From 7e87ccb2a1c31cbf857f8b0efd2ff0e320412fd2 Mon Sep 17 00:00:00 2001
From: ha7ilm <retzlerandras@gmail.com>
Date: Sun, 19 Feb 2017 16:06:08 +0100
Subject: [PATCH] Working interpolator.

---
 csdr.c    | 2 +-
 libcsdr.c | 6 ++++--
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/csdr.c b/csdr.c
index c135c61..d297f61 100644
--- a/csdr.c
+++ b/csdr.c
@@ -860,7 +860,7 @@ int main(int argc, char *argv[])
 		sscanf(argv[2],"%d",&factor);
 		assert(factor >= 1);
 
-		float transition_bw = 0.05;
+		float transition_bw = 0.01;
 		if(argc>=4) sscanf(argv[3],"%g",&transition_bw);
 		assert(transition_bw >= 0 && transition_bw < 1.);
 
diff --git a/libcsdr.c b/libcsdr.c
index 2e02c8b..5483f79 100644
--- a/libcsdr.c
+++ b/libcsdr.c
@@ -394,8 +394,10 @@ int fir_interpolate_cc(complexf *input, complexf *output, int input_size, int in
 		{
 			float acci=0;
 			float accq=0;
-			for(int ti=ip, si=0; ti<taps_length; ti+=interpolation, si++) acci += (iof(input,i+si)) * taps[ti]; //@fir_interpolate_cc: i loop
-			for(int ti=ip, si=0; ti<taps_length; ti+=interpolation, si++) accq += (qof(input,i+si)) * taps[ti]; //@fir_interpolate_cc: q loop
+			//int tistart = (interpolation-ip)%interpolation; 
+			int tistart = (interpolation-ip); //why does this work? why don't we need the % part?
+			for(int ti=tistart, si=0; ti<taps_length; ti+=interpolation, si++) acci += (iof(input,i+si)) * taps[ti]; //@fir_interpolate_cc: i loop
+			for(int ti=tistart, si=0; ti<taps_length; ti+=interpolation, si++) accq += (qof(input,i+si)) * taps[ti]; //@fir_interpolate_cc: q loop
 			iof(output,oi)=acci;
 			qof(output,oi)=accq;
 			oi++;