PIC18F258 Datasheet, PDF (315/384 Pages) Microchip Technology – High Performance, 28/40-Pin Enhanced FLASH Microcontrollers with CAN

PIC18FXX8
SUBLW
Subtract W from literal
Syntax:
[ label ] SUBLW k
Operands:
0 ≤ k ≤ 255
Operation:
k – (W) → W
Status Affected: N, OV, C, DC, Z
Encoding:
0000 1000 kkkk kkkk
Description:
W is subtracted from the eight-bit
literal 'k'. The result is placed in
W.
Words:
1
Cycles:
1
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
literal ’k’
Process
Data
Write to W
Example 1:
SUBLW 0x02
Before Instruction
W
=1
C
=?
After Instruction
W
=1
C
= 1 ; result is positive
Z
=0
N
=0
Example 2:
SUBLW 0x02
Before Instruction
W
=2
C
=?
After Instruction
W
=0
C
= 1 ; result is zero
Z
=1
N
=0
Example 3:
SUBLW 0x02
Before Instruction
W
=3
C
=?
After Instruction
W
= FF ; (2’s complement)
C
= 0 ; result is negative
Z
=0
N
=1
 2002 Microchip Technology Inc.
SUBWF
Subtract W from f
Syntax:
[ label ] SUBWF f [,d [,a]]
Operands:
0 ≤ f ≤ 255
d ∈ [0,1]
a ∈ [0,1]
Operation:
(f) – (W) → dest
Status Affected: N, OV, C, DC, Z
Encoding:
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 regis-
ter '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:
1
Cycles:
1
Q Cycle Activity:
Q1
Q2
Decode
Read
register ’f’
Q3
Process
Data
Q4
Write to
destination
Example 1:
SUBWF REG
Before Instruction
REG = 3
W
=2
C
=?
After Instruction
REG = 1
W
=2
C
=1
Z
=0
N
=0
; result is positive
Example 2:
SUBWF REG, W
Before Instruction
REG = 2
W
=2
C
=?
After Instruction
REG = 2
W
=0
C
=1
Z
=1
N
=0
; result is zero
Example 3:
SUBWF REG
Before Instruction
REG = 0x01
W
= 0x02
C
=?
After Instruction
REG = 0xFFh ;(2’s complement)
W
= 0x02
C
= 0x00 ; result is negative
Z
= 0x00
N
= 0x01
DS41159B-page 313