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