PIC17C42 Microchip Technology, PIC17C42 Datasheet - Page 122

• Manufacturer Part Number: PIC17C42
• Description: High-Performance 8-Bit CMOS EPROM/ROM Microcontroller
• Manufacturer: Microchip Technology

PIC17C4X
DCFSNZ
Syntax:
Operands:
Operation:
Status Affected:
Encoding:
Description:
Words:
Cycles:
Q Cycle Activity:
If skip:
Example:
DS30412C-page 122
Before Instruction
After Instruction
Forced NOP
Decode
TEMP_VALUE
TEMP_VALUE
If TEMP_VALUE
If TEMP_VALUE
Q1
Q1
PC
PC
register 'f'
Decrement f, skip if not 0
[ label ] DCFSNZ f,d
0
d
(f) – 1
skip if not 0
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 instruction,
which is already fetched, is discarded,
and an NOP is executed instead mak-
ing it a two-cycle instruction.
1
1(2)
HERE
ZERO
NZERO
None
Read
NOP
0010
Q2
Q2
f
[0,1]
255
=
=
=
=
=
(dest);
DCFSNZ
:
:
011d
?
TEMP_VALUE - 1,
0;
Address (ZERO)
0;
Address (NZERO)
Execute
Execute
Q3
Q3
TEMP, 1
ffff
destination
Write to
NOP
Q4
Q4
ffff
GOTO
Syntax:
Operands:
Operation:
Status Affected:
Encoding:
Description:
Words:
Cycles:
Q Cycle Activity:
Example:
After Instruction
Forced NOP
Decode
PC =
Q1
Address (THERE)
Read literal
Unconditional Branch
[ label ]
0
k
k<12:8>
PC
None
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.
1
2
GOTO THERE
'k'<7:0>
NOP
110k
Q2
k
PC<12:0>;
1996 Microchip Technology Inc.
8191
GOTO k
kkkk
PCLATH<4:0>,
Execute
Execute
PCLATH<7:5>
Q3
kkkk
NOP
NOP
Q4
kkkk