/// <summary>
/// The generic fetch method for all hart implementations
/// </summary>
private void Fetch()
{
// Done!
// Fetch the first instruction and run the loop. Get the first 2 Bytes from the Base Address aka PC
var pc = register.ReadUnsignedInt(register.ProgramCounter);
var instructionCoding = memory.GetHalfWord(pc);
Logger.Info("Instruction {ins:X} fetched", BitConverter.ToString(instructionCoding.ToArray()));
while (ContinueIfValid(instructionCoding))
{
// Loop for the commands
var instruction = instructionDecoder.Decode(instructionCoding);
if (rvMode)
{
var isCustom = (instructionCoding.First() & 0x7F) == 0x00;
if (isCustom)
{
Logger.Info("Processing RV custom command.");
var customCoding = memory.GetWord(pc);
var isHalt = customCoding.SequenceEqual(new byte[] { 0x00, 0x00, 0x00, 0x00 });
if (isHalt)
{
// Stop the simulation!
break;
}
var payload = typeDecoder.DecodeCustom(instruction, customCoding);
var rvOpcode = new RvOpcode(memory, register, environment);
var inc = rvOpcode.Execute(instruction, payload);
if (inc)
{
// Go to the next instruction...
register.NextInstruction(4);
}
}
else
{
// Handle instruction as usual..
HandleCompliantMode(pc, instructionCoding, instruction);
}
}
else
{
HandleCompliantMode(pc, instructionCoding, instruction);
}
// Stop the instruction fetch if an error occured or the state is stopped
var currentState = environment.GetCurrentState();
if (currentState == State.FatalError || currentState == State.Stopped)
{
break;
}
// Done. Next run.
pc = register.ReadUnsignedInt(register.ProgramCounter);
instructionCoding = memory.GetHalfWord(pc);
Logger.Info("Instruction {ins:X} fetched", BitConverter.ToString(instructionCoding.ToArray()));
}
if (environment.GetCurrentState() == State.FatalError)
{
Console.Error.WriteLine("# FATAL ERROR occured : " + environment.GetStateDescription());
}
if (environment.GetCurrentState() == State.Stopped)
{
Console.Out.WriteLine("# Hart Stopped");
}
environment.NotifyStopped();
}