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CPU Data Paths and Control2-18 SPRU733
2.7.7 Interrupt Flag Register (IFR)
The interrupt flag register (IFR) contains the status of INT4−INT15 and NMI
interrupt. Each corresponding bit in the IFR is set to 1 when that interrupt
occurs; otherwise, the bits are cleared to 0. If you want to check the status of
interrupts, use the MVC instruction to read the IFR. (See the MVC instruction
description, page 3-180, for information on how to use this instruction.) The
IFR is shown in Figure 2−8 and described in Table 2−10.
Figure 2−8. Interrupt Flag Register (IFR)
31 16
Reserved
R-0
15141312111098765432 10
IF15 IF14 IF13 IF12 IF11 IF10 IF9 IF8 IF7 IF6 IF5 IF4 Reserved NMIF 0
R-0 R-0 R-0 R-0
Legend: R = Readable by the MVC instruction; -n = value after reset
Table 2−10. Interrupt Flag Register (IFR) Field Descriptions
Bit Field Value Description
31−16 Reserved 0 Reserved. The reserved bit location is always read as 0. A value written to this
field has no effect.
15−4 IFn Interrupt flag. Indicates the status of the corresponding maskable interrupt. An
interrupt flag may be manually set by setting the corresponding bit (ISn) in the
interrupt set register (ISR) or manually cleared by setting the corresponding bit
(ICn) in the interrupt clear register (ICR).
0 Interrupt has not occurred.
1 Interrupt has occurred.
3−2
Reserved 0 Reserved. The reserved bit location is always read as 0. A value written to this
field has no effect.
1 NMIF Nonmaskable interrupt flag.
0 Interrupt has not occurred.
1 Interrupt has occurred.
0
0 0 Reset interrupt flag.