PIC18F2331/2431/4331/4431
SUBLW
Subtract W from Literal
SUBWF
Syntax:
Subtract W from f
Syntax:
[ label ] SUBLW
0 k 255
k
[ label ] SUBWF f [,d [,a]]
Operands:
Operation:
Status Affected:
Encoding:
Description:
Operands:
0 f 255
d [0,1]
a [0,1]
k – (W) W
N, OV, C, DC, Z
Operation:
(f) – (W) dest
0000
1000
kkkk
kkkk
Status Affected:
Encoding:
N, OV, C, DC, Z
W is subtracted from the 8-bit
literal, ‘k’. The result is placed in W.
0101
11da
ffff
ffff
Description:
Subtract W from register, ‘f’ (2’s
complement method). If ‘d’ is ‘0’, the
result is stored in W. If ‘d’ is ‘1’, the
result is stored back in register, ‘f’.
If = ‘a’ is ‘0’, the Access Bank will be
selected, overriding the BSR value. If
‘a’ is ‘1’, then the bank will be selected
as per the BSR value.
Words:
Cycles:
1
1
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
literal ‘k’
Process
Data
Write to
W
Example 1:
SUBLW 0x02
Words:
Cycles:
1
1
Before Instruction
W
C
=
=
1
?
Q Cycle Activity:
Q1
Q2
Q3
Q4
After Instruction
Decode
Read
register ‘f’
Process
Data
Write to
destination
W
C
Z
=
1
=
=
=
1
0
0
; result is positive
Example 1:
SUBWF REG
N
Before Instruction
Example 2:
SUBLW 0x02
REG
W
C
=
=
=
3
2
?
Before Instruction
W
C
=
=
2
?
After Instruction
REG
W
C
Z
N
=
1
2
1
0
0
After Instruction
=
=
=
=
W
C
Z
=
0
; result is positive
=
=
=
1
1
0
; result is zero
N
Example 2:
Before Instruction
SUBWF REG, W
Example 3:
Before Instruction
SUBLW 0x02
REG
W
C
=
=
=
2
2
?
W
C
=
=
3
?
After Instruction
After Instruction
W
C
Z
=
FF ; (2’s complement)
REG
W
C
Z
N
=
2
0
=
=
=
0
0
1
; result is negative
=
=
=
=
1
1
0
; result is zero
N
Example 3:
Before Instruction
SUBWF REG
REG
W
C
=
=
=
0x01
0x02
?
After Instruction
REG
W
C
Z
N
=
0xFFh ; (2’s complement)
0x02
0x00 ; result is negative
0x00
0x01
=
=
=
=
2010 Microchip Technology Inc.
DS39616D-page 319
MICROCHIP [ MICROCHIP ]
