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696
March 2002 Release
1-800-255-7778
Virtex-II Pro™ Platform FPGA Documentation
Chapter 11:
Instruction Set
R
mullw
Multiply Low Word
Description
The contents of register
r
A are multiplied with the contents of register
r
B, forming a 64-bit
signed product. The least-significant 32 bits of the result are loaded into register
r
D.
If the signed product cannot be represented in 32 bits and OE
=
1, XER[SO, OV] are set to 1.
This overflow indication is correct only if the operands are interpreted as signed integers.
The result loaded into register
r
D is always correct, regardless of whether the operands are
interpreted as signed or unsigned integers.
This instruction can be used with
mulhw
to calculate a full 64-bit product.
Pseudocode
prod
0:63
←
(
r
A)
×
(
r
B) signed
(
r
D)
←
prod
32:63
Registers Altered
•
r
D.
•
CR[CR0]
LT, GT, EQ, SO
if Rc
=
1.
•
XER[SO, OV] if OE
=
1.
Exceptions
•
None.
Compatibility
This instruction is defined by the PowerPC user instruction-set architecture (UISA). It is
implemented by all PowerPC processors.
mullw
r
D,
r
A,
r
B
(OE=0, Rc=0)
mullw.
r
D,
r
A,
r
B
(OE=0, Rc=1)
mullwo
r
D,
r
A,
r
B
(OE=1, Rc=0)
mullwo.
r
D,
r
A,
r
B
(OE=1, Rc=1)
XO Instruction Form
31
r
D
r
A
r
B
OE
235
Rc
0
6
1
1
1
6
2
1
2
2
3
1
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