Function new_m120 

pub fn new_m120(
    prg_rom: Box<[u8]>,
    chr_rom: Box<[u8]>,
    mirroring: Mirroring,
) -> Result<DiscreteMapper, MapperError>

Mapper 120 (Tobidase Daisakusen FDS-conversion protection).

Errors

MapperError::Invalid on a bad PRG/CHR size.