From 8ec66f50c64501e30ed6adae94f89b90b48de7f0 Mon Sep 17 00:00:00 2001
From: Alejandro Soto <alejandro@34project.org>
Date: Sat, 19 Nov 2022 19:36:21 -0600
Subject: Implement interval timer simulation

---
 tb/interval_timer.cpp   | 97 +++++++++++++++++++++++++++++++++++++++++++++++++
 tb/interval_timer.hpp   | 31 ++++++++++++++++
 tb/top/conspiracion.cpp |  8 ++++
 3 files changed, 136 insertions(+)
 create mode 100644 tb/interval_timer.cpp
 create mode 100644 tb/interval_timer.hpp

diff --git a/tb/interval_timer.cpp b/tb/interval_timer.cpp
new file mode 100644
index 0000000..f593894
--- /dev/null
+++ b/tb/interval_timer.cpp
@@ -0,0 +1,97 @@
+#include "avalon.hpp"
+#include "interval_timer.hpp"
+
+namespace taller::avalon
+{
+	interval_timer::interval_timer(std::uint32_t base) noexcept
+	: slave(base, 32, 4)
+	{}
+
+	void interval_timer::tick() noexcept
+	{
+		if(!status_run)
+		{
+			return;
+		} else if(count > 0)
+		{
+			--count;
+		} else
+		{
+			count = period;
+			status_to = 1;
+			status_run = control_cont;
+		}
+	}
+
+	bool interval_timer::read(std::uint32_t addr, std::uint32_t &data) noexcept
+	{
+		switch(addr)
+		{
+			case 0:
+				data
+					= status_run << 1
+					| status_to  << 0;
+
+				break;
+
+			case 1:
+				data
+					= control_cont << 1
+					| control_ito  << 0;
+
+				break;
+
+			case 2:
+				data = period & 0xffff;
+				break;
+
+			case 3:
+				data = period >> 16;
+				break;
+
+			case 4:
+				data = snap & 0xffff;
+				break;
+
+			case 5:
+				data = snap >> 16;
+				break;
+		}
+
+		return true;
+	}
+
+	bool interval_timer::write(std::uint32_t addr, std::uint32_t data, unsigned byte_enable) noexcept
+	{
+		switch(addr)
+		{
+			case 0:
+				status_to = 0;
+				break;
+
+			case 1:
+				control_ito = !!(data & (1 << 0));
+				control_cont = !!(data & (1 << 1));
+
+				status_run = (status_run && !!(data << (1 << 3))) || !!(data << (1 << 2));
+				break;
+
+			case 2:
+				period = (period & 0xffff'0000) | (data & 0xffff);
+				count = period;
+				break;
+
+			case 3:
+				period = (period & 0xffff) | (data & 0xffff) << 16;
+				count = period;
+				break;
+
+			case 4:
+			case 5:
+				snap = count;
+				break;
+		}
+
+		return true;
+	}
+}
diff --git a/tb/interval_timer.hpp b/tb/interval_timer.hpp
new file mode 100644
index 0000000..7cce265
--- /dev/null
+++ b/tb/interval_timer.hpp
@@ -0,0 +1,31 @@
+#ifndef TALLER_INTERVAL_TIMER_HPP
+#define TALLER_INTERVAL_TIMER_HPP
+
+#include <cstdint>
+
+#include "avalon.hpp"
+
+namespace taller::avalon
+{
+	class interval_timer : public slave
+	{
+		public:
+			interval_timer(std::uint32_t base) noexcept;
+
+			void tick() noexcept;
+
+			virtual bool read(std::uint32_t addr, std::uint32_t &data) noexcept final override;
+			virtual bool write(std::uint32_t addr, std::uint32_t data, unsigned byte_enable) noexcept final override;
+
+		private:
+			std::uint32_t count;
+			std::uint32_t period;
+			std::uint32_t snap;
+			bool          status_to = false;
+			bool          status_run = false;
+			bool          control_ito = false;
+			bool          control_cont = false;
+	};
+}
+
+#endif
diff --git a/tb/top/conspiracion.cpp b/tb/top/conspiracion.cpp
index 984cb58..d710bde 100644
--- a/tb/top/conspiracion.cpp
+++ b/tb/top/conspiracion.cpp
@@ -25,6 +25,7 @@
 #include "../const.hpp"
 #include "../mem.hpp"
 #include "../jtag_uart.hpp"
+#include "../interval_timer.hpp"
 #include "../null.hpp"
 #include "../window.hpp"
 #include "../vga.hpp"
@@ -251,6 +252,7 @@ int main(int argc, char **argv)
 
 	mem<std::uint32_t> hps_ddr3(0x0000'0000, 512 << 20);
 	jtag_uart ttyj0(0x3000'0000);
+	interval_timer timer(0x3002'0000);
 	mem<std::uint32_t> vram(0x3800'0000, 64 << 20);
 	null vram_null(0x3800'0000, 64 << 20, 2);
 	window vram_window(vram, 0x0000'0000);
@@ -266,6 +268,7 @@ int main(int argc, char **argv)
 
 	avl.attach(hps_ddr3);
 	avl.attach(ttyj0);
+	avl.attach(timer);
 
 	for(auto &slave : consts)
 	{
@@ -329,6 +332,11 @@ int main(int argc, char **argv)
 		top.clk_clk = !top.clk_clk;
 		top.eval();
 
+		if(top.clk_clk)
+		{
+			timer.tick();
+		}
+
 		if(!avl.tick(top.clk_clk))
 		{
 			failed = true;
-- 
cgit v1.2.3