Table 2-32. Move-To/Move-From Special-Purpose Register Instructions (Uisa); Table 2-33. Powerpc Encodings - IBM PowerPC 750GX User Manual

Implementation Note: The PowerPC Architecture indicates that in some implementations the Move-to
Condition Register Fields (mtcrf) instruction might perform more slowly when only a portion of the fields are
updated as opposed to all of the fields. The Condition Register access latency for the 750GX is the same in
both cases.
Move-to/Move-from Special-Purpose Register Instructions (UISA)
Table 2-32 lists the mtspr and mfspr instructions.

Table 2-32. Move-to/Move-from Special-Purpose Register Instructions (UISA)

Name
Move-to Special-Purpose Register
Move-from Special-Purpose Register
Table 2-33 lists the SPR numbers for both user-level and supervisor-level accesses.

Table 2-33. PowerPC Encodings

Register Name
CTR
DABR
DAR
DBAT0L
DBAT0U
DBAT1L
DBAT1U
DBAT2L
DBAT2U
DBAT3L
DBAT3U
DBAT4L
DBAT4U
DBAT5L
DBAT5U
DBAT6L
DBAT6U
Note:
1. The order of the two 5-bit halves of the SPR number is reversed compared with actual instruction coding. For mtspr and mfspr
instructions, the SPR number coded in assembly language does not appear directly as a 10-bit binary number in the instruction.
The number coded is split into two 5-bit halves that are reversed in the instruction, with the high-order five bits appearing in bits
16–20 of the instruction and the low-order five bits in bits 11–15.
2. The TB Registers are referred to as TBRs rather than SPRs and can be written to using the mtspr instruction in supervisor mode
and the TBR numbers here. The TB Registers can be read in user mode using either the mftb or mfspr instruction and specifying
TBR 268 for TBL and SPR 269 for TBU.
gx_02.fm.(1.2)
March 27, 2006
(Page 1 of 3)
1
SPR
Decimal SPR[5–9]
9 00000
1013 11111
19 00000
537 10000
536 10000
539 10000
538 10000
541 11110
540 11110
543 11110
542 11110
569 10001
568 10001
571 10001
570 10001
573 10001
572 10001
IBM PowerPC 750GX and 750GL RISC Microprocessor
Mnemonic
mtspr
mfspr
Access
SPR[0–4]
01001 User (UISA)
10101 Supervisor (OEA)
10011 Supervisor (OEA)
11001 Supervisor (OEA)
11000 Supervisor (OEA)
11011 Supervisor (OEA)
11010 Supervisor (OEA)
11101 Supervisor (OEA)
11100 Supervisor (OEA)
11111 Supervisor (OEA)
11110 Supervisor (OEA)
11001 Supervisor (OEA)
11000 Supervisor (OEA)
11011 Supervisor (OEA)
11010 Supervisor (OEA)
11101 Supervisor (OEA)
11100 Supervisor (OEA)
User's Manual
Syntax
SPR,rS
rD,SPR
mfspr/mtspr
Both
Both
Both
Both
Both
Both
Both
Both
Both
Both
Both
Both
Both
Both
Both
Both
Both
Programming Model
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