
MOTOROLA
Chapter 3. Instruction Set Model
3-33
Instruction Set Summary
3.2.6.1
System Linkage Instructions
This section describes the system linkage instructions (see Table 3-30). The
sc
instruction
is a user-level instruction that permits a user program to call on the system to perform a
service and causes the processor to take an exception. The Return from Interrupt (
rfi
)
instruction is a supervisor-level instruction that is useful for returning from an exception
handler.
The Return from Critical Interrupt (
rfci
) instruction is a supervisor-level instruction that is
only implemented in the G2_LE processor core. The
rfci
instruction is useful for returning
from a critical interrupt exception handler. This new instruction is described in
Section 3.2.8, “Implementation-Specific Instructions.”
3.2.6.2
Processor Control Instructions—OEA
Processor control instructions are used to read from and write to the condition register (CR),
machine state register (MSR), and special-purpose registers (SPRs), and to read from the
time base register (TBU or TBL).
3.2.6.2.1
Move To/From Machine State Register Instructions
Table 3-31 lists the instructions provided by the core for reading from or writing to the
MSR.
3.2.6.2.2
Move To/From Special-Purpose Register Instructions
Simplified mnemonics are provided for the
mtspr
and
mfspr
instructions so they can be
coded with the SPR name as part of the mnemonic rather than as a numeric operand. See
Appendix F, “Simplified Mnemonics,” in the
Programming Environments Manual
, for
simplified mnemonic examples. The
mtspr
and
mfspr
instructions are shown in
Table 3-32.
Table 3-30. System Linkage Instructions
Name
Mnemonic
Operand Syntax
Return from Interrupt
rfi
—
System Call
sc
—
Table 3-31. Move To/From Machine State Register Instructions
Name
Mnemonic
Operand Syntax
Move from Machine State Register
mfmsr
r
D
Move to Machine State Register
mtmsr
r
S
F
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