Allow 'Don't Care' to be parsed into LutLang (#105)

Author: matth2k

src/bin/parse-verilog.rs

@@ -4,7 +4,10 @@ use std::{
 };
 
 use clap::Parser;
-use lut_synth::verilog::{sv_parse_wrapper, SVModule};
+use lut_synth::{
+    lut::verify_expr,
+    verilog::{sv_parse_wrapper, SVModule},
+};
 /// Parse structural verilog into a LutLang Expression
 #[derive(Parser, Debug)]
 #[command(version, about, long_about = None)]
@@ -62,13 +65,16 @@ fn main() -> std::io::Result<()> {
                 .get_exprs()
                 .map_err(|s| std::io::Error::new(std::io::ErrorKind::Other, s))?;
             for (y, expr) in exprs {
+                verify_expr(&expr)
+                    .map_err(|s| std::io::Error::new(std::io::ErrorKind::Other, s))?;
                 eprintln!("{}: {}", y, expr);
                 println!("{}", expr);
             }
         } else {
             let expr = f
                 .to_single_expr()
                 .map_err(|s| std::io::Error::new(std::io::ErrorKind::Other, s))?;
+            verify_expr(&expr).map_err(|s| std::io::Error::new(std::io::ErrorKind::Other, s))?;
             eprintln!("{:?}", f.get_outputs());
             println!("{}", expr);
         }

src/lut.rs

@@ -22,8 +22,8 @@ define_language! {
     pub enum LutLang {
         Const(bool),
         Program(u64), // The only node type that is not a net
-        Var(Symbol),
         "x" = DC,
+        Var(Symbol),
         "NOR" = Nor([Id; 2]),
         "MUX" = Mux([Id; 3]), // s, a, b
         "AND" = And([Id; 2]),
@@ -61,9 +61,10 @@ impl LutLang {
             }
             LutLang::Var(f) => match f.as_str() {
                 "NOR" | "LUT" | "MUX" | "AND" | "XOR" | "NOT" | "BUS" | "DC" | "x" | "REG"
-                | "CYCLE" | "ARG" => Err(
-                    "Variable name is already reserved. Check for missing parentheses.".to_string(),
-                ),
+                | "CYCLE" | "ARG" => Err(format!(
+                    "Variable name '{}' is already reserved. Check for missing parentheses.",
+                    f.as_str()
+                )),
                 _ => Ok(()),
             },
             _ => Ok(()),

src/rewrite.rs

@@ -524,7 +524,7 @@ impl Applier<lut::LutLang, LutAnalysis> for ShannonCondense {
         }
         let k = operands.len();
         assert!(k <= 5);
-        let new_prog = p << (1 << k) | q;
+        let new_prog = (p << (1 << k)) | q;
         let new_prog_id = egraph.add(lut::LutLang::Program(new_prog));
         let sel = subst[self.sel];
         let mut c = Vec::from(&[new_prog_id, sel]);