/* * jdmaster.c * * Copyright (C) 1991-1997, Thomas G. Lane. * 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_scaled_size != cinfo->min_DCT_scaled_size || cinfo->comp_info[1].DCT_scaled_size != cinfo->min_DCT_scaled_size || cinfo->comp_info[2].DCT_scaled_size != cinfo->min_DCT_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 */{#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); #ifdef IDCT_SCALING_SUPPORTED /* Compute actual output image dimensions and DCT scaling choices. */ if (cinfo->scale_num * 8 <= cinfo->scale_denom) { /* Provide 1/8 scaling */ cinfo->output_width = (JDIMENSION) jdiv_round_up((long) cinfo->image_width, 8L); cinfo->output_height = (JDIMENSION) jdiv_round_up((long) cinfo->image_height, 8L); cinfo->min_DCT_scaled_size = 1; } else if (cinfo->scale_num * 4 <= cinfo->scale_denom) { /* Provide 1/4 scaling */ cinfo->output_width = (JDIMENSION) jdiv_round_up((long) cinfo->image_width, 4L); cinfo->output_height = (JDIMENSION) jdiv_round_up((long) cinfo->image_height, 4L); cinfo->min_DCT_scaled_size = 2; } else if (cinfo->scale_num * 2 <= cinfo->scale_denom) { /* Provide 1/2 scaling */ cinfo->output_width = (JDIMENSION) jdiv_round_up((long) cinfo->image_width, 2L); cinfo->output_height = (JDIMENSION) jdiv_round_up((long) cinfo->image_height, 2L); cinfo->min_DCT_scaled_size = 4; } else { /* Provide 1/1 scaling */ cinfo->output_width = cinfo->image_width; cinfo->output_height = cinfo->image_height; cinfo->min_DCT_scaled_size = DCTSIZE; } /* 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 assumes that the supported DCT scalings are powers of 2. */ for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; ci++, compptr++) { int ssize = cinfo->min_DCT_scaled_size; while (ssize < DCTSIZE && (compptr->h_samp_factor * ssize * 2 <= cinfo->max_h_samp_factor * cinfo->min_DCT_scaled_size) && (compptr->v_samp_factor * ssize * 2 <= cinfo->max_v_samp_factor * cinfo->min_DCT_scaled_size)) { ssize = ssize * 2; } compptr->DCT_scaled_size = ssize; } /* 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_scaled_size), (long) (cinfo->max_h_samp_factor * DCTSIZE)); compptr->downsampled_height = (JDIMENSION) jdiv_round_up((long) cinfo->image_height * (long) (compptr->v_samp_factor * compptr->DCT_scaled_size), (long) (cinfo->max_v_samp_factor * DCTSIZE)); } #else /* !IDCT_SCALING_SUPPORTED */ /* Hardwire it to "no scaling" */ cinfo->output_width = cinfo->image_width; cinfo->output_height = cinfo->image_height; /* jdinput.c has already initialized DCT_scaled_size to DCTSIZE, * and has computed unscaled downsampled_width and downsampled_height. */ #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:#if RGB_PIXELSIZE != 3 cinfo->out_color_components = RGB_PIXELSIZE; break;#endif /* else share code with YCbCr */ 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) { ERREXIT(cinfo, JERR_ARITH_NOTIMPL); } else { if (cinfo->progressive_mode) {#ifdef D_PROGRESSIVE_SUPPORTED jinit_phuff_decoder(cinfo);#else ERREXIT(cinfo, JERR_NOT_COMPILED);#endif } 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;Lines 1–500 of 557. Load more
/* * jdmaster.c * * Copyright (C) 1991-1997, Thomas G. Lane. * 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_scaled_size != cinfo->min_DCT_scaled_size || cinfo->comp_info[1].DCT_scaled_size != cinfo->min_DCT_scaled_size || cinfo->comp_info[2].DCT_scaled_size != cinfo->min_DCT_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 */ { #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); #ifdef IDCT_SCALING_SUPPORTED /* Compute actual output image dimensions and DCT scaling choices. */ if (cinfo->scale_num * 8 <= cinfo->scale_denom) { /* Provide 1/8 scaling */ cinfo->output_width = (JDIMENSION) jdiv_round_up((long) cinfo->image_width, 8L); cinfo->output_height = (JDIMENSION) jdiv_round_up((long) cinfo->image_height, 8L); cinfo->min_DCT_scaled_size = 1; } else if (cinfo->scale_num * 4 <= cinfo->scale_denom) { /* Provide 1/4 scaling */ cinfo->output_width = (JDIMENSION) jdiv_round_up((long) cinfo->image_width, 4L); cinfo->output_height = (JDIMENSION) jdiv_round_up((long) cinfo->image_height, 4L); cinfo->min_DCT_scaled_size = 2; } else if (cinfo->scale_num * 2 <= cinfo->scale_denom) { /* Provide 1/2 scaling */ cinfo->output_width = (JDIMENSION) jdiv_round_up((long) cinfo->image_width, 2L); cinfo->output_height = (JDIMENSION) jdiv_round_up((long) cinfo->image_height, 2L); cinfo->min_DCT_scaled_size = 4; } else { /* Provide 1/1 scaling */ cinfo->output_width = cinfo->image_width; cinfo->output_height = cinfo->image_height; cinfo->min_DCT_scaled_size = DCTSIZE; } /* 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 assumes that the supported DCT scalings are powers of 2. */ for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; ci++, compptr++) { int ssize = cinfo->min_DCT_scaled_size; while (ssize < DCTSIZE && (compptr->h_samp_factor * ssize * 2 <= cinfo->max_h_samp_factor * cinfo->min_DCT_scaled_size) && (compptr->v_samp_factor * ssize * 2 <= cinfo->max_v_samp_factor * cinfo->min_DCT_scaled_size)) { ssize = ssize * 2; } compptr->DCT_scaled_size = ssize; } /* 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_scaled_size), (long) (cinfo->max_h_samp_factor * DCTSIZE)); compptr->downsampled_height = (JDIMENSION) jdiv_round_up((long) cinfo->image_height * (long) (compptr->v_samp_factor * compptr->DCT_scaled_size), (long) (cinfo->max_v_samp_factor * DCTSIZE)); } #else /* !IDCT_SCALING_SUPPORTED */ /* Hardwire it to "no scaling" */ cinfo->output_width = cinfo->image_width; cinfo->output_height = cinfo->image_height; /* jdinput.c has already initialized DCT_scaled_size to DCTSIZE, * and has computed unscaled downsampled_width and downsampled_height. */ #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: #if RGB_PIXELSIZE != 3 cinfo->out_color_components = RGB_PIXELSIZE; break; #endif /* else share code with YCbCr */ 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) { ERREXIT(cinfo, JERR_ARITH_NOTIMPL); } else { if (cinfo->progressive_mode) { #ifdef D_PROGRESSIVE_SUPPORTED jinit_phuff_decoder(cinfo); #else ERREXIT(cinfo, JERR_NOT_COMPILED); #endif } 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;