PIC18FXX20
MULLW
Multiply Literal with W
MULWF
Multiply W with f
Syntax:
[ label ] MULLW
0 ≤ k ≤ 255
(W) x k → PRODH:PRODL
k
Syntax:
Operands:
[ label ] MULWF f [,a]
0 ≤ f ≤ 255
a ∈ [0,1]
(W) x (f) → PRODH:PRODL
None
Operands:
Operation:
Status Affected:
Encoding:
Operation:
Status Affected:
Encoding:
None
0000
1101
kkkk
kkkk
0000
001a
ffff
ffff
Description:
An unsigned multiplication is car-
ried out between the contents of
W and the 8-bit literal 'k'. The
16-bit result is placed in
PRODH:PRODL register pair.
PRODH contains the high byte.
W is unchanged.
None of the status flags are
affected.
Note that neither overflow nor
carry is possible in this opera-
tion. A zero result is possible but
not detected.
Description:
An unsigned multiplication is car-
ried out between the contents of
W and the register file location 'f'.
The 16-bit result is stored in the
PRODH:PRODL register pair.
PRODH contains the high byte.
Both W and 'f' are unchanged.
None of the status flags are
affected.
Note that neither overflow nor
carry is possible in this opera-
tion. A zero result is possible but
not detected. If ‘a’ is 0, the
Access Bank will be selected,
overriding the BSR value. If
‘a’= 1, then the bank will be
selected as per the BSR value
(default).
Words:
Cycles:
1
1
Q Cycle Activity:
Q1
Q2
Q3
Q4
Write
registers
PRODH:
PRODL
Decode
Read
Process
literal 'k'
Data
Words:
Cycles:
1
1
Q Cycle Activity:
Q1
Q2
Q3
Q4
MULLW
0xC4
Example:
Decode
Read
Process
Write
Before Instruction
register 'f'
Data
registers
PRODH:
PRODL
W
=
0xE2
PRODH
=
=
?
?
PRODL
After Instruction
W
MULWF
REG, 1
Example:
=
0xE2
PRODH
PRODL
=
=
0xAD
0x08
Before Instruction
W
=
0xC4
REG
=
=
=
0xB5
PRODH
?
?
PRODL
After Instruction
W
=
0xC4
REG
=
=
=
0xB5
0x8A
0x94
PRODH
PRODL
DS39609A-page 286
Advance Information
2003 Microchip Technology Inc.
MICROCHIP [ MICROCHIP ]
