1. Lab 3 - Branching & Subroutines
MPC8360 Micro Controllers
Lab 3 - Branching & Subroutines
Fall , 2010

2. LIFO = Last In First Out Stack Data Structure Pop Push Data 4
Stack Pointer
Data 3
Stack Pointer
Data 2
Stack Pointer
Data 1
Stack Pointer
Stack Pointer
Stack

3. Pseudo code Basic Subroutine Call Warning For R3 =1 to 100 Push R3
Push Parameter
bl Sub1
Pop Result
Pop R3
Sub1:
Pop Parameter ….
Push Result
bclr
Warning
Pseudo code
Param
Result R3 LR
Stack

4. Main Program Structure
…..
Push used registers Push
Push subroutine parameters Push
Call subroutine bl Sub1
Pop return parameters Pop
Pop used registers Pop

5. Subroutine Structure Label Sub1: Pop parameters Pop
Subroutine code …..
Push return parameters Push
Return bclr

6. Subroutine Calling a Subroutine…
Push LR
Push Registers
Push Parameter
bl Sub2
Pop Result
Pop Registers Pop LR
bclr
Sub2:
Pop Parameter ….
Push Result
bclr
Param
Result
Regs LR
OLD Data LR
Stack

7. Stack implementation The Stack will be implemented in the memory.
Each student will decide the address of his stack (somewhere in 0x0001_ x0100_0000)
Use R31 as the Stack Pointer (SP)
Push & Pop should not be implemented as subroutines
No need to check for Overflow / Underflow
Do not use Step-Over when debugging

8. General Notes
Make sure to bring the codes you have written in previous labs.
Please READ the exercise before you start working on it !!
Please assign final reports in *.doc (office 2003) format only

9. Quick Overview