private void changeSTATMode(int mode, MMU mmu)
{
byte STAT = (byte)(mmu.STAT & ~0x3);
mmu.STAT = (byte)(STAT | mode);
//Accessing OAM - Mode 2 (80 cycles)
if (mode == 2 && isBit(5, STAT))
{ // Bit 5 - Mode 2 OAM Interrupt (1=Enable) (Read/Write)
mmu.requestInterrupt(LCD_INTERRUPT);
}
//case 3: //Accessing VRAM - Mode 3 (172 cycles) Total M2+M3 = 252 Cycles
//HBLANK - Mode 0 (204 cycles) Total M2+M3+M0 = 456 Cycles
else if (mode == 0 && isBit(3, STAT))
{ // Bit 3 - Mode 0 H-Blank Interrupt (1=Enable) (Read/Write)
mmu.requestInterrupt(LCD_INTERRUPT);
}
//VBLANK - Mode 1 (4560 cycles - 10 lines)
else if (mode == 1 && isBit(4, STAT))
{ // Bit 4 - Mode 1 V-Blank Interrupt (1=Enable) (Read/Write)
mmu.requestInterrupt(LCD_INTERRUPT);
}
}
public void update(MMU mmu)
{
byte JOYP = mmu.JOYP;
if (!isBit(4, JOYP))
{
mmu.JOYP = (byte)((JOYP & 0xF0) | pad);
if (pad != 0xF)
{
mmu.requestInterrupt(JOYPAD_INTERRUPT);
}
}
if (!isBit(5, JOYP))
{
mmu.JOYP = (byte)((JOYP & 0xF0) | buttons);
if (buttons != 0xF)
{
mmu.requestInterrupt(JOYPAD_INTERRUPT);
}
}
if ((JOYP & 0b00110000) == 0b00110000)
{
mmu.JOYP = 0xFF;
}
}
private void handleDivider(int cycles, MMU mmu)
{
divCounter += cycles;
while (divCounter >= DMG_DIV_FREQ)
{
mmu.DIV++;
divCounter -= DMG_DIV_FREQ;
}
}
private void drawScanLine(MMU mmu)
{
byte LCDC = mmu.LCDC;
if (isBit(0, LCDC))
{ //Bit 0 - BG Display (0=Off, 1=On)
renderBG(mmu);
}
if (isBit(1, LCDC))
{ //Bit 1 - OBJ (Sprite) Display Enable
renderSprites(mmu);
}
}
public void POWER_ON(string cartName)
{
mmu = new MMU();
cpu = new CPU(mmu);
ppu = new PPU(window);
timer = new TIMER();
joypad = new JOYPAD();
mmu.loadGamePak(cartName);
power_switch = true;
Task t = Task.Factory.StartNew(EXECUTE, TaskCreationOptions.LongRunning);
}
private void renderBG(MMU mmu)
{
byte WX = (byte)(mmu.WX - 7); //WX needs -7 Offset
byte WY = mmu.WY;
byte LY = mmu.LY;
byte LCDC = mmu.LCDC;
byte SCY = mmu.SCY;
byte SCX = mmu.SCX;
byte BGP = mmu.BGP;
bool isWin = isWindow(LCDC, WY, LY);
byte y = isWin ? (byte)(LY - WY) : (byte)(LY + SCY);
byte tileLine = (byte)((y & 7) * 2);
ushort tileRow = (ushort)(y / 8 * 32);
ushort tileMap = isWin ? getWindowTileMapAdress(LCDC) : getBGTileMapAdress(LCDC);
byte hi = 0;
byte lo = 0;
for (int p = 0; p < SCREEN_WIDTH; p++)
{
byte x = isWin && p >= WX ? (byte)(p - WX) : (byte)(p + SCX);
if ((p & 0x7) == 0 || ((p + SCX) & 0x7) == 0)
{
ushort tileCol = (ushort)(x / 8);
ushort tileAdress = (ushort)(tileMap + tileRow + tileCol);
ushort tileLoc;
if (isSignedAdress(LCDC))
{
tileLoc = (ushort)(getTileDataAdress(LCDC) + mmu.readVRAM(tileAdress) * 16);
}
else
{
tileLoc = (ushort)(getTileDataAdress(LCDC) + ((sbyte)mmu.readVRAM(tileAdress) + 128) * 16);
}
lo = mmu.readVRAM((ushort)(tileLoc + tileLine));
hi = mmu.readVRAM((ushort)(tileLoc + tileLine + 1));
}
int colorBit = 7 - (x & 7); //inversed
int colorId = GetColorIdBits(colorBit, lo, hi);
int colorIdThroughtPalette = GetColorIdThroughtPalette(BGP, colorId);
bmp.SetPixel(p, LY, color[colorIdThroughtPalette]);
}
}
private void handleTimer(int cycles, MMU mmu)
{
if (mmu.TAC_ENABLED)
{
timerCounter += cycles;
while (timerCounter >= TAC_FREQ[mmu.TAC_FREQ])
{
mmu.TIMA++;
timerCounter -= TAC_FREQ[mmu.TAC_FREQ];
}
if (mmu.TIMA == 0xFF)
{
mmu.requestInterrupt(TIMER_INTERRUPT);
mmu.TIMA = mmu.TMA;
}
}
}
private void renderSprites(MMU mmu)
{
byte LY = mmu.LY;
byte LCDC = mmu.LCDC;
for (int i = 0x9C; i >= 0; i -= 4)
{ //0x9F OAM Size, 40 Sprites x 4 bytes:
int y = mmu.readOAM(i) - 16; //Byte0 - Y Position //needs 16 offset
int x = mmu.readOAM(i + 1) - 8; //Byte1 - X Position //needs 8 offset
byte tile = mmu.readOAM(i + 2); //Byte2 - Tile/Pattern Number
byte attr = mmu.readOAM(i + 3); //Byte3 - Attributes/Flags
if ((LY >= y) && (LY < (y + spriteSize(LCDC))))
{
byte palette = isBit(4, attr) ? mmu.OBP1 : mmu.OBP0; //Bit4 Palette number **Non CGB Mode Only** (0=OBP0, 1=OBP1)
int tileRow = isYFlipped(attr) ? spriteSize(LCDC) - 1 - (LY - y) : (LY - y);
ushort tileddress = (ushort)(0x8000 + (tile * 16) + (tileRow * 2));
byte lo = mmu.readVRAM(tileddress);
byte hi = mmu.readVRAM((ushort)(tileddress + 1));
for (int p = 0; p < 8; p++)
{
int IdPos = isXFlipped(attr) ? p : 7 - p;
int colorId = GetColorIdBits(IdPos, lo, hi);
int colorIdThroughtPalette = GetColorIdThroughtPalette(palette, colorId);
if ((x + p) >= 0 && (x + p) < SCREEN_WIDTH)
{
if (!isTransparent(colorId) && (isAboveBG(attr) || isBGWhite(mmu.BGP, x + p, LY)))
{
bmp.SetPixel(x + p, LY, color[colorIdThroughtPalette]);
}
}
}
}
}
}
public void update(int cycles, MMU mmu)
{
scanlineCounter += cycles;
byte currentMode = (byte)(mmu.STAT & 0x3); //Current Mode Mask
if (isLCDEnabled(mmu.LCDC))
{
switch (currentMode)
{
case 2: //Accessing OAM - Mode 2 (80 cycles)
if (scanlineCounter >= OAM_CYCLES)
{
changeSTATMode(3, mmu);
scanlineCounter -= OAM_CYCLES;
}
break;
case 3: //Accessing VRAM - Mode 3 (172 cycles) Total M2+M3 = 252 Cycles
if (scanlineCounter >= VRAM_CYCLES)
{
changeSTATMode(0, mmu);
drawScanLine(mmu);
scanlineCounter -= VRAM_CYCLES;
}
break;
case 0: //HBLANK - Mode 0 (204 cycles) Total M2+M3+M0 = 456 Cycles
if (scanlineCounter >= HBLANK_CYCLES)
{
mmu.LY++;
scanlineCounter -= HBLANK_CYCLES;
if (mmu.LY == SCREEN_HEIGHT)
{ //check if we arrived Vblank
changeSTATMode(1, mmu);
mmu.requestInterrupt(VBLANK_INTERRUPT);
RenderFrame();
}
else
{ //not arrived yet so return to 2
changeSTATMode(2, mmu);
}
}
break;
case 1: //VBLANK - Mode 1 (4560 cycles - 10 lines)
if (scanlineCounter >= SCANLINE_CYCLES)
{
mmu.LY++;
scanlineCounter -= SCANLINE_CYCLES;
if (mmu.LY > SCREEN_VBLANK_HEIGHT)
{ //check end of VBLANK
changeSTATMode(2, mmu);
mmu.LY = 0;
}
}
break;
}
if (mmu.LY == mmu.LYC)
{ //handle coincidence Flag
mmu.STAT = bitSet(2, mmu.STAT);
if (isBit(6, mmu.STAT))
{
mmu.requestInterrupt(LCD_INTERRUPT);
}
}
else
{
mmu.STAT = bitClear(2, mmu.STAT);
}
}
else
{ //LCD Disabled
scanlineCounter = 0;
mmu.LY = 0;
mmu.STAT = (byte)(mmu.STAT & ~0x3);
}
}
public void update(int cycles, MMU mmu)
{
handleDivider(cycles, mmu);
handleTimer(cycles, mmu);
}