Fixes for concurrency and the fibonacci example

src/types.rs

@@ -0,0 +1,45 @@
+use std::fmt;
+
+/// 12-bit unsigned integer for MCS-4 address space
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
+pub struct U12(u16);
+
+impl U12 {
+    pub fn new(value: u16) -> Self {
+        U12(value & 0xFFF)
+    }
+
+    pub fn value(&self) -> u16 {
+        self.0
+    }
+
+    pub fn inc(&mut self) {
+        self.0 = (self.0 + 1) & 0xFFF;
+    }
+
+    pub fn set(&mut self, value: u16) {
+        self.0 = value & 0xFFF;
+    }
+
+    pub fn wrapping_add(&self, value: u16) -> Self {
+        U12::new(self.0.wrapping_add(value))
+    }
+}
+
+impl fmt::Display for U12 {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{:03X}", self.0)
+    }
+}
+
+impl From<u16> for U12 {
+    fn from(value: u16) -> Self {
+        U12::new(value)
+    }
+}
+
+impl From<U12> for u16 {
+    fn from(value: U12) -> Self {
+        value.value()
+    }
+}