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+# gcmtool.py
+Python3 script for unpack/pack/rebuild GCM/iso file format. This tool can rebuild FileStringTable (FST) of GCM and patch boot.bin with a new apploader.img, boot.dol, add/remove/edit folder and files of the game. MIT License.
+
+## User manual
+Unpack GCM/iso file **source_gcm.iso** in the default new folder _game_code-DVD_number_. If optional_dest_folder is specified we unpack in _optional_dest_folder_.
+```
+gcmtool.py --unpack source_gcm.iso optional_dest_folder
+```
+
+Pack **source_folder** in the default new GCM/iso file _source_folder.iso_. If optional_dest_file.iso is specified we pack in _optional_dest_file.iso_. If one of the files or system files contains length change we have to use --rebuild-fst command before packing.
+```
+gcmtool.py --pack source_folder optional_dest_file.iso
+```
+Rebuild the FST file system of an unpacked GCM/iso and patch boot.bin for a new apploader, dol, and add/remove/edit of folders and files.
+```
+gcmtool.py --rebuild-fst source_folder
+```
+Print stats about the GCM/iso file or the unpacked GCM/iso folder. This stats contains informations about full memory mapping sorted by offset (files and system files), get empty spaces informations using optional align -a (default=4).
+```
+gcmtool.py --stats path -a 4 
+```
+Japanese charset is not handled for now except if you have installed Japanese local.
+
+The original GCM/iso and repack GCM/iso are different most of the time. This is because GCM DVD contains "empty spaces" with data unused (old datas or random datas I don't know). So this datas are useless and loss during unpack.
+
+The sorting of files during FST rebuild is deferent from the original and this is full compatible with the GameCube dol API.
+
+## Extracted file tree
+root folder contains all files of the unpacked GCM/iso
+
+sys folder contains GCM system files of the game:
+* boot.bin
+* bi2.bin
+* apploader.img
+* boot.dol
+* fst.bin