This is just a C rewrite of 3DSFAT16Tool, which was orginally written by @cearp and has been improved upon by @swarzesherz. You may use this to dump and decrypt / inject and encrypt the FAT16 partition from your NAND backup. Other than the original script, this doesn't need Python and additional libraries installed on your PC. It also...
[Port/Release] 3DSFAT16Tool - C Rewrite by d0k3
[Port/Release] 3DSFAT16Tool - C Rewrite by d0k3