systemc: Implement some simple accessor functions in sc_main.cc.

These functions just read or write values with minimal amounts of
logic.

Change-Id: I22d5b49a2550a88a854d1619f08b0055c1312271
Reviewed-on: https://gem5-review.googlesource.com/10847
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Gabe Black <gabeblack@google.com>
diff --git a/src/systemc/core/sc_main.cc b/src/systemc/core/sc_main.cc
index 3c4fdbb..a7a77a4 100644
--- a/src/systemc/core/sc_main.cc
+++ b/src/systemc/core/sc_main.cc
@@ -33,6 +33,7 @@
 #include "python/pybind11/pybind.hh"
 #include "sim/init.hh"
 #include "systemc/ext/core/sc_main.hh"
+#include "systemc/ext/utils/sc_report_handler.hh"
 
 // A default version of this function in case one isn't otherwise defined.
 // This ensures everything will link properly whether or not the user defined
@@ -107,6 +108,11 @@
 }
 EmbeddedPyBind embed_("systemc", &systemc_pybind);
 
+sc_stop_mode _stop_mode = SC_STOP_FINISH_DELTA;
+sc_status _status = SC_ELABORATION;
+
+uint64_t _deltaCycles = 0;
+
 } // anonymous namespace
 
 int
@@ -142,14 +148,18 @@
 void
 sc_set_stop_mode(sc_stop_mode mode)
 {
-    warn("%s not implemented.\n", __PRETTY_FUNCTION__);
+    if (sc_is_running()) {
+        SC_REPORT_ERROR("attempt to set sc_stop mode "
+                        "after start will be ignored", "");
+        return;
+    }
+    _stop_mode = mode;
 }
 
 sc_stop_mode
 sc_get_stop_mode()
 {
-    warn("%s not implemented.\n", __PRETTY_FUNCTION__);
-    return SC_STOP_FINISH_DELTA;
+    return _stop_mode;
 }
 
 void
@@ -168,15 +178,13 @@
 sc_dt::uint64
 sc_delta_count()
 {
-    warn("%s not implemented.\n", __PRETTY_FUNCTION__);
-    return 0;
+    return _deltaCycles;
 }
 
 bool
 sc_is_running()
 {
-    warn("%s not implemented.\n", __PRETTY_FUNCTION__);
-    return false;
+    return _status & (SC_RUNNING | SC_PAUSED);
 }
 
 bool
@@ -196,8 +204,8 @@
 bool
 sc_pending_activity()
 {
-    warn("%s not implemented.\n", __PRETTY_FUNCTION__);
-    return false;
+    return sc_pending_activity_at_current_time() ||
+           sc_pending_activity_at_future_time();
 }
 
 sc_time
@@ -210,8 +218,7 @@
 sc_status
 sc_get_status()
 {
-    warn("%s not implemented.\n", __PRETTY_FUNCTION__);
-    return SC_ELABORATION;
+    return _status;
 }
 
 } // namespace sc_core