Add utils/mask.py

This creates a 2bpp file the same size as the ROM. The ROM can be renamed 2bpp and the mask image can be overlaid on the ROM image to show what's disassembled.

1 files changed, 45 insertions, 0 deletions

diff --git a/utils/mask.py b/utils/mask.py
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+++ b/utils/mask.py
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+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+"""
+Usage: python3 mask.py [pokegold-spaceworld.map] [mask.png]
+
+Generate a 2BPP visualizing the space used by each bank in the ROM.
+"""
+
+import sys
+
+from mapreader import MapReader
+
+def main():
+    mapfile = sys.argv[1] if len(sys.argv) >= 2 else 'pokegold-spaceworld.map'
+    filename = sys.argv[2] if len(sys.argv) >= 3 else 'mask.w1024.2bpp'
+
+    num_banks = 0x40
+    bank_mask = 0x3FFF
+    bank_size = 0x4000 # bytes
+
+    r = MapReader()
+    with open(mapfile, 'r', encoding='utf-8') as f:
+        l = f.readlines()
+    r.read_map_data(l)
+
+    default_bank_data = {'sections': [], 'used': 0, 'slack': bank_size}
+    with open(filename, 'wb') as f:
+        for bank in range(num_banks):
+            hits = bytearray([0x00] * bank_size)
+            data = r.bank_data['rom bank'].get(bank, default_bank_data)
+            for s in data['sections']:
+                if s['beg'] > s['end']:
+                    continue
+                if s['beg'] == 0x0000 and s['end'] > 0xFFFF:
+                    # https://github.com/gbdev/rgbds/issues/515
+                    continue
+                beg = s['beg'] & bank_mask
+                end = s['end'] & bank_mask
+                for i in range(beg, end + 1):
+                    hits[i] = 0xFF
+            f.write(hits)
+
+if __name__ == '__main__':
+    main()