X-Git-Url: https://git.stderr.nl/gitweb?a=blobdiff_plain;f=FFT_support.cpp;h=e482b2d2dd0e44cd17f94e9c6671c34a9ec31620;hb=cb3d93a7136a4f0225c91465e28f8d4369afb2dc;hp=6f21e5a24afa1e9cca6fe74a37bfa4965ff6d2ea;hpb=1efd07a9676d63cd5ffe6535ee45101e87f89c86;p=matthijs%2Fprojects%2Fmontium-fft.git

diff --git a/FFT_support.cpp b/FFT_support.cpp
index 6f21e5a..e482b2d 100644
--- a/FFT_support.cpp
+++ b/FFT_support.cpp
@@ -4,10 +4,10 @@
 
 
 /* Didn't the Montium use Q15 instead of Q14? */
-#define FIXED_POINT 14
+#define FIXED_POINT 15
 #define WORD_SIZE   16
 
-#define WORDS_PER_LINE 4
+#define WORDS_PER_LINE 8
 #define WORDS_PER_GROUP 1
 
 mem input_a_re, input_a_im, input_b_re, input_b_im, output_a_re, output_a_im, output_b_re, output_b_im, twiddle_re, twiddle_im; 
@@ -55,46 +55,75 @@ void pre_run()
 	input_a_im   = alloc_mem(P1M0);
 	input_b_re   = alloc_mem(P2M0);
 	input_b_im   = alloc_mem(P3M0);
-	output_a_re  = alloc_mem(P0M1);
-	output_a_im  = alloc_mem(P1M1);
-	output_b_re  = alloc_mem(P2M1);
-	output_b_im  = alloc_mem(P3M1);
+	
+	twiddle_re   = alloc_mem(P4M0);
+	twiddle_im   = alloc_mem(P4M1);
 	
 	/* TODO: Init memory and twiddles */
-	for (i=0;i<SIZE/2;i++)
+	for (i=0;i<PARAM_N_t/2;i++)
 	{
-		set_mem(twiddle_re->id, i, to_fixed(cos(2*M_PI/SIZE*i)));
-		set_mem(twiddle_im->id, i, to_fixed(sin(2*M_PI/SIZE*i)));
+		set_mem(twiddle_re->id, i, to_fixed(cos(i*2*M_PI/PARAM_N_t)));
+		set_mem(twiddle_im->id, i, to_fixed(sin(i*2*M_PI/PARAM_N_t)));
 	}
 	
-	for (i=0;i<SIZE;i++)
+	for (i=0;i<PARAM_N_t;i++)
 	{
-		int value = to_fixed(sin((float)i/SIZE*2*2*M_PI));
-		if (i<SIZE/2)
+		/* We take the sine from 0 to 2*2*Pi, ie two periods. We divide 
+		 * the value by PARAM_N_t to prevent overflow. */
+		int value = to_fixed(sin((float)i*2*2*M_PI/PARAM_N_t)/PARAM_N_t);
+
+		if (i<PARAM_N_t/2)
 		{
-			set_mem(input_a_re->id, i, value);
-			set_mem(input_a_im->id, i, 0);
+			if (i % 2 == 0) {
+				set_mem(input_a_re->id, i, value);
+				set_mem(input_a_im->id, i, 0);
+			} else {
+				set_mem(input_b_re->id, i, value);
+				set_mem(input_b_im->id, i, 0);
+			}
 		}
 		else
 		{
-			set_mem(input_a_re->id, i - SIZE / 2, value);
-			set_mem(input_a_im->id, i - SIZE / 2, 0);
+			if (i % 2 == 0) {
+				set_mem(input_b_re->id, i - PARAM_N_t/2, value);
+				set_mem(input_b_im->id, i - PARAM_N_t/2, 0);
+			} else {
+				set_mem(input_a_re->id, i - PARAM_N_t/2, value);
+				set_mem(input_a_im->id, i - PARAM_N_t/2, 0);
+			}
 		}
 	}
-}
-
-void post_run()
-{
+	
 	printf("re(W)\n");
-	print_mem(twiddle_re, 0, SIZE, true);
+	print_mem(twiddle_re, 0, PARAM_N_t/2, true);
 	printf("im(W)\n");
-	print_mem(twiddle_im, 0, SIZE, true);
+	print_mem(twiddle_im, 0, PARAM_N_t/2, true);
 	printf("re(in_a)\n");
-	print_mem(input_a_re, 0, SIZE, true);
+	print_mem(input_a_re, 0, PARAM_N_t/2, true);
 	printf("re(in_b)\n");
-	print_mem(input_b_re, 0, SIZE, true);
-	printf("re(out_a)\n");
-	print_mem(output_a_re, 0, SIZE, true);
-	printf("im(out_a)\n");
-	print_mem(output_a_im, 0, SIZE, true);
+	print_mem(input_b_re, 0, PARAM_N_t/2, true);
+}
+
+void post_run()
+{
+	if (PARAM_n_t % 2 == 0) {
+		/* When the number of stages is odd, the 
+		 * outputs end up at the left memories again */
+		output_a_re  = alloc_mem(P0M0);
+		output_a_im  = alloc_mem(P1M0);
+		output_b_re  = alloc_mem(P2M0);
+		output_b_im  = alloc_mem(P3M0);
+	} else {
+		output_a_re  = alloc_mem(P0M1);
+		output_a_im  = alloc_mem(P1M1);
+		output_b_re  = alloc_mem(P2M1);
+		output_b_im  = alloc_mem(P3M1);
+	}
+	printf("re(out)\n");
+	print_mem(output_a_re, 0, PARAM_N_t/2, true);
+	print_mem(output_b_re, 0, PARAM_N_t/2, true);
+	printf("im(out)\n");
+	print_mem(output_a_im, 0, PARAM_N_t/2, true);
+	print_mem(output_b_im, 0, PARAM_N_t/2, true);
+
 }