How can I get the range of numbers that would produce certain flag conditions when subtracted from 4-CodePudding

I started learning Z80 recently, but I'm struggling with flags.

I want to get the range of register "B" in Z80 assembly.

This is the problem that I faced. Register "A" is 43H (in Hexadecimal number) and I want to sub register "B" from that, doing in 8-bit subtraction.

How can I get the each range of register "B" that would produce:

CodePudding user response：

67 - x sets C if x >= 0 and x < 68.
It sets S if x > 67 or x < -60.
It sets V if x < -60.

In hexadecimal, 43h - x sets C if x < 44h.
It sets S if x > 43h and x < c4h.
It sets V if x > 7fh and x < c4h.