Datasheet

 1999-2013 Microchip Technology Inc. DS39026D-page 223
PIC18CXX2
SUBLW Subtract WREG from literal
Syntax:
[ label ]
SUBLW k
Operands: 0 k 255
Operation: k – (WREG) WREG
Status Affected: N,OV, C, DC, Z
Encoding:
0000 1000 kkkk kkkk
Description: WREG is subtracted from the
eight-bit literal 'k'. The result is
placed in WREG.
Words: 1
Cycles: 1
Q Cycle Activity:
Q1 Q2 Q3 Q4
Decode Read
literal 'k'
Process
Data
Write to
WREG
Example 1:
SUBLW 0x02
Before Instruction
WREG = 1
C=?
After Instruction
WREG = 1
C = 1 ; result is positive
Z=0
N=0
Example 2:
SUBLW 0x02
Before Instruction
WREG = 2
C=?
After Instruction
WREG = 0
C = 1 ; result is zero
Z=1
N=0
Example 3:
SUBLW 0x02
Before Instruction
WREG = 3
C=?
After Instruction
WREG = FF ; (2’s complement)
C = 0 ; result is negative
Z=0
N=1
SUBWF Subtract WREG from f
Syntax:
[ label ]
SUBWF f [,d [,a]
Operands: 0 f 255
d  [0,1]
a  [0,1]
Operation: (f) – (WREG) dest
Status Affected: N,OV, C, DC, Z
Encoding:
0101 11da ffff ffff
Description: Subtract WREG from register 'f'
(2’s complement method). If 'd' is
0, the result is stored in WREG. 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: 1
Cycles: 1
Q Cycle Activity:
Q1 Q2 Q3 Q4
Decode Read
register 'f'
Process
Data
Write to
destination
Example 1:
SUBWF REG, 1, 0
Before Instruction
REG = 3
WREG = 2
C=?
After Instruction
REG = 1
WREG = 2
C = 1 ; result is positive
Z=0
N=0
Example 2:
SUBWF REG, 0, 0
Before Instruction
REG = 2
WREG = 2
C=?
After Instruction
REG = 2
WREG = 0
C = 1 ; result is zero
Z=1
N=0
Example 3:
SUBWF REG, 1, 0
Before Instruction
REG = 1
WREG = 2
C=?
After Instruction
REG = FFh ;(2’s complement)
WREG = 2
C = 0 ; result is negative
Z=0
N=1