PIC18F2450/4450
SUBLW
Subtract W from Literal
SUBLW
SUBWF
Subtract W from f
Syntax:
k
Syntax:
SUBWF f {,d {,a}}
Operands:
Operation:
Status Affected:
Encoding:
Description
0 ≤ k ≤ 255
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
0101 11da
W is subtracted from the eight-bit
literal ‘k’. The result is placed in W.
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).
Words:
Cycles:
1
1
Q Cycle Activity:
Q1
Q2
Q3
Q4
If ‘a’ is ‘0’, the Access Bank is
selected. If ‘a’ is ‘1’, the BSR is used
to select the GPR bank (default).
If ‘a’ is ‘0’ and the extended instruction
set is enabled, this instruction
operates in Indexed Literal Offset
Addressing mode whenever
f ≤ 95 (5Fh). See Section 19.2.3
“Byte-Oriented and Bit-Oriented
Instructions in Indexed Literal Offset
Mode” for details.
Decode
Read
literal ‘k’
Process
Data
Write to W
Example 1:
SUBLW 02h
Before Instruction
W
C
=
=
01h
?
After Instruction
W
C
Z
=
01h
=
=
=
1
0
0
; result is positive
N
Words:
Cycles:
1
1
Example 2:
SUBLW 02h
Before Instruction
W
C
=
=
02h
?
Q Cycle Activity:
Q1
Q2
Q3
Q4
After Instruction
Decode
Read
register ‘f’
Process
Data
Write to
destination
W
C
Z
=
00h
=
=
=
1
1
0
; result is zero
N
Example 1:
SUBWF
REG, 1, 0
Before Instruction
Example 3:
SUBLW 02h
REG
W
=
3
2
?
Before Instruction
=
=
W
C
=
=
03h
?
C
After Instruction
After Instruction
REG
W
C
=
1
2
1
0
0
W
C
Z
=
FFh ; (2’s complement)
=
=
=
=
=
=
=
0
0
1
; result is negative
; result is positive
Z
N
N
Example 2:
SUBWF
REG, 0, 0
Before Instruction
REG
W
=
=
=
2
2
?
C
After Instruction
REG
W
C
=
2
0
1
1
0
=
=
=
=
; result is zero
Z
N
Example 3:
SUBWF
REG, 1, 0
Before Instruction
REG
W
=
=
=
1
2
?
C
After Instruction
REG
W
C
=
FFh ;(2’s complement)
2
0
0
1
=
=
=
=
; result is negative
Z
N
© 2006 Microchip Technology Inc.
Advance Information
DS39760A-page 247
MICROCHIP [ MICROCHIP ]
