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ALF Computer 32
Architecture
The Alfy ASM language is the assembly language for the ALF32 Computer. This virtual CPU has:
- A Harvard Architecture (Program RAM and Data RAM are separate)
- 32 bits instructions
- 64 registers that are 32 bits wide (r0 to r63)
- 49 KB of RAM
- 49 KB of Program RAM
All RAM accesses must be 4 Byte aligned
Simulation
Alfy ASM is simulated using CPUSim version 4. To use the simulator:
- Download CPUSim version 4
- Download the alf_computer32.cpu
- Load it into the simulator
To run a simulation, you may run it in interactive or non-interactive mode.
Read the installation instructions.
Interactive Mode
To run CPUSim, open a shell and write
java -classpath .:richtextfx-fat-0.6.10.jar cpusim.Main -m alf_computer32.cpu -t file.asm
This will open the UI, load the AlfyComputer_32.cpu and the file.asm.
Non-Interactive Mode
To run CPUSim, open a shell and write
java -classpath .:richtextfx-fat-0.6.10.jar cpusim.Main -c -m alf_computer32.cpu -t file.asm
This will load the alf_computer32.cpu and run the file.asm.
Running a program
After loading a machine and a program, to run it:
- In the menu bar, go to Execute and select Assemble & load. This will assemble the program and load it into the program memory
- In the Menu bar, go to Execute and select Debug. This will switch the UI into debug mode. There you can select several options:
- Start Over - restart the program
- Go - run the program
- Step by Instr - go forward one instruction in the program
- Back one Instr - go back one instruction in the program
The Alfy ASM Lanaguge
| Instruction | Equivalent |
|---|---|
| set r1 value (16 bits) | r1 = value |
| mov r1 r2 | r1 = r2 |
| load r1 r2 | r2 = MEM [r1] |
| store r1 r2 | MEM [r1] = r2 |
| pload r1 r2 | r2 = PMEM [r1] |
| pstore r1 r2 | PMEM [r1] = r2 |
| push r1 | sp = sp - 4 MEM [sp] = r1 |
| pop r1 | r1 = MEM [sp] sp = sp + 4 |
| pushsp | temp = sp sp = sp - 4 MEM [sp] = temp |
| popsp | sp = MEM [sp] |
| jmp label | goto label |
| run label | sp = sp - 4 MEM [sp] = ip goto etiquete |
| ret | sp = sp + 4 ip = MEM [sp] |
| (pseudo) label_title: | label label_title |
| stop | stop the program |
| add r1 r2 r3 | r1 = r2 + r3 |
| sub r1 r2 r3 | r1 = r2 - r3 |
| mul r1 r2 r3 | r1 = r2 * r3 |
| div r1 r2 r3 | r1 = r2 / r3 |
| mod r1 r2 r3 | r1 = r2 mod r3 |
| dec r1 value (unsigned 16 bits) | r1 = r1 - value |
| inc r1 value (unsigned 16 bits) | r1 = r1 + value |
| test r1 r2 | t = r1 - r2 |
| je label | if t = 0 goto label |
| jne label | if t != 0 goto label |
| jg label | if t > 0 goto label |
| jge label | if t >= 0 goto label |
| jl label | if t < 0 goto label |
| jle label | if t ⇐ 0 goto label |
| and r1 r2 r3 | r1 = r2 AND r3 (bitwise, bit by bit) |
| or r1 r2 r3 | r1 = r2 OR r3 (bitwise, bit by bit) |
| xor r1 r2 r3 | r1 = r2 XOR r3 (bitwise, bit by bit) |
| shl r1 r2 (left shift) | r1 = r1 « r2 |
| shr r1 r2 (right shift) | r1 = r1 » r2 |
| read r1 | r1 = read character from keyboard |
| write r1 | write character r1 to the display |
| readnumber r1 | r1 = read number from keyboard |
| writenumber r1 | write number r1 to the display |
