internal static bool goodchecksum(IList <byte> romdata, RomMapMode mode, int size)
{
int snestopc(int snesAddress) => RomUtil.ConvertSnesToPc(snesAddress, mode, size);
var checksum = (int)getchecksum(romdata);
return(((romdata[snestopc(0x00FFDE)] ^ romdata[snestopc(0x00FFDC)]) == 0xFF) &&
((romdata[snestopc(0x00FFDF)] ^ romdata[snestopc(0x00FFDD)]) == 0xFF) &&
((romdata[snestopc(0x00FFDE)] & 0xFF) == (checksum & 0xFF)) &&
((romdata[snestopc(0x00FFDF)] & 0xFF) == ((checksum >> 8) & 0xFF)));
}
internal static void fixchecksum(IList <byte> romdata, RomMapMode mode, int size)
{
int snestopc(int snesAddress) => RomUtil.ConvertSnesToPc(snesAddress, mode, size);
// randomdude999: clear out checksum bytes before recalculating checksum, this should make it correct on roms that don't have a checksum yet
romdata.writeromdata(snestopc(0x00FFDC), 0xFFFF0000);
var checksum = getchecksum(romdata);
romdata.writeromdata_byte(snestopc(0x00FFDE), (byte)(checksum & 255));
romdata.writeromdata_byte(snestopc(0x00FFDF), (byte)((checksum >> 8) & 255));
romdata.writeromdata_byte(snestopc(0x00FFDC), (byte)((checksum & 255) ^ 255));
romdata.writeromdata_byte(snestopc(0x00FFDD), (byte)(((checksum >> 8) & 255) ^ 255));
}
