Slightly improve event timing if state changes.

Also introduce a push_force call to reschedule already pending events if
the state will not change. (nw)

src/lib/netlist/devices/nld_7493.cpp

@@ -1,7 +1,7 @@
 // license:GPL-2.0+
 // copyright-holders:Couriersud
 /*
- * nld_7493.c
+ * nld_7493.cpp
  *
  */
 
@@ -34,6 +34,7 @@ namespace netlist
 		{
 		}
 
+	private:
 		NETLIB_RESETI();
 		NETLIB_UPDATEI();
 
@@ -57,7 +58,6 @@ namespace netlist
 			}
 		}
 
-	private:
 		logic_input_t m_R1;
 		logic_input_t m_R2;
 
@@ -70,7 +70,7 @@ namespace netlist
 		logic_output_t m_QD;
 
 		state_var<netlist_sig_t> m_reset;
-		state_var_u8 m_a;
+		state_var<netlist_sig_t> m_a;
 		state_var_u8 m_bcd;
 	};
 
@@ -118,10 +118,10 @@ namespace netlist
 		{
 			m_CLKA.inactivate();
 			m_CLKB.inactivate();
-			m_QA.push(0, NLTIME_FROM_NS(40));
+			m_QA.push_force(0, NLTIME_FROM_NS(40));
-			m_QB.push(0, NLTIME_FROM_NS(40));
+			m_QB.push_force(0, NLTIME_FROM_NS(40));
-			m_QC.push(0, NLTIME_FROM_NS(40));
+			m_QC.push_force(0, NLTIME_FROM_NS(40));
-			m_QD.push(0, NLTIME_FROM_NS(40));
+			m_QD.push_force(0, NLTIME_FROM_NS(40));
 			m_a = m_bcd = 0;
 		}
 	}

src/lib/netlist/devices/nlid_truthtable.h

@@ -183,21 +183,13 @@ namespace netlist
 			{
 				auto *t = &m_ttp->m_timing[timebase];
 				for (std::size_t i = 0; i < m_NO; ++i)
-				{
+					m_Q[i].push((out >> i) & 1, m_ttp->m_timing_nt[t[i]]);
-					m_Q[i].push(out & 1, m_ttp->m_timing_nt[*t]);
-					++t;
-					out >>= 1;
-				}
 			}
 			else
 			{
 				auto *t = &m_ttp->m_timing[timebase];
 				for (std::size_t i = 0; i < m_NO; ++i)
-				{
+					m_Q[i].set_Q_time((out >> i) & 1, mt + m_ttp->m_timing_nt[t[i]]);
-					m_Q[i].net().set_Q_time(out & 1, mt + m_ttp->m_timing_nt[*t]);
-					++t;
-					out >>= 1;
-				}
 			}
 
 			if (m_NI > 1)

src/lib/netlist/nl_base.h

@@ -698,7 +698,7 @@ namespace netlist
 
 		void reset();
 
-		void toggle_new_Q() NL_NOEXCEPT             { m_new_Q ^= 1;   }
+		void toggle_new_Q() NL_NOEXCEPT              { m_new_Q ^= 1;   }
 		void force_queue_execution() NL_NOEXCEPT    { m_new_Q = (m_cur_Q ^ 1);   }
 
 		void push_to_queue(const netlist_time delay) NL_NOEXCEPT;
@@ -707,7 +707,7 @@ namespace netlist
 
 		void update_devs() NL_NOEXCEPT;
 
-		const netlist_time time() const NL_NOEXCEPT { return m_time; }
+		netlist_time time() const NL_NOEXCEPT { return m_time; }
 		void set_time(const netlist_time ntime) NL_NOEXCEPT { m_time = ntime; }
 
 		bool isRailNet() const { return !(m_railterminal == nullptr); }
@@ -760,9 +760,17 @@ namespace netlist
 		netlist_sig_t new_Q() const NL_NOEXCEPT { return m_new_Q; }
 		void initial(const netlist_sig_t val) NL_NOEXCEPT { m_cur_Q = m_new_Q = val; }
 
-		void set_Q(const netlist_sig_t newQ, const netlist_time delay) NL_NOEXCEPT
+		void set_Q_and_push(const netlist_sig_t newQ, const netlist_time delay) NL_NOEXCEPT
 		{
-			if (newQ != m_new_Q)
+			if (newQ != m_new_Q )
+			{
+				m_new_Q = newQ;
+				push_to_queue(delay);
+			}
+		}
+		void set_Q_and_push_force(const netlist_sig_t newQ, const netlist_time delay) NL_NOEXCEPT
+		{
+			if (newQ != m_new_Q || is_queued())
 			{
 				m_new_Q = newQ;
 				push_to_queue(delay);
@@ -826,7 +834,17 @@ namespace netlist
 
 		void push(const netlist_sig_t newQ, const netlist_time delay) NL_NOEXCEPT
 		{
-			m_my_net.set_Q(newQ, delay); // take the shortcut
+			m_my_net.set_Q_and_push(newQ, delay); // take the shortcut
+		}
+
+		void push_force(const netlist_sig_t newQ, const netlist_time delay) NL_NOEXCEPT
+		{
+			m_my_net.set_Q_and_push_force(newQ, delay); // take the shortcut
+		}
+
+		void set_Q_time(const netlist_sig_t newQ, const netlist_time at) NL_NOEXCEPT
+		{
+			m_my_net.set_Q_time(newQ, at); // take the shortcut
 		}
 
 	private:
@@ -1374,8 +1392,10 @@ namespace netlist
 
 	inline void detail::net_t::push_to_queue(const netlist_time delay) NL_NOEXCEPT
 	{
-		if (!is_queued() && (num_cons() != 0))
+		if ((num_cons() != 0))
 		{
+			if (is_queued())
+				netlist().queue().remove(this);
 			m_time = netlist().time() + delay;
 			m_in_queue = (m_active > 0);     /* queued ? */
 			if (m_in_queue)
@@ -1383,6 +1403,7 @@ namespace netlist
 		}
 	}
 
+	// FIXME: this could be removed after testing
 	inline void detail::net_t::reschedule_in_queue(const netlist_time delay) NL_NOEXCEPT
 	{
 		if (is_queued())