From de246ea6174e3a6d5fe0dd554d5208f24c2932bb Mon Sep 17 00:00:00 2001
From: Martin Braun <martin.braun@ettus.com>
Date: Thu, 13 Jun 2019 08:13:57 -0700
Subject: rfnoc: clock_iface: Add flag for clock to be (im-)mutable

An immutable clock means it has a locked frequency, and attempts to
change the frequency will cause an exception to be thrown.
---
 host/lib/include/uhdlib/rfnoc/clock_iface.hpp | 22 +++++++++++++++++++++-
 1 file changed, 21 insertions(+), 1 deletion(-)

(limited to 'host/lib/include')

diff --git a/host/lib/include/uhdlib/rfnoc/clock_iface.hpp b/host/lib/include/uhdlib/rfnoc/clock_iface.hpp
index 807382f13..ae61a645e 100644
--- a/host/lib/include/uhdlib/rfnoc/clock_iface.hpp
+++ b/host/lib/include/uhdlib/rfnoc/clock_iface.hpp
@@ -8,6 +8,8 @@
 #define INCLUDED_UHD_RFNOC_CLOCK_IFACE_HPP
 
 #include <uhd/config.hpp>
+#include <uhd/exception.hpp>
+#include <uhd/utils/log.hpp>
 #include <atomic>
 #include <string>
 
@@ -16,12 +18,18 @@ namespace uhd { namespace rfnoc {
 class clock_iface
 {
 public:
-    clock_iface(const std::string& name) : _name(name)
+    clock_iface(const std::string& name) : _name(name), _is_mutable(true)
     {
         _is_running = false;
         _freq       = 0.0;
     }
 
+    clock_iface(const std::string& name, const double freq, const bool is_mutable = true)
+        : _name(name), _freq(freq), _is_mutable(is_mutable)
+    {
+        _is_running = false;
+    }
+
     clock_iface()                       = delete;
     clock_iface(const clock_iface& rhs) = delete;
     clock_iface(clock_iface&& rhs)      = delete;
@@ -38,6 +46,11 @@ public:
         return _is_running;
     }
 
+    inline bool is_mutable() const
+    {
+        return _is_mutable;
+    }
+
     inline void set_running(bool is_running)
     {
         _is_running = is_running;
@@ -48,8 +61,14 @@ public:
         return _freq;
     }
 
+    //! If the clock is immutable, this will throw if freq is different from the
+    // current frequency.
     inline void set_freq(double freq)
     {
+        if (!_is_mutable && freq != _freq.load()) {
+            UHD_LOG_ERROR(_name, "Trying to change an immutable clock!");
+            throw uhd::runtime_error("Trying to change an immutable clock!");
+        }
         _freq = freq;
     }
 
@@ -57,6 +76,7 @@ private:
     const std::string _name;
     std::atomic<bool> _is_running;
     std::atomic<double> _freq;
+    const bool _is_mutable;
 };
 
 }} // namespace uhd::rfnoc
-- 
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