Datasheet

PIC18F2331/2431/4331/4431
DS39616D-page 312  2010 Microchip Technology Inc.
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 Q3 Q4
Decode No
operation
POP TOS
value
No
operation
Example:
POP
GOTO NEW
Before Instruction
TOS = 0x0031A2
Stack (1 level down) = 0x014332
After Instruction
TOS = 0x014332
PC = 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 to implement a
software stack by modifying TOS, and
then push it onto the return stack.
Words: 1
Cycles: 1
Q Cycle Activity:
Q1 Q2 Q3 Q4
Decode PUSH
PC + 2 onto
return stack
No
operation
No
operation
Example:
PUSH
Before Instruction
TOS = 0x00345A
PC = 0x000124
After Instruction
PC = 0x000126
TOS = 0x000126
Stack (1 level down) = 0x00345A