1 files changed, 112 insertions, 0 deletions
diff --git a/Transceiver52M/arch/common/fft.c b/Transceiver52M/arch/common/fft.c
new file mode 100644
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+++ b/Transceiver52M/arch/common/fft.c
@@ -0,0 +1,112 @@
+/*
+ * Fast Fourier transform 
+ *
+ * Copyright (C) 2012 Tom Tsou <tom@tsou.cc>
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero 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 Affero General Public License for more details.
+ * 
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ * See the COPYING file in the main directory for details.
+ */
+
+#include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+#include <fftw3.h>
+
+#include "fft.h"
+
+struct fft_hdl {
+	float *fft_in;
+	float *fft_out;
+	int len;
+	fftwf_plan fft_plan;
+};
+
+/*! \brief Initialize FFT backend 
+ *  \param[in] reverse FFT direction
+ *  \param[in] m FFT length 
+ *  \param[in] istride input stride count
+ *  \param[in] ostride output stride count
+ *  \param[in] in input buffer (FFTW aligned)
+ *  \param[in] out output buffer (FFTW aligned)
+ *  \param[in] ooffset initial offset into output buffer
+ *
+ * If the reverse is non-NULL, then an inverse FFT will be used. This is a
+ * wrapper for advanced non-contiguous FFTW usage. See FFTW documentation for
+ * further details.
+ *
+ *   http://www.fftw.org/doc/Advanced-Complex-DFTs.html
+ *
+ * It is currently unknown how the offset of the output buffer affects FFTW
+ * memory alignment.
+ */
+struct fft_hdl *init_fft(int reverse, int m, int istride, int ostride,
+			 float *in, float *out, int ooffset)
+{
+	int rank = 1;
+	int n[] = { m };
+	int howmany = istride;
+	int idist = 1;
+	int odist = 1;
+	int *inembed = n;
+	int *onembed = n;
+	fftwf_complex *obuffer, *ibuffer;
+
+	struct fft_hdl *hdl = (struct fft_hdl *) malloc(sizeof(struct fft_hdl));
+	if (!hdl)
+		return NULL;
+
+	int direction = FFTW_FORWARD;
+	if (reverse)
+		direction = FFTW_BACKWARD;
+
+	ibuffer = (fftwf_complex *) in;
+	obuffer = (fftwf_complex *) out + ooffset;
+
+	hdl->fft_in = in;
+	hdl->fft_out = out;
+	hdl->fft_plan = fftwf_plan_many_dft(rank, n, howmany,
+					    ibuffer, inembed, istride, idist,
+					    obuffer, onembed, ostride, odist,
+					    direction, FFTW_MEASURE);
+	return hdl;
+}
+
+void *fft_malloc(size_t size)
+{
+	return fftwf_malloc(size);
+}
+
+void fft_free(void *ptr)
+{
+	free(ptr);
+}
+
+/*! \brief Free FFT backend resources 
+ */
+void free_fft(struct fft_hdl *hdl)
+{
+	fftwf_destroy_plan(hdl->fft_plan);
+	free(hdl);
+}
+
+/*! \brief Run multiple DFT operations with the initialized plan
+ *  \param[in] hdl handle to an intitialized fft struct
+ *
+ * Input and output buffers are configured with init_fft().
+ */
+int cxvec_fft(struct fft_hdl *hdl)
+{
+	fftwf_execute(hdl->fft_plan);
+	return 0;
+}