From 7fda6b2c2269a575fd6722085c9c9ace41c1c512 Mon Sep 17 00:00:00 2001
From: Ben Reynwar
Date: Sun, 18 Mar 2012 20:04:07 -0400
Subject: core: fixed point sin/cos generator properly folds frequencies
 outside nyquist range to alias signal.

---
 gnuradio-core/src/lib/general/gr_fxpt.h | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

(limited to 'gnuradio-core/src')

diff --git a/gnuradio-core/src/lib/general/gr_fxpt.h b/gnuradio-core/src/lib/general/gr_fxpt.h
index 5cf736dfb..9f5937d1a 100644
--- a/gnuradio-core/src/lib/general/gr_fxpt.h
+++ b/gnuradio-core/src/lib/general/gr_fxpt.h
@@ -26,7 +26,7 @@
 #include <gr_types.h>
 
 /*!
- * \brief fixed point sine and cosine and friend GR_CORE_APIs.
+ * \brief fixed point sine and cosine and friends.
  * \ingroup misc
  *
  *   fixed pt	radians
@@ -48,6 +48,10 @@ public:
   static gr_int32
   float_to_fixed (float x)
   {
+    // Fold x into -PI to PI.
+    int d = (int)floor(x/2/PI+0.5);
+    x -= d*2*PI;
+    // And convert to an integer.
     return (gr_int32) ((float) x * TWO_TO_THE_31 / PI);
   }
 
-- 
cgit