I started a game of True Swing Golf (USA version) a while back, and I am quite far through the game.
However the game takes your player name from the NDS profile, so I am stuck with something that is not my name and I'd like to change it. How vain!?

I extracted the save using TWLSaveTool and then did some experiments with DeSmuME.

However, the save game has a checksum that I have been unable to figure out.

Here are a bunch of save games, and a small .c program to display the checksum of each save: https://forumfiles.com/fdhbXemfb3/true-swing-golf-NDS-saves_zip
Each save file is named as the NDS profile player name I used to create it, and all other settings are equal.
All saves were created from blank by deleting the previous save in the game and restarting DeSmuME.

What I've found so far:
- 0x0 .. 0x3 = checksum (4 bytes)
- 0x4 .. 0x7 = some flags
- 0x4 = increments with every save (not shown in attached save files)
- 0x5 = set to 1/true after the game has been initialised (player has been created)
- 0x8 .. 0xB = magic phrase "DSG " (game codename was DS Golf)
- 0xC .. 0x27 = unknown, can be changed with no effect on save game loading
- 0x20 and 0x24 = change with every save; in-game timer?

- 0x28 .. END = seems to be the area that is protected by checksum
I have corrupted a handful of places over this range and they all resulted in "corrupt save data" error on game launch.
(note: it's possible to corrupt the save in a way that doesn't raise an error on launch = the "See Player Data" button will not appear on the title screen)

- 0x5C .. 0x73 = player name (I want to change this)
- 0x74 .. 0xAB(?) = player message

So, I guess there are two approaches to changing my name in the save:

1. crack the checksum and recalculate it after changing the player name data
2. create a temporary cheat code or rom patch to stop the check for a corrupt save file

I'd appreciate some help or advice on how to achieve either!

Thanks