问题
I'm working with code that has the following four assembly instructions:
CPSR_cxsf SPSR_cxsf CPSR_c SPSR_c
I've been having a hard time trying to figure out what the difference between these exception modes is. Can anyone advice?
回答1:
c, x, s and f refers to the different parts of the status registers:
c = Control
x = eXtension
s = Status
f = Flags
The purpose of using e.g. CPSR_c is that it allows you to update only parts of the status register (in this case the control bits) without affecting the other parts.
来源：https://stackoverflow.com/questions/15641149/current-program-status-register-exception-modes