PIC18CXX2_13 Datasheet, PDF (224/304 Pages) Microchip Technology – High Performance Microcontrollers with 10-bit A/D

PIC18CXX2
SUBWFB
Subtract WREG from f with Borrow
Syntax:
[ label ] SUBWFB f [,d [,a]
Operands:
0  f  255
d  [0,1]
a  [0,1]
Operation:
(f) – (WREG) – (C) dest
Status Affected: N,OV, C, DC, Z
Encoding:
0101 10da ffff ffff
Description:
Subtract WREG and the carry flag
(borrow) from register 'f' (2’s comple-
ment 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:
SUBWFB REG, 1, 0
Before Instruction
REG
= 0x19
WREG = 0x0D
C
=1
After Instruction
REG
= 0x0C
WREG
C
Z
N
= 0x0D
=1
=0
=0
(0001 1001)
(0000 1101)
(0000 1011)
(0000 1101)
; result is positive
Example 2:
SUBWFB REG, 0, 0
Before Instruction
REG
= 0x1B
WREG = 0x1A
C
=0
After Instruction
REG
= 0x1B
WREG = 0x00
C
=1
Z
=1
N
=0
(0001 1011)
(0001 1010)
(0001 1011)
; result is zero
Example 3:
SUBWFB REG, 1, 0
Before Instruction
REG
= 0x03
WREG = 0x0E
C
=1
After Instruction
REG
= 0xF5
WREG
C
Z
N
= 0x0E
=0
=0
=1
(0000 0011)
(0000 1101)
(1111 0100)
; [2’s comp]
(0000 1101)
; result is negative
SWAPF
Swap f
Syntax:
Operands:
Operation:
Status Affected:
Encoding:
Description:
Words:
Cycles:
[ label ] SWAPF f [,d [,a]
0  f  255
d  [0,1]
a  [0,1]
(f<3:0>)  dest<7:4>,
(f<7:4>)  dest<3:0>
None
0011 10da ffff ffff
The upper and lower nibbles of reg-
ister 'f' are exchanged. If 'd' is 0, the
result is placed in WREG. If 'd' is 1,
the result is placed 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).
1
1
Q Cycle Activity:
Q1
Q2
Decode
Read
register 'f'
Q3
Process
Data
Q4
Write to
destination
Example:
SWAPF REG, 1, 0
Before Instruction
REG
= 0x53
After Instruction
REG
= 0x35
DS39026D-page 224
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