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