PIC17C756A MICROCHIP [Microchip Technology], PIC17C756A Datasheet - Page 211

• Manufacturer Part Number: PIC17C756A
• Description: High-Performance 8-bit CMOS EPROM Microcontrollers with 10-bit A/D
• Manufacturer: MICROCHIP [Microchip Technology]

DECF
Syntax:
Operands:
Operation:
Status Affected:
Encoding:
Description:
Words:
Cycles:
Q Cycle Activity:
Example:
2000 Microchip Technology Inc.
Before Instruction
After Instruction
Decode
CNT
Z
CNT
Z
Q1
=
=
=
=
register ’f’
Decrement f
[ label ] DECF f,d
0
d
(f) – 1
OV, C, DC, Z
Decrement register ’f’. If ’d’ is 0, the
result is stored in WREG. If ’d’ is 1, the
result is stored back in register ’f’.
1
1
DECF
Read
0000
Q2
0x01
0
0x00
1
f
[0,1]
255
(dest)
CNT,
011d
Process
Data
Q3
1
ffff
destination
Write to
Q4
ffff
DECFSZ
Syntax:
Operands:
Operation:
Status Affected:
Encoding:
Description:
Words:
Cycles:
Q Cycle Activity:
If skip:
Example:
Before Instruction
After Instruction
operation
Decode
Q1
PC
CNT
If CNT
If CNT
Q1
No
PC =
PC =
=
=
=
register ’f’
operation
Decrement f, skip if 0
[ label ] DECFSZ f,d
0
d
(f) – 1
skip if result = 0
None
The contents of register ’f’ are decre-
mented. If ’d’ is 0, the result is placed in
WREG. If ’d’ is 1, the result is placed
back in register ’f’.
If the result is 0, the next instruction,
which is already fetched is discarded
and a NOP is executed instead, making
it a two-cycle instruction.
1
1(2)
HERE
NZERO
ZERO
Read
0001
Q2
Q2
No
Address (HERE)
CNT - 1
0;
Address (HERE)
0;
Address (NZERO)
f
[0,1]
PIC17C7XX
255
(dest);
011d
DECFSZ
GOTO
operation
Process
Data
Q3
Q3
No
DS30289B-page 211
ffff
CNT, 1
HERE
destination
operation
Write to
Q4
Q4
No
ffff