PIC18F2220/2320/4220/4320
SUBLW
Subtract W from literal
SUBWF
Syntax:
Subtract W from f
Syntax:
[ label ] SUBLW k
0 ≤ k ≤ 255
[ label ] SUBWF f [,d [,a]]
Operands:
Operation:
Status Affected:
Encoding:
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
Description:
W is subtracted from the eight-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’ (default). 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 (default).
Words:
Cycles:
1
1
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
literal ‘k’
Process
Data
Write to W
SUBLW 0x02
Example 1:
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
=
1
C
=
=
=
1
0
0
; result is positive
Z
SUBWF REG
Example 1:
N
SUBLW 0x02
Example 2:
Before Instruction
REG
W
C
=
=
=
3
2
?
Before Instruction
W
C
=
=
2
?
After Instruction
After Instruction
REG
W
=
=
1
2
W
=
0
C
Z
N
=
=
=
1
0
0
; result is positive
C
Z
N
=
=
=
1
1
0
; result is zero
SUBWF REG, W
Example 2:
SUBLW 0x02
Example 3:
Before Instruction
Before Instruction
REG
=
2
2
?
W
C
=
=
3
?
W
C
=
=
After Instruction
After Instruction
W
=
FF ; (2’s complement)
REG
=
2
0
C
Z
N
=
=
=
0
0
1
; result is negative
W
=
C
Z
N
=
=
=
1
1
0
; result is zero
SUBWF REG
Example 3:
Before Instruction
REG
=
0x01
W
C
=
=
0x02
?
After Instruction
REG
W
=
=
0xFFh ;(2’s complement)
0x02
C
Z
N
=
=
=
0x00 ; result is negative
0x00
0x01
2003 Microchip Technology Inc.
DS39599C-page 291
MICROCHIP [ MICROCHIP ]
