MPC555
/
MPC556
CENTRAL PROCESSING UNIT
MOTOROLA
USER’S MANUAL
Rev. 15 October 2000
3-48
3.15.4.12 Implementation-Dependent Software Emulation Interrupt
An implementation-dependent software emulation interrupt occurs in the following in-
stances:
• When executing any non-implemented instruction. This includes all illegal and un-
implemented optional instructions and all floating-point instructions.
• When executing a
mtspr
or
mfspr
that specifies on-core non-implemented reg-
ister, regardless of SPR
0
.
• When executing a
mtspr
or
mfspr
that specifies off-core non-implemented reg-
ister and SPR
0
= 0 or MSR
PR
= 0 (no program interrupt condition).
• Program interrupt is generated if ((MSR
FE0
| MSR
FE1
) and FPSCR
FEX
) is set as
a result of move to FPSCR instruction, move to MSR instruction, or the execution
of the
rfi
instruction.
• Floating-point enabled exception type program interrupt is not generated by float-
ing-point arithmetic instructions, instead if ((MSR
FE0
| MSR
FE1
) &FPSCR
FEX
) is
set, the floating-point assist interrupt is generated.
In addition, the following registers are set:
Register Name
Bits
Description
Save/Restore Register 0 (SRR0)
Set to the effective address of the instruction that caused the
interrupt
Save/Restore Register 1 (SRR1)
1:4
Set to 0
10:15
Set to 0
Other
Loaded from bits 16:31 of MSR
1
Machine State Register (MSR)
IP
No change
ME
No change
LE
Bit is copied from ILE
Other
Set to 0
NOTES:
1. In the current implementation bit 30 of the SRR1 is never cleared other then by loading zero value from
MSR RI.
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Freescale Semiconductor, Inc.
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