Tweak asm-diff settings

README.md

@@ -18,6 +18,14 @@ Recompilable code that creates 1:1 binaries for the commercial videogame Castlev
 1. Run `make extract` to generate the assembly files
 1. Run `make all` to compile the binaries into the `build/` directory
 
+## Check for function matching
+
+Thanks to [asm-differ](https://github.com/simonlindholm/asm-differ) you can check if a funtion written in C matches its assembly counterpart.
+
+1. Be sure to resolve the submodule with `git submodule update --init`
+1. Ensure to create a matching binary with `make clean && make extract && make all && mkdir expected && cp -r build expected/`
+1. Choose a function to match (eg. `func_8018E964`), an overlay (eg. `st/mad`) and then invoke `python3 ./tools/asm-differ/diff.py -mwo --overlay st/mad func_8018E964`
+
 ## Non-matching build
 
 Some of the functions that do not fully match the original game can be compiled by defining `#define NON_MATCHING` on a header file or by passing `-DNON_MATCHING to the compiler. In theory they might be logically equivalent in-game, but I cannot promise that. Few of them could match by tuning or changing the compiler.

diff_settings.py

@@ -1,8 +1,21 @@
 #!/usr/bin/env python3
 
+def add_custom_arguments(parser):
+    parser.add_argument(
+        "--overlay",
+        default="dra",
+        dest='overlay',
+        help="Defines which overlay to use for the diff (main, dra, st/mad, etc.)",
+    )
+
 def apply(config, args):
+    overlay = args.overlay or 'dra'
+    isMapOverlay = overlay.startswith("st/")
+    name = overlay[3:] if isMapOverlay else overlay
+    longname = f'st{overlay[3:]}' if isMapOverlay else overlay
+
     config["arch"] = "mipsel"
-    config['baseimg'] = f'dra.bin'
-    config['myimg'] = f'build/dra.bin'
-    config['mapfile'] = f'build/dra.map'
-    config['source_directories'] = ['src/dra', 'include', 'asm/dra']
+    config['baseimg'] = f'{name}.bin'
+    config['myimg'] = f'build/{name}.bin'
+    config['mapfile'] = f'build/{longname}.map'
+    config['source_directories'] = [f'src/{overlay}', 'include', f'asm/{overlay}']