ghost/monty/sinusoid/smallft.h

   1 /********************************************************************
   2  *                                                                  *
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   7  *                                                                  *
   8  * THE OggGhost SOURCE CODE IS (C) COPYRIGHT 1994-2007              *
   9  * the Xiph.Org FOundation http://www.xiph.org/                     *
  10  *                                                                  *
  11  ********************************************************************
  12
  13  function: unnormalized powers-of-two forward fft transform
  14  last mod: $Id: smallft.c 7573 2004-08-16 01:26:52Z conrad $
  15
  16  ********************************************************************/
  17
  18 /* FFT implementation from OggSquish, minus cosine transforms,
  19  * minus all but radix 2/4 case.  In Vorbis we only need this
  20  * cut-down version.
  21  *
  22  * To do more than just power-of-two sized vectors, see the full
  23  * version I wrote for NetLib.
  24  *
  25  * Note that the packing is a little strange; rather than the FFT r/i
  26  * packing following R_0, R_n, R_1, I_1, R_2, I_2 ... R_n-1, I_n-1,
  27  * it follows R_0, R_1, I_1, R_2, I_2 ... R_n-1, I_n-1, I_n like the
  28  * FORTRAN version
  29  */
  30
  31 #ifndef _V_SMFT_H_
  32 #define _V_SMFT_H_
  33
  34 typedef struct {
  35   int n;
  36   float *trigcache;
  37   int *splitcache;
  38 } drft_lookup;
  39
  40 extern void drft_forward(drft_lookup *l,float *data);
  41 extern int drft_init(drft_lookup *l,int n);
  42 extern void drft_clear(drft_lookup *l);
  43
  44 #endif