https://github.com/ihaveamac/3dsconv - use the terminal on "macOS"
if the .3ds is decrypted (if you dumped this game card, you should do it decrypted):
Code:
python2 3dsconv.py game.3ds
if the .3ds is encrypted:
Code:
python2 3dsconv.py --gen-ncchinfo game.3ds
# use ncchinfo.bin with Decrypt9, place xorpads in the same folder as the .3ds
python2 3dsconv.py game.3ds
... or use the newest release of Decrypt9 to convert it to CIA right on the console