PIC17C7XX_13 Datasheet, PDF (212/306 Pages) Microchip Technology – High-Performance 8-bit CMOS EPROM Microcontrollers with 10-bit A/D

PIC17C7XX
DCFSNZ
Syntax:
Operands:
Operation:
Status Affected:
Encoding:
Description:
Words:
Cycles:
Q Cycle Activity:
Q1
Decode
Decrement f, skip if not 0
[label] DCFSNZ f,d
0  f  255
d  [0,1]
(f) – 1  (dest);
skip if not 0
None
0010 011d ffff ffff
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 not 0, the next instruc-
tion, which is already fetched is dis-
carded and a NOP is executed instead,
making it a two-cycle instruction.
1
1(2)
Q2
Read
register 'f'
Q3
Process
Data
Q4
Write to
destination
If skip:
Q1
No
operation
Q2
No
operation
Q3
No
operation
Q4
No
operation
Example:
HERE
ZERO
NZERO
DCFSNZ TEMP, 1
:
:
Before Instruction
TEMP_VALUE
=?
After Instruction
TEMP_VALUE = TEMP_VALUE - 1,
If TEMP_VALUE = 0;
PC
= Address (ZERO)
If TEMP_VALUE  0;
PC
= Address (NZERO)
GOTO
Unconditional Branch
Syntax:
[ label ] GOTO k
Operands:
0  k  8191
Operation:
k  PC<12:0>;
k<12:8>  PCLATH<4:0>,
PC:13> PCLATH<7:5>
Status Affected: None
Encoding:
110k kkkk kkkk kkkk
Description:
GOTO allows an unconditional branch
anywhere within an 8K page boundary.
The thirteen-bit immediate value is
loaded into PC bits <12:0>. Then the
upper eight bits of PC are loaded into
PCLATH. GOTO is always a two-cycle
instruction.
Words:
1
Cycles:
2
Q Cycle Activity:
Q1
Q2
Q3
Q4
Decode
Read literal
'k'
Process
Data
Write to PC
No
operation
No
operation
No
operation
No
operation
Example:
GOTO THERE
After Instruction
PC = Address (THERE)
DS30289C-page 212
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