CPU Emulator
Simple CPU emulator written in Rust
The instruction set implemented in this program is from this page (only difference is that STO is STA).
Instruction list
| Name | Code | Opcode | Definition |
|---|---|---|---|
| Load | LDA XY |
1XY | Load the memory address of XY into the accumulator |
| Store | STA XY |
2XY | Store accumulator value in memory address XY |
| Add | ADD XY |
3XY | Add value of memory address XY to accumulator |
| Subtract | SUB XY |
4XY | Subtract the value of memory address XY from accumulator |
| Input | IN |
500 | Take user input and store in accumulator |
| Output | OUT |
600 | Write value of accumulator to shell |
| Halt | HLT |
700 | Halt execution of the program |
| Set | SET XY |
8XY | Set the loaded memory address (loaded via LDA) to the memory address of XY |
| Jump | JMP XY |
9XY | Change the program counter to memory address XY |
| Call | CALL LABEL |
N/A | This instruction internally changes into a JMP XY call to jump to a label. |
Example programs
Add two numbers
MAIN:
CALL GETINPUTS
CALL ADDNUMS
CALL PRINTOUT
GETINPUTS:
IN
STA 50
IN
STA 51
ADDNUMS:
LDA 50
ADD 51
STA 52
PRINTOUT:
LDA 52
OUT
HLT
Subtract one number from another
MAIN:
CALL GETINPUTS
CALL SUBTRACT
CALL PRINTOUT
GETINPUTS:
IN
STA 50
IN
STA 51
SUBTRACT:
LDA 50
SUB 51
STA 52
PRINTOUT:
LDA 52
OUT
HLT
Infinite get input & print loop
MAIN:
CALL LOOP
LOOP:
IN
OUT
CALL LOOP
Pre-defining data
MAIN:
LDA 50
ADD 51
OUT
HLT
50 DAT 10
51 DAT 11
The above code means that at address 50, the number 10 will be stored, and at address 51, the number 11 will be stored. Upon execution 50 will be loaded into the accumulator, 51 will then be added to the accumulator and the accumulator will be outputted. Followed by a halt instruction.
Execution
- Build the binaries
./path/to/binary --compile source.file target.file./path/to/binary --run target.file