PIC18FXX8 Datasheet, PDF (300/402 Pages) Microchip Technology – 28/40-Pin High-Performance, Enhanced Flash Microcontrollers with CAN Module

PIC18FXX8
COMF
Syntax:
Operands:
Operation:
Status Affected:
Encoding:
Description:
Words:
Cycles:
Q Cycle Activity:
Q1
Decode
Complement f
[ label ] COMF
0 ≤ f ≤ 255
d ∈ [0,1]
a ∈ [0,1]
( f ) → dest
N, Z
f [,d [,a]]
0001 11da ffff ffff
The contents of register ‘f’ are
complemented. If ‘d’ is ‘0’, the result is
stored in W. 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’ = 1, then
the bank will be selected as per the
BSR value (default).
1
1
Q2
Read
register ‘f’
Q3
Process
Data
Q4
Write to
destination
Example:
COMF
Before Instruction
REG =
After Instruction
REG =
W
=
0x13
0x13
0xEC
REG, W
CPFSEQ
Compare f with W, Skip if f = W
Syntax:
[ label ] CPFSEQ f [,a]
Operands:
0 ≤ f ≤ 255
a ∈ [0,1]
Operation:
(f) – (W),
skip if (f) = (W)
(unsigned comparison)
Status Affected: None
Encoding:
0110 001a ffff ffff
Description:
Compares the contents of data memory
location ‘f’ to the contents of W by
performing an unsigned subtraction.
If ‘f’ = W, then the fetched instruction is
discarded and a NOP is executed
instead, making this a two-cycle
instruction. If ‘a’ is ‘0’, the Access Bank
will be selected, overriding the BSR
value. If ‘a’ = 1, then the bank will be
selected as per the BSR value (default).
Words:
1
Cycles:
1(2)
Note: 3 cycles if skip and followed
by a 2-word instruction.
Q Cycle Activity:
Q1
Q2
Q3
Decode
Read
register ‘f’
Process
Data
If skip:
Q1
Q2
Q3
No
operation
No
operation
No
operation
If skip and followed by 2-word instruction:
Q1
Q2
Q3
No
operation
No
operation
No
operation
No
operation
No
operation
No
operation
Q4
No
operation
Q4
No
operation
Q4
No
operation
No
operation
Example:
HERE
NEQUAL
EQUAL
CPFSEQ REG
:
:
Before Instruction
PC Address =
W
=
REG
=
After Instruction
If REG
=
PC
=
If REG
≠
PC
=
HERE
?
?
W;
Address (EQUAL)
W;
Address (NEQUAL)
DS41159D-page 298
 2004 Microchip Technology Inc.