
PIC18FXX39
DS30485A-page 238
Preliminary
2002 Microchip Technology Inc.
MULLW
Multiply Literal with W
Syntax:
[ label ] MULLW
k
Operands:
0
≤ k ≤ 255
Operation:
(W) x k
→ PRODH:PRODL
Status Affected:
None
Encoding:
0000
1101
kkkk
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.
Words:
1
Cycles:
1
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
literal 'k'
Process
Data
Write
registers
PRODH:
PRODL
Example:
MULLW
0xC4
Before Instruction
W=
0xE2
PRODH
=
?
PRODL
=
?
After Instruction
W=
0xE2
PRODH
=
0xAD
PRODL
=
0x08
MULWF
Multiply W with f
Syntax:
[ label ] MULWF
f [,a]
Operands:
0
≤ f ≤ 255
a
∈ [0,1]
Operation:
(W) x (f)
→ PRODH:PRODL
Status Affected:
None
Encoding:
0000
001a
ffff
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:
1
Cycles:
1
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
register 'f'
Process
Data
Write
registers
PRODH:
PRODL
Example:
MULWF
REG, 1
Before Instruction
W=
0xC4
REG
=
0xB5
PRODH
=
?
PRODL
=
?
After Instruction
W=
0xC4
REG
=
0xB5
PRODH
=
0x8A
PRODL
=
0x94