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Assembler Language Reference

mfspr (Move from Special-Purpose Register) Instruction

Purpose

Copies the contents of a special-purpose register into a general-purpose register.

Syntax

Bits Value
0-5 31
6-10 RT
11-20 spr
21-30 339
31 Rc
mfspr RT, SPR

Note: The special-purpose register is a split field.

See Extended Mnemonics of Moving from or to Special-Purpose Registers for more information.

Description

The mfspr instruction copies the contents of the special-purpose register SPR into target general-purpose register (GPR) RT.

The special-purpose register identifier SPR can have any of the values specified in the following table. The order of the two 5-bit halves of the SPR number is reversed.

SPR Values
Decimal spr5:9 spr0:4 Register Name Privileged
1 00000 00001 XER No
8 00000 01000 LR No
9 00000 01001 CTR No
18 00000 10010 DSISR Yes
19 00000 10011 DAR Yes
22 00000 10110 DEC2 Yes
25 00000 11001 SDR1 Yes
26 00000 11010 SRR0 Yes
27 00000 11011 SRR1 Yes
272 01000 10000 SPRG0 Yes
273 01000 10001 SPRG1 Yes
274 01000 10010 SPRG2 Yes
275 01000 10011 SPRG3 Yes
282 01000 11010 EAR Yes
284 01000 11100 TBL Yes
285 01000 11101 TBU Yes
528 10000 10000 IBAT0U Yes
529 10000 10001 IBAT0L Yes
530 10000 10010 IBAT1U Yes
531 10000 10011 IBAT1L Yes
532 10000 10100 IBAT2U Yes
533 10000 10101 IBAT2L Yes
534 10000 10110 IBAT3U Yes
535 10000 10111 IBAT3L Yes
536 10000 11000 DBAT0U Yes
537 10000 11001 DBAT0L Yes
538 10000 11010 DBAT1U Yes
539 10000 11011 DBAT1L Yes
540 10000 11100 DBAT2U Yes
541 10000 11101 DBAT2L Yes
542 10000 11110 DBAT3U Yes
543 10000 11111 DBAT3L Yes
0 00000 00000 MQ1 No
4 00000 00100 RTCU1 No
5 00000 00101 RTCL1 No
6 00000 00110 DEC2 No

1Supported only in the POWER family architecture.

2In the PowerPC architecture moving from the DEC register is privileged and the SPR value is 22. In the POWER family architecture moving from the DEC register is not privileged and the SPR value is 6. For more information, see Fixed-Point Move to or from Special-Purpose Registers Instructions .

If the SPR field contains any value other than those listed in the SPR Values table, the instruction form is invalid.

The mfspr instruction has one syntax form and does not affect the Fixed-Point Exception Register or Condition Register Field 0.

Parameters

RT Specifies target general-purpose register where result of operation is stored.
SPR Specifies source special-purpose register for operation.

Examples

The following code copies the contents of the Fixed-Point Exception Register into GPR 6:

mfspr 6,1
# GPR 6 now contains the bit settings of the Fixed
# Point Exception Register.

Related Information

Fixed-Point Processor .

Fixed-Point Move to or from Special-Purpose Registers Instructions .

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