pete > courses > CS 202 Spring 24 > Tier 2, Phase 2, Problem 02: ARM32 ALU
Tier 2, Phase 2, Problem 02: ARM32 ALU
For this problem, you will construct an ALU for an ARM32 processor. It will support all the arithmetic and logical operations entailed by the ARM32 instructions we have looked at in class, as well as some that will come in handy when constructing the full processor (which is the Phase 2 project).
Your submission will consist of two files, described in detail below:
- alu.circ
- test-vector.txt
Note that a working solution to this assignment will be necessary to complete the Phase 2 project.
Interface & Behavior
The file alu.circ must contain a subcircuit named main with the following inputs and outputs:
| name | width | direction |
|---|---|---|
| operand_0 | 32 bits | in |
| operand_1 | 32 bits | in |
| operation | 4 bits | input |
| result | 32 bits | out |
And the following behavior:
| when "operation" is… | "result" should be… |
|---|---|
| 0000 | operand_0 bitwise-and operand_1 |
| 0001 | operand_0 bitwise-xor operand_1 |
| 0010 | operand_0 minus operand_1 |
| 0011 | operand_1 minus operand_0 |
| 0100 | operand_0 plus operand_1 |
| 1100 | operand_0 bitwise-or operand_1 |
| 1101 | operand_0 |
| 1111 | bitwise-not of operand_0 |
For arithmetic operations, assume all values are two’s complement. You may ignore overflow.
You may assume that values of "operation" not in the table above will never be given.
Note that we will not be able to test (and therefore give feedback on) the functionality of your circuit unless its inputs and outputs are exactly as specified above.
Restrictions
You are limited to components from the following Logisim libraries:
- Wiring
- Gates
- Plexers
- Arithmetic
- Memory
You may add as many subcircuits as you deem appropriate.
Testing
You must submit a test-vector.txt file that adequately tests your circuit. When devising your tests, here are some things to keep in mind:
You may assume all built-in components provided by Logisim function correctly.
As a result, your tests should focus on how you’ve connected together those components. Given the design of your circuit and the components it comprises, how might you have misconnected things? Where might a wire have gone astray? Write tests that verify that your wires go where you want them to go and do what you want them to do.
Submission Instructions
Copy the alu.circ and test-vector.txt files to weathertop and then run:
$ 202 submit t2p2p02 alu.circ $ 202 submit t2p2p02 test-vector.txt
Submissions will not be accepted after 2pm on Wednesday, 10 April.