PIC18F2220/2320/4220/4320
POP
Pop Top of Return Stack
PUSH
Push Top of Return Stack
Syntax:
[ label ] POP
None
Syntax:
[ label ] PUSH
None
Operands:
Operation:
Status Affected:
Encoding:
Operands:
Operation:
Status Affected:
Encoding:
(TOS) → bit bucket
None
(PC+2) → TOS
None
0000
0000
0000
0110
0000
0000
0000
0101
Description:
The TOS value is pulled off the
return stack and is discarded. The
TOS value then becomes the previ-
ous 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.
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 to implement
a software stack by modifying TOS,
and then push it onto the return
stack.
Words:
Cycles:
1
1
Words:
Cycles:
1
1
Q Cycle Activity:
Q1
Q2
Q3
Q4
Q Cycle Activity:
Q1
Decode
PUSH PC+2
onto return
stack
No
operation
No
operation
Q2
Q3
Q4
Decode
No
operation
POP TOS
value
No
operation
PUSH
Example:
POP
GOTO
Example:
Before Instruction
NEW
TOS
PC
=
=
0x00345A
0x000124
Before Instruction
TOS
=
=
0x0031A2
0x014332
After Instruction
Stack (1 level down)
PC
=
=
=
0x000126
0x000126
0x00345A
TOS
After Instruction
Stack (1 level down)
TOS
PC
=
=
0x014332
NEW
DS39599C-page 284
2003 Microchip Technology Inc.
MICROCHIP [ MICROCHIP ]
