2 files changed, 33 insertions, 0 deletions

diff --git a/lib/xixanta/src/assembler.rs b/lib/xixanta/src/assembler.rs
index 2f0292e..54ba4c3 100644
--- a/lib/xixanta/src/assembler.rs
+++ b/lib/xixanta/src/assembler.rs
@@ -4630,6 +4630,19 @@ JAL procedure
     }
 
     #[test]
+    fn lobyte_with_arithmetic() {
+        let res = just_bundles(
+            r#"lda #.lobyte(@address - 1)
+@address:
+nop
+    "#,
+        );
+
+        assert_eq!(res[0].bytes[0], 0xA9);
+        assert_eq!(res[0].bytes[1], 0x01);
+    }
+
+    #[test]
     fn warnings_on_empty_proc_scope_macro() {
         let res = just_assemble(
             r#".proc Proc
diff --git a/lib/xixanta/src/parser.rs b/lib/xixanta/src/parser.rs
index 9f8ffc7..10340c4 100644
--- a/lib/xixanta/src/parser.rs
+++ b/lib/xixanta/src/parser.rs
@@ -1194,6 +1194,12 @@ impl Parser {
         // Skip any possible whitespace before the optional opening paren.
         self.skip_whitespace(line);
 
+        // If arguments are wrapped in a parenthesis, and the look ahead index
+        // is larger than zero, then the following code will temporarily
+        // subtract it. This is in a similar fashion as what we do in
+        // extract_paren_expression().
+        let mut la_subtracted = false;
+
         // Scope the end of the argument list. If the arguments are enclosed on
         // parenthesis, take that into account, otherwise we will parse until
         // the end of the cleaned line.
@@ -1203,6 +1209,14 @@ impl Parser {
             self.next();
             self.skip_whitespace(line);
 
+            // Arguments are in a parenthesis and we were looking
+            // ahead. Temporarily decrease the index and change 'la_subtracted'
+            // so we increase it back at the end.
+            if self.look_ahead_index > 0 {
+                self.look_ahead_index -= 1;
+                la_subtracted = true;
+            }
+
             // If there is a parenthesis it might be either that the command
             // enclosed its arguments into parenthesis, or that the first
             // argument is using parenthesis to disambiguate with an
@@ -1282,6 +1296,12 @@ impl Parser {
             }
         }
 
+        // Was the look ahead index subtracted temporarily? If so now it's time
+        // to increase it again.
+        if la_subtracted {
+            self.look_ahead_index += 1;
+        }
+
         Ok(args)
     }