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52 FUJITSU MICROELECTRONICS LIMITED CM71-00105-1E
CHAPTER 4 RESET AND "EIT" PROCESSING
4.4
4.4.6 Guarded Access Break
Guarded access break is a function that carries out a break processing instead of generating an exception
when an instruction access protection violation or a data access protection violation occurs during
debugging.
Whether each access protection violation is treated as a break or an exception processing is determined by
the debugger. The guarded access break does not occur during normal operation.
If the debugger determines to carry out the break processing when instruction break has been accepted in
the user state, the following operations are carried out.
1. Transition to privilege mode is carried out, the stack flag (S) is cleared, 4 is set to the interrupt level
mask register (ILM), and then the mode is shifted to the debug state.
"0" → UM "0" → S"4" → ILM
2. The contents of the program status (PS) are saved to the PS save register (PSSR).
PS → PSSR
3. The contents of the program counter (PC) of an exception source instruction are saved to the PS save
register (PCSR).
PC → PCSR
4. An instruction is fetched from the emulator debug instruction register (EIDR1), and the handler is
executed.