nuclear@2: /*
nuclear@2:  * jdinput.c
nuclear@2:  *
nuclear@2:  * Copyright (C) 1991-1997, Thomas G. Lane.
nuclear@2:  * This file is part of the Independent JPEG Group's software.
nuclear@2:  * For conditions of distribution and use, see the accompanying README file.
nuclear@2:  *
nuclear@2:  * This file contains input control logic for the JPEG decompressor.
nuclear@2:  * These routines are concerned with controlling the decompressor's input
nuclear@2:  * processing (marker reading and coefficient decoding).  The actual input
nuclear@2:  * reading is done in jdmarker.c, jdhuff.c, and jdphuff.c.
nuclear@2:  */
nuclear@2: 
nuclear@2: #define JPEG_INTERNALS
nuclear@2: #include "jinclude.h"
nuclear@2: #include "jpeglib.h"
nuclear@2: 
nuclear@2: 
nuclear@2: /* Private state */
nuclear@2: 
nuclear@2: typedef struct {
nuclear@2:   struct jpeg_input_controller pub; /* public fields */
nuclear@2: 
nuclear@2:   boolean inheaders;		/* TRUE until first SOS is reached */
nuclear@2: } my_input_controller;
nuclear@2: 
nuclear@2: typedef my_input_controller * my_inputctl_ptr;
nuclear@2: 
nuclear@2: 
nuclear@2: /* Forward declarations */
nuclear@2: METHODDEF(int) consume_markers JPP((j_decompress_ptr cinfo));
nuclear@2: 
nuclear@2: 
nuclear@2: /*
nuclear@2:  * Routines to calculate various quantities related to the size of the image.
nuclear@2:  */
nuclear@2: 
nuclear@2: LOCAL(void)
nuclear@2: initial_setup (j_decompress_ptr cinfo)
nuclear@2: /* Called once, when first SOS marker is reached */
nuclear@2: {
nuclear@2:   int ci;
nuclear@2:   jpeg_component_info *compptr;
nuclear@2: 
nuclear@2:   /* Make sure image isn't bigger than I can handle */
nuclear@2:   if ((long) cinfo->image_height > (long) JPEG_MAX_DIMENSION ||
nuclear@2:       (long) cinfo->image_width > (long) JPEG_MAX_DIMENSION)
nuclear@2:     ERREXIT1(cinfo, JERR_IMAGE_TOO_BIG, (unsigned int) JPEG_MAX_DIMENSION);
nuclear@2: 
nuclear@2:   /* For now, precision must match compiled-in value... */
nuclear@2:   if (cinfo->data_precision != BITS_IN_JSAMPLE)
nuclear@2:     ERREXIT1(cinfo, JERR_BAD_PRECISION, cinfo->data_precision);
nuclear@2: 
nuclear@2:   /* Check that number of components won't exceed internal array sizes */
nuclear@2:   if (cinfo->num_components > MAX_COMPONENTS)
nuclear@2:     ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->num_components,
nuclear@2: 	     MAX_COMPONENTS);
nuclear@2: 
nuclear@2:   /* Compute maximum sampling factors; check factor validity */
nuclear@2:   cinfo->max_h_samp_factor = 1;
nuclear@2:   cinfo->max_v_samp_factor = 1;
nuclear@2:   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
nuclear@2:        ci++, compptr++) {
nuclear@2:     if (compptr->h_samp_factor<=0 || compptr->h_samp_factor>MAX_SAMP_FACTOR ||
nuclear@2: 	compptr->v_samp_factor<=0 || compptr->v_samp_factor>MAX_SAMP_FACTOR)
nuclear@2:       ERREXIT(cinfo, JERR_BAD_SAMPLING);
nuclear@2:     cinfo->max_h_samp_factor = MAX(cinfo->max_h_samp_factor,
nuclear@2: 				   compptr->h_samp_factor);
nuclear@2:     cinfo->max_v_samp_factor = MAX(cinfo->max_v_samp_factor,
nuclear@2: 				   compptr->v_samp_factor);
nuclear@2:   }
nuclear@2: 
nuclear@2:   /* We initialize DCT_scaled_size and min_DCT_scaled_size to DCTSIZE.
nuclear@2:    * In the full decompressor, this will be overridden by jdmaster.c;
nuclear@2:    * but in the transcoder, jdmaster.c is not used, so we must do it here.
nuclear@2:    */
nuclear@2:   cinfo->min_DCT_scaled_size = DCTSIZE;
nuclear@2: 
nuclear@2:   /* Compute dimensions of components */
nuclear@2:   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
nuclear@2:        ci++, compptr++) {
nuclear@2:     compptr->DCT_scaled_size = DCTSIZE;
nuclear@2:     /* Size in DCT blocks */
nuclear@2:     compptr->width_in_blocks = (JDIMENSION)
nuclear@2:       jdiv_round_up((long) cinfo->image_width * (long) compptr->h_samp_factor,
nuclear@2: 		    (long) (cinfo->max_h_samp_factor * DCTSIZE));
nuclear@2:     compptr->height_in_blocks = (JDIMENSION)
nuclear@2:       jdiv_round_up((long) cinfo->image_height * (long) compptr->v_samp_factor,
nuclear@2: 		    (long) (cinfo->max_v_samp_factor * DCTSIZE));
nuclear@2:     /* downsampled_width and downsampled_height will also be overridden by
nuclear@2:      * jdmaster.c if we are doing full decompression.  The transcoder library
nuclear@2:      * doesn't use these values, but the calling application might.
nuclear@2:      */
nuclear@2:     /* Size in samples */
nuclear@2:     compptr->downsampled_width = (JDIMENSION)
nuclear@2:       jdiv_round_up((long) cinfo->image_width * (long) compptr->h_samp_factor,
nuclear@2: 		    (long) cinfo->max_h_samp_factor);
nuclear@2:     compptr->downsampled_height = (JDIMENSION)
nuclear@2:       jdiv_round_up((long) cinfo->image_height * (long) compptr->v_samp_factor,
nuclear@2: 		    (long) cinfo->max_v_samp_factor);
nuclear@2:     /* Mark component needed, until color conversion says otherwise */
nuclear@2:     compptr->component_needed = TRUE;
nuclear@2:     /* Mark no quantization table yet saved for component */
nuclear@2:     compptr->quant_table = NULL;
nuclear@2:   }
nuclear@2: 
nuclear@2:   /* Compute number of fully interleaved MCU rows. */
nuclear@2:   cinfo->total_iMCU_rows = (JDIMENSION)
nuclear@2:     jdiv_round_up((long) cinfo->image_height,
nuclear@2: 		  (long) (cinfo->max_v_samp_factor*DCTSIZE));
nuclear@2: 
nuclear@2:   /* Decide whether file contains multiple scans */
nuclear@2:   if (cinfo->comps_in_scan < cinfo->num_components || cinfo->progressive_mode)
nuclear@2:     cinfo->inputctl->has_multiple_scans = TRUE;
nuclear@2:   else
nuclear@2:     cinfo->inputctl->has_multiple_scans = FALSE;
nuclear@2: }
nuclear@2: 
nuclear@2: 
nuclear@2: LOCAL(void)
nuclear@2: per_scan_setup (j_decompress_ptr cinfo)
nuclear@2: /* Do computations that are needed before processing a JPEG scan */
nuclear@2: /* cinfo->comps_in_scan and cinfo->cur_comp_info[] were set from SOS marker */
nuclear@2: {
nuclear@2:   int ci, mcublks, tmp;
nuclear@2:   jpeg_component_info *compptr;
nuclear@2:   
nuclear@2:   if (cinfo->comps_in_scan == 1) {
nuclear@2:     
nuclear@2:     /* Noninterleaved (single-component) scan */
nuclear@2:     compptr = cinfo->cur_comp_info[0];
nuclear@2:     
nuclear@2:     /* Overall image size in MCUs */
nuclear@2:     cinfo->MCUs_per_row = compptr->width_in_blocks;
nuclear@2:     cinfo->MCU_rows_in_scan = compptr->height_in_blocks;
nuclear@2:     
nuclear@2:     /* For noninterleaved scan, always one block per MCU */
nuclear@2:     compptr->MCU_width = 1;
nuclear@2:     compptr->MCU_height = 1;
nuclear@2:     compptr->MCU_blocks = 1;
nuclear@2:     compptr->MCU_sample_width = compptr->DCT_scaled_size;
nuclear@2:     compptr->last_col_width = 1;
nuclear@2:     /* For noninterleaved scans, it is convenient to define last_row_height
nuclear@2:      * as the number of block rows present in the last iMCU row.
nuclear@2:      */
nuclear@2:     tmp = (int) (compptr->height_in_blocks % compptr->v_samp_factor);
nuclear@2:     if (tmp == 0) tmp = compptr->v_samp_factor;
nuclear@2:     compptr->last_row_height = tmp;
nuclear@2:     
nuclear@2:     /* Prepare array describing MCU composition */
nuclear@2:     cinfo->blocks_in_MCU = 1;
nuclear@2:     cinfo->MCU_membership[0] = 0;
nuclear@2:     
nuclear@2:   } else {
nuclear@2:     
nuclear@2:     /* Interleaved (multi-component) scan */
nuclear@2:     if (cinfo->comps_in_scan <= 0 || cinfo->comps_in_scan > MAX_COMPS_IN_SCAN)
nuclear@2:       ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->comps_in_scan,
nuclear@2: 	       MAX_COMPS_IN_SCAN);
nuclear@2:     
nuclear@2:     /* Overall image size in MCUs */
nuclear@2:     cinfo->MCUs_per_row = (JDIMENSION)
nuclear@2:       jdiv_round_up((long) cinfo->image_width,
nuclear@2: 		    (long) (cinfo->max_h_samp_factor*DCTSIZE));
nuclear@2:     cinfo->MCU_rows_in_scan = (JDIMENSION)
nuclear@2:       jdiv_round_up((long) cinfo->image_height,
nuclear@2: 		    (long) (cinfo->max_v_samp_factor*DCTSIZE));
nuclear@2:     
nuclear@2:     cinfo->blocks_in_MCU = 0;
nuclear@2:     
nuclear@2:     for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
nuclear@2:       compptr = cinfo->cur_comp_info[ci];
nuclear@2:       /* Sampling factors give # of blocks of component in each MCU */
nuclear@2:       compptr->MCU_width = compptr->h_samp_factor;
nuclear@2:       compptr->MCU_height = compptr->v_samp_factor;
nuclear@2:       compptr->MCU_blocks = compptr->MCU_width * compptr->MCU_height;
nuclear@2:       compptr->MCU_sample_width = compptr->MCU_width * compptr->DCT_scaled_size;
nuclear@2:       /* Figure number of non-dummy blocks in last MCU column & row */
nuclear@2:       tmp = (int) (compptr->width_in_blocks % compptr->MCU_width);
nuclear@2:       if (tmp == 0) tmp = compptr->MCU_width;
nuclear@2:       compptr->last_col_width = tmp;
nuclear@2:       tmp = (int) (compptr->height_in_blocks % compptr->MCU_height);
nuclear@2:       if (tmp == 0) tmp = compptr->MCU_height;
nuclear@2:       compptr->last_row_height = tmp;
nuclear@2:       /* Prepare array describing MCU composition */
nuclear@2:       mcublks = compptr->MCU_blocks;
nuclear@2:       if (cinfo->blocks_in_MCU + mcublks > D_MAX_BLOCKS_IN_MCU)
nuclear@2: 	ERREXIT(cinfo, JERR_BAD_MCU_SIZE);
nuclear@2:       while (mcublks-- > 0) {
nuclear@2: 	cinfo->MCU_membership[cinfo->blocks_in_MCU++] = ci;
nuclear@2:       }
nuclear@2:     }
nuclear@2:     
nuclear@2:   }
nuclear@2: }
nuclear@2: 
nuclear@2: 
nuclear@2: /*
nuclear@2:  * Save away a copy of the Q-table referenced by each component present
nuclear@2:  * in the current scan, unless already saved during a prior scan.
nuclear@2:  *
nuclear@2:  * In a multiple-scan JPEG file, the encoder could assign different components
nuclear@2:  * the same Q-table slot number, but change table definitions between scans
nuclear@2:  * so that each component uses a different Q-table.  (The IJG encoder is not
nuclear@2:  * currently capable of doing this, but other encoders might.)  Since we want
nuclear@2:  * to be able to dequantize all the components at the end of the file, this
nuclear@2:  * means that we have to save away the table actually used for each component.
nuclear@2:  * We do this by copying the table at the start of the first scan containing
nuclear@2:  * the component.
nuclear@2:  * The JPEG spec prohibits the encoder from changing the contents of a Q-table
nuclear@2:  * slot between scans of a component using that slot.  If the encoder does so
nuclear@2:  * anyway, this decoder will simply use the Q-table values that were current
nuclear@2:  * at the start of the first scan for the component.
nuclear@2:  *
nuclear@2:  * The decompressor output side looks only at the saved quant tables,
nuclear@2:  * not at the current Q-table slots.
nuclear@2:  */
nuclear@2: 
nuclear@2: LOCAL(void)
nuclear@2: latch_quant_tables (j_decompress_ptr cinfo)
nuclear@2: {
nuclear@2:   int ci, qtblno;
nuclear@2:   jpeg_component_info *compptr;
nuclear@2:   JQUANT_TBL * qtbl;
nuclear@2: 
nuclear@2:   for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
nuclear@2:     compptr = cinfo->cur_comp_info[ci];
nuclear@2:     /* No work if we already saved Q-table for this component */
nuclear@2:     if (compptr->quant_table != NULL)
nuclear@2:       continue;
nuclear@2:     /* Make sure specified quantization table is present */
nuclear@2:     qtblno = compptr->quant_tbl_no;
nuclear@2:     if (qtblno < 0 || qtblno >= NUM_QUANT_TBLS ||
nuclear@2: 	cinfo->quant_tbl_ptrs[qtblno] == NULL)
nuclear@2:       ERREXIT1(cinfo, JERR_NO_QUANT_TABLE, qtblno);
nuclear@2:     /* OK, save away the quantization table */
nuclear@2:     qtbl = (JQUANT_TBL *)
nuclear@2:       (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
nuclear@2: 				  SIZEOF(JQUANT_TBL));
nuclear@2:     MEMCOPY(qtbl, cinfo->quant_tbl_ptrs[qtblno], SIZEOF(JQUANT_TBL));
nuclear@2:     compptr->quant_table = qtbl;
nuclear@2:   }
nuclear@2: }
nuclear@2: 
nuclear@2: 
nuclear@2: /*
nuclear@2:  * Initialize the input modules to read a scan of compressed data.
nuclear@2:  * The first call to this is done by jdmaster.c after initializing
nuclear@2:  * the entire decompressor (during jpeg_start_decompress).
nuclear@2:  * Subsequent calls come from consume_markers, below.
nuclear@2:  */
nuclear@2: 
nuclear@2: METHODDEF(void)
nuclear@2: start_input_pass (j_decompress_ptr cinfo)
nuclear@2: {
nuclear@2:   per_scan_setup(cinfo);
nuclear@2:   latch_quant_tables(cinfo);
nuclear@2:   (*cinfo->entropy->start_pass) (cinfo);
nuclear@2:   (*cinfo->coef->start_input_pass) (cinfo);
nuclear@2:   cinfo->inputctl->consume_input = cinfo->coef->consume_data;
nuclear@2: }
nuclear@2: 
nuclear@2: 
nuclear@2: /*
nuclear@2:  * Finish up after inputting a compressed-data scan.
nuclear@2:  * This is called by the coefficient controller after it's read all
nuclear@2:  * the expected data of the scan.
nuclear@2:  */
nuclear@2: 
nuclear@2: METHODDEF(void)
nuclear@2: finish_input_pass (j_decompress_ptr cinfo)
nuclear@2: {
nuclear@2:   cinfo->inputctl->consume_input = consume_markers;
nuclear@2: }
nuclear@2: 
nuclear@2: 
nuclear@2: /*
nuclear@2:  * Read JPEG markers before, between, or after compressed-data scans.
nuclear@2:  * Change state as necessary when a new scan is reached.
nuclear@2:  * Return value is JPEG_SUSPENDED, JPEG_REACHED_SOS, or JPEG_REACHED_EOI.
nuclear@2:  *
nuclear@2:  * The consume_input method pointer points either here or to the
nuclear@2:  * coefficient controller's consume_data routine, depending on whether
nuclear@2:  * we are reading a compressed data segment or inter-segment markers.
nuclear@2:  */
nuclear@2: 
nuclear@2: METHODDEF(int)
nuclear@2: consume_markers (j_decompress_ptr cinfo)
nuclear@2: {
nuclear@2:   my_inputctl_ptr inputctl = (my_inputctl_ptr) cinfo->inputctl;
nuclear@2:   int val;
nuclear@2: 
nuclear@2:   if (inputctl->pub.eoi_reached) /* After hitting EOI, read no further */
nuclear@2:     return JPEG_REACHED_EOI;
nuclear@2: 
nuclear@2:   val = (*cinfo->marker->read_markers) (cinfo);
nuclear@2: 
nuclear@2:   switch (val) {
nuclear@2:   case JPEG_REACHED_SOS:	/* Found SOS */
nuclear@2:     if (inputctl->inheaders) {	/* 1st SOS */
nuclear@2:       initial_setup(cinfo);
nuclear@2:       inputctl->inheaders = FALSE;
nuclear@2:       /* Note: start_input_pass must be called by jdmaster.c
nuclear@2:        * before any more input can be consumed.  jdapimin.c is
nuclear@2:        * responsible for enforcing this sequencing.
nuclear@2:        */
nuclear@2:     } else {			/* 2nd or later SOS marker */
nuclear@2:       if (! inputctl->pub.has_multiple_scans)
nuclear@2: 	ERREXIT(cinfo, JERR_EOI_EXPECTED); /* Oops, I wasn't expecting this! */
nuclear@2:       start_input_pass(cinfo);
nuclear@2:     }
nuclear@2:     break;
nuclear@2:   case JPEG_REACHED_EOI:	/* Found EOI */
nuclear@2:     inputctl->pub.eoi_reached = TRUE;
nuclear@2:     if (inputctl->inheaders) {	/* Tables-only datastream, apparently */
nuclear@2:       if (cinfo->marker->saw_SOF)
nuclear@2: 	ERREXIT(cinfo, JERR_SOF_NO_SOS);
nuclear@2:     } else {
nuclear@2:       /* Prevent infinite loop in coef ctlr's decompress_data routine
nuclear@2:        * if user set output_scan_number larger than number of scans.
nuclear@2:        */
nuclear@2:       if (cinfo->output_scan_number > cinfo->input_scan_number)
nuclear@2: 	cinfo->output_scan_number = cinfo->input_scan_number;
nuclear@2:     }
nuclear@2:     break;
nuclear@2:   case JPEG_SUSPENDED:
nuclear@2:     break;
nuclear@2:   }
nuclear@2: 
nuclear@2:   return val;
nuclear@2: }
nuclear@2: 
nuclear@2: 
nuclear@2: /*
nuclear@2:  * Reset state to begin a fresh datastream.
nuclear@2:  */
nuclear@2: 
nuclear@2: METHODDEF(void)
nuclear@2: reset_input_controller (j_decompress_ptr cinfo)
nuclear@2: {
nuclear@2:   my_inputctl_ptr inputctl = (my_inputctl_ptr) cinfo->inputctl;
nuclear@2: 
nuclear@2:   inputctl->pub.consume_input = consume_markers;
nuclear@2:   inputctl->pub.has_multiple_scans = FALSE; /* "unknown" would be better */
nuclear@2:   inputctl->pub.eoi_reached = FALSE;
nuclear@2:   inputctl->inheaders = TRUE;
nuclear@2:   /* Reset other modules */
nuclear@2:   (*cinfo->err->reset_error_mgr) ((j_common_ptr) cinfo);
nuclear@2:   (*cinfo->marker->reset_marker_reader) (cinfo);
nuclear@2:   /* Reset progression state -- would be cleaner if entropy decoder did this */
nuclear@2:   cinfo->coef_bits = NULL;
nuclear@2: }
nuclear@2: 
nuclear@2: 
nuclear@2: /*
nuclear@2:  * Initialize the input controller module.
nuclear@2:  * This is called only once, when the decompression object is created.
nuclear@2:  */
nuclear@2: 
nuclear@2: GLOBAL(void)
nuclear@2: jinit_input_controller (j_decompress_ptr cinfo)
nuclear@2: {
nuclear@2:   my_inputctl_ptr inputctl;
nuclear@2: 
nuclear@2:   /* Create subobject in permanent pool */
nuclear@2:   inputctl = (my_inputctl_ptr)
nuclear@2:     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
nuclear@2: 				SIZEOF(my_input_controller));
nuclear@2:   cinfo->inputctl = (struct jpeg_input_controller *) inputctl;
nuclear@2:   /* Initialize method pointers */
nuclear@2:   inputctl->pub.consume_input = consume_markers;
nuclear@2:   inputctl->pub.reset_input_controller = reset_input_controller;
nuclear@2:   inputctl->pub.start_input_pass = start_input_pass;
nuclear@2:   inputctl->pub.finish_input_pass = finish_input_pass;
nuclear@2:   /* Initialize state: can't use reset_input_controller since we don't
nuclear@2:    * want to try to reset other modules yet.
nuclear@2:    */
nuclear@2:   inputctl->pub.has_multiple_scans = FALSE; /* "unknown" would be better */
nuclear@2:   inputctl->pub.eoi_reached = FALSE;
nuclear@2:   inputctl->inheaders = TRUE;
nuclear@2: }