Datasheet

PIC17C4X
DS30412C-page 122  1996 Microchip Technology Inc.
DCFSNZ Decrement f, skip if not 0
Syntax: [
label ] DCFSNZ f,d
Operands: 0 ≤ f ≤ 255
d ∈ [0,1]
Operation: (f) – 1 → (dest);
skip if not 0
Status Affected: None
Encoding:
0010 011d ffff ffff
Description:
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.
Words: 1
Cycles: 1(2)
Q Cycle Activity:
Q1 Q2 Q3 Q4
Decode Read
register 'f'
Execute Write to
destination
If skip:
Q1 Q2 Q3 Q4
Forced NOP NOP Execute NOP
Example:
HERE DCFSNZ TEMP, 1
ZERO :
NZERO :
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<15:13> → 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'<7:0>
Execute NOP
Forced NOP NOP Execute NOP
Example:
GOTO THERE
After Instruction
PC = Address (THERE)