From f806d765aab07876d073b60ad3cc5d3df321b87f Mon Sep 17 00:00:00 2001
From: eb
Date: Fri, 15 Aug 2008 01:12:02 +0000
Subject: Trial fix for ticket:258 / integer overflow undefined / phase
 accumulator.  Thanks to Stefan Bruens and Philip Ballister for working on
 this.

According to the fine print in the C and C++ standards, if a signed
integer type overflows, the result is undefined.  As of gcc 4.3, gcc
was proving that our code was overflowing, and took advantage of the
"undefined" result to short circuit the evaluation.

Moral of the story:  if you're using a fixed point phase accumulator,
or anything else where you're counting on overflow happening, be sure
that your variable is unsigned.

See also http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37067 and
http://www.airs.com/blog/archives/120



git-svn-id: http://gnuradio.org/svn/gnuradio/trunk@9296 221aa14e-8319-0410-a670-987f0aec2ac5
---
 gnuradio-core/src/lib/general/gr_fxpt_nco.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

(limited to 'gnuradio-core/src/lib/general')

diff --git a/gnuradio-core/src/lib/general/gr_fxpt_nco.h b/gnuradio-core/src/lib/general/gr_fxpt_nco.h
index 6487a5f48..ca0d54f02 100644
--- a/gnuradio-core/src/lib/general/gr_fxpt_nco.h
+++ b/gnuradio-core/src/lib/general/gr_fxpt_nco.h
@@ -30,7 +30,7 @@
  * \ingroup misc
  */
 class gr_fxpt_nco {
-  gr_int32	d_phase;
+  gr_uint32	d_phase;
   gr_int32	d_phase_inc;
 
 public:
-- 
cgit