jddctmgr.cpp File Reference

#include "jinclude.h"
#include "jpeglib.h"
#include "jdct.h"

Include dependency graph for jddctmgr.cpp:

Classes
struct	my_idct_controller
union	multiplier_table

Macros
#define	JPEG_INTERNALS
#define	PROVIDE_ISLOW_TABLES
#define	CONST_BITS   14

Typedefs
typedef my_idct_controller *	my_idct_ptr

Functions
static void	start_pass (j_decompress_ptr cinfo)
void	jinit_inverse_dct (j_decompress_ptr cinfo)

Macro Definition Documentation

#define JPEG_INTERNALS

#define PROVIDE_ISLOW_TABLES

#define CONST_BITS   14

Typedef Documentation

typedef my_idct_controller* my_idct_ptr

Function Documentation

static void start_pass ( j_decompress_ptr  cinfo )

static

{
  my_idct_ptr idct = (my_idct_ptr) cinfo->idct;
  int ci, i;
  jpeg_component_info *compptr;
  int method = 0;
  inverse_DCT_method_ptr method_ptr = NULL;
  JQUANT_TBL * qtbl;

  for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
       ci++, compptr++) {
    /* Select the proper IDCT routine for this component's scaling */
    switch (compptr->DCT_scaled_size) {
#ifdef IDCT_SCALING_SUPPORTED
    case 1:
      method_ptr = jpeg_idct_1x1;
      method = JDCT_ISLOW;  /* jidctred uses islow-style table */
      break;
    case 2:
      method_ptr = jpeg_idct_2x2;
      method = JDCT_ISLOW;  /* jidctred uses islow-style table */
      break;
    case 4:
      method_ptr = jpeg_idct_4x4;
      method = JDCT_ISLOW;  /* jidctred uses islow-style table */
      break;
#endif
    case DCTSIZE:
      switch (cinfo->dct_method) {
#ifdef DCT_ISLOW_SUPPORTED
      case JDCT_ISLOW:
    method_ptr = jpeg_idct_islow;
    method = JDCT_ISLOW;
    break;
#endif
#ifdef DCT_IFAST_SUPPORTED
      case JDCT_IFAST:
    method_ptr = jpeg_idct_ifast;
    method = JDCT_IFAST;
    break;
#endif
#ifdef DCT_FLOAT_SUPPORTED
      case JDCT_FLOAT:
    method_ptr = jpeg_idct_float;
    method = JDCT_FLOAT;
    break;
#endif
      default:
    ERREXIT(cinfo, JERR_NOT_COMPILED);
    break;
      }
      break;
    default:
      ERREXIT1(cinfo, JERR_BAD_DCTSIZE, compptr->DCT_scaled_size);
      break;
    }
    idct->pub.inverse_DCT[ci] = method_ptr;
    /* Create multiplier table from quant table.
     * However, we can skip this if the component is uninteresting
     * or if we already built the table.  Also, if no quant table
     * has yet been saved for the component, we leave the
     * multiplier table all-zero; we'll be reading zeroes from the
     * coefficient controller's buffer anyway.
     */
    if (! compptr->component_needed || idct->cur_method[ci] == method)
      continue;
    qtbl = compptr->quant_table;
    if (qtbl == NULL)       /* happens if no data yet for component */
      continue;
    idct->cur_method[ci] = method;
    switch (method) {
#ifdef PROVIDE_ISLOW_TABLES
    case JDCT_ISLOW:
      {
    /* For LL&M IDCT method, multipliers are equal to raw quantization
     * coefficients, but are stored as ints to ensure access efficiency.
     */
    ISLOW_MULT_TYPE * ismtbl = (ISLOW_MULT_TYPE *) compptr->dct_table;
    for (i = 0; i < DCTSIZE2; i++) {
      ismtbl[i] = (ISLOW_MULT_TYPE) qtbl->quantval[i];
    }
      }
      break;
#endif
#ifdef DCT_IFAST_SUPPORTED
    case JDCT_IFAST:
      {
    /* For AA&N IDCT method, multipliers are equal to quantization
     * coefficients scaled by scalefactor[row]*scalefactor[col], where
     *   scalefactor[0] = 1
     *   scalefactor[k] = cos(k*PI/16) * sqrt(2)    for k=1..7
     * For integer operation, the multiplier table is to be scaled by
     * IFAST_SCALE_BITS.
     */
    IFAST_MULT_TYPE * ifmtbl = (IFAST_MULT_TYPE *) compptr->dct_table;
#define CONST_BITS 14
    static const int16_t aanscales[DCTSIZE2] = {
      /* precomputed values scaled up by 14 bits */
      16384, 22725, 21407, 19266, 16384, 12873,  8867,  4520,
      22725, 31521, 29692, 26722, 22725, 17855, 12299,  6270,
      21407, 29692, 27969, 25172, 21407, 16819, 11585,  5906,
      19266, 26722, 25172, 22654, 19266, 15137, 10426,  5315,
      16384, 22725, 21407, 19266, 16384, 12873,  8867,  4520,
      12873, 17855, 16819, 15137, 12873, 10114,  6967,  3552,
       8867, 12299, 11585, 10426,  8867,  6967,  4799,  2446,
       4520,  6270,  5906,  5315,  4520,  3552,  2446,  1247
    };
    SHIFT_TEMPS

    for (i = 0; i < DCTSIZE2; i++) {
      ifmtbl[i] = (IFAST_MULT_TYPE)
        DESCALE(MULTIPLY16V16((int32_t) qtbl->quantval[i],
                  (int32_t) aanscales[i]),
            CONST_BITS-IFAST_SCALE_BITS);
    }
      }
      break;
#endif
#ifdef DCT_FLOAT_SUPPORTED
    case JDCT_FLOAT:
      {
    /* For float AA&N IDCT method, multipliers are equal to quantization
     * coefficients scaled by scalefactor[row]*scalefactor[col], where
     *   scalefactor[0] = 1
     *   scalefactor[k] = cos(k*PI/16) * sqrt(2)    for k=1..7
     */
    FLOAT_MULT_TYPE * fmtbl = (FLOAT_MULT_TYPE *) compptr->dct_table;
    int row, col;
    static const double aanscalefactor[DCTSIZE] = {
      1.0, 1.387039845, 1.306562965, 1.175875602,
      1.0, 0.785694958, 0.541196100, 0.275899379
    };

    i = 0;
    for (row = 0; row < DCTSIZE; row++) {
      for (col = 0; col < DCTSIZE; col++) {
        fmtbl[i] = (FLOAT_MULT_TYPE)
          ((double) qtbl->quantval[i] *
           aanscalefactor[row] * aanscalefactor[col]);
        i++;
      }
    }
      }
      break;
#endif
    default:
      ERREXIT(cinfo, JERR_NOT_COMPILED);
      break;
    }
  }
}

void jinit_inverse_dct

(

j_decompress_ptr

cinfo

)

{
  my_idct_ptr idct;
  int ci;
  jpeg_component_info *compptr;

  idct = (my_idct_ptr)
    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
                SIZEOF(my_idct_controller));
  cinfo->idct = (struct jpeg_inverse_dct *) idct;
  idct->pub.start_pass = start_pass;

  for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
       ci++, compptr++) {
    /* Allocate and pre-zero a multiplier table for each component */
    compptr->dct_table =
      (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
                  SIZEOF(multiplier_table));
    MEMZERO(compptr->dct_table, SIZEOF(multiplier_table));
    /* Mark multiplier table not yet set up for any method */
    idct->cur_method[ci] = -1;
  }
}