// Starts the interpreter
private void StartInterpreteter()
{
// Ends any previous interpreter session
interpreting = false;
// Initialises the interpreter
interpreter = InitialiseInterpreter();
if (interpreter == null)
{
return;
}
// Initialises the interpreter output
screen = InitialiseScreen();
if (screen == null)
{
return;
}
// Initialises the interpreter keyboard
keyboard = InitialiseKeyboard();
if (keyboard == null)
{
return;
}
// Sets up the clock to output at frameRate Hz (processes at clockSpeed Hz) and starts the interpreter
interpreting = true;
clockTimer = new Timer();
clockTimer.Interval = 1000 / frameRate;
clockTimer.Tick += new System.EventHandler(ClockTick);
clockTimer.Start();
}
private void OPCode_DXYN(byte register1, byte register2, byte number, CHIP8_Screen screen)
{
// Gets the sprite
byte[] rows = new byte[number];
for (int i = 0; i < number; i++)
{
rows[i] = memory[addressRegister + i];
}
// Draws the sprite
registers[0xF] = screen.Draw(registers[register1], registers[register2], rows);
}
public Window()
{
InitializeComponent();
// Sets the resolution
this.ClientSize = new Size(InterpreterOutput.ClientRectangle.Width,
MenuStrip.ClientRectangle.Height + InterpreterOutput.ClientRectangle.Height);
// Sets CHIP-8 Objects to null
interpreter = null;
screen = null;
keyboard = null;
}
// Performs a single clock cycle
public void PerformCycle(ref CHIP8_Screen screen, ref CHIP8_Keyboard keyboard)
{
// Doesn't perform an operation if waiting for a key press
if (awaitingKeyPress)
{
AwaitKey(keyboard);
return;
}
// Gets an OP code from memory
byte byte1 = memory[programCounter++];
byte byte2 = memory[programCounter++];
// Processes the OP code
ProcessOPCode(byte1, byte2, ref screen, ref keyboard);
return;
}
/*
* OP Codes:
* Each method executes the corresponding OP code instruction indicated by its name
*/
private void OPCode_00E0(ref CHIP8_Screen screen)
{
screen.Clear();
}
// Processes an OP code instruction
private void ProcessOPCode(byte byte1, byte byte2, ref CHIP8_Screen screen, ref CHIP8_Keyboard keyboard)
{
// Finds the function to execute for the current OP code, gets its arguments, then calls the function
switch ((byte1 & 0xF0) >> 4) // Filters through the first nibble
{
case 0x0:
switch (byte1 & 0x0F) // Filters through the second nibble
{
case 0x0:
switch (byte2) // Filters through the second byte
{
case 0xE0: // 00E0
OPCode_00E0(ref screen);
break;
case 0xEE: // 00EE
OPCode_00EE();
break;
}
break;
}
break;
case 0x1: // 1NNN
OPCode_1NNN((UInt16)(((UInt16)(byte1 & 0x0F) << 8) + (UInt16)byte2));
break;
case 0x2: // 2NNN
OPCode_2NNN((UInt16)(((UInt16)(byte1 & 0x0F) << 8) + (UInt16)byte2));
break;
case 0x3: // 3XNN
OPCode_3XNN((byte)(byte1 & 0x0F), byte2);
break;
case 0x4: // 4XNN
OPCode_4XNN((byte)(byte1 & 0x0F), byte2);
break;
case 0x5:
switch (byte2 & 0x0F) // Filters through the fourth nibble
{
case 0x0: // 5XY0
OPCode_5XY0((byte)(byte1 & 0x0F), (byte)((byte2 & 0xF0) >> 4));
break;
}
break;
case 0x6: // 6XNN
OPCode_6XNN((byte)(byte1 & 0x0F), byte2);
break;
case 0x7: // 7XNN
OPCode_7XNN((byte)(byte1 & 0x0F), byte2);
break;
case 0x8:
switch (byte2 & 0x0F) // Filters through the fourth nibble
{
case 0x0: // 8XY0
OPCode_8XY0((byte)(byte1 & 0x0F), (byte)((byte2 & 0xF0) >> 4));
break;
case 0x1: // 8XY1
OPCode_8XY1((byte)(byte1 & 0x0F), (byte)((byte2 & 0xF0) >> 4));
break;
case 0x2: // 8XY2
OPCode_8XY2((byte)(byte1 & 0x0F), (byte)((byte2 & 0xF0) >> 4));
break;
case 0x3: // 8XY3
OPCode_8XY3((byte)(byte1 & 0x0F), (byte)((byte2 & 0xF0) >> 4));
break;
case 0x4: // 8XY4
OPCode_8XY4((byte)(byte1 & 0x0F), (byte)((byte2 & 0xF0) >> 4));
break;
case 0x5: // 8XY5
OPCode_8XY5((byte)(byte1 & 0x0F), (byte)((byte2 & 0xF0) >> 4));
break;
case 0x6: // 8XY6
OPCode_8XY6((byte)(byte1 & 0x0F), (byte)((byte2 & 0xF0) >> 4));
break;
case 0x7: // 8XY7
OPCode_8XY7((byte)(byte1 & 0x0F), (byte)((byte2 & 0xF0) >> 4));
break;
case 0xE: // 8XYE
OPCode_8XYE((byte)(byte1 & 0x0F), (byte)((byte2 & 0xF0) >> 4));
break;
}
break;
case 0x9:
switch (byte2 & 0x0F) // Filters through the fourth nibble
{
case 0x0: // 9XY0
OPCode_9XY0((byte)(byte1 & 0x0F), (byte)((byte2 & 0xF0) >> 4));
break;
}
break;
case 0xA: // ANNN
OPCode_ANNN((UInt16)(((UInt16)(byte1 & 0x0F) << 8) + (UInt16)byte2));
break;
case 0xB: // BNNN
OPCode_BNNN((UInt16)(((UInt16)(byte1 & 0x0F) << 8) + (UInt16)byte2));
break;
case 0xC: // CXNN
OPCode_CXNN((byte)(byte1 & 0x0F), byte2);
break;
case 0xD: // DXYN
OPCode_DXYN((byte)(byte1 & 0x0F), (byte)((byte2 & 0xF0) >> 4), (byte)(byte2 & 0x0F), screen);
break;
case 0xE:
switch (byte2) // Filters through the second byte
{
case 0x9E: // EX9E
OPCode_EX9E((byte)(byte1 & 0x0F), keyboard);
break;
case 0xA1: // EXA1
OPCode_EXA1((byte)(byte1 & 0x0F), keyboard);
break;
}
break;
case 0xF:
switch (byte2) // Filters through the second byte
{
case 0x07: // FX07
OPCode_FX07((byte)(byte1 & 0x0F));
break;
case 0x0A: // FX0A
OPCode_FX0A((byte)(byte1 & 0x0F), keyboard);
break;
case 0x15: // FX15
OPCode_FX15((byte)(byte1 & 0x0F));
break;
case 0x18: // FX18
OPCode_FX18((byte)(byte1 & 0x0F));
break;
case 0x1E: // FX1E
OPCode_FX1E((byte)(byte1 & 0x0F));
break;
case 0x29: // FX29
OPCode_FX29((byte)(byte1 & 0x0F));
break;
case 0x33: // FX33
OPCode_FX33((byte)(byte1 & 0x0F));
break;
case 0x55: // FX55
OPCode_FX55((byte)(byte1 & 0x0F));
break;
case 0x65: // FX65
OPCode_FX65((byte)(byte1 & 0x0F));
break;
}
break;
}
}