From 572a64f0acb459583abfccbc8288158822fa2f77 Mon Sep 17 00:00:00 2001
From: Josh Blum <josh@joshknows.com>
Date: Sat, 29 Jan 2011 21:03:29 +0000
Subject: usrp-e100: clock control use boost math gcd for divider calculation

---
 host/lib/usrp/usrp_e100/clock_ctrl.cpp | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

(limited to 'host/lib')

diff --git a/host/lib/usrp/usrp_e100/clock_ctrl.cpp b/host/lib/usrp/usrp_e100/clock_ctrl.cpp
index e2c4889bc..dd7f8507b 100644
--- a/host/lib/usrp/usrp_e100/clock_ctrl.cpp
+++ b/host/lib/usrp/usrp_e100/clock_ctrl.cpp
@@ -24,6 +24,7 @@
 #include <boost/foreach.hpp>
 #include <boost/format.hpp>
 #include <boost/operators.hpp>
+#include <boost/math/common_factor_rt.hpp> //gcd
 #include <algorithm>
 #include <utility>
 #include <iostream>
@@ -216,12 +217,14 @@ public:
         _chan_rate = rate;
         _out_rate = rate;
 
-        _ad9522_regs.enable_clock_doubler = 1;
+        _ad9522_regs.enable_clock_doubler = 1; //doubler always on
+        const double ref_rate = REFERENCE_INPUT_RATE*2;
 
-        //bypass prescalers and counters == 1
-        _ad9522_regs.set_r_counter(125);
+        //bypass prescaler such that N = B
+        long gcd = boost::math::gcd(long(ref_rate), long(rate));
+        _ad9522_regs.set_r_counter(int(ref_rate/gcd));
         _ad9522_regs.a_counter = 0;
-        _ad9522_regs.set_b_counter(384);
+        _ad9522_regs.set_b_counter(int(rate/gcd));
         _ad9522_regs.prescaler_p = ad9522_regs_t::PRESCALER_P_DIV1;
 
         //setup external vcxo
-- 
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