PIC18F1220_07 Datasheet, PDF (222/308 Pages) Microchip Technology – 18/20/28-Pin High-Performance, Enhanced Flash Microcontrollers with 10-bit A/D and nanoWatt Technology

PIC18F1220/1320
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
= 0x0031A2
= 0x014332
= 0x014332
= 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 implement-
ing 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)
= 0x00345A
= 0x000124
= 0x000126
= 0x000126
= 0x00345A
DS39605F-page 220
© 2007 Microchip Technology Inc.