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- /* fft/c_main.c
- *
- * Copyright (C) 1996, 1997, 1998, 1999, 2000, 2007 Brian Gough
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 3 of the License, or (at
- * your option) any later version.
- *
- * This program is distributed in the hope that it will be useful, but
- * WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- * General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
- */
- #include "gsl_fft__c_pass.h"
- int
- FUNCTION(gsl_fft_complex,forward) (TYPE(gsl_complex_packed_array) data,
- const size_t stride,
- const size_t n,
- const TYPE(gsl_fft_complex_wavetable) * wavetable,
- TYPE(gsl_fft_complex_workspace) * work)
- {
- gsl_fft_direction sign = gsl_fft_forward;
- int status = FUNCTION(gsl_fft_complex,transform) (data, stride, n,
- wavetable, work, sign);
- return status;
- }
- int
- FUNCTION(gsl_fft_complex,backward) (TYPE(gsl_complex_packed_array) data,
- const size_t stride,
- const size_t n,
- const TYPE(gsl_fft_complex_wavetable) * wavetable,
- TYPE(gsl_fft_complex_workspace) * work)
- {
- gsl_fft_direction sign = gsl_fft_backward;
- int status = FUNCTION(gsl_fft_complex,transform) (data, stride, n,
- wavetable, work, sign);
- return status;
- }
- int
- FUNCTION(gsl_fft_complex,inverse) (TYPE(gsl_complex_packed_array) data,
- const size_t stride,
- const size_t n,
- const TYPE(gsl_fft_complex_wavetable) * wavetable,
- TYPE(gsl_fft_complex_workspace) * work)
- {
- gsl_fft_direction sign = gsl_fft_backward;
- int status = FUNCTION(gsl_fft_complex,transform) (data, stride, n,
- wavetable, work, sign);
- if (status)
- {
- return status;
- }
- /* normalize inverse fft with 1/n */
- {
- const ATOMIC norm = ONE / (ATOMIC)n;
- size_t i;
- for (i = 0; i < n; i++)
- {
- REAL(data,stride,i) *= norm;
- IMAG(data,stride,i) *= norm;
- }
- }
- return status;
- }
- int
- FUNCTION(gsl_fft_complex,transform) (TYPE(gsl_complex_packed_array) data,
- const size_t stride,
- const size_t n,
- const TYPE(gsl_fft_complex_wavetable) * wavetable,
- TYPE(gsl_fft_complex_workspace) * work,
- const gsl_fft_direction sign)
- {
- const size_t nf = wavetable->nf;
- size_t i;
- size_t q, product = 1;
- TYPE(gsl_complex) *twiddle1, *twiddle2, *twiddle3, *twiddle4,
- *twiddle5, *twiddle6;
- size_t state = 0;
- BASE * const scratch = work->scratch;
- BASE * in = data;
- size_t istride = stride;
- BASE * out = scratch;
- size_t ostride = 1;
- if (n == 0)
- {
- GSL_ERROR ("length n must be positive integer", GSL_EDOM);
- }
- if (n == 1)
- { /* FFT of 1 data point is the identity */
- return 0;
- }
- if (n != wavetable->n)
- {
- GSL_ERROR ("wavetable does not match length of data", GSL_EINVAL);
- }
- if (n != work->n)
- {
- GSL_ERROR ("workspace does not match length of data", GSL_EINVAL);
- }
- for (i = 0; i < nf; i++)
- {
- const size_t factor = wavetable->factor[i];
- product *= factor;
- q = n / product;
- if (state == 0)
- {
- in = data;
- istride = stride;
- out = scratch;
- ostride = 1;
- state = 1;
- }
- else
- {
- in = scratch;
- istride = 1;
- out = data;
- ostride = stride;
- state = 0;
- }
- if (factor == 2)
- {
- twiddle1 = wavetable->twiddle[i];
- FUNCTION(fft_complex,pass_2) (in, istride, out, ostride, sign,
- product, n, twiddle1);
- }
- else if (factor == 3)
- {
- twiddle1 = wavetable->twiddle[i];
- twiddle2 = twiddle1 + q;
- FUNCTION(fft_complex,pass_3) (in, istride, out, ostride, sign,
- product, n, twiddle1, twiddle2);
- }
- else if (factor == 4)
- {
- twiddle1 = wavetable->twiddle[i];
- twiddle2 = twiddle1 + q;
- twiddle3 = twiddle2 + q;
- FUNCTION(fft_complex,pass_4) (in, istride, out, ostride, sign,
- product, n, twiddle1, twiddle2,
- twiddle3);
- }
- else if (factor == 5)
- {
- twiddle1 = wavetable->twiddle[i];
- twiddle2 = twiddle1 + q;
- twiddle3 = twiddle2 + q;
- twiddle4 = twiddle3 + q;
- FUNCTION(fft_complex,pass_5) (in, istride, out, ostride, sign,
- product, n, twiddle1, twiddle2,
- twiddle3, twiddle4);
- }
- else if (factor == 6)
- {
- twiddle1 = wavetable->twiddle[i];
- twiddle2 = twiddle1 + q;
- twiddle3 = twiddle2 + q;
- twiddle4 = twiddle3 + q;
- twiddle5 = twiddle4 + q;
- FUNCTION(fft_complex,pass_6) (in, istride, out, ostride, sign,
- product, n, twiddle1, twiddle2,
- twiddle3, twiddle4, twiddle5);
- }
- else if (factor == 7)
- {
- twiddle1 = wavetable->twiddle[i];
- twiddle2 = twiddle1 + q;
- twiddle3 = twiddle2 + q;
- twiddle4 = twiddle3 + q;
- twiddle5 = twiddle4 + q;
- twiddle6 = twiddle5 + q;
- FUNCTION(fft_complex,pass_7) (in, istride, out, ostride, sign,
- product, n, twiddle1, twiddle2,
- twiddle3, twiddle4, twiddle5,
- twiddle6);
- }
- else
- {
- twiddle1 = wavetable->twiddle[i];
- FUNCTION(fft_complex,pass_n) (in, istride, out, ostride, sign,
- factor, product, n, twiddle1);
- }
- }
- if (state == 1) /* copy results back from scratch to data */
- {
- for (i = 0; i < n; i++)
- {
- REAL(data,stride,i) = REAL(scratch,1,i) ;
- IMAG(data,stride,i) = IMAG(scratch,1,i) ;
- }
- }
- return 0;
- }
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