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+/*
+ * jdmaster.c
+ *
+ * Copyright (C) 1991-1997, Thomas G. Lane.
+ * Modified 2002-2011 by Guido Vollbeding.
+ * This file is part of the Independent JPEG Group's software.
+ * For conditions of distribution and use, see the accompanying README file.
+ *
+ * This file contains master control logic for the JPEG decompressor.
+ * These routines are concerned with selecting the modules to be executed
+ * and with determining the number of passes and the work to be done in each
+ * pass.
+ */
+
+#define JPEG_INTERNALS
+#include "jinclude.h"
+#include "jpeglib.h"
+
+
+/* Private state */
+
+typedef struct {
+ struct jpeg_decomp_master pub; /* public fields */
+
+ int pass_number; /* # of passes completed */
+
+ boolean using_merged_upsample; /* TRUE if using merged upsample/cconvert */
+
+ /* Saved references to initialized quantizer modules,
+ * in case we need to switch modes.
+ */
+ struct jpeg_color_quantizer * quantizer_1pass;
+ struct jpeg_color_quantizer * quantizer_2pass;
+} my_decomp_master;
+
+typedef my_decomp_master * my_master_ptr;
+
+
+/*
+ * Determine whether merged upsample/color conversion should be used.
+ * CRUCIAL: this must match the actual capabilities of jdmerge.c!
+ */
+
+LOCAL(boolean)
+use_merged_upsample (j_decompress_ptr cinfo)
+{
+#ifdef UPSAMPLE_MERGING_SUPPORTED
+ /* Merging is the equivalent of plain box-filter upsampling */
+ if (cinfo->do_fancy_upsampling || cinfo->CCIR601_sampling)
+ return FALSE;
+ /* jdmerge.c only supports YCC=>RGB color conversion */
+ if (cinfo->jpeg_color_space != JCS_YCbCr || cinfo->num_components != 3 ||
+ cinfo->out_color_space != JCS_RGB ||
+ cinfo->out_color_components != RGB_PIXELSIZE)
+ return FALSE;
+ /* and it only handles 2h1v or 2h2v sampling ratios */
+ if (cinfo->comp_info[0].h_samp_factor != 2 ||
+ cinfo->comp_info[1].h_samp_factor != 1 ||
+ cinfo->comp_info[2].h_samp_factor != 1 ||
+ cinfo->comp_info[0].v_samp_factor > 2 ||
+ cinfo->comp_info[1].v_samp_factor != 1 ||
+ cinfo->comp_info[2].v_samp_factor != 1)
+ return FALSE;
+ /* furthermore, it doesn't work if we've scaled the IDCTs differently */
+ if (cinfo->comp_info[0].DCT_h_scaled_size != cinfo->min_DCT_h_scaled_size ||
+ cinfo->comp_info[1].DCT_h_scaled_size != cinfo->min_DCT_h_scaled_size ||
+ cinfo->comp_info[2].DCT_h_scaled_size != cinfo->min_DCT_h_scaled_size ||
+ cinfo->comp_info[0].DCT_v_scaled_size != cinfo->min_DCT_v_scaled_size ||
+ cinfo->comp_info[1].DCT_v_scaled_size != cinfo->min_DCT_v_scaled_size ||
+ cinfo->comp_info[2].DCT_v_scaled_size != cinfo->min_DCT_v_scaled_size)
+ return FALSE;
+ /* ??? also need to test for upsample-time rescaling, when & if supported */
+ return TRUE; /* by golly, it'll work... */
+#else
+ return FALSE;
+#endif
+}
+
+
+/*
+ * Compute output image dimensions and related values.
+ * NOTE: this is exported for possible use by application.
+ * Hence it mustn't do anything that can't be done twice.
+ * Also note that it may be called before the master module is initialized!
+ */
+
+GLOBAL(void)
+jpeg_calc_output_dimensions (j_decompress_ptr cinfo)
+/* Do computations that are needed before master selection phase.
+ * This function is used for full decompression.
+ */
+{
+#ifdef IDCT_SCALING_SUPPORTED
+ int ci;
+ jpeg_component_info *compptr;
+#endif
+
+ /* Prevent application from calling me at wrong times */
+ if (cinfo->global_state != DSTATE_READY)
+ ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
+
+ /* Compute core output image dimensions and DCT scaling choices. */
+ jpeg_core_output_dimensions(cinfo);
+
+#ifdef IDCT_SCALING_SUPPORTED
+
+ /* In selecting the actual DCT scaling for each component, we try to
+ * scale up the chroma components via IDCT scaling rather than upsampling.
+ * This saves time if the upsampler gets to use 1:1 scaling.
+ * Note this code adapts subsampling ratios which are powers of 2.
+ */
+ for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
+ ci++, compptr++) {
+ int ssize = 1;
+ while (cinfo->min_DCT_h_scaled_size * ssize <=
+ (cinfo->do_fancy_upsampling ? DCTSIZE : DCTSIZE / 2) &&
+ (cinfo->max_h_samp_factor % (compptr->h_samp_factor * ssize * 2)) == 0) {
+ ssize = ssize * 2;
+ }
+ compptr->DCT_h_scaled_size = cinfo->min_DCT_h_scaled_size * ssize;
+ ssize = 1;
+ while (cinfo->min_DCT_v_scaled_size * ssize <=
+ (cinfo->do_fancy_upsampling ? DCTSIZE : DCTSIZE / 2) &&
+ (cinfo->max_v_samp_factor % (compptr->v_samp_factor * ssize * 2)) == 0) {
+ ssize = ssize * 2;
+ }
+ compptr->DCT_v_scaled_size = cinfo->min_DCT_v_scaled_size * ssize;
+
+ /* We don't support IDCT ratios larger than 2. */
+ if (compptr->DCT_h_scaled_size > compptr->DCT_v_scaled_size * 2)
+ compptr->DCT_h_scaled_size = compptr->DCT_v_scaled_size * 2;
+ else if (compptr->DCT_v_scaled_size > compptr->DCT_h_scaled_size * 2)
+ compptr->DCT_v_scaled_size = compptr->DCT_h_scaled_size * 2;
+ }
+
+ /* Recompute downsampled dimensions of components;
+ * application needs to know these if using raw downsampled data.
+ */
+ for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
+ ci++, compptr++) {
+ /* Size in samples, after IDCT scaling */
+ compptr->downsampled_width = (JDIMENSION)
+ jdiv_round_up((long) cinfo->image_width *
+ (long) (compptr->h_samp_factor * compptr->DCT_h_scaled_size),
+ (long) (cinfo->max_h_samp_factor * cinfo->block_size));
+ compptr->downsampled_height = (JDIMENSION)
+ jdiv_round_up((long) cinfo->image_height *
+ (long) (compptr->v_samp_factor * compptr->DCT_v_scaled_size),
+ (long) (cinfo->max_v_samp_factor * cinfo->block_size));
+ }
+
+#endif /* IDCT_SCALING_SUPPORTED */
+
+ /* Report number of components in selected colorspace. */
+ /* Probably this should be in the color conversion module... */
+ switch (cinfo->out_color_space) {
+ case JCS_GRAYSCALE:
+ cinfo->out_color_components = 1;
+ break;
+ case JCS_RGB:
+ cinfo->out_color_components = RGB_PIXELSIZE;
+ break;
+ case JCS_YCbCr:
+ cinfo->out_color_components = 3;
+ break;
+ case JCS_CMYK:
+ case JCS_YCCK:
+ cinfo->out_color_components = 4;
+ break;
+ default: /* else must be same colorspace as in file */
+ cinfo->out_color_components = cinfo->num_components;
+ break;
+ }
+ cinfo->output_components = (cinfo->quantize_colors ? 1 :
+ cinfo->out_color_components);
+
+ /* See if upsampler will want to emit more than one row at a time */
+ if (use_merged_upsample(cinfo))
+ cinfo->rec_outbuf_height = cinfo->max_v_samp_factor;
+ else
+ cinfo->rec_outbuf_height = 1;
+}
+
+
+/*
+ * Several decompression processes need to range-limit values to the range
+ * 0..MAXJSAMPLE; the input value may fall somewhat outside this range
+ * due to noise introduced by quantization, roundoff error, etc. These
+ * processes are inner loops and need to be as fast as possible. On most
+ * machines, particularly CPUs with pipelines or instruction prefetch,
+ * a (subscript-check-less) C table lookup
+ * x = sample_range_limit[x];
+ * is faster than explicit tests
+ * if (x < 0) x = 0;
+ * else if (x > MAXJSAMPLE) x = MAXJSAMPLE;
+ * These processes all use a common table prepared by the routine below.
+ *
+ * For most steps we can mathematically guarantee that the initial value
+ * of x is within MAXJSAMPLE+1 of the legal range, so a table running from
+ * -(MAXJSAMPLE+1) to 2*MAXJSAMPLE+1 is sufficient. But for the initial
+ * limiting step (just after the IDCT), a wildly out-of-range value is
+ * possible if the input data is corrupt. To avoid any chance of indexing
+ * off the end of memory and getting a bad-pointer trap, we perform the
+ * post-IDCT limiting thus:
+ * x = range_limit[x & MASK];
+ * where MASK is 2 bits wider than legal sample data, ie 10 bits for 8-bit
+ * samples. Under normal circumstances this is more than enough range and
+ * a correct output will be generated; with bogus input data the mask will
+ * cause wraparound, and we will safely generate a bogus-but-in-range output.
+ * For the post-IDCT step, we want to convert the data from signed to unsigned
+ * representation by adding CENTERJSAMPLE at the same time that we limit it.
+ * So the post-IDCT limiting table ends up looking like this:
+ * CENTERJSAMPLE,CENTERJSAMPLE+1,...,MAXJSAMPLE,
+ * MAXJSAMPLE (repeat 2*(MAXJSAMPLE+1)-CENTERJSAMPLE times),
+ * 0 (repeat 2*(MAXJSAMPLE+1)-CENTERJSAMPLE times),
+ * 0,1,...,CENTERJSAMPLE-1
+ * Negative inputs select values from the upper half of the table after
+ * masking.
+ *
+ * We can save some space by overlapping the start of the post-IDCT table
+ * with the simpler range limiting table. The post-IDCT table begins at
+ * sample_range_limit + CENTERJSAMPLE.
+ *
+ * Note that the table is allocated in near data space on PCs; it's small
+ * enough and used often enough to justify this.
+ */
+
+LOCAL(void)
+prepare_range_limit_table (j_decompress_ptr cinfo)
+/* Allocate and fill in the sample_range_limit table */
+{
+ JSAMPLE * table;
+ int i;
+
+ table = (JSAMPLE *)
+ (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
+ (5 * (MAXJSAMPLE+1) + CENTERJSAMPLE) * SIZEOF(JSAMPLE));
+ table += (MAXJSAMPLE+1); /* allow negative subscripts of simple table */
+ cinfo->sample_range_limit = table;
+ /* First segment of "simple" table: limit[x] = 0 for x < 0 */
+ MEMZERO(table - (MAXJSAMPLE+1), (MAXJSAMPLE+1) * SIZEOF(JSAMPLE));
+ /* Main part of "simple" table: limit[x] = x */
+ for (i = 0; i <= MAXJSAMPLE; i++)
+ table[i] = (JSAMPLE) i;
+ table += CENTERJSAMPLE; /* Point to where post-IDCT table starts */
+ /* End of simple table, rest of first half of post-IDCT table */
+ for (i = CENTERJSAMPLE; i < 2*(MAXJSAMPLE+1); i++)
+ table[i] = MAXJSAMPLE;
+ /* Second half of post-IDCT table */
+ MEMZERO(table + (2 * (MAXJSAMPLE+1)),
+ (2 * (MAXJSAMPLE+1) - CENTERJSAMPLE) * SIZEOF(JSAMPLE));
+ MEMCOPY(table + (4 * (MAXJSAMPLE+1) - CENTERJSAMPLE),
+ cinfo->sample_range_limit, CENTERJSAMPLE * SIZEOF(JSAMPLE));
+}
+
+
+/*
+ * Master selection of decompression modules.
+ * This is done once at jpeg_start_decompress time. We determine
+ * which modules will be used and give them appropriate initialization calls.
+ * We also initialize the decompressor input side to begin consuming data.
+ *
+ * Since jpeg_read_header has finished, we know what is in the SOF
+ * and (first) SOS markers. We also have all the application parameter
+ * settings.
+ */
+
+LOCAL(void)
+master_selection (j_decompress_ptr cinfo)
+{
+ my_master_ptr master = (my_master_ptr) cinfo->master;
+ boolean use_c_buffer;
+ long samplesperrow;
+ JDIMENSION jd_samplesperrow;
+
+ /* Initialize dimensions and other stuff */
+ jpeg_calc_output_dimensions(cinfo);
+ prepare_range_limit_table(cinfo);
+
+ /* Width of an output scanline must be representable as JDIMENSION. */
+ samplesperrow = (long) cinfo->output_width * (long) cinfo->out_color_components;
+ jd_samplesperrow = (JDIMENSION) samplesperrow;
+ if ((long) jd_samplesperrow != samplesperrow)
+ ERREXIT(cinfo, JERR_WIDTH_OVERFLOW);
+
+ /* Initialize my private state */
+ master->pass_number = 0;
+ master->using_merged_upsample = use_merged_upsample(cinfo);
+
+ /* Color quantizer selection */
+ master->quantizer_1pass = NULL;
+ master->quantizer_2pass = NULL;
+ /* No mode changes if not using buffered-image mode. */
+ if (! cinfo->quantize_colors || ! cinfo->buffered_image) {
+ cinfo->enable_1pass_quant = FALSE;
+ cinfo->enable_external_quant = FALSE;
+ cinfo->enable_2pass_quant = FALSE;
+ }
+ if (cinfo->quantize_colors) {
+ if (cinfo->raw_data_out)
+ ERREXIT(cinfo, JERR_NOTIMPL);
+ /* 2-pass quantizer only works in 3-component color space. */
+ if (cinfo->out_color_components != 3) {
+ cinfo->enable_1pass_quant = TRUE;
+ cinfo->enable_external_quant = FALSE;
+ cinfo->enable_2pass_quant = FALSE;
+ cinfo->colormap = NULL;
+ } else if (cinfo->colormap != NULL) {
+ cinfo->enable_external_quant = TRUE;
+ } else if (cinfo->two_pass_quantize) {
+ cinfo->enable_2pass_quant = TRUE;
+ } else {
+ cinfo->enable_1pass_quant = TRUE;
+ }
+
+ if (cinfo->enable_1pass_quant) {
+#ifdef QUANT_1PASS_SUPPORTED
+ jinit_1pass_quantizer(cinfo);
+ master->quantizer_1pass = cinfo->cquantize;
+#else
+ ERREXIT(cinfo, JERR_NOT_COMPILED);
+#endif
+ }
+
+ /* We use the 2-pass code to map to external colormaps. */
+ if (cinfo->enable_2pass_quant || cinfo->enable_external_quant) {
+#ifdef QUANT_2PASS_SUPPORTED
+ jinit_2pass_quantizer(cinfo);
+ master->quantizer_2pass = cinfo->cquantize;
+#else
+ ERREXIT(cinfo, JERR_NOT_COMPILED);
+#endif
+ }
+ /* If both quantizers are initialized, the 2-pass one is left active;
+ * this is necessary for starting with quantization to an external map.
+ */
+ }
+
+ /* Post-processing: in particular, color conversion first */
+ if (! cinfo->raw_data_out) {
+ if (master->using_merged_upsample) {
+#ifdef UPSAMPLE_MERGING_SUPPORTED
+ jinit_merged_upsampler(cinfo); /* does color conversion too */
+#else
+ ERREXIT(cinfo, JERR_NOT_COMPILED);
+#endif
+ } else {
+ jinit_color_deconverter(cinfo);
+ jinit_upsampler(cinfo);
+ }
+ jinit_d_post_controller(cinfo, cinfo->enable_2pass_quant);
+ }
+ /* Inverse DCT */
+ jinit_inverse_dct(cinfo);
+ /* Entropy decoding: either Huffman or arithmetic coding. */
+ if (cinfo->arith_code)
+ jinit_arith_decoder(cinfo);
+ else {
+ jinit_huff_decoder(cinfo);
+ }
+
+ /* Initialize principal buffer controllers. */
+ use_c_buffer = cinfo->inputctl->has_multiple_scans || cinfo->buffered_image;
+ jinit_d_coef_controller(cinfo, use_c_buffer);
+
+ if (! cinfo->raw_data_out)
+ jinit_d_main_controller(cinfo, FALSE /* never need full buffer here */);
+
+ /* We can now tell the memory manager to allocate virtual arrays. */
+ (*cinfo->mem->realize_virt_arrays) ((j_common_ptr) cinfo);
+
+ /* Initialize input side of decompressor to consume first scan. */
+ (*cinfo->inputctl->start_input_pass) (cinfo);
+
+#ifdef D_MULTISCAN_FILES_SUPPORTED
+ /* If jpeg_start_decompress will read the whole file, initialize
+ * progress monitoring appropriately. The input step is counted
+ * as one pass.
+ */
+ if (cinfo->progress != NULL && ! cinfo->buffered_image &&
+ cinfo->inputctl->has_multiple_scans) {
+ int nscans;
+ /* Estimate number of scans to set pass_limit. */
+ if (cinfo->progressive_mode) {
+ /* Arbitrarily estimate 2 interleaved DC scans + 3 AC scans/component. */
+ nscans = 2 + 3 * cinfo->num_components;
+ } else {
+ /* For a nonprogressive multiscan file, estimate 1 scan per component. */
+ nscans = cinfo->num_components;
+ }
+ cinfo->progress->pass_counter = 0L;
+ cinfo->progress->pass_limit = (long) cinfo->total_iMCU_rows * nscans;
+ cinfo->progress->completed_passes = 0;
+ cinfo->progress->total_passes = (cinfo->enable_2pass_quant ? 3 : 2);
+ /* Count the input pass as done */
+ master->pass_number++;
+ }
+#endif /* D_MULTISCAN_FILES_SUPPORTED */
+}
+
+
+/*
+ * Per-pass setup.
+ * This is called at the beginning of each output pass. We determine which
+ * modules will be active during this pass and give them appropriate
+ * start_pass calls. We also set is_dummy_pass to indicate whether this
+ * is a "real" output pass or a dummy pass for color quantization.
+ * (In the latter case, jdapistd.c will crank the pass to completion.)
+ */
+
+METHODDEF(void)
+prepare_for_output_pass (j_decompress_ptr cinfo)
+{
+ my_master_ptr master = (my_master_ptr) cinfo->master;
+
+ if (master->pub.is_dummy_pass) {
+#ifdef QUANT_2PASS_SUPPORTED
+ /* Final pass of 2-pass quantization */
+ 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);
+}