Microchip Technology ARD00330 データシート
PIC18F87J72 FAMILY
DS39979A-page 380
Preliminary
2010 Microchip Technology Inc.
SUBFSR
Subtract Literal from FSR
Syntax:
SUBFSR f, k
Operands:
0
k 63
f
[ 0, 1, 2 ]
Operation:
FSRf – k
FSRf
Status Affected:
None
Encoding:
1110
1001
ffkk
kkkk
Description:
The 6-bit literal ‘k’ is subtracted from
the contents of the FSR specified
by ‘f’.
the contents of the FSR specified
by ‘f’.
Words:
1
Cycles:
1
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
Write to
destination
Example:
SUBFSR 2, 23h
Before Instruction
FSR2
=
03FFh
After Instruction
FSR2
=
03DCh
SUBULNK
Subtract Literal from FSR2 and Return
Syntax:
SUBULNK k
Operands:
0
k 63
Operation:
FSR2 – k
FSR2,
(TOS)
PC
Status Affected:
None
Encoding:
1110
1001
11kk
kkkk
Description:
The 6-bit literal ‘k’ is subtracted from the
contents of the FSR2. A RETURN is then
executed by loading the PC with the
TOS.
contents of the FSR2. A RETURN is then
executed by loading the PC with the
TOS.
The instruction takes two cycles to
execute; a NOP is performed during the
second cycle.
execute; a NOP is performed during the
second cycle.
This may be thought of as a special case
of the SUBFSR instruction, where f = 3
(binary ‘11’); it operates only on FSR2.
of the SUBFSR instruction, where f = 3
(binary ‘11’); it operates only on FSR2.
Words:
1
Cycles:
2
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read
register ‘f’
Process
Data
Write to
destination
No
Operation
No
Operation
No
Operation
No
Operation
Example:
SUBULNK 23h
Before Instruction
FSR2
=
03FFh
PC
=
0100h
After Instruction
FSR2
=
03DCh
PC
=
(TOS)