A C# library that simulates a CPU.

• CPUSIM
  • Usage
  • Running code

Config builder usage:

var config = new CpuConfigurationBuilder()
            .Option1(parameter)
            .Option2(parameter)
            .Build();

SetMemorySize(size) tells the simulator the size of the memory.

Note: low-bit CPU's can't handle large memories, as it is limited by the instruction size. For example in a 16 bit CPU the opcode is 8 bit. The JUMP instruction has 8 bits left for the destination address. The largest address we can fit in 8 bits is 255.

.SetMemorySize(128)         // 128 bit memory

SetOpcodeSize(size) tells the simulator the size of the opcode per instruction.

.SetOpcodeSize(8)           // 8 bit opcode

SetInstructionSize(size) tells the simulator the size of the whole instruction. This is essentially the "X bit" number for your CPU.

.SetInstructionSize(16)     // 16 bit instruction set

AddRegister(name, size) adds a register to the CPU. Size is in bits.

.AddRegister("ax", 16)

AddRegister(name, size, halt) adds a register to the CPU. Boolean decides if the register will be treated as a halt bit.

.AddRegister("halt", 1, true)

AddMicroInstruction(MicroInstruction) adds a microinstruction to the CPU.

.AddMicroInstruction(MicroInstruction.RegisterToRegister("ax-bx", "ax", "bx"))

For a list of microinstructions click here.

AddInstructionField(name, size, type) prepares instruction fields for the Instructions.

.AddInstructionField("ignore8", 8, CpuFieldType.Ignore)

AddCpuInstruction(name, opCode, micros, fields) adds the instructions to the CPU. These are the instructions that will be used in the code.

.AddCpuInstruction("ADD",
                    CpuValue.FromInteger(3, 8),
                    new[] {"ax-bx", "zero-ax", "ir(9-16)-ax", "add"},
                    new[] {"data8"})

Simply construct a new Cpu with the config you've created, write code, compile and execute.

var cpu = new Cpu(config);

const string code = @"
    READ
    ADD 1
    WRITE
    HALT
";
cpu.Compile(code);
cpu.Execute();