kiss_fft_alloc()

kiss_fft_cfg kiss_fft_alloc	(	int	nfft,
		int	inverse_fft,
		void *	mem,
		size_t *	lenmem )

Definition at line 333 of file kiss_fft.c.

{
    kiss_fft_cfg st=NULL;
    size_t memneeded = sizeof(struct kiss_fft_state)
        + sizeof(kiss_fft_cpx)*(nfft-1); /* twiddle factors*/
 
    if ( lenmem==NULL ) {
        st = ( kiss_fft_cfg)KISS_FFT_MALLOC( memneeded );
    }else{
        if (mem != NULL && *lenmem >= memneeded)
            st = (kiss_fft_cfg)mem;
        *lenmem = memneeded;
    }
    if (st) {
        int i;
        st->nfft=nfft;
        st->inverse = inverse_fft;
 
        for (i=0;i<nfft;++i) {
            const double pi=3.141592653589793238462643383279502884197169399375105820974944;
            double phase = -2*pi*i / nfft;
            if (st->inverse)
                phase *= -1;
            kf_cexp(st->twiddles+i, phase );
        }
 
        kf_factor(nfft,st->factors);
    }
    return st;
}

References kiss_fft_state::factors, kiss_fft_state::inverse, kf_cexp, kf_factor(), KISS_FFT_MALLOC, kiss_fft_state::nfft, and kiss_fft_state::twiddles.

Referenced by kiss_fftr_alloc().

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