3.3.2.5 Processor Version Register (PVR)
The PVR is a read-only register that uniquely identifies a standard product or Core+ASIC
implementation.
Software can examine the PVR to recognize implementation-dependent features and
determine
available hardware resources.
Access to the PVR is
privileged. See "Privileged SPRs" on page 3-42 for more information.
1
0
31
1
Figure
3-7.
Processor
Version
Register
(PVR)
I 0:31 I Assigned PVR value
3.3.3
Condition
Register (CR)
The CR contains eight 4-bit fields (CRO-CR7), as shown in Figure 3-8. The fields contain conditions
detected during the execution of integer or
logical compare instructions, as indicated
in
the instruction
descriptions
in
Chapter 24, "Instruction
Set'
The CR contents can be used
in
conditional branch
instructions.
The CR
can
be modified
in
any of the following ways:
•
mtcrf
sets specified CR fields by writing to the CR from a GPR, under control of a mask specified
as
an
instruction field.
•
mcrf
sets a specified CR field by copying another CR field to it.
•
mcrxr
copies certain bits of the XER into a designated CR field, and then clears the corresponding
XER bits.
• The "with update" forms of integer instructions implicitly update CR[CRO].
• Integer
compare instructions update a specified CR field.
•
The CR-Iogical instructions update a specified CR bit with the result of a logical operation on a
specified pair of CR bit
fields.
• Conditional
branch instructions can test a CR bit as one of the branch conditions.
If a CR field is set by a compare instruction, the bits are set as described
in
"CR Fields after Compare
Instructions."
The CR is part of the user programming model.
3-12 PPC405GP User's Manual
Preliminary
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