Is this a simulation of some theoretical 8-bit CPU, or is it a simulation of a real, existing 8-bit CPU?
For what it's worth, there are many existing C-code emulations of actual 1970s 8-bit CPUs on the Net. (6800, 8080, Z80, 6502, etc, etc, etc.) Studying those may assist you in managing to get past the tricky bits.
In my own Z80 emulation work, I have leaned heavily on 'Yaze' and 'Dasm', with a few extra features and debugging of my own.
For what it's worth, there are many existing C-code emulations of actual 1970s 8-bit CPUs on the Net. (6800, 8080, Z80, 6502, etc, etc, etc.) Studying those may assist you in managing to get past the tricky bits.
In my own Z80 emulation work, I have leaned heavily on 'Yaze' and 'Dasm', with a few extra features and debugging of my own.