Implement interval timer simulation

1 files changed, 97 insertions, 0 deletions

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;
+	}
+}