public void clearDisplay()
{
if (display != null)
{
display.Source = Utli.loadBitmap(getScreenBitmap(blankScreenBuffer));
}
}
void workerProgressChanged(object sender, ProgressChangedEventArgs e)
{
//update screen
if (display != null)
{
display.Source = Utli.loadBitmap(getScreenBitmap(screenBuffer));
}
}
public void connectDisplay(System.Windows.Controls.Image display)
{
this.display = display;
if (display != null)
{
display.Source = Utli.loadBitmap(getScreenBitmap(screenBuffer));
}
}
public string getAssemblyCode()
{
string outputLine = "";
ushort addr = (ushort)(Chip8.ROM_BASE_ADDR + addrOfInstruc);
//add address
outputLine = outputLine + addr.ToString("x2").ToUpper();
//add spaces
outputLine += string.Join("", Enumerable.Repeat(' ', 4));
//add machine code
outputLine = outputLine + Utli.getHighByte(opcode).ToString("x2").ToUpper() + " " + Utli.getLowerByte(opcode).ToString("x2").ToUpper();
//add spaces
outputLine += string.Join("", Enumerable.Repeat(' ', 10));
//add assembly code
outputLine = outputLine + mnemonicInstuc;
return(outputLine);
}
public bool debugStepRoutine()
{
cpuStep();
updateTimers();
display.Source = Utli.loadBitmap(getScreenBitmap(screenBuffer));
//break point check
if (debugMode && (!cpuHalt))
{
for (int j = 0; j < brkPtAddresses.Count(); j++)
{
if (pc == brkPtAddresses[j])
{
return(true);
}
}
}
return(false);
}
public void cpuStep()
{
//fetch instruction
ushort opcode = (ushort)((mainMemory[pc] << 8) | mainMemory[pc + 1]);
pc += 2;
//decode and execute instruction
switch (Utli.getUpperByteHighNibble(opcode))
{
case 0x0:
{
if (Utli.getLowerByteHighNibble(opcode) == 0xE)
{
switch (Utli.getLowerByteLowNibble(opcode))
{
case 0x0: // Clears the screen.
Array.Clear(screenBuffer, 0, screenBuffer.Length);
//drawflag = true;
break;
case 0xE: //Returns from a subroutine.
pc = mainMemory[stackPtr];
stackPtr++;
pc = (ushort)((mainMemory[stackPtr] << 8) | pc);
stackPtr++;
break;
default:
Console.WriteLine("Unknown Opcode - " + "0x" + opcode.ToString("x2"));
break;
}
}
else
{
if ((opcode & 0x0FFF) == 0)
{
Console.WriteLine("0NNN - Calls RCA 1802 program at address NNN. Not necessary for most ROMs.");
}
else
{
Console.WriteLine("Unknown Opcode - " + "0x" + opcode.ToString("x2"));
}
pc += 2;
}
}
break;
case 0x1: //Jumps to address NNN.
pc = (ushort)(opcode & 0x0FFF);
break;
case 0x2: //Calls subroutine at NNN.
stackPtr--;
mainMemory[stackPtr] = Utli.getHighByte(pc);
stackPtr--;
mainMemory[stackPtr] = Utli.getLowerByte(pc);
pc = (ushort)(opcode & 0x0FFF);
break;
case 0x3: //3XNN Skips the next instruction if VX equals NN.
if (vRegs[Utli.getUpperByteLowNibble(opcode)] == Utli.getLowerByte(opcode))
{
pc += 2;
}
break;
case 0x4: //4XNN Skips the next instruction if VX doesn't equal NN.
if (vRegs[Utli.getUpperByteLowNibble(opcode)] != Utli.getLowerByte(opcode))
{
pc += 2;
}
break;
case 0x5: //5XY0 Skips the next instruction if VX equals VY.
if (vRegs[Utli.getUpperByteLowNibble(opcode)] == vRegs[Utli.getLowerByteHighNibble(opcode)])
{
pc += 2;
}
break;
case 0x6: //6XNN Sets VX to NN.
vRegs[Utli.getUpperByteLowNibble(opcode)] = Utli.getLowerByte(opcode);
break;
case 0x7: //7XNN Adds NN to VX.
vRegs[Utli.getUpperByteLowNibble(opcode)] += Utli.getLowerByte(opcode);
break;
case 0x8:
{
switch (Utli.getLowerByteLowNibble(opcode))
{
case 0x0: // 8XY0 Sets VX to the value of VY.
vRegs[Utli.getUpperByteLowNibble(opcode)] = vRegs[Utli.getLowerByteHighNibble(opcode)];
break;
case 0x1: // 8XY1 Sets VX to VX or VY.
vRegs[Utli.getUpperByteLowNibble(opcode)] |= vRegs[Utli.getLowerByteHighNibble(opcode)];
break;
case 0x2: // 8XY2 Sets VX to VX and VY.
vRegs[Utli.getUpperByteLowNibble(opcode)] &= vRegs[Utli.getLowerByteHighNibble(opcode)];
break;
case 0x3: // 8XY3 Sets VX to VX xor VY.
vRegs[Utli.getUpperByteLowNibble(opcode)] ^= vRegs[Utli.getLowerByteHighNibble(opcode)];
break;
case 0x4: // 8XY4 Adds VY to VX. VF is set to 1 when there's a carry, and to 0 when there isn't.
{
int carryCheck = vRegs[Utli.getUpperByteLowNibble(opcode)] + vRegs[Utli.getLowerByteHighNibble(opcode)];
if (carryCheck > 0xFF)
{
vRegs[0xF] = 1;
}
else
{
vRegs[0xF] = 0;
}
vRegs[Utli.getUpperByteLowNibble(opcode)] += vRegs[Utli.getLowerByteHighNibble(opcode)];
}
break;
case 0x5: //8XY5 VY is subtracted from VX. VF is set to 0 when there's a borrow, and 1 when there isn't.
{
if (vRegs[Utli.getLowerByteHighNibble(opcode)] > vRegs[Utli.getUpperByteLowNibble(opcode)])
{
vRegs[0xF] = 0;
}
else
{
vRegs[0xF] = 1;
}
vRegs[Utli.getUpperByteLowNibble(opcode)] -= vRegs[Utli.getLowerByteHighNibble(opcode)];
}
break;
case 0x6: //8XY6 Shifts VX right by one.
// VF is set to the value of the least significant bit of VX before the shift.
{
vRegs[0xF] = (byte)(0x1 & vRegs[Utli.getUpperByteLowNibble(opcode)]);
vRegs[Utli.getUpperByteLowNibble(opcode)] >>= 1;
}
break;
case 0x7: //8XY7 Sets VX to VY minus VX. VF is set to 0 when there's a borrow, and 1 when there isn't.
{
if (vRegs[Utli.getUpperByteLowNibble(opcode)] > vRegs[Utli.getLowerByteHighNibble(opcode)])
{
vRegs[0xF] = 0;
}
else
{
vRegs[0xF] = 1;
}
vRegs[Utli.getUpperByteLowNibble(opcode)] = (byte)(vRegs[Utli.getLowerByteHighNibble(opcode)] - vRegs[Utli.getUpperByteLowNibble(opcode)]);
}
break;
case 0xE: //8XYE Shifts VX left by one. VF is set to the value of the
// most significant bit of VX before the shift.
{
vRegs[0xF] = (byte)(vRegs[Utli.getUpperByteLowNibble(opcode)] >> 7);
vRegs[Utli.getUpperByteLowNibble(opcode)] <<= 1;
}
break;
default:
Console.WriteLine("Unknown Opcode - " + "0x" + opcode.ToString("x2"));
break;
}
}
break;
case 0x9: //9XY0 Skips the next instruction if VX doesn't equal VY..
if (vRegs[Utli.getUpperByteLowNibble(opcode)] != vRegs[Utli.getLowerByteHighNibble(opcode)])
{
pc += 2;
}
break;
case 0xA: //ANNN Sets Ireg to the address NNN.
Ireg = (ushort)(opcode & 0x0FFF);
break;
case 0xB: //BNNN Jumps to the address NNN plus V0.
pc = (ushort)((opcode & 0x0FFF) + vRegs[0x0]);
break;
case 0xC: //CXNN Sets VX to the result of a bitwise and operation on a random number and NN.
Random rand = new Random();
byte random = (byte)rand.Next(0x00, 0xFF); ////0xFF is the maximum and the 0 is our minimum
vRegs[Utli.getUpperByteLowNibble(opcode)] = (byte)(random & Utli.getLowerByte(opcode));
break;
case 0xD:
{
//DXYN Draws a sprite at coordinate (VX, VY) that has a width of 8 pixels and a height of N pixels.
// Each row of 8 pixels is read as bit-coded starting from memory location Ireg;
// Ireg value doesn’t change after the execution of this instruction.
// As described above, VF is set to 1 if any screen pixels are flipped from set to unset when the sprite is drawn,
// and to 0 if that doesn’t happen
int xCor = vRegs[Utli.getUpperByteLowNibble(opcode)];
int yCor = vRegs[Utli.getLowerByteHighNibble(opcode)];
int nHeight = Utli.getLowerByteLowNibble(opcode);
vRegs[0xF] = 0;
for (int i = yCor; i < (yCor + nHeight); i++)
{
Byte pixel = mainMemory[Ireg + (i - yCor)];
for (int j = xCor; j < (xCor + 8); j++)
{
int pixelVal = (0x1 & (pixel >> ((xCor + 7) - j)));
if (pixelVal == 0x1)
{
if (screenBuffer[(i * SCREEN_WIDTH) + j] == 1)
{
vRegs[0xF] = 1;
}
screenBuffer[(i * SCREEN_WIDTH) + j] ^= 1;
}
}
}
//drawflag = true;
}
break;
case 0xE:
{
switch (Utli.getLowerByte(opcode))
{
case 0x9E: //EX9E Skips the next instruction if the key stored in VX is pressed.
if (gamePad[vRegs[Utli.getUpperByteLowNibble(opcode)]] == 1)
{
pc += 2;
}
break;
case 0xA1: //EXA1 Skips the next instruction if the key stored in VX isn't pressed.
if (gamePad[vRegs[Utli.getUpperByteLowNibble(opcode)]] != 1)
{
pc += 2;
}
break;
default:
Console.WriteLine("Unknown Opcode - " + "0x" + opcode.ToString("x2"));
break;
}
}
break;
case 0xF:
{
switch (Utli.getLowerByte(opcode))
{
case 0x07: //FX07 Sets VX to the value of the delay timer.
vRegs[Utli.getUpperByteLowNibble(opcode)] = delayTimer;
break;
case 0x0A: //FX0A A key press is awaited, and then stored in VX.
{
bool keyPressed = false;
for (int i = 0; i < gamePad.Length; i++)
{
if (gamePad[i] == 1)
{
keyPressed = true;
i = gamePad.Length + 1; //end loop
}
}
if (!keyPressed)
{
pc -= 2;
}
}
break;
case 0x15: // FX15 Sets the delay timer to VX.
delayTimer = vRegs[Utli.getUpperByteLowNibble(opcode)];
break;
case 0x18: // FX18 Sets the sound timer to VX.
soundTimer = vRegs[Utli.getUpperByteLowNibble(opcode)];
break;
case 0x1E: //FX1E Adds VX to Ireg.
Ireg += vRegs[Utli.getUpperByteLowNibble(opcode)];
break;
case 0x29: //FX29 Sets Ireg to the location of the sprite for the character in VX.
// Characters 0-F (in hexadecimal) are represented by a 4x5 font.
Ireg = (ushort)(vRegs[Utli.getUpperByteLowNibble(opcode)] * 5);
break;
case 0x33: //FX33 Stores the binary-coded decimal representation of VX,
//with the most significant of three digits at the address in I,
//the middle digit at I plus 1, and the least significant digit at I plus 2.
mainMemory[Ireg] = (byte)(vRegs[Utli.getUpperByteLowNibble(opcode)] / 100);
mainMemory[Ireg + 1] = (byte)((vRegs[Utli.getUpperByteLowNibble(opcode)] / 10) % 10);
mainMemory[Ireg + 2] = (byte)((vRegs[Utli.getUpperByteLowNibble(opcode)] % 100) % 10);
break;
case 0x55: //FX55 Stores V0 to VX (including VX) in memory starting at address Ireg.
//I is set to I + X + 1 after operation
for (int i = 0; i <= Utli.getUpperByteLowNibble(opcode); i++)
{
mainMemory[Ireg + i] = vRegs[i];
}
Ireg = (ushort)(Ireg + Utli.getUpperByteLowNibble(opcode) + 1);
break;
case 0x65: //FX65 Fills V0 to VX (including VX) with values from memory starting at address Ireg.
for (int i = 0; i <= Utli.getUpperByteLowNibble(opcode); i++)
{
vRegs[i] = mainMemory[Ireg + i];
}
Ireg = (ushort)(Ireg + Utli.getUpperByteLowNibble(opcode) + 1);
break;
default:
Console.WriteLine("Unknown Opcode - " + "0x" + opcode.ToString("x2"));
break;
}
}
break;
default:
Console.WriteLine("Unimplemented Opcode - " + "0x" + opcode.ToString("x2"));
break;
}
}
public string getOpcodeStringFormat()
{
return(Utli.getHighByte(opcode).ToString("x2").ToUpper() + " " + Utli.getLowerByte(opcode).ToString("x2").ToUpper());
}
