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March 2002 Release
399
Virtex-II Pro™ Platform FPGA Documentation
1-800-255-7778
Integer Instructions
R
Algebraic-Comparison Instructions
shows the PowerPC
algebraic-comparison
instructions. During comparison, both
operands are treated as signed integers. If a comparison is made with a signed-immediate
value (SIMM), that value is sign-extended by the processor prior to performing the
comparison.
Logical-Comparison Instructions
shows the PowerPC
logical-comparison
instructions. During comparison, both
operands are treated as unsigned integers. If a comparison is made with an unsigned-
immediate value (UIMM), that value is zero extended by the processor prior to performing
the comparison.
Rotate Instructions
Rotate instructions operate on 32-bit data in the GPRs, returning the result in a second
GPR. These instructions rotate data to the left—the direction of least-significant bit to most-
significant bit. Bits rotated out of the most-significant bit (bit 0) are rotated into the least-
significant bit (bit 31). Programmers can achieve apparent right rotation using these left-
rotation instructions by specifying a rotation amount of 32-
n
, where
n
is the number of bits
to rotate right.
If the rotate instruction has the record (Rc) bit set to 1 in the instruction encoding, CR0
(CR[0:3]) is updated to reflect the result of the operation. A set Rc bit is indicated by the “.”
suffix in the instruction mnemonic. Rotate instructions do not update any bits in the XER
register.
In the operand syntax for rotate instructions, the rA operand specifies the
destination
register rather than a source register.
r
S is used to specify the source register.
Simplified mnemonics using the rotate instructions are provided for easy coding of
extraction, insertion, left or right justification, and other bit-manipulation operations. See
for more information.
Table 3-34:
Algebraic-Comparison Instructions
Mnemonic
Name
Operation
Operand
Syntax
cmp
Compare
crf
D[LT,GT,EQ] are loaded with the result of
algebraically comparing (
r
A) with (
r
B). CR[SO] is
loaded with a copy of XER[SO].
crf
D,0,
r
A
,r
B
cmpi
Compare Immediate
crf
D[LT,GT,EQ] are loaded with the result of
algebraically comparing (
r
A) with SIMM. CR[SO]
is loaded with a copy of XER[SO].
crf
D,0,
r
A
,
SIMM
Table 3-35:
Logical-Comparison Instructions
Mnemonic
Name
Operation
Operand
Syntax
cmpl
Compare Logical
crf
D[LT,GT,EQ] are loaded with the result of
logically comparing (
r
A) with (
r
B). CR[SO] is
loaded with a copy of XER[SO].
crf
D,0,
r
A
,r
B
cmpli
Compare Logical Immediate
crf
D[LT,GT,EQ] are loaded with the result of
logically comparing (
r
A) with UIMM. CR[SO] is
loaded with a copy of XER[SO].
crf
D,0,
r
A
,
UIMM
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