Added real transforms

1 files changed, 117 insertions, 0 deletions

diff --git a/src/ffts_real.c b/src/ffts_real.c
new file mode 100644
index 0000000..5f3bb02
--- /dev/null
+++ b/src/ffts_real.c
@@ -0,0 +1,117 @@
+/*
+ 
+ This file is part of FFTS -- The Fastest Fourier Transform in the South
+  
+ Copyright (c) 2012, Anthony M. Blake <amb@anthonix.com>
+ Copyright (c) 2012, The University of Waikato 
+ 
+ All rights reserved.
+
+ Redistribution and use in source and binary forms, with or without
+ modification, are permitted provided that the following conditions are met:
+ 	* Redistributions of source code must retain the above copyright
+ 		notice, this list of conditions and the following disclaimer.
+ 	* Redistributions in binary form must reproduce the above copyright
+ 		notice, this list of conditions and the following disclaimer in the
+ 		documentation and/or other materials provided with the distribution.
+ 	* Neither the name of the organization nor the
+	  names of its contributors may be used to endorse or promote products
+ 		derived from this software without specific prior written permission.
+
+ THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ DISCLAIMED. IN NO EVENT SHALL ANTHONY M. BLAKE BE LIABLE FOR ANY
+ DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+*/
+
+#include "ffts_real.h"
+
+void ffts_free_1d_real(ffts_plan_t *p) {
+	ffts_free(p->plans[0]);
+	free(p->A);
+	free(p->B);
+	free(p->plans);
+	free(p->buf);
+	free(p);
+}
+
+void ffts_execute_1d_real(ffts_plan_t *p, const void *vin, void *vout) {
+	float *out = (float *)vout;
+	float *buf = (float *)p->buf;
+	float *A = p->A;
+	float *B = p->B;
+
+	p->plans[0]->transform(p->plans[0], vin, buf);
+
+	size_t N = p->N;
+	buf[N] = buf[0];
+	buf[N+1] = buf[1];
+
+	size_t i;
+	for(i=0;i<N/2;i++) {
+		out[2*i]   = buf[2*i]*A[2*i] - buf[2*i+1]*A[2*i+1] + buf[N-2*i]*B[2*i] + buf[N-2*i+1]*B[2*i+1];
+		out[2*i+1] = buf[2*i+1]*A[2*i] + buf[2*i]*A[2*i+1] + buf[N-2*i]*B[2*i+1] - buf[N-2*i+1]*B[2*i];
+		out[2*N - 2*i] = out[2*i];
+		out[2*N - 2*i + 1] = -out[2*i+1];
+	}
+	
+	out[N] = buf[0] - buf[1];
+	out[N+1] = 0.0f;
+	
+}
+
+void ffts_execute_1d_real_inv(ffts_plan_t *p, const void *vin, void *vout) {
+	float *out = (float *)vout;
+	float *in = (float *)vin;
+	float *buf = (float *)p->buf;
+	float *A = p->A;
+	float *B = p->B;
+	size_t N = p->N;
+	
+	size_t i;
+	for(i=0;i<N/2;i++) {
+		buf[2*i]   = in[2*i]*A[2*i] + in[2*i+1]*A[2*i+1] + in[N-2*i]*B[2*i] - in[N-2*i+1]*B[2*i+1];
+		buf[2*i+1] = in[2*i+1]*A[2*i] - in[2*i]*A[2*i+1] - in[N-2*i]*B[2*i+1] - in[N-2*i+1]*B[2*i];
+	}
+	
+	p->plans[0]->transform(p->plans[0], buf, out);
+	
+}
+
+ffts_plan_t *ffts_init_1d_real(size_t N, int sign) {
+	ffts_plan_t *p = malloc(sizeof(ffts_plan_t));
+
+	if(sign < 0) p->transform = &ffts_execute_1d_real;
+	else         p->transform = &ffts_execute_1d_real_inv;
+	
+	p->destroy = &ffts_free_1d_real;
+	p->N = N;
+	p->rank = 1;
+	p->plans = malloc(sizeof(ffts_plan_t **) * 1);
+
+	p->plans[0] = ffts_init_1d(N/2, sign); 
+
+	p->buf = valloc(sizeof(float) * 2 * (N/2) + 1);
+
+	p->A = valloc(sizeof(float) * N);
+	p->B = valloc(sizeof(float) * N);
+
+	int i;
+	for (i = 0; i < N/2; i++) {
+		p->A[2 * i]     = 0.5 * (1.0 - sin (2 * PI / (double) N * (double) i));
+		p->A[2 * i + 1] = 0.5 * (-1.0 * cos (2 * PI / (double) N * (double) i));
+		p->B[2 * i]     = 0.5 * (1.0 + sin (2 * PI / (double) N * (double) i));
+		p->B[2 * i + 1] = 0.5 * (1.0 * cos (2 * PI / (double) N * (double) i));
+	}
+	
+	return p;
+}
+
+