PIC18F2331_10 Datasheet, PDF (320/392 Pages) Microchip Technology – 28/40/44-Pin Enhanced Flash Microcontrollers with nanoWatt Technology, High-Performance PWM and A/D

PIC18F2331/2431/4331/4431
SUBWFB
Syntax:
Operands:
Operation:
Status Affected:
Encoding:
Description:
Words:
Cycles:
Q Cycle Activity:
Q1
Decode
Subtract W from f with Borrow
[ label ] SUBWFB f [,d [,a]]
0  f  255
d  [0,1]
a  [0,1]
(f) – (W) – (C) dest
N, OV, C, DC, Z
0101 10da ffff ffff
Subtract W and the Carry flag (borrow)
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’. 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.
1
1
Q2
Read
register ‘f’
Q3
Process
Data
Q4
Write to
destination
Example 1:
SUBWFB REG, 1, 0
Before Instruction
REG =
W
=
C
=
After Instruction
REG =
W
=
C
=
Z
=
N
=
0x19
0x0D
0x01
0x0C
0x0D
0x01
0x00
0x00
(0001 1001)
(0000 1101)
(0000 1011)
(0000 1101)
; result is positive
Example 2:
SUBWFB REG, 0, 0
Before Instruction
REG =
W
=
C
=
After Instruction
REG =
W
=
C
=
Z
=
N
=
0x1B
0x1A
0x00
0x1B
0x00
0x01
0x01
0x00
(0001 1011)
(0001 1010)
(0001 1011)
; result is zero
Example 3:
SUBWFB REG, 1, 0
Before Instruction
REG =
W
=
C
=
After Instruction
REG =
0x03
0x0E
0x01
0xF5
W
= 0x0E
C
= 0x00
Z
= 0x00
N
= 0x01
(0000 0011)
(0000 1101)
(1111 0100)
; [2’s comp]
(0000 1101)
; result is negative
SWAPF
Syntax:
Operands:
Operation:
Status Affected:
Encoding:
Description:
Words:
Cycles:
Q Cycle Activity:
Q1
Decode
Swap f
[ 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 register,
‘f’, are exchanged. If ‘d’ is ‘0’, the result
is placed in W. If ‘d’ is ‘1’, the result is
placed in register, ‘f’. If ‘a’ is ‘0’, the
Access Bank will be selected, overrid-
ing the BSR value. If ‘a’ is ‘1’, then the
bank will be selected as per the BSR
value.
1
1
Q2
Read
register ‘f’
Q3
Process
Data
Q4
Write to
destination
Example:
SWAPF REG
Before Instruction
REG = 0x53
After Instruction
REG = 0x35
DS39616D-page 320
 2010 Microchip Technology Inc.