1 /*****************************************************************************
2 * fft.h: Headers for iterative implementation of a FFT
3 *****************************************************************************
6 * Mainly taken from XMMS's code
8 * Authors: Richard Boulton <richard@tartarus.org>
10 * This program is free software; you can redistribute it and/or modify
11 * it under the terms of the GNU General Public License as published by
12 * the Free Software Foundation; either version 2 of the License, or
13 * (at your option) any later version.
15 * This program is distributed in the hope that it will be useful,
16 * but WITHOUT ANY WARRANTY; without even the implied warranty of
17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 * GNU General Public License for more details.
20 * You should have received a copy of the GNU General Public License
21 * along with this program; if not, write to the Free Software
22 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
23 *****************************************************************************/
28 #define FFT_BUFFER_SIZE_LOG 9
30 #define FFT_BUFFER_SIZE (1 << FFT_BUFFER_SIZE_LOG)
32 /* sound sample - should be an signed 16 bit value */
33 typedef short int sound_sample;
35 struct _struct_fft_state {
36 /* Temporary data stores to perform FFT in. */
37 float real[FFT_BUFFER_SIZE];
38 float imag[FFT_BUFFER_SIZE];
41 unsigned int bitReverse[FFT_BUFFER_SIZE];
43 /* The next two tables could be made to use less space in memory, since they
44 * overlap hugely, but hey. */
45 float sintable[FFT_BUFFER_SIZE / 2];
46 float costable[FFT_BUFFER_SIZE / 2];
50 typedef struct _struct_fft_state fft_state;
51 fft_state *visual_fft_init (void);
52 void fft_perform (const sound_sample *input, float *output, fft_state *state);
53 void fft_close (fft_state *state);