1 files changed, 48 insertions, 0 deletions
diff --git a/src/components/device_bus.rs b/src/components/device_bus.rs
new file mode 100644
index 0000000..a15d836
--- /dev/null
+++ b/src/components/device_bus.rs
@@ -0,0 +1,48 @@
+use crate::*;
+
+
+pub trait DeviceBus {
+    /// Attempt to wake the system.
+    fn wake(&mut self) -> bool;
+    /// Get a device by slot number.
+    fn get_device(&mut self, slot: u8) -> Option<&mut dyn Device>;
+    // Read from a device port.
+    fn read(&mut self, port: u8) -> u8 {
+        match self.get_device(port >> 4) {
+            Some(device) => device.read(port & 0xF),
+            None => 0,
+        }
+    }
+    // Write to a device port.
+    fn write(&mut self, port: u8, value: u8) -> Option<Signal> {
+        match self.get_device(port >> 4) {
+            Some(device) => device.write(port & 0xF, value),
+            None => None,
+        }
+    }
+    /// Reset all connected devices.
+    fn reset(&mut self) {
+        for slot in 0..16 {
+            if let Some(device) = self.get_device(slot) {
+                device.reset();
+            }
+        }
+    }
+}
+
+
+pub trait Device {
+    fn read(&mut self, port: u8) -> u8;
+    fn write(&mut self, port: u8, value: u8) -> Option<Signal>;
+    /// Return and clear the wake flag for this device.
+    fn wake(&mut self) -> bool;
+    /// Reset device to the initial state.
+    fn reset(&mut self);
+}
+
+impl Device for () {
+    fn read(&mut self, _: u8) -> u8 { 0 }
+    fn write(&mut self, _: u8, _: u8) -> Option<Signal> { None }
+    fn wake(&mut self) -> bool { false }
+    fn reset(&mut self) { }
+}