systemc: Implement sc_buffer.

This required a small change to sc_signal so that the value change
event and the change stamp for it were accessible.

Change-Id: Ife0545d84f3b25e98da079786c30ffa51025cce7
Reviewed-on: https://gem5-review.googlesource.com/c/12804
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>

2 files changed, 42 insertions, 18 deletions

diff --git a/src/systemc/ext/channel/sc_buffer.hh b/src/systemc/ext/channel/sc_buffer.hh
index 22081605e..21dc52be0 100644
--- a/src/systemc/ext/channel/sc_buffer.hh
+++ b/src/systemc/ext/channel/sc_buffer.hh
@@ -32,7 +32,6 @@
 
 #include "../core/sc_module.hh" // for sc_gen_unique_name
 #include "sc_signal.hh"
-#include "warn_unimpl.hh" // for warn_unimpl
 
 namespace sc_core
 {
@@ -49,27 +48,28 @@ class sc_buffer : public sc_signal<T, WRITER_POLICY>
     {}
 
     virtual void
-    write(const T&)
+    write(const T &t)
     {
-        sc_channel_warn_unimpl(__PRETTY_FUNCTION__);
+        this->m_new_val = t;
+        this->request_update();
     }
 
     sc_buffer<T, WRITER_POLICY> &
-    operator = (const T &)
+    operator = (const T &arg)
     {
-        sc_channel_warn_unimpl(__PRETTY_FUNCTION__);
+        write(arg);
         return *this;
     }
     sc_buffer<T, WRITER_POLICY> &
-    operator = (const sc_signal<T, WRITER_POLICY> &)
+    operator = (const sc_signal<T, WRITER_POLICY> &arg)
     {
-        sc_channel_warn_unimpl(__PRETTY_FUNCTION__);
+        write(arg.read());
         return *this;
     }
     sc_buffer<T, WRITER_POLICY> &
-    operator = (const sc_buffer<T, WRITER_POLICY> &)
+    operator = (const sc_buffer<T, WRITER_POLICY> &arg)
     {
-        sc_channel_warn_unimpl(__PRETTY_FUNCTION__);
+        write(arg.read());
         return *this;
     }
 
@@ -79,7 +79,8 @@ class sc_buffer : public sc_signal<T, WRITER_POLICY>
     virtual void
     update()
     {
-        sc_channel_warn_unimpl(__PRETTY_FUNCTION__);
+        this->m_cur_val = this->m_new_val;
+        this->_signalChange();
     }
 
   private:
diff --git a/src/systemc/ext/channel/sc_signal.hh b/src/systemc/ext/channel/sc_signal.hh
index 022bd3394..bbe2d0116 100644
--- a/src/systemc/ext/channel/sc_signal.hh
+++ b/src/systemc/ext/channel/sc_signal.hh
@@ -151,6 +151,14 @@ class sc_signal : public sc_signal_inout_if<T>,
             return;
 
         m_cur_val = m_new_val;
+        _signalChange();
+        _changeStamp = ::sc_gem5::getChangeStamp();
+        _valueChangedEvent.notify(SC_ZERO_TIME);
+    }
+
+    void
+    _signalChange()
+    {
         _changeStamp = ::sc_gem5::getChangeStamp();
         _valueChangedEvent.notify(SC_ZERO_TIME);
     }
@@ -293,18 +301,23 @@ class sc_signal<bool, WRITER_POLICY> :
             return;
 
         m_cur_val = m_new_val;
-        uint64_t change_stamp = ::sc_gem5::getChangeStamp();
-        _changeStamp = change_stamp;
-        _valueChangedEvent.notify(SC_ZERO_TIME);
+        _signalChange();
         if (m_cur_val) {
-            _posStamp = change_stamp;
+            _posStamp = ::sc_gem5::getChangeStamp();
             _posedgeEvent.notify(SC_ZERO_TIME);
         } else {
-            _negStamp = change_stamp;
+            _negStamp = ::sc_gem5::getChangeStamp();
             _negedgeEvent.notify(SC_ZERO_TIME);
         }
     }
 
+    void
+    _signalChange()
+    {
+        _changeStamp = ::sc_gem5::getChangeStamp();
+        _valueChangedEvent.notify(SC_ZERO_TIME);
+    }
+
     bool m_cur_val;
     bool m_new_val;
 
@@ -438,11 +451,21 @@ class sc_signal<sc_dt::sc_logic, WRITER_POLICY> :
             return;
 
         m_cur_val = m_new_val;
-        _valueChangedEvent.notify(SC_ZERO_TIME);
-        if (m_cur_val == sc_dt::SC_LOGIC_1)
+        _signalChange();
+        if (m_cur_val == sc_dt::SC_LOGIC_1) {
+            _posStamp = ::sc_gem5::getChangeStamp();
             _posedgeEvent.notify(SC_ZERO_TIME);
-        else if (m_cur_val == sc_dt::SC_LOGIC_0)
+        } else if (m_cur_val == sc_dt::SC_LOGIC_0) {
+            _negStamp = ::sc_gem5::getChangeStamp();
             _negedgeEvent.notify(SC_ZERO_TIME);
+        }
+    }
+
+    void
+    _signalChange()
+    {
+        _changeStamp = ::sc_gem5::getChangeStamp();
+        _valueChangedEvent.notify(SC_ZERO_TIME);
     }
 
     sc_dt::sc_logic m_cur_val;