perform the
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* post-IDCT limiting thus:
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* x = range_limit[x & MASK];
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* where MASK is 2 bits wider than legal sample data, ie 10 bits for 8-bit
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* samples. Under normal circumstances this is more than enough range and
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* a correct output will be generated; with bogus input data the mask will
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* cause wraparound, and we will safely generate a bogus-but-in-range output.
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* For the post-IDCT step, we want to convert the data from signed to unsigned
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* representation by adding CENTERJSAMPLE at the same time that we limit it.
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* So the post-IDCT limiting table ends up looking like this:
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* CENTERJSAMPLE,CENTERJSAMPLE+1,...,MAXJSAMPLE,
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* MAXJSAMPLE (repeat 2*(MAXJSAMPLE+1)-CENTERJSAMPLE times),
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* 0 (repeat 2*(MAXJSAMPLE+1)-CENTERJSAMPLE times),
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* 0,1,...,CENTERJSAMPLE-1
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* Negative inputs select values from the upper half of the table after
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* masking.
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*
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* We can save some space by overlapping the start of the post-IDCT table
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* with the simpler range limiting table. The post-IDCT table begins at
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* sample_range_limit + CENTERJSAMPLE.
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*
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* Note that the table is allocated in near data space on PCs; it's small
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* enough and used often enough to justify this.
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*/
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LOCAL(void)
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prepare_range_limit_table (j_decompress_ptr cinfo)
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/* Allocate and fill in the sample_range_limit table */
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{
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JSAMPLE * table;
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int i;
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table = (JSAMPLE *)
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(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
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(5 * (MAXJSAMPLE+1) + CENTERJSAMPLE) * SIZEOF(JSAMPLE));
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table += (MAXJSAMPLE+1); /* allow negative subscripts of simple table */
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cinfo->sample_range_limit = table;
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/* First segment of "simple" table: limit[x] = 0 for x < 0 */
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MEMZERO(table - (MAXJSAMPLE+1), (MAXJSAMPLE+1) * SIZEOF(JSAMPLE));
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/* Main part of "simple" table: limit[x] = x */
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for (i = 0; i <= MAXJSAMPLE; i++)
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table[i] = (JSAMPLE) i;
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table += CENTERJSAMPLE; /* Point to where post-IDCT table starts */
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/* End of simple table, rest of first half of post-IDCT table */
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for (i = CENTERJSAMPLE; i < 2*(MAXJSAMPLE+1); i++)
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table[i] = MAXJSAMPLE;
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/* Second half of post-IDCT table */
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MEMZERO(table + (2 * (MAXJSAMPLE+1)),
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(2 * (MAXJSAMPLE+1) - CENTERJSAMPLE) * SIZEOF(JSAMPLE));
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MEMCOPY(table + (4 * (MAXJSAMPLE+1) - CENTERJSAMPLE),
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cinfo->sample_range_limit, CENTERJSAMPLE * SIZEOF(JSAMPLE));
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}
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/*
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* Master selection of decompression modules.
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* This is done once at jpeg_start_decompress time. We determine
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* which modules will be used and give them appropriate initialization calls.
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* We also initialize the decompressor input side to begin consuming data.
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*
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* Since jpeg_read_header has finished, we know what is in the SOF
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* and (first) SOS markers. We also have all the application parameter
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* settings.
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*/
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LOCAL(void)
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master_selection (j_decompress_ptr cinfo)
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{
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my_master_ptr master = (my_master_ptr) cinfo->master;
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boolean use_c_buffer;
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long samplesperrow;
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JDIMENSION jd_samplesperrow;
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/* Initialize dimensions and other stuff */
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jpeg_calc_output_dimensions(cinfo);
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prepare_range_limit_table(cinfo);
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/* Width of an output scanline must be representable as JDIMENSION. */
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samplesperrow = (long) cinfo->output_width * (long) cinfo->out_color_components;
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jd_samplesperrow = (JDIMENSION) samplesperrow;
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if ((long) jd_samplesperrow != samplesperrow)
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ERREXIT(cinfo, JERR_WIDTH_OVERFLOW);
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/* Initialize my private state */
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master->pass_number = 0;
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master->using_merged_upsample = use_merged_upsample(cinfo);
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/* Color quantizer selection */
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master->quantizer_1pass = NULL;
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master->quantizer_2pass = NULL;
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/* No mode changes if not using buffered-image mode. */
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if (! cinfo->quantize_colors || ! cinfo->buffered_image) {
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cinfo->enable_1pass_quant = FALSE;
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cinfo->enable_external_quant = FALSE;
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cinfo->enable_2pass_quant = FALSE;
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}
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if (cinfo->quantize_colors) {
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if (cinfo->raw_data_out)
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ERREXIT(cinfo, JERR_NOTIMPL);
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/* 2-pass quantizer only works in 3-component color space. */
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if (cinfo->out_color_components != 3) {
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cinfo->enable_1pass_quant = TRUE;
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cinfo->enable_external_quant = FALSE;
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cinfo->enable_2pass_quant = FALSE;
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cinfo->colormap = NULL;
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} else if (cinfo->colormap != NULL) {
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cinfo->enable_external_quant = TRUE;
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} else if (cinfo->two_pass_quantize) {
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cinfo->enable_2pass_quant = TRUE;
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} else {
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cinfo->enable_1pass_quant = TRUE;
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}
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if (cinfo->enable_1pass_quant) {
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#ifdef QUANT_1PASS_SUPPORTED
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jinit_1pass_quantizer(cinfo);
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master->quantizer_1pass = cinfo->cquantize;
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#else
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ERREXIT(cinfo, JERR_NOT_COMPILED);
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#endif
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}
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/* We use the 2-pass code to map to external colormaps. */
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if (cinfo->enable_2pass_quant || cinfo->enable_external_quant) {
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#ifdef QUANT_2PASS_SUPPORTED
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jinit_2pass_quantizer(cinfo);
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master->quantizer_2pass = cinfo->cquantize;
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#else
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ERREXIT(cinfo, JERR_NOT_COMPILED);
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#endif
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}
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/* If both quantizers are initialized, the 2-pass one is left active;
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* this is necessary for starting with quantization to an external map.
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*/
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}
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/* Post-processing: in particular, color conversion first */
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if (! cinfo->raw_data_out) {
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if (master->using_merged_upsample) {
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#ifdef UPSAMPLE_MERGING_SUPPORTED
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jinit_merged_upsampler(cinfo); /* does color conversion too */
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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_color_deconverter(cinfo);
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jinit_upsampler(cinfo);
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}
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jinit_d_post_controller(cinfo, cinfo->enable_2pass_quant);
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}
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/* Inverse DCT */
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jinit_inverse_dct(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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/* Initialize principal buffer controllers. */
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use_c_buffer = cinfo->inputctl->has_multiple_scans || cinfo->buffered_image;
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jinit_d_coef_controller(cinfo, use_c_buffer);
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if (! cinfo->raw_data_out)
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jinit_d_main_controller(cinfo, FALSE /* never need full buffer here */);
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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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#ifdef D_MULTISCAN_FILES_SUPPORTED
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/* If jpeg_start_decompress will read the whole file, initialize
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* progress monitoring appropriately. The input step is counted
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* as one pass.
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*/
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if (cinfo->progress != NULL && ! cinfo->buffered_image &&
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cinfo->inputctl->has_multiple_scans) {
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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 {
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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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}
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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 = (cinfo->enable_2pass_quant ? 3 : 2);
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/* Count the input pass as done */
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master->pass_number++;
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}
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#endif /* D_MULTISCAN_FILES_SUPPORTED */
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}
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/*
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* Per-pass setup.
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* This is called at the beginning of each output pass. We determine which
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* modules will be active during this pass and give them appropriate
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* start_pass calls. We also set is_dummy_pass to indicate whether this
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* is a "real" output pass or a dummy pass for color quantization.
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* (In the latter case, jdapistd.c will crank the pass to completion.)
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*/
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METHODDEF(void)
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prepare_for_output_pass (j_decompress_ptr cinfo)
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{
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my_master_ptr master = (my_master_ptr) cinfo->master;
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if (master->pub.is_dummy_pass) {
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#ifdef QUANT_2PASS_SUPPORTED
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/* Final pass of 2-pass quantization */
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master->pub.is_dummy_pass = FALSE;
|
|
(*cinfo->cquantize->start_pass) (cinfo, FALSE);
|
|
(*cinfo->post->start_pass) (cinfo, JBUF_CRANK_DEST);
|
|
(*cinfo->main->start_pass) (cinfo, JBUF_CRANK_DEST);
|
|
#else
|
|
ERREXIT(cinfo, JERR_NOT_COMPILED);
|
|
#endif /* QUANT_2PASS_SUPPORTED */
|
|
} else {
|
|
if (cinfo->quantize_colors && cinfo->colormap == NULL) {
|
|
/* Select new quantization method */
|
|
if (cinfo->two_pass_quantize && cinfo->enable_2pass_quant) {
|
|
cinfo->cquantize = master->quantizer_2pass;
|
|
master->pub.is_dummy_pass = TRUE;
|
|
} else if (cinfo->enable_1pass_quant) {
|
|
cinfo->cquantize = master->quantizer_1pass;
|
|
} else {
|
|
ERREXIT(cinfo, JERR_MODE_CHANGE);
|
|
}
|
|
}
|
|
(*cinfo->idct->start_pass) (cinfo);
|
|
(*cinfo->coef->start_output_pass) (cinfo);
|
|
if (! cinfo->raw_data_out) {
|
|
if (! master->using_merged_upsample)
|
|
(*cinfo->cconvert->start_pass) (cinfo);
|
|
(*cinfo->upsample->start_pass) (cinfo);
|
|
if (cinfo->quantize_colors)
|
|
(*cinfo->cquantize->start_pass) (cinfo, master->pub.is_dummy_pass);
|
|
(*cinfo->post->start_pass) (cinfo,
|
|
(master->pub.is_dummy_pass ? JBUF_SAVE_AND_PASS : JBUF_PASS_THRU));
|
|
(*cinfo->main->start_pass) (cinfo, JBUF_PASS_THRU);
|
|
}
|
|
}
|
|
|
|
/* Set up progress monitor's pass info if present */
|
|
if (cinfo->progress != NULL) {
|
|
cinfo->progress->completed_passes = master->pass_number;
|
|
cinfo->progress->total_passes = master->pass_number +
|
|
(master->pub.is_dummy_pass ? 2 : 1);
|
|
/* In buffered-image mode, we assume one more output pass if EOI not
|
|
* yet reached, but no more passes if EOI has been reached.
|
|
*/
|
|
if (cinfo->buffered_image && ! cinfo->inputctl->eoi_reached) {
|
|
cinfo->progress->total_passes += (cinfo->enable_2pass_quant ? 2 : 1);
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
/*
|
|
* Finish up at end of an output pass.
|
|
*/
|
|
|
|
METHODDEF(void)
|
|
finish_output_pass (j_decompress_ptr cinfo)
|
|
{
|
|
my_master_ptr master = (my_master_ptr) cinfo->master;
|
|
|
|
if (cinfo->quantize_colors)
|
|
(*cinfo->cquantize->finish_pass) (cinfo);
|
|
master->pass_number++;
|
|
}
|
|
|
|
|
|
#ifdef D_MULTISCAN_FILES_SUPPORTED
|
|
|
|
/*
|
|
* Switch to a new external colormap between output passes.
|
|
*/
|
|
|
|
GLOBAL(void)
|
|
jpeg_new_colormap (j_decompress_ptr cinfo)
|
|
{
|
|
my_master_ptr master = (my_master_ptr) cinfo->master;
|
|
|
|
/* Prevent application from calling me at wrong times */
|
|
if (cinfo->global_state != DSTATE_BUFIMAGE)
|
|
ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
|
|
|
|
if (cinfo->quantize_colors && cinfo->enable_external_quant &&
|
|
cinfo->colormap != NULL) {
|
|
/* Select 2-pass quantizer for external colormap use */
|
|
cinfo->cquantize = master->quantizer_2pass;
|
|
/* Notify quantizer of colormap change */
|
|
(*cinfo->cquantize->new_color_map) (cinfo);
|
|
master->pub.is_dummy_pass = FALSE; /* just in case */
|
|
} else
|
|
ERREXIT(cinfo, JERR_MODE_CHANGE);
|
|
}
|
|
|
|
#endif /* D_MULTISCAN_FILES_SUPPORTED */
|
|
|
|
|
|
/*
|
|
* Initialize master decompression control and select active modules.
|
|
* This is performed at the start of jpeg_start_decompress.
|
|
*/
|
|
|
|
GLOBAL(void)
|
|
jinit_master_decompress (j_decompress_ptr cinfo)
|
|
{
|
|
my_master_ptr master;
|
|
|
|
master = (my_master_ptr)
|
|
(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
|
|
SIZEOF(my_decomp_master));
|
|
cinfo->master = (struct jpeg_decomp_master *) master;
|
|
master->pub.prepare_for_output_pass = prepare_for_output_pass;
|
|
master->pub.finish_output_pass = finish_output_pass;
|
|
|
|
master->pub.is_dummy_pass = FALSE;
|
|
|
|
master_selection(cinfo);
|
|
}
|