PIC18CXX2
COMF
Complement f
Compare f with WREG, skip if f =
WREG
CPFSEQ
Syntax:
Operands:
[ label ] COMF f,d,a
0 ≤ f ≤ 255
Syntax:
[ label ] CPFSEQ f,a
0 ≤ f ≤ 255
d
a
[0,1]
[0,1]
Operands:
a
[0,1]
Operation:
Operation:
(f) → dest
(f) – (WREG),
skip if (f) = (WREG)
(unsigned comparison)
Status Affected:
Encoding:
N,Z
0001
11da
ffff
ffff
Status Affected:
Encoding:
None
Description:
The contents of register ’f’ are com-
plemented. If ’d’ is 0 the result is
0110
001a
ffff
ffff
stored in WREG. If ’d’ is 1 the result
is stored back in register ’f’
Description:
Compares the contents of data
memory location 'f' to the contents
(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).
of WREG by performing an
unsigned subtraction.
If 'f' = WREG, then the fetched
instruction is discarded and an NOP
is executed instead making this a
two-cycle instruction. If ’a’ is 0, the
Access Bank will be selected, over-
riding the BSR value. If ’a’ = 1,
then the bank will be selected as
per the BSR value (default).
Words:
Cycles:
1
1
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
register ’f’
Process
Data
Write to
destination
Words:
Cycles:
1
1(2)
Note: 3 cycles if skip and followed
by a 2-word instruction
COMF
REG, 0, 0
Example:
Before Instruction
Q Cycle Activity:
Q1
REG
=
0x13
After Instruction
Q2
Q3
Q4
REG
WREG
=
=
0x13
0xEC
Decode
Read
register ’f’
Process
Data
No
operation
If skip:
Q1
Q2
Q3
Q4
No
No
No
No
operation
operation
operation
operation
If skip and followed by 2-word instruction:
Q1
Q2
Q3
Q4
No
No
No
No
operation
operation
operation
operation
No
No
No
No
operation
operation
operation
operation
HERE
CPFSEQ REG, 0
Example:
NEQUAL
EQUAL
:
:
Before Instruction
PC Address
=
HERE
WREG
REG
=
=
?
?
After Instruction
If REG
PC
=
=
WREG;
Address (EQUAL)
If REG
PC
≠
=
WREG;
Address (NEQUAL)
DS39026B-page 208
Preliminary
7/99 Microchip Technology Inc.
MICROCHIP [ MICROCHIP ]
