Restore - NEC V850ES/F 3-L Series User Manual

Chapter 5

5.5.2 Restore

1
Figure 5-11
Caution
Note
248
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
PSW.EP
0
PSW.NP
0
PC EIPC
PSW EIPSW
Original processing restored
RETI instruction processing
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.
The solid lines show the CPU processing flow.
User's Manual U18743EE1V2UM00
Interrupt Controller (INTC)
1
PC FEPC
PSW FEPSW