And full(ish) test coverage

src/device.rs

@@ -28,7 +28,7 @@ pub trait Device: std::fmt::Debug {
 
     fn deo2(&mut self, vm: &mut Uxn, port: u8, val: u16) -> Result<(), DeviceError> {
         let slot = port & 0xF;
-        if slot < 0xF {
+        if slot == 0xF {
             return Err(DeviceError::AddressOverflow);
         }
         let [high, low] = val.to_be_bytes();

tests/vm_tests.rs

@@ -1,3 +1,7 @@
+use std::cell::RefCell;
+use std::rc::Rc;
+
+use uxn::device::buff::BuffDevice;
 use uxn::isa::Icode;
 use uxn::vm::*;
 
@@ -714,6 +718,68 @@ fn test_sta2() {
     assert_eq!(vm.lda2(0x010c), Ok(0xFFEE));
 }
 
+#[test]
+fn test_dei() {
+    nofmt::pls! {
+        let mut vm = Uxn::of1(&[
+            Icode::LIT, 0x30, Icode::DEI, Icode::BRK,
+        ]);
+        let dev = Rc::new(RefCell::new(BuffDevice::new()));
+        vm.deo1(0x30, 0xFF).unwrap();
+        vm.deo1(0x31, 0xEE).unwrap();
+        vm.devices[3] = dev.clone();
+    }
+    assert_eq!(vm.run(64), Err(UxnError::Break));
+    assert_eq!(vm.wst.borrow().idx(), 1);
+    assert_eq!(vm.wst.borrow().peek1(), Ok(0xFF));
+}
+
+#[test]
+fn test_dei2() {
+    nofmt::pls! {
+        let mut vm = Uxn::of1(&[
+            Icode::LIT, 0x30, Icode::DEI | Icode::SHORT, Icode::BRK,
+        ]);
+        let dev = Rc::new(RefCell::new(BuffDevice::new()));
+        vm.deo2(0x30, 0xFFEE).unwrap();
+        vm.devices[3] = dev.clone();
+    }
+    assert_eq!(vm.run(64), Err(UxnError::Break));
+    assert_eq!(vm.wst.borrow().idx(), 2);
+    assert_eq!(vm.wst.borrow().peek2(), Ok(0xFFEE));
+}
+
+#[test]
+fn test_deo() {
+    nofmt::pls! {
+        let mut vm = Uxn::of1(&[
+            Icode::LIT | Icode::SHORT, 0xFF, 0x30, Icode::DEO, Icode::BRK,
+        ]);
+        let dev = Rc::new(RefCell::new(BuffDevice::new()));
+        vm.devices[3] = dev.clone();
+    }
+    assert_eq!(vm.run(64), Err(UxnError::Break));
+    assert_eq!(vm.wst.borrow().idx(), 0);
+    assert_eq!(vm.dei1(0x30), Ok(0xFF));
+}
+
+#[test]
+fn test_deo2() {
+    nofmt::pls! {
+        let mut vm = Uxn::of1(&[
+            Icode::LIT | Icode::SHORT, 0xFF, 0xEE,
+            Icode::LIT, 0x30,
+            Icode::DEO | Icode::SHORT,
+            Icode::BRK,
+        ]);
+        let dev = Rc::new(RefCell::new(BuffDevice::new()));
+        vm.devices[3] = dev.clone();
+    }
+    assert_eq!(vm.run(64), Err(UxnError::Break));
+    assert_eq!(vm.wst.borrow().idx(), 0);
+    assert_eq!(vm.dei2(0x30), Ok(0xFFEE));
+}
+
 #[test]
 fn test_add() {
     nofmt::pls! {