PIC18F6520-I Datasheet, PDF (290/380 Pages) Micrel Semiconductor – 64/80-Pin High-Performance, 256 Kbit to 1 Mbit Enhanced Flash Microcontrollers with A/D

PIC18F6520/8520/6620/8620/6720/8720
POP
Pop Top of Return Stack
Syntax:
[ label ] POP
Operands:
None
Operation:
(TOS) → bit bucket
Status Affected: None
Encoding:
0000 0000 0000 0110
Description:
The TOS value is pulled off the
return stack and is discarded. The
TOS value then becomes the
previous value that was pushed
onto the return stack.
This instruction is provided to
enable the user to properly manage
the return stack to incorporate a
software stack.
Words:
1
Cycles:
1
Q Cycle Activity:
Q1
Q2
Decode
No
operation
Q3
POP TOS
value
Q4
No
operation
Example:
POP
GOTO
Before Instruction
TOS
Stack (1 level down)
After Instruction
TOS
PC
NEW
= 0031A2h
= 014332h
= 014332h
= NEW
PUSH
Push Top of Return Stack
Syntax:
[ label ] PUSH
Operands:
None
Operation:
(PC+2) → TOS
Status Affected: None
Encoding:
0000 0000 0000 0101
Description:
The PC+2 is pushed onto the top of
the return stack. The previous TOS
value is pushed down on the stack.
This instruction allows
implementing a software stack by
modifying TOS and then pushing it
onto the return stack.
Words:
1
Cycles:
1
Q Cycle Activity:
Q1
Q2
Decode
PUSH PC+2
onto return
stack
Q3
No
operation
Q4
No
operation
Example:
PUSH
Before Instruction
TOS
PC
After Instruction
PC
TOS
Stack (1 level down)
= 00345Ah
= 000124h
= 000126h
= 000126h
= 00345Ah
DS39609B-page 288
 2004 Microchip Technology Inc.