idct.c | Explore in Territory

/********************************************************************
 *                                                                  *
 * THIS FILE IS PART OF THE OggTheora SOFTWARE CODEC SOURCE CODE.   *
 * USE, DISTRIBUTION AND REPRODUCTION OF THIS LIBRARY SOURCE IS     *
 * GOVERNED BY A BSD-STYLE SOURCE LICENSE INCLUDED WITH THIS SOURCE *
 * IN 'COPYING'. PLEASE READ THESE TERMS BEFORE DISTRIBUTING.       *
 *                                                                  *
 * THE Theora SOURCE CODE IS COPYRIGHT (C) 2002-2009                *
 * by the Xiph.Org Foundation and contributors http://www.xiph.org/ *
 *                                                                  *
 ********************************************************************

  function:
    last mod: $Id$

 ********************************************************************/

#include <string.h>
#include "internal.h"
#include "dct.h"

/*Performs an inverse 8 point Type-II DCT transform.
  The output is scaled by a factor of 2 relative to the orthonormal version of
   the transform.
  _y: The buffer to store the result in.
      Data will be placed in every 8th entry (e.g., in a column of an 8x8
       block).
  _x: The input coefficients.
      The first 8 entries are used (e.g., from a row of an 8x8 block).*/
static void idct8(ogg_int16_t *_y,const ogg_int16_t _x[8]){ … }

/*Performs an inverse 8 point Type-II DCT transform.
  The output is scaled by a factor of 2 relative to the orthonormal version of
   the transform.
  _y: The buffer to store the result in.
      Data will be placed in every 8th entry (e.g., in a column of an 8x8
       block).
  _x: The input coefficients.
      Only the first 4 entries are used.
      The other 4 are assumed to be 0.*/
static void idct8_4(ogg_int16_t *_y,const ogg_int16_t _x[8]){ … }

/*Performs an inverse 8 point Type-II DCT transform.
  The output is scaled by a factor of 2 relative to the orthonormal version of
   the transform.
  _y: The buffer to store the result in.
      Data will be placed in every 8th entry (e.g., in a column of an 8x8
       block).
  _x: The input coefficients.
      Only the first 3 entries are used.
      The other 5 are assumed to be 0.*/
static void idct8_3(ogg_int16_t *_y,const ogg_int16_t _x[8]){ … }

/*Performs an inverse 8 point Type-II DCT transform.
  The output is scaled by a factor of 2 relative to the orthonormal version of
   the transform.
  _y: The buffer to store the result in.
      Data will be placed in every 8th entry (e.g., in a column of an 8x8
       block).
  _x: The input coefficients.
      Only the first 2 entries are used.
      The other 6 are assumed to be 0.*/
static void idct8_2(ogg_int16_t *_y,const ogg_int16_t _x[8]){ … }

/*Performs an inverse 8 point Type-II DCT transform.
  The output is scaled by a factor of 2 relative to the orthonormal version of
   the transform.
  _y: The buffer to store the result in.
      Data will be placed in every 8th entry (e.g., in a column of an 8x8
       block).
  _x: The input coefficients.
      Only the first entry is used.
      The other 7 are assumed to be 0.*/
static void idct8_1(ogg_int16_t *_y,const ogg_int16_t _x[1]){ … }

/*Performs an inverse 8x8 Type-II DCT transform.
  The input is assumed to be scaled by a factor of 4 relative to orthonormal
   version of the transform.
  All coefficients but the first 3 in zig-zag scan order are assumed to be 0:
   x  x  0  0  0  0  0  0
   x  0  0  0  0  0  0  0
   0  0  0  0  0  0  0  0
   0  0  0  0  0  0  0  0
   0  0  0  0  0  0  0  0
   0  0  0  0  0  0  0  0
   0  0  0  0  0  0  0  0
   0  0  0  0  0  0  0  0
  _y: The buffer to store the result in.
      This may be the same as _x.
  _x: The input coefficients.*/
static void oc_idct8x8_3(ogg_int16_t _y[64],ogg_int16_t _x[64]){ … }

/*Performs an inverse 8x8 Type-II DCT transform.
  The input is assumed to be scaled by a factor of 4 relative to orthonormal
   version of the transform.
  All coefficients but the first 10 in zig-zag scan order are assumed to be 0:
   x  x  x  x  0  0  0  0
   x  x  x  0  0  0  0  0
   x  x  0  0  0  0  0  0
   x  0  0  0  0  0  0  0
   0  0  0  0  0  0  0  0
   0  0  0  0  0  0  0  0
   0  0  0  0  0  0  0  0
   0  0  0  0  0  0  0  0
  _y: The buffer to store the result in.
      This may be the same as _x.
  _x: The input coefficients.*/
static void oc_idct8x8_10(ogg_int16_t _y[64],ogg_int16_t _x[64]){ … }

/*Performs an inverse 8x8 Type-II DCT transform.
  The input is assumed to be scaled by a factor of 4 relative to orthonormal
   version of the transform.
  _y: The buffer to store the result in.
      This may be the same as _x.
  _x: The input coefficients.*/
static void oc_idct8x8_slow(ogg_int16_t _y[64],ogg_int16_t _x[64]){ … }

/*Performs an inverse 8x8 Type-II DCT transform.
  The input is assumed to be scaled by a factor of 4 relative to orthonormal
   version of the transform.*/
void oc_idct8x8_c(ogg_int16_t _y[64],ogg_int16_t _x[64],int _last_zzi){ … }
godot/thirdparty/libtheora/idct.c
