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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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* This file contains input control logic for the JPEG decompressor.
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* These routines are concerned with controlling the decompressor's input
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* processing (marker reading and coefficient decoding). The actual input
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* reading is done in jdmarker.c, jdhuff.c, and jdphuff.c.
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#define JPEG_INTERNALS
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struct jpeg_input_controller pub; /* public fields */
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wxjpeg_boolean inheaders; /* TRUE until first SOS is reached */
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} my_input_controller;
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typedef my_input_controller * my_inputctl_ptr;
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/* Forward declarations */
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METHODDEF(int) consume_markers JPP((j_decompress_ptr cinfo));
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* Routines to calculate various quantities related to the size of the image.
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initial_setup (j_decompress_ptr cinfo)
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/* Called once, when first SOS marker is reached */
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jpeg_component_info *compptr;
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/* Make sure image isn't bigger than I can handle */
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if ((long) cinfo->image_height > (long) JPEG_MAX_DIMENSION ||
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(long) cinfo->image_width > (long) JPEG_MAX_DIMENSION)
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ERREXIT1(cinfo, JERR_IMAGE_TOO_BIG, (unsigned int) JPEG_MAX_DIMENSION);
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/* For now, precision must match compiled-in value... */
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if (cinfo->data_precision != BITS_IN_JSAMPLE)
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ERREXIT1(cinfo, JERR_BAD_PRECISION, cinfo->data_precision);
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/* Check that number of components won't exceed internal array sizes */
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if (cinfo->num_components > MAX_COMPONENTS)
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ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->num_components,
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/* Compute maximum sampling factors; check factor validity */
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cinfo->max_h_samp_factor = 1;
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cinfo->max_v_samp_factor = 1;
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for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
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if (compptr->h_samp_factor<=0 || compptr->h_samp_factor>MAX_SAMP_FACTOR ||
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compptr->v_samp_factor<=0 || compptr->v_samp_factor>MAX_SAMP_FACTOR)
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ERREXIT(cinfo, JERR_BAD_SAMPLING);
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cinfo->max_h_samp_factor = MAX(cinfo->max_h_samp_factor,
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compptr->h_samp_factor);
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cinfo->max_v_samp_factor = MAX(cinfo->max_v_samp_factor,
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compptr->v_samp_factor);
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/* We initialize DCT_scaled_size and min_DCT_scaled_size to DCTSIZE.
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* In the full decompressor, this will be overridden by jdmaster.c;
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* but in the transcoder, jdmaster.c is not used, so we must do it here.
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cinfo->min_DCT_scaled_size = DCTSIZE;
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/* Compute dimensions of components */
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for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
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compptr->DCT_scaled_size = DCTSIZE;
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/* Size in DCT blocks */
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compptr->width_in_blocks = (JDIMENSION)
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jdiv_round_up((long) cinfo->image_width * (long) compptr->h_samp_factor,
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(long) (cinfo->max_h_samp_factor * DCTSIZE));
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compptr->height_in_blocks = (JDIMENSION)
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jdiv_round_up((long) cinfo->image_height * (long) compptr->v_samp_factor,
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(long) (cinfo->max_v_samp_factor * DCTSIZE));
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/* downsampled_width and downsampled_height will also be overridden by
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* jdmaster.c if we are doing full decompression. The transcoder library
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* doesn't use these values, but the calling application might.
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compptr->downsampled_width = (JDIMENSION)
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jdiv_round_up((long) cinfo->image_width * (long) compptr->h_samp_factor,
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(long) cinfo->max_h_samp_factor);
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compptr->downsampled_height = (JDIMENSION)
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jdiv_round_up((long) cinfo->image_height * (long) compptr->v_samp_factor,
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(long) cinfo->max_v_samp_factor);
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/* Mark component needed, until color conversion says otherwise */
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compptr->component_needed = TRUE;
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/* Mark no quantization table yet saved for component */
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compptr->quant_table = NULL;
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/* Compute number of fully interleaved MCU rows. */
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cinfo->total_iMCU_rows = (JDIMENSION)
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jdiv_round_up((long) cinfo->image_height,
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(long) (cinfo->max_v_samp_factor*DCTSIZE));
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/* Decide whether file contains multiple scans */
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if (cinfo->comps_in_scan < cinfo->num_components || cinfo->progressive_mode)
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cinfo->inputctl->has_multiple_scans = TRUE;
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cinfo->inputctl->has_multiple_scans = FALSE;
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per_scan_setup (j_decompress_ptr cinfo)
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/* Do computations that are needed before processing a JPEG scan */
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/* cinfo->comps_in_scan and cinfo->cur_comp_info[] were set from SOS marker */
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int ci, mcublks, tmp;
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jpeg_component_info *compptr;
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if (cinfo->comps_in_scan == 1) {
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/* Noninterleaved (single-component) scan */
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compptr = cinfo->cur_comp_info[0];
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/* Overall image size in MCUs */
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cinfo->MCUs_per_row = compptr->width_in_blocks;
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cinfo->MCU_rows_in_scan = compptr->height_in_blocks;
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/* For noninterleaved scan, always one block per MCU */
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compptr->MCU_width = 1;
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compptr->MCU_height = 1;
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compptr->MCU_blocks = 1;
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compptr->MCU_sample_width = compptr->DCT_scaled_size;
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compptr->last_col_width = 1;
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/* For noninterleaved scans, it is convenient to define last_row_height
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* as the number of block rows present in the last iMCU row.
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tmp = (int) (compptr->height_in_blocks % compptr->v_samp_factor);
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if (tmp == 0) tmp = compptr->v_samp_factor;
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compptr->last_row_height = tmp;
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/* Prepare array describing MCU composition */
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cinfo->blocks_in_MCU = 1;
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cinfo->MCU_membership[0] = 0;
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/* Interleaved (multi-component) scan */
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if (cinfo->comps_in_scan <= 0 || cinfo->comps_in_scan > MAX_COMPS_IN_SCAN)
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ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->comps_in_scan,
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/* Overall image size in MCUs */
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cinfo->MCUs_per_row = (JDIMENSION)
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jdiv_round_up((long) cinfo->image_width,
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(long) (cinfo->max_h_samp_factor*DCTSIZE));
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cinfo->MCU_rows_in_scan = (JDIMENSION)
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jdiv_round_up((long) cinfo->image_height,
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(long) (cinfo->max_v_samp_factor*DCTSIZE));
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cinfo->blocks_in_MCU = 0;
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for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
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compptr = cinfo->cur_comp_info[ci];
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/* Sampling factors give # of blocks of component in each MCU */
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compptr->MCU_width = compptr->h_samp_factor;
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compptr->MCU_height = compptr->v_samp_factor;
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compptr->MCU_blocks = compptr->MCU_width * compptr->MCU_height;
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compptr->MCU_sample_width = compptr->MCU_width * compptr->DCT_scaled_size;
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/* Figure number of non-dummy blocks in last MCU column & row */
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tmp = (int) (compptr->width_in_blocks % compptr->MCU_width);
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if (tmp == 0) tmp = compptr->MCU_width;
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compptr->last_col_width = tmp;
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tmp = (int) (compptr->height_in_blocks % compptr->MCU_height);
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if (tmp == 0) tmp = compptr->MCU_height;
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compptr->last_row_height = tmp;
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/* Prepare array describing MCU composition */
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mcublks = compptr->MCU_blocks;
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if (cinfo->blocks_in_MCU + mcublks > D_MAX_BLOCKS_IN_MCU)
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ERREXIT(cinfo, JERR_BAD_MCU_SIZE);
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while (mcublks-- > 0) {
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cinfo->MCU_membership[cinfo->blocks_in_MCU++] = ci;
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* Save away a copy of the Q-table referenced by each component present
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* in the current scan, unless already saved during a prior scan.
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* In a multiple-scan JPEG file, the encoder could assign different components
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* the same Q-table slot number, but change table definitions between scans
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* so that each component uses a different Q-table. (The IJG encoder is not
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* currently capable of doing this, but other encoders might.) Since we want
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* to be able to dequantize all the components at the end of the file, this
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* means that we have to save away the table actually used for each component.
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* We do this by copying the table at the start of the first scan containing
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* The JPEG spec prohibits the encoder from changing the contents of a Q-table
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* slot between scans of a component using that slot. If the encoder does so
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* anyway, this decoder will simply use the Q-table values that were current
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* at the start of the first scan for the component.
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* The decompressor output side looks only at the saved quant tables,
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* not at the current Q-table slots.
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latch_quant_tables (j_decompress_ptr cinfo)
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jpeg_component_info *compptr;
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for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
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compptr = cinfo->cur_comp_info[ci];
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/* No work if we already saved Q-table for this component */
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if (compptr->quant_table != NULL)
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/* Make sure specified quantization table is present */
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qtblno = compptr->quant_tbl_no;
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if (qtblno < 0 || qtblno >= NUM_QUANT_TBLS ||
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cinfo->quant_tbl_ptrs[qtblno] == NULL)
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ERREXIT1(cinfo, JERR_NO_QUANT_TABLE, qtblno);
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/* OK, save away the quantization table */
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qtbl = (JQUANT_TBL *)
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(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
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MEMCOPY(qtbl, cinfo->quant_tbl_ptrs[qtblno], SIZEOF(JQUANT_TBL));
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compptr->quant_table = qtbl;
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* Initialize the input modules to read a scan of compressed data.
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* The first call to this is done by jdmaster.c after initializing
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* the entire decompressor (during jpeg_start_decompress).
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* Subsequent calls come from consume_markers, below.
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start_input_pass (j_decompress_ptr cinfo)
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per_scan_setup(cinfo);
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latch_quant_tables(cinfo);
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(*cinfo->entropy->start_pass) (cinfo);
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#if defined(__VISAGECPP__)
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(*cinfo->coef->start_input_pass2) (cinfo);
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(*cinfo->coef->start_input_pass) (cinfo);
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cinfo->inputctl->consume_input = cinfo->coef->consume_data;
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* Finish up after inputting a compressed-data scan.
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* This is called by the coefficient controller after it's read all
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* the expected data of the scan.
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finish_input_pass (j_decompress_ptr cinfo)
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cinfo->inputctl->consume_input = consume_markers;
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* Read JPEG markers before, between, or after compressed-data scans.
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* Change state as necessary when a new scan is reached.
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* Return value is JPEG_SUSPENDED, JPEG_REACHED_SOS, or JPEG_REACHED_EOI.
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* The consume_input method pointer points either here or to the
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* coefficient controller's consume_data routine, depending on whether
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* we are reading a compressed data segment or inter-segment markers.
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consume_markers (j_decompress_ptr cinfo)
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my_inputctl_ptr inputctl = (my_inputctl_ptr) cinfo->inputctl;
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if (inputctl->pub.eoi_reached) /* After hitting EOI, read no further */
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return JPEG_REACHED_EOI;
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val = (*cinfo->marker->read_markers) (cinfo);
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case JPEG_REACHED_SOS: /* Found SOS */
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if (inputctl->inheaders) { /* 1st SOS */
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initial_setup(cinfo);
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inputctl->inheaders = FALSE;
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/* Note: start_input_pass must be called by jdmaster.c
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* before any more input can be consumed. jdapimin.c is
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* responsible for enforcing this sequencing.
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} else { /* 2nd or later SOS marker */
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if (! inputctl->pub.has_multiple_scans)
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ERREXIT(cinfo, JERR_EOI_EXPECTED); /* Oops, I wasn't expecting this! */
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start_input_pass(cinfo);
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case JPEG_REACHED_EOI: /* Found EOI */
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inputctl->pub.eoi_reached = TRUE;
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if (inputctl->inheaders) { /* Tables-only datastream, apparently */
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if (cinfo->marker->saw_SOF)
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ERREXIT(cinfo, JERR_SOF_NO_SOS);
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/* Prevent infinite loop in coef ctlr's decompress_data routine
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* if user set output_scan_number larger than number of scans.
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if (cinfo->output_scan_number > cinfo->input_scan_number)
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cinfo->output_scan_number = cinfo->input_scan_number;
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* Reset state to begin a fresh datastream.
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reset_input_controller (j_decompress_ptr cinfo)
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my_inputctl_ptr inputctl = (my_inputctl_ptr) cinfo->inputctl;
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inputctl->pub.consume_input = consume_markers;
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inputctl->pub.has_multiple_scans = FALSE; /* "unknown" would be better */
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inputctl->pub.eoi_reached = FALSE;
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inputctl->inheaders = TRUE;
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/* Reset other modules */
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(*cinfo->err->reset_error_mgr) ((j_common_ptr) cinfo);
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(*cinfo->marker->reset_marker_reader) (cinfo);
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/* Reset progression state -- would be cleaner if entropy decoder did this */
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cinfo->coef_bits = NULL;
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* Initialize the input controller module.
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* This is called only once, when the decompression object is created.
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jinit_input_controller (j_decompress_ptr cinfo)
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my_inputctl_ptr inputctl;
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/* Create subobject in permanent pool */
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inputctl = (my_inputctl_ptr)
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(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
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SIZEOF(my_input_controller));
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cinfo->inputctl = (struct jpeg_input_controller *) inputctl;
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/* Initialize method pointers */
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inputctl->pub.consume_input = consume_markers;
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inputctl->pub.reset_input_controller = reset_input_controller;
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inputctl->pub.start_input_pass = start_input_pass;
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inputctl->pub.finish_input_pass = finish_input_pass;
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/* Initialize state: can't use reset_input_controller since we don't
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* want to try to reset other modules yet.
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inputctl->pub.has_multiple_scans = FALSE; /* "unknown" would be better */
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inputctl->pub.eoi_reached = FALSE;
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inputctl->inheaders = TRUE;
added
removed
src/jpeg/jdinput.c
