PIC18F010T-I/SN View Datasheet(PDF) - Microchip Technology
Part Name
Description
Manufacturer
PIC18F010T-I/SN Datasheet PDF : 176 Pages
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PIC18F010/020
DECFSZ
Decrement f, skip if 0
Syntax:
[ label ] DECFSZ f [ ,d [,a] ]
Operands:
0 ≤ f ≤ 255
d ∈ [0,1]
a ∈ [0,1]
Operation:
(f) – 1 → dest,
skip if result = 0
Status Affected: None
Encoding:
0010 11da ffff ffff
Description:
The contents of register 'f' are dec-
remented. If 'd' is 0, the result is
placed in WREG. If 'd' is 1, the
result is placed back in register 'f'
(default).
If the result is 0, the next instruc-
tion, which is already fetched, is
discarded, and a NOP is executed
instead making it a two-cycle
instruction. If ’a’ is 0, the Access
Bank will be selected, overriding
the BSR value. If ’a’ is 1, the Bank
will be selected as per the BSR
value.
Words:
1
Cycles:
1(2)
Note: 3 cycles if skip and followed
by a 2-word instruction.
Q Cycle Activity:
Q1
Q2
Q3
Decode
Read
register ’f’
Process
Data
If skip:
Q1
Q2
Q3
No
operation
No
operation
No
operation
If skip and followed by 2-word instruction:
Q4
Write to
destination
Q4
No
operation
Q1
No
operation
No
operation
Q2
No
operation
No
operation
Q3
No
operation
No
operation
Q4
No
operation
No
operation
Example:
HERE
DECFSZ
GOTO
CONTINUE
CNT
LOOP
Before Instruction
PC
= Address (HERE)
After Instruction
CNT =
If CNT =
PC =
If CNT ≠
PC =
CNT - 1
0;
Address (CONTINUE)
0;
Address (HERE+2)
DCFSNZ
Decrement f, skip if not 0
Syntax:
[label] DCFSNZ f [ ,d [,a] ]
Operands:
0 ≤ f ≤ 255
d ∈ [0,1]
a ∈ [0,1]
Operation:
(f) – 1 → dest,
skip if result ≠ 0
Status Affected: None
Encoding:
0100 11da ffff ffff
Description:
The contents of register 'f' are dec-
remented. If 'd' is 0, the result is
placed in WREG. If 'd' is 1, the
result is placed back in register 'f'
(default).
If the result is not 0, the next
instruction, which is already
fetched, is discarded, and a NOP is
executed instead making it a two-
cycle instruction. If ’a’ is 0, the
Access Bank will be selected,
overriding the BSR value. If ’a’ is
1, the Bank will be selected as per
the BSR value.
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
Read
register ’f’
Process
Data
Write to
destination
If skip:
Q1
Q2
Q3
Q4
No
operation
No
operation
No
operation
No
operation
If skip and followed by 2-word instruction:
Q1
No
operation
No
operation
Q2
No
operation
No
operation
Q3
No
operation
No
operation
Q4
No
operation
No
operation
Example:
HERE
ZERO
NZERO
DCFSNZ TEMP
:
:
Before Instruction
TEMP
=?
After Instruction
TEMP
If TEMP
PC
If TEMP
PC
= TEMP - 1,
= 0;
= Address (ZERO)
≠ 0;
= Address (NZERO)
2001 Microchip Technology Inc.
Preliminary
DS41142A-page 115
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