Contiki-NG
ifft.h
1 /*
2  * Copyright (c) 2008, Swedish Institute of Computer Science
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
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9  * notice, this list of conditions and the following disclaimer.
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13  * 3. Neither the name of the Institute nor the names of its contributors
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15  * without specific prior written permission.
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
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28  *
29  * -----------------------------------------------------------------
30  * ifft - Integer FFT (fast fourier transform) library
31  *
32  *
33  *
34  * Author : Joakim Eriksson
35  * Created : 2008-03-27
36  * Updated : $Date: 2008/04/25 22:12:25 $
37  * $Revision: 1.2 $
38  */
39 
40 #ifndef IFFT_H
41 #define IFFT_H
42 #include "contiki.h"
43 
44 /* ifft(xre[], n) - integer (fixpoint) version of Fast Fourier Transform
45  An integer version of FFT that takes in-samples in an int16_t array
46  and does an fft on n samples in the array.
47  The result of the FFT is stored in the same array as the samples
48  was stored.
49 
50  Note: This fft is designed to be used with 8 bit values (e.g. not
51  16 bit values). The reason for the int16_t array is for keeping some
52  'room' for the calculations. It is also designed for doing fairly small
53  FFT:s since to large sample arrays might cause it to overflow during
54  calculations.
55 */
56 void ifft(int16_t xre[], int16_t xim[], uint16_t n);
57 
58 #endif /* IFFT_H */