Restore - NEC V850E/Dx3 Preliminary User's Manual

Interrupt Controller (INTC)
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5.5.2 Restore

Recovery from software exception processing is carried out by the RETI
instruction.
By executing the RETI instruction, the CPU carries out the following
processing and shifts control to the restored PC's address.
(1) Loads the restored PC and PSW from EIPC and EIPSW because the EP
bit of the PSW is 1.
(2) Transfers control to the address of the restored PC and PSW.
Figure 5-11 illustrates the processing of the RETI instruction.
RETI instruction
1
PSW.EP
0
PSW.NP
0
PC EIPC
PSW EIPSW
Original processing restored
Figure 5-11 RETI instruction processing
Caution When the PSW.EP bit and the PSW.NP bit are changed by the LDSR
instruction during the software exception 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 1 using the LDSR instruction immediately before the RETI
instruction.
Note The solid lines show the CPU processing flow.
Preliminary User's Manual U17566EE1V2UM00
1
PC FEPC
PSW FEPSW
Chapter 5
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