> UB for signed char Signed overflow is undefined in C, but this was implemented in ASM. I'm not familiar with the m68k isa, but I'd be very surprised if it do

> UB for signed char Signed overflow is undefined in C, but this was implemented in ASM. I'm not familiar with the m68k isa, but I'd be very surprised if it doesn't define signed values to wraparound as is natural for a two's complement implementation.