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714
March 2002 Release
1-800-255-7778
Virtex-II Pro™ Platform FPGA Documentation
Chapter 11:
Instruction Set
R
rlwnm
Rotate Left Word then AND with Mask
Description
The MB field and ME field specify bit positions in a 32-bit mask,
m
.
m
is generated with 1-
bits starting at MB and ending at ME, with 0-bits elsewhere. If MB is at a higher bit position
than ME, the 1-bits in the mask wrap from the highest bit position to the lowest. Rotate-
instruction masks are further described in
The contents of register
r
S are rotated left by the number of bit positions specified by the
contents of register
r
B
27:31
. The rotated data is ANDed with the mask and the result is
loaded into register
r
A.
This instruction can be used to extract and rotate bit fields.
Simplified mnemonics defined for this instruction are described in
Pseudocode
m
←
MASK(MB, ME)
r
←
ROTL((
r
S), (
r
B)
27:31
)
(
r
A)
←
r
∧
m
Registers Altered
•
r
A.
•
CR[CR0]
LT, GT, EQ, SO
if Rc
=
1.
Exceptions
•
None.
Compatibility
This instruction is defined by the PowerPC user instruction-set architecture (UISA). It is
implemented by all PowerPC processors.
rlwnm
r
A,
r
S
,
r
B, MB, ME
(Rc=0)
rlwnm.
r
A,
r
S
,
r
B, MB, ME
(Rc=1)
M Instruction Form
23
r
S
r
A
r
B
MB
ME
Rc
0
6
1
1
1
6
2
1
2
6
3
1
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