From 85a382d9348e5673bae1791ceacf9853ef19f6aa Mon Sep 17 00:00:00 2001
From: Nico Lube <nl@leds.de>
Date: Fri, 17 Apr 2026 11:07:57 +0200
Subject: [PATCH] Support deprecated G54 aperture-select prefix.

Accepts standalone `G54*` and the combined `G54Dnn*` form still emitted
by gerbv on save. See gerber spec 8.1.1.

Fixes: #16
---
 src/parser.rs            | 24 ++++++++++++++++
 tests/component_tests.rs | 59 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 83 insertions(+)

diff --git a/src/parser.rs b/src/parser.rs
index cb4e9bb..d894407 100644
--- a/src/parser.rs
+++ b/src/parser.rs
@@ -263,6 +263,30 @@ fn parse_line<T: Read>(
                         _ => Err(ContentError::UnknownCommand {}),
                     },
                 ]),
+                '5' => {
+                    // G54 is the deprecated aperture-select prefix (gerber spec 8.1.1).
+                    // The combined `G54Dnn*` form is still emitted by gerbv on save.
+                    match linechars.next().ok_or(ContentError::UnknownCommand {})? {
+                        '4' => {
+                            let select = Ok(FunctionCode::GCode(GCode::SelectAperture).into());
+                            match linechars.next() {
+                                None | Some('*') => Ok(vec![select]),
+                                Some('D') => {
+                                    linechars.next_back();
+                                    Ok(vec![
+                                        select,
+                                        parse_aperture_selection_or_command(
+                                            line,
+                                            linechars.clone(),
+                                        ),
+                                    ])
+                                }
+                                Some(_) => Ok(vec![Err(ContentError::UnknownCommand {})]),
+                            }
+                        }
+                        _ => Ok(vec![Err(ContentError::UnknownCommand {})]),
+                    }
+                }
                 _ => Ok(vec![Err(ContentError::UnknownCommand {})]),
             }
         }
diff --git a/tests/component_tests.rs b/tests/component_tests.rs
index 78de3c4..94475d8 100644
--- a/tests/component_tests.rs
+++ b/tests/component_tests.rs
@@ -319,6 +319,65 @@ fn aperture_selection() {
     )
 }
 
+/// Test deprecated `G54` aperture selection (gerber spec 8.1.1).
+/// Accepts both `G54*` (standalone) and the combined `G54Dnn*` form (emitted by gerbv on save).
+#[test]
+fn deprecated_g54_aperture_selection() {
+    // given
+    logging_init();
+
+    let reader = gerber_to_reader(
+        "
+    %FSLAX23Y23*%
+    %MOMM*%
+
+    %ADD10C, 0.01*%
+    %ADD11R, 0.01X0.15*%
+
+    G04 Deprecated combined G54Dnn form*
+    G54D10*
+    G04 Deprecated standalone G54 form*
+    G54*
+    G04 Deprecated combined G54Dnn form again*
+    G54D11*
+
+    M02*
+    ",
+    );
+
+    // when
+    parse_and_filter!(reader, commands, filtered_commands, |cmd| matches!(
+        cmd,
+        Ok(Command::FunctionCode(FunctionCode::DCode(
+            DCode::SelectAperture(_)
+        ))) | Ok(Command::FunctionCode(FunctionCode::GCode(
+            GCode::SelectAperture
+        )))
+    ));
+
+    // then
+    assert_eq!(
+        filtered_commands,
+        vec![
+            Ok(Command::FunctionCode(FunctionCode::GCode(
+                GCode::SelectAperture
+            ))),
+            Ok(Command::FunctionCode(FunctionCode::DCode(
+                DCode::SelectAperture(10)
+            ))),
+            Ok(Command::FunctionCode(FunctionCode::GCode(
+                GCode::SelectAperture
+            ))),
+            Ok(Command::FunctionCode(FunctionCode::GCode(
+                GCode::SelectAperture
+            ))),
+            Ok(Command::FunctionCode(FunctionCode::DCode(
+                DCode::SelectAperture(11)
+            ))),
+        ]
+    )
+}
+
 /// Test the D01* statements (linear)
 #[test]
 #[allow(non_snake_case)]