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Chapter 7
Interrupt/Exception Processing Function
Preliminary User’s Manual U14913EE1V0UM00
7.3.2 Restore
Recovery from maskable interrupt processing is carried out by the RETI instruction.
When the RETI instruction is executed, the CPU performs the following steps, and transfers control to
the address of the restored PC.
(1) Restores the values of the PC and the PSW from EIPC and EIPSW because the EP bit of the PSW
is 0 and the NP bit of the PSW is 0.
(2) Transfers control to the address of the restored PC and PSW.
Figure 7-8 illustrates the processing of the RETI instruction.
Figure 7-8: RETI Instruction Processing
Note: For the ISPR register, see 7.3.6 In-service priority register (ISPR).
Caution: When the PSW.EP bit and the PSW.NP bit are changed by the LDSR instruction during
maskable interrupt processing, in order to restore the PC and PSW correctly during
recovery by the RETI instruction, it is necessary to set PSW.EP back to 0 and PSW.NP
back to 0 using the LDSR instruction immediately before the RETI instruction.
Remark:
The solid lines show the CPU processing flow.
PSW.EP
RETI instruction
PC
PSW
EIPC
EIPSW
PSW.NP
Original processing restored
PC
PSW
FEPC
FEPSW
1
1
0
0
Содержание V850E/CA1 ATOMIC
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