Datasheet

 1997 Microchip Technology Inc. DS30444E - page 127
PIC16C9XX
DECFSZ Decrement f, Skip if 0
Syntax: [
label ] DECFSZ f,d
Operands: 0 ≤ f ≤ 127
d ∈ [0,1]
Operation: (f) - 1 → (destination);
skip if result = 0
Status Affected: None
Encoding:
00 1011 dfff ffff
Description:
The contents of register 'f' are decre-
mented. If 'd' is 0 the result is placed in the
W register. If 'd' is 1 the result is placed
back in register 'f'.
If the result is 1, the next instruction, is
executed. If the result is 0, then a NOP is
executed instead making it a 2T
CY instruc-
tion.
Words: 1
Cycles: 1(2)
Q Cycle Activity: Q1 Q2 Q3 Q4
Decode Read
register 'f'
Process
data
Write to
destination
If Skip: (2nd Cycle)
Q1 Q2 Q3 Q4
No-
Operation
No-
Operation
No-
Operation
No-
Operation
Example
HERE DECFSZ CNT, 1
GOTO LOOP
CONTINUE •
•
•
Before Instruction
PC = address HERE
After Instruction
CNT = CNT - 1
if CNT = 0,
PC = address CONTINUE
if CNT ≠ 0,
PC = address HERE+1
GOTO Unconditional Branch
Syntax: [
label ] GOTO k
Operands: 0 ≤ k ≤ 2047
Operation: k → PC<10:0>
PCLATH<4:3> → PC<12:11>
Status Affected: None
Encoding:
10 1kkk kkkk kkkk
Description:
GOTO is an unconditional branch. The
eleven bit immediate value is loaded
into PC bits <10:0>. The upper bits of
PC are loaded from PCLATH<4:3>.
GOTO is a two cycle instruction.
Words: 1
Cycles: 2
Q Cycle Activity: Q1 Q2 Q3 Q4
1st Cycle
Decode Read
literal 'k'
Process
data
Write to
PC
2nd Cycle
No-
Operation
No-
Operation
No-
Operation
No-
Operation
Example
GOTO THERE
After Instruction
PC = Address THERE