osd-contiki/core/lib/ifft.h
2008-03-27 12:12:24 +00:00

59 lines
2.5 KiB
C

/*
* Copyright (c) 2008, Swedish Institute of Computer Science
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the Institute nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* -----------------------------------------------------------------
* ifft - Integer FFT (fast fourier transform) library
*
*
*
* Author : Joakim Eriksson
* Created : 2008-03-27
* Updated : $Date: 2008/03/27 12:12:24 $
* $Revision: 1.1 $
*/
#ifndef IFFT_H
#define IFFT_H
#include "contiki-conf.h"
/* ifft(xre[], n) - integer (fixpoint) version of Fast Fourier Transform
An integer version of FFT that takes in-samples in an int16_t array
and does an fft on n samples in the array.
The result of the FFT is stored in the same array as the samples
was stored.
Note: This fft is designed to be used with 8 bit values (e.g. not
16 bit values). The reason for the int16_t array is for keeping some
'room' for the calculations. It is also designed for doing fairly small
FFT:s since to large sample arrays might cause it to overflow during
calculations.
*/
void ifft(int16_t xre[], uint16_t n);
#endif /* IFFT_H */