陷阱调用代码：

[A1] MVK TRAP_HANDLER,B0 ;load 32-bit trap address

[A1] mvkh TRAP_HANDLER,B0 ;

[A1] B B0 ;branch to trap handler

[A1] MVC CSR, B0 ;read CSR

[A1] AND -2, B0, B1 ;disable interrupts:GIE=0

[A1] MVC B1, CSR ;write to CSR

[A1] MVK TRAP_RETURN, B1 ;load 32-bit return address

[A1] MVKH TRAP_RETURN, B1 ;

TRAP_RETURN: (post-trap code)

陷阱返回代码：

B B1 ;return

MVC B0, CSR ;restore CSR

NOP 4 ;delay slots