Merge pull request #696 from pah/apple-zero-max-time

sc_time: add constexpr, improve sc_max_time(), cleanup

src/sysc/kernel/sc_simcontext.cpp

@@ -339,7 +339,6 @@ sc_simcontext::init()
     m_collectable = new sc_process_list;
     m_time_params = new sc_time_params;
     m_curr_time = SC_ZERO_TIME;
-    m_max_time = SC_ZERO_TIME;
     m_change_stamp = 0;
     m_delta_count = 0;
     m_initial_delta_count_at_current_time = 0;
@@ -406,8 +405,8 @@ sc_simcontext::sc_simcontext() :
     m_write_check(SC_SIGNAL_WRITE_CHECK_DEFAULT_), m_next_proc_id(-1),
     m_child_events(), m_child_objects(), m_delta_events(), m_timed_events(0),
     m_trace_files(), m_something_to_trace(false), m_runnable(0), m_collectable(0),
-    m_time_params(), m_curr_time(SC_ZERO_TIME), m_max_time(SC_ZERO_TIME),
-    m_change_stamp(0), m_delta_count(0), m_initial_delta_count_at_current_time(0),
+    m_time_params(), m_change_stamp(0),
+    m_delta_count(0), m_initial_delta_count_at_current_time(0),
     m_forced_stop(false), m_paused(false),
     m_ready_to_simulate(false), m_elaboration_done(false),
     m_execution_phase(phase_initialize), m_error(0),
@@ -877,7 +876,7 @@ sc_simcontext::simulate( const sc_time& duration )
 	return;
     }
 
-    sc_time non_overflow_time = max_time() - m_curr_time;
+    sc_time non_overflow_time = sc_time::max() - m_curr_time;
     if ( duration > non_overflow_time )
     {
         SC_REPORT_ERROR(SC_ID_SIMULATION_TIME_OVERFLOW_, "");
@@ -1640,7 +1639,7 @@ SC_API sc_time sc_time_to_pending_activity( const sc_simcontext* simc_p )
     // If there is an activity pending at the current time
     // return a delta of zero.
 
-    sc_time result=SC_ZERO_TIME; // time of pending activity.
+    sc_time result; // time of pending activity.
 
     if ( simc_p->pending_activity_at_current_time() )
     {
@@ -1651,7 +1650,7 @@ SC_API sc_time sc_time_to_pending_activity( const sc_simcontext* simc_p )
 
     else
     {
-        result = simc_p->max_time();
+        result = sc_time::max();
         simc_p->next_time(result);
         result -= sc_time_stamp();
     }
@@ -1757,7 +1756,7 @@ sc_start( const sc_time& duration, sc_starvation_policy p )
 SC_API void
 sc_start()
 {
-    sc_start( sc_max_time() - sc_time_stamp(),
+    sc_start( sc_time::max() - sc_time_stamp(),
               SC_EXIT_ON_STARVATION );
 }
 
@@ -1812,12 +1811,6 @@ SC_API sc_object* sc_find_object( const char* name )
 }
 
 
-SC_API const sc_time&
-sc_max_time()
-{
-    return sc_get_curr_simcontext()->max_time();
-}
-
 SC_API const sc_time&
 sc_time_stamp()
 {

src/sysc/kernel/sc_simcontext.h

@@ -297,7 +297,6 @@ class SC_API sc_simcontext
     friend SC_API void    sc_set_default_time_unit( double, sc_time_unit );
     friend SC_API sc_time sc_get_default_time_unit();
 
-    const sc_time& max_time() const;
     const sc_time& time_stamp() const;
 
     sc_dt::uint64 change_stamp() const;
@@ -422,8 +421,7 @@ class SC_API sc_simcontext
 
     sc_time_params*             m_time_params;
     sc_time                     m_curr_time;
-    mutable sc_time             m_max_time;
-
+
     sc_invoke_method*           m_method_invoker_p;
     sc_dt::uint64               m_change_stamp; // "time" change occurred.
     sc_dt::uint64               m_delta_count;
@@ -604,18 +602,6 @@ sc_simcontext::next_proc_id()
     return ( ++ m_next_proc_id );
 }
 
-
-inline
-const sc_time&
-sc_simcontext::max_time() const
-{
-    if ( m_max_time == SC_ZERO_TIME )
-    {
-        m_max_time = sc_time::from_value( ~sc_dt::UINT64_ZERO );
-    }
-    return m_max_time;
-}
-
 inline
 sc_dt::uint64
 sc_simcontext::change_stamp() const
@@ -773,7 +759,12 @@ sc_set_random_seed( unsigned int seed_ );
 
 extern SC_API void sc_initialize();
 
-extern SC_API const sc_time& sc_max_time();    // Get maximum time value.
+inline const sc_time& sc_max_time() // Get maximum time value.
+{
+    static constexpr sc_time max_time = sc_time::max();
+    return max_time;
+}
+
 extern SC_API const sc_time& sc_time_stamp();  // Current simulation time.
 extern SC_API double sc_simulation_time();     // Current time in default time units.
 

src/sysc/kernel/sc_time.cpp

@@ -477,11 +477,6 @@ sc_get_default_time_unit()
     return sc_time::from_value( time_unit );
 }
 
-
-// ----------------------------------------------------------------------------
-
-const sc_time SC_ZERO_TIME;
-
 } // namespace sc_core
 
 // $Log: sc_time.cpp,v $

src/sysc/kernel/sc_time.h

@@ -67,19 +67,19 @@ class SC_API sc_time_tuple;
 // integer of at least 64 bits declared as sc_time::value_type.
 // ----------------------------------------------------------------------------
 
-#define SC_TIME_DT sc_dt::uint64 
+#define SC_TIME_DT sc_dt::uint64
 
 // ----------------------------------------------------------------------------
 //  ENUM : sc_time_unit
 //
 //  Enumeration of time units.
-//  NOTE: From IEEE Std 1666-2023 onwards, enumeration constant values are 
-//        implementation-defined. The constant values for SC_SEC, SC_MS, 
-//        SC_US, SC_NS, SC_PS and SC_FS follow IEEE Std 1666-2011 to enable 
+//  NOTE: From IEEE Std 1666-2023 onwards, enumeration constant values are
+//        implementation-defined. The constant values for SC_SEC, SC_MS,
+//        SC_US, SC_NS, SC_PS and SC_FS follow IEEE Std 1666-2011 to enable
 //        backwards compatibility.
 // ----------------------------------------------------------------------------
 
-enum sc_time_unit { SC_SEC = 5, SC_MS = 4, SC_US = 3, SC_NS = 2, 
+enum sc_time_unit { SC_SEC = 5, SC_MS = 4, SC_US = 3, SC_NS = 2,
                     SC_PS = 1, SC_FS = 0, SC_AS = -1, SC_ZS = -2, SC_YS = -3 };
 
 // ----------------------------------------------------------------------------
@@ -116,24 +116,17 @@ class SC_API sc_time
 
     // constructors
 
-    sc_time();
-    sc_time( const sc_time& );
+    constexpr sc_time() = default;
     sc_time( double, sc_time_unit );
 
     // convert time object from string
-    // For C++ versions prior to C++17, offer some (non-standard) backwards compatibility
-    // using std::string instead of std::string_view
     explicit sc_time( std::string_view strv );
     static sc_time from_string( std::string_view strv );
 
     // deprecated, use from_value(v)
     sc_time( double, bool scale );
     sc_time( value_type, bool scale );
 
-    // assignment operator
-
-    sc_time& operator = ( const sc_time& );
-
     // conversion functions
 
     value_type value() const;  // relative to the time resolution
@@ -145,6 +138,8 @@ class SC_API sc_time
     static sc_time from_value( value_type );
     static sc_time from_seconds( double );
 
+    static constexpr sc_time max();
+
     // relational operators
 
     bool operator == ( const sc_time& ) const;
@@ -175,10 +170,13 @@ class SC_API sc_time
     void print( ::std::ostream& os = std::cout ) const;
 
 private: // implementation-defined
+    struct max_time_tag {};
+    explicit constexpr sc_time( max_time_tag );
+
     sc_time( double, sc_time_unit, sc_simcontext* );
 
 private:
-    value_type m_value;
+    value_type m_value{};
 };
 
 // ----------------------------------------------------------------------------
@@ -224,19 +222,9 @@ inline ::std::ostream& operator << ( ::std::ostream&, const sc_time& );
 
 // IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII
 
-extern SC_API const sc_time SC_ZERO_TIME;
-
 // constructors
 
-inline
-sc_time::sc_time()
-: m_value( 0 )
-{}
-
-inline
-sc_time::sc_time( const sc_time& t )
-: m_value( t.m_value )
-{}
+inline constexpr sc_time SC_ZERO_TIME;
 
 inline
 sc_time_tuple::sc_time_tuple( value_type v )
@@ -261,15 +249,15 @@ sc_time::from_seconds( double v )
     return sc_time( v, SC_SEC );
 }
 
+inline constexpr
+sc_time::sc_time( max_time_tag )
+  : m_value( ~value_type{} )
+{}
 
-// assignment operator
-
-inline
-sc_time&
-sc_time::operator = ( const sc_time& t )
+inline constexpr
+sc_time sc_time::max()
 {
-    m_value = t.m_value;
-    return *this;
+    return sc_time( max_time_tag{} );
 }