source: liacs/MIR2010/SourceCode/cximage/jpeg/jdinput.c@ 422

/*

 * 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;

}





/*

 * 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;

}