Added bus model and InactiveW5500 state

src/w5500.rs

@@ -1 +1,34 @@
-pub struct W5500 {}
+use crate::inactive_w5500::InactiveW5500;
+use crate::uninitialized_w5500::UninitializedW5500;
+use bus::{ActiveBus, ActiveFourWire, ActiveThreeWire, FourWire, ThreeWire};
+use embedded_hal::digital::v2::OutputPin;
+use embedded_hal::spi::FullDuplex;
+
+pub struct W5500<SpiBus: ActiveBus> {
+    bus: SpiBus,
+}
+
+impl<SpiBus: ActiveBus> W5500<SpiBus> {
+    pub fn new(bus: SpiBus) -> Self {
+        W5500 { bus }
+    }
+    pub fn reset(self) -> UninitializedW5500<SpiBus> {
+        // TODO reset chip
+        UninitializedW5500::new(self.bus)
+    }
+    //TODO open_udp_socket
+}
+
+impl<Spi: FullDuplex<u8>, ChipSelect: OutputPin> W5500<ActiveFourWire<Spi, ChipSelect>> {
+    pub fn deactivate(self) -> (InactiveW5500<FourWire<ChipSelect>>, Spi) {
+        let (bus, spi) = self.bus.deactivate();
+        (InactiveW5500::new(bus), spi)
+    }
+}
+
+impl<Spi: FullDuplex<u8>> W5500<ActiveThreeWire<Spi>> {
+    pub fn deactivate(self) -> (InactiveW5500<ThreeWire>, Spi) {
+        let (bus, spi) = self.bus.deactivate();
+        (InactiveW5500::new(bus), spi)
+    }
+}