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PIC18F258 Datasheet, PDF (296/384 Pages) Microchip Technology – High Performance, 28/40-Pin Enhanced FLASH Microcontrollers with CAN | |||
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PIC18FXX8
COMF
Complement f
Syntax:
[ label ] COMF f [,d [,a]]
Operands:
0 ⤠f ⤠255
d â [0,1]
a â [0,1]
Operation:
( f ) â dest
Status Affected: N, Z
Encoding:
0001 11da ffff ffff
Description:
The contents of register âfâ are com-
plemented. If âdâ is 0, the result is
stored in W. If âdâ is 1, the result is
stored back in register âfâ (default). If
âaâ is 0, the Access Bank will be
selected, overriding the BSR value.
If âaâ = 1, then the bank will be
selected as per the BSR value
(default).
Words:
1
Cycles:
1
Q Cycle Activity:
Q1
Q2
Decode
Read
register âfâ
Example:
COMF
Q3
Process
Data
REG, W
Q4
Write to
destination
Before Instruction
REG = 0x13
After Instruction
REG = 0x13
W
= 0xEC
CPFSEQ
Compare f with W, skip if f = W
Syntax:
[ label ] CPFSEQ f [,a]
Operands:
0 ⤠f ⤠255
a â [0,1]
Operation:
(f) â (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 instruc-
tion is discarded and a NOP is exe-
cuted instead, making this a
two-cycle instruction. If âaâ is 0, the
Access Bank will be selected, over-
riding the BSR value. If âaâ = 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
Q4
Decode
If skip:
Q1
Read
register âfâ
Q2
Process
Data
Q3
No
operation
Q4
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
No
operation
Q4
No
operation
No
operation
Example:
HERE
NEQUAL
EQUAL
CPFSEQ REG
:
:
Before Instruction
PC Address =
W
=
REG
=
After Instruction
HERE
?
?
If REG
PC
If REG
PC
= W;
= Address (EQUAL)
â W;
= Address (NEQUAL)
DS41159B-page 294
 2002 Microchip Technology Inc.
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