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MPC555
/
MPC556
CENTRAL PROCESSING UNIT
MOTOROLA
USER’S MANUAL
Rev. 15 October 2000
3-46
3.15.4.4 Instruction Storage Interrupt
An instruction storage interrupt is never generated by the hardware. The software may
branch to this location as a result of an implementation-specific instruction storage pro-
tection error interrupt.
3.15.4.5 Alignment Interrupt
An alignment exception occurs as a result of one of the following conditions:
• The operand of a floating-point load or store is not word aligned.
• The operand of load/store multiple is not word aligned.
• The operand of
lwarx
or
stwcx
is not word aligned.
• The operand of load/store individual scalar instruction is not naturally aligned
when MSR
LE
= 1.
• An attempt to execute multiple/string instruction is made when MSR
LE
= 1.
3.15.4.6 Floating-Point Enabled Exception Type Program Interrupt
A floating-point enabled exception type program interrupt is generated if ((MSR
FE0
|
MSR
FE1
) &FPSCR
FEX
) is set as a result of move to FPSCR instruction, move to MSR
instruction or the execution of the
rfi
instruction. A floating-point enabled exception
type program interrupt is not generated by floating-point arithmetic instructions. In-
stead if ((MSR
FE0
| MSR
FE1
) &FPSCR
FEX
) is set, the floating-point assist interrupt is
generated.
3.15.4.7 Illegal Instruction Type Program Interrupt
An illegal instruction type program interrupt is not generated by the MPC555 /
MPC556. An implementation dependent software emulation interrupt is generated in-
stead.
3.15.4.8 Privileged Instruction Type Program interrupt
A privileged instruction type program interrupt is
generated for an on-core valid SPR
field or any SPR encoded as an external to the core special register if SPR
0
= 1 and
MSR
PR
= 1, as well as an attempt to execute privileged instruction when MSR
PR
= 1.
Register Name
Bits
Description
Data/Storage Interrupt Status
Register (DSISR)
0:14
Set to 0
15:16
Set to bits 29:30 of the instruction if X-form and to 0b00 if D-
form
17
Set to Bit 25 of the instruction if X-form and to Bit 5 if D-form
18:21
Set to bits 21:24 of the instruction if X-form and to bits 1:4 if
D-form
22:31
Set to bits 6:15 of the instruction
Data Address Register (DAR)
Set to the effective address of the data access that caused
the interrupt
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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