add ReadyValid<T>

crates/fayalite/src/util.rs

@@ -25,3 +25,5 @@ pub use scoped_ref::ScopedRef;
 pub use misc::{
     interned_bit, iter_eq_by, BitSliceWriteWithBase, DebugAsDisplay, DebugAsRawString, MakeMutSlice,
 };
+
+pub mod ready_valid;

crates/fayalite/src/util/ready_valid.rs

@@ -0,0 +1,34 @@
+use crate::prelude::*;
+
+#[hdl]
+pub struct ReadyValid<T> {
+    pub data: HdlOption<T>,
+    #[hdl(flip)]
+    pub ready: Bool,
+}
+
+impl<T: Type> ReadyValid<T> {
+    #[hdl]
+    pub fn fire(expr: Expr<Self>) -> Expr<Bool> {
+        #[hdl]
+        let fire: Bool = wire();
+        #[hdl]
+        match expr.data {
+            HdlNone => connect(fire, false),
+            HdlSome(_) => connect(fire, expr.ready),
+        }
+        fire
+    }
+    #[hdl]
+    pub fn map<R: Type>(
+        expr: Expr<Self>,
+        f: impl FnOnce(Expr<T>) -> Expr<R>,
+    ) -> Expr<ReadyValid<R>> {
+        let data = HdlOption::map(expr.data, f);
+        #[hdl]
+        let mapped = wire(ReadyValid[Expr::ty(data).HdlSome]);
+        connect(mapped.data, data);
+        connect(expr.ready, mapped.ready);
+        mapped
+    }
+}