PIC18CXX2
BTG
Bit Toggle f
BOV
Branch if Overflow
Syntax:
Operands:
[ label ] BTG f,b,a
Syntax:
[ label ] BOV
n
0 ≤ f ≤ 255
0 ≤ b < 7
Operands:
Operation:
-128 ≤ n ≤ 127
if overflow bit is ’1’
(PC) + 2 + 2n → PC
a
[0,1]
Operation:
(f<b>) → f<b>
Status Affected:
Encoding:
None
Status Affected:
Encoding:
None
1110
0100
nnnn
nnnn
0111
bbba
ffff
ffff
Description:
If the Overflow bit is ’1’, then the
program will branch.
Description:
Bit ’b’ in data memory location ’f’ is
inverted. 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).
The 2’s complement number ’2n’ is
added to the PC. Since the PC will
have incremented to fetch the next
instruction, the new address will be
PC+2+2n. This instruction is then
a two-cycle instruction.
Words:
Cycles:
1
1
Words:
Cycles:
1
1(2)
Q Cycle Activity:
Q1
Q2
Q3
Q4
Q Cycle Activity:
If Jump:
Decode
Read
register ’f’
Process
Data
Write
register ’f’
Q1
Q2
Q3
Q4
Decode
Read literal
’n’
Process
Data
Write to PC
BTG
PORTC, 4, 0
Example:
No
operation
No
operation
No
operation
No
operation
Before Instruction:
PORTC
=
0111 0101 [0x75]
If No Jump:
Q1
After Instruction:
Q2
Q3
Q4
PORTC
=
0110 0101 [0x65]
Decode
Read literal
’n’
Process
Data
No
operation
HERE
BOV Jump
Example:
Before Instruction
PC
=
address (HERE)
After Instruction
If Overflow=
PC
If Overflow=
PC
1;
=
address (Jump)
0;
=
address (HERE+2)
7/99 Microchip Technology Inc.
Preliminary
DS39026B-page 205
MICROCHIP [ MICROCHIP ]
