| Name | ID |
|---|---|
| Mo’men Ahmed | 2200768 |
| John Sameh | 2200414 |
1. Compiling the code
2. Using simulation instead of physical board
3. Running the program till start of main using a breakpoint
| Register | Value |
|---|---|
| R13 (SP) | 0x20000660 |
| R14 (LR) | 0x08000233 |
| R15 (PC) | 0x08000314 |
4. Start of program in disassembly
Instruction: 0x08000314 B580 PUSH {r7,lr}.
Interpretation: The same as the program counter (PC).
5. Instruction execution
Registers changed: R13 (SP), R15 (PC).
Relation with instruction:
- SP was reduced by 2 to (from
0x20000660to0x20000658) because two register values were pushed to the stack. - The PC was increased by 2 because the difference between each two instructions is two.
6. Finding first 4-byte long instructions
7. Finding values of some registers before executing my_strcpy
| Register | Value |
|---|---|
| R13 (SP) | 0x20000628 |
| R14 (LR) | 0x08000233 |
| R15 (PC) | 0x08000344 |
8. Executing my_strcpy function
| Register | Value |
|---|---|
| R13 (SP) | 0x20000628 |
| R14 (LR) | 0x08000349 |
| R15 (PC) | 0x08000374 |
| The LR was changed to point to the new location to be returned to. The PC was changed to the new instruction address matching the disassembly window. |
9. Registers holding my_strcpy arguments
| Argument | Register | Value |
|---|---|---|
src_ptr | R0 0x20000644 | ”Hello, world!” |
dst_ptr | R1 0x08000630 | "" |
10. Viewing values of arguments in memory using Memory Windows
11 and 12. Content
| Argument | Content |
|---|---|
src_ptr | Hello, world! |
dst_ptr | . |
13.
| Register | Function |
|---|---|
| R0 | Points to the character to be copied |
| R2 | Holds the character copied |
| R1 | Character is pasted here |
 |
14. Values before stepping out of the function
| Register | Value |
|---|---|
| R13 (SP) | 0x20000620 |
| R14 (LR) | 0x08000349 |
| R15 (PC) | 0x08000386 |
15. PC after stepping out of the function
R15 (PC): 0x08000348
16. Relationship between previous LR and PC
They are equal. The program returned to the point in main before entering the function.
17. Verifying my_capitalize
