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User’s Manual
Preliminary PPC440x5 CPU Core
instalfa.fm.
September 12, 2002
Page 521 of 589
Used in rotate-and-mask instructions to specify the ending bit of a mask.
NB (16:20) Specifies the number of bytes to move in an immediate string load or store.
OPCD (0:5) Primary opcode. Primary opcodes, in decimal, appear in the instruction format diagrams
presented with individual instructions. The OPCD field name does not appear in
instruction descriptions.
OE (21) Enables setting the OV and SO fields in the fixed-point exception register (XER) for
extended arithmetic.
RA (11:15) A GPR used as a source or target.
RB (16:20) A GPR used as a source.
Rc (31) Record bit.
0 Do not set the CR.
1 Set the CR to reflect the result of an operation.
See Condition Register (CR) on page 67 for a further discussion of how the CR bits are
set.
RS (6:10) A GPR used as a source.
RT (6:10) A GPR used as a target.
SH (16:20) Specifies a shift amount.
SPRF (11:20) Specifies a special purpose register (SPR). This field represents the SPR Number
(SPRN) with the upper and lower five bits reversed (that is,
SPRF = SPRN[5:9] || SPRN[0:4]).
TO (6:10) Specifies the conditions on which to trap, as described under tw and twi instructions.
WS (16:20) Specifies the portion of a TLB entry to be read/written by tlbre/tlbwe.
XO (21:30) Extended opcode for instructions without an OE field. Extended opcodes, in decimal,
appear in the instruction format diagrams presented with individual instructions. The XO
field name does not appear in instruction descriptions.
XO (22:30) Extended opcode for instructions with an OE field. Extended opcodes, in decimal,
appear in the instruction format diagrams presented with individual instructions. The XO
field name does not appear in instruction descriptions.
A.1.2 Instruction Format Diagrams
The instruction formats (allso called “forms”) illustrated in Figure A-1 through Figure A-9 are valid combina-
tions of instruction fields. Table A-5 on page 559 indicates which “form” is utilized by each PPC440x5
opcode. Fields indicated by slashes (/, //, or ///) are reserved. The figures are adapted from the PowerPC
User Instruction Set Architecture.