Control Register File
CPU Data Paths and Control
2-18
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
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
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
IF
n
Interrupt flag. Indicates the status of the corresponding maskable interrupt. An
interrupt flag may be manually set by setting the corresponding bit (IS
n
) in the
interrupt set register (ISR) or manually cleared by setting the corresponding bit
(IC
n
) 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.