Datasheet

PIC18F2331/2431/4331/4431
DS39616D-page 310  2010 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 kkkk
Description: An unsigned multiplication is carried
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 operation. 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 ffff
Description: An unsigned multiplication is carried
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 operation. 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.
Words: 1
Cycles: 1
Q Cycle Activity:
Q1 Q2 Q3 Q4
Decode Read
register ‘f’
Process
Data
Write
registers
PRODH:
PRODL
Example:
MULWF REG
Before Instruction
W=0xC4
REG = 0xB5
PRODH = ?
PRODL = ?
After Instruction
W=0xC4
REG = 0xB5
PRODH = 0x8A
PRODL = 0x94