IBM PowerPC 604 User Manual page 119

Table 2-41 summarizes the instructions used for reading from and writing to the MSR.
Table 2-41. Move to/from Machine State Register Instructions
Name Mnemonic Operand Syntax
Move to Machine State Register mtmsr
rs
Move from Machine State Register mfmsr rD
The OEA defines encodings of the
mtspr
and
mfspr
instructions to provide access to
supervisor-level registers. The instructions are listed in Table 2-42.
Table 2-42. Move to/from Special-Purpose Register Instructions (OEA)
Name
Mnemonic
Operand Syntax
Move to Special Purpose Register mtspr
SPR,rS
Move from Special Purpose Register mfspr rD,SPR
Encodings for the 604-specific SPRs are listed in Table 2-43.
Table 2-43 SPR Encodings for 604-Deflned Registers (mfspr)
SPR
1
Register Name
Deel ma I
spfl5-9J
spr[0-4)
952 11101 11000
MMC RO
953 11101 11001 PMC1
954 11101 11010 PMC2
955 11101 11011 SIA
959 11101 11111 SDA
1010 11111 10010 IABR
1023 11111 11111 PIR
1 Note that the order of the
two
5-bit halves of the SPR number Is reversed CO"l>&r&d with actual Instruction
coding.
For mtspr and mfspr instructions, the SPR number coded in assembly languaQe does not appear directly as
a 10-bit binary number in the Instruction. The number coded is split into two 5-tlit halves that are reversed In
the Instruction, with the high-order 5 bits appearing in bits 16-20 of the instruction and the low-order 5 bits In
bits 11-15.
Simplified mnemonics are provided for the
mtspr
and
mfspr
instructions in Appendix F,
"Simplified Mnemonics," in The Programming Environments Manual.
For a discussion of
context synchronization requirements when altering certain SPRs, refer
to
Appendix E,
"Synchronization Programming Examples,"
in The Programming Environments Manual.
Chapter 2. PowerPC 604 Processor Programming Model
2·53
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