/hlp-proj-indiv

High-Level Programming Individual Project. Emulation of a subset of Arm UAL instructions using functional-programming paradigms, implemented in F#.

Primary LanguageF#

HLP Individual Project

Introduction

This repo contains fsharp source files to run and test a part of the ARM simulator. The code has been modularised and the main working module is Memory which can be found in Program.fs in the root directory.

Module Description

Main Functions

The module currently implements two main functions: parse and execute. It can be used in conjuction with top-level code to parse recognizable memory instructions (see below for more info) into an Memory.Instr record type which can then be used by the execute function to simulate an ARM processor.

Entrypoints

  1. parse

    • Input : LineData record which seperates opcodes, suffixes, conditions and operands as different string or d.u. types
    • Output : Result<Parse<Instr>,string> option which is a monadic value option type of value.
      • None signifies none of the opcodes present are recognizable by the parse function
      • Some(_) signifies that the opcode present was recognizable by the parse function but the result type must determine whether parse was successful
      • After extracting the option, Parse<Instr> can be extracted if parse was successful. This contains recognized intruction records that are valid atleast in their format and general order.
      • If there is an error, the object wrapped by some will contain an Error<string> to promt the user.
      • Using monad types execution is not stalled at any stage and instead errors are propagated through the pipeline.

  2. execute

    • Input: Parse<Instr> MachineMemory<Instr> DataPath
    • Output: Result<(MachineMemory<Instr> * DataPath), string>
    • This uses the machinememory map and datapath provided to execute an instruction which is similar to simulating the instruction. The resulting output is either an error with a string describing an error or a successful execute with modified machine memory and datapath objects.

Supported Commands (OPC)

  1. LDR
  2. LDRB
  3. STR

Formats

Type Operand1 Operand2 Operand3 Format Example
A REG1 REG2 - OPC REG1, [REG2]
B REG REG REG OPC REG1, [REG2, REG3]
C REG REG REG OPC REG, [REG, REG3]!
D REG REG REG OPC REG, [REG], REG3
B REG REG LIT OPC REG1, [REG2, LIT]
C REG REG LIT OPC REG, [REG, LIT]!
D REG REG LIT OPC REG, [REG], LIT

Type Definitions

  1. A simply load/store from/to REG1 and the memory index given by REG2. If it is an LDERB instruction then, any valid address is accepted, however if the suffix B is not used then the address given must be divisible by 4 otherwise errors will be thrown

Tests

  • All tests can be found in the file Test.fs. To access these tests, simply run the command dotnet run at the root directory of the folder.
  • Currently, only unit tests are implemented due to time limitations.
  • There are currently 40 tests and all pass as shown in the screenshot below.