private void WaitForKeyPress(object sender, EventArgs e)
{
WaitingForKey?.Invoke(this, e);
HideCaret(this.Handle);
this.BackColor = SystemColors.ControlDark;
this.KeyDown += SetKey;
this.LostFocus += TapToSetTextBox_LostFocus;
this.DoubleClick += TapToSetTextBox_LostFocus;
}
/// <summary>
/// It takes from _memory the instruction indicated by the program counter and executes it
/// </summary>
private void ExecuteNext()
{
ushort opcode = (ushort)(_memory[_PC & 0xFFF] * 0x100 + _memory[(_PC + 1) & 0xFFF]);
_PC += 2;
byte u = (byte)((opcode >> 12) & 0xF);
byte p = (byte)((opcode >> 0) & 0xF);
byte y = (byte)((opcode >> 4) & 0xF);
byte x = (byte)((opcode >> 8) & 0xF);
byte kk = (byte)((opcode >> 0) & 0xFF);
ushort nnn = (ushort)((opcode >> 0) & 0xFFF);
switch (u)
{
case 0:
if (opcode == 0x0E0)
{
Array.Clear(_screen, 0, _screen.Length);
}
else if (opcode == 0x0EE)
{
_PC = _stack.Pop();
}
else
{
throw new UnsupportedInstructionException(opcode.ToString("X4"));
}
break;
case 1:
_PC = nnn;
break;
case 2:
_stack.Push(_PC);
_PC = nnn;
break;
case 3:
if (_V[x] == kk)
{
_PC += 2;
}
break;
case 4:
if (_V[x] != kk)
{
_PC += 2;
}
break;
case 5:
if (_V[x] == _V[y])
{
_PC += 2;
}
break;
case 6:
_V[x] = kk;
break;
case 7:
_V[x] += kk;
break;
case 8:
switch (p)
{
case 0:
_V[x] = _V[y];
break;
case 1:
_V[x] |= _V[y];
break;
case 2:
_V[x] &= _V[y];
break;
case 3:
_V[x] ^= _V[y];
break;
case 4:
_V[0xF] = (byte)(_V[x] + _V[y] > byte.MaxValue ? 1 : 0);
_V[x] += _V[y];
break;
case 5:
_V[0xF] = (byte)(_V[x] > _V[y] ? 1 : 0);
_V[x] -= _V[y];
break;
case 6:
_V[0xF] = (byte)(_V[x] & 0x0001);
_V[x] >>= 1;
break;
case 7:
_V[0xF] = (byte)(_V[y] > _V[x] ? 1 : 0);
_V[x] = (byte)(_V[y] - _V[x]);
break;
case 0xE:
_V[0xF] = (byte)((_V[x] & 0x80) == 0x80 ? 1 : 0);
_V[x] <<= 1;
break;
default:
throw new UnsupportedInstructionException(opcode.ToString("X4"));
break;
}
break;
case 9:
if (_V[x] != _V[y])
{
_PC += 2;
}
break;
case 0xA:
_I = nnn;
break;
case 0xB:
_PC = (ushort)(nnn + _V[0]);
break;
case 0xC:
_V[x] = (byte)(_random.Next(byte.MaxValue + 1) & kk);
break;
case 0xD:
int x1 = _V[x];
int y1 = _V[y];
_V[15] = 0;
for (int i = 0; i < p; i++)
{
byte mem = _memory[_I + i];
for (int j = 0; j < 8; j++)
{
byte pixel = (byte)((mem >> (7 - j)) & 0x01);
int index = x1 + j + (y1 + i) * ScreenWidth;
index %= 2048;
if (pixel == 1 && _screen[index] != 0)
{
_V[15] = 1;
}
_screen[index] = (byte)(_screen[index] ^ pixel);
}
}
break;
case 0xE:
if (kk == 0x9E)
{
if ((_currentKey == _keyboardMapper.Convert(_V[x])))
{
_PC += 2;
}
}
else if (kk == 0xA1)
{
if ((_currentKey != _keyboardMapper.Convert(_V[x])))
{
_PC += 2;
}
}
else
{
throw new UnsupportedInstructionException(opcode.ToString("X4"));
}
break;
case 0xF:
switch (kk)
{
case 0x07:
_V[x] = _delayTimer;
break;
case 0x0A:
while (_currentKey != _keyboardMapper.Convert(_V[x]))
{
WaitingForKey?.Invoke(this, EventArgs.Empty);
autoEvent.WaitOne();
}
break;
case 0x15:
_delayTimer = _V[x];
break;
case 0x18:
_soundTimer = _V[x];
break;
case 0x1E:
_I += _V[x];
break;
case 0x29:
_I = (ushort)(_V[x] * 5);
break;
case 0x33:
_memory[_I] = (byte)(_V[x] / 100);
_memory[_I + 1] = (byte)((_V[x] % 100) / 10);
_memory[_I + 2] = (byte)(_V[x] % 10);
break;
case 0x55:
Array.Copy(_V, 0, _memory, _I, x + 1);
break;
case 0x65:
Array.Copy(_memory, _I, _V, 0, x + 1);
break;
default:
throw new UnsupportedInstructionException(opcode.ToString("X4"));
break;
}
break;
default:
throw new UnsupportedInstructionException(opcode.ToString("X4"));
break;
}
}