private static void PPUClock()
{
board.OnPPUClock();
if ((VClock < 240) || (VClock == vbl_vclock_End))
{
if (bkg_enabled || spr_enabled)
{
if (HClock < 256)
{
#region BKG FETCHES 0 - 255
// UNUSED AT 248-255
switch (HClock & 7)
{
case 0:
{
// Fetch address of nametable
bkg_fetch_address = 0x2000 | (vram_address & 0x0FFF);
board.OnPPUAddressUpdate(ref bkg_fetch_address);
break;
}
case 1: bkg_fetch_nametable = board.ReadNMT(ref bkg_fetch_address); break;
case 2:
{
// Fetch address for attr byte
bkg_fetch_address = 0x23C0 | (vram_address & 0xC00) | (vram_address >> 4 & 0x38) | (vram_address >> 2 & 0x7);
board.OnPPUAddressUpdate(ref bkg_fetch_address);
break;
}
case 3: bkg_fetch_attr = (byte)(board.ReadNMT(ref bkg_fetch_address) >> ((vram_address >> 4 & 0x04) | (vram_address & 0x02))); break;
case 4:
{
// Fetch bit 0 address
bkg_fetch_address = bkg_patternAddress | (bkg_fetch_nametable << 4) | 0 | (vram_address >> 12 & 7);
board.OnPPUAddressUpdate(ref bkg_fetch_address);
break;
}
case 5: bkg_fetch_bit0 = board.ReadCHR(ref bkg_fetch_address, false); break;
case 6:
{
// Fetch bit 1 address
bkg_fetch_address = bkg_patternAddress | (bkg_fetch_nametable << 4) | 8 | (vram_address >> 12 & 7);
board.OnPPUAddressUpdate(ref bkg_fetch_address);
break;
}
case 7:
{
bkg_fetch_bit1 = board.ReadCHR(ref bkg_fetch_address, false);
if (HClock == 255)
{
// Increment Y
if ((vram_address & 0x7000) != 0x7000)
{
vram_address += 0x1000;
}
else
{
vram_address ^= 0x7000;
switch (vram_address & 0x3E0)
{
case 0x3A0: vram_address ^= 0xBA0; break;
case 0x3E0: vram_address ^= 0x3E0; break;
default: vram_address += 0x20; break;
}
}
}
else
{
// Increment X
if ((vram_address & 0x001F) == 0x001F)
{
vram_address ^= 0x041F;
}
else
{
vram_address++;
}
}
// Render BKG tile
bkg_pos = (HClock + 9) % 336;
for (bkg_render_i = 0; bkg_render_i < 8 && bkg_pos < 272; bkg_render_i++, bkg_pos++, bkg_fetch_bit0 <<= 1, bkg_fetch_bit1 <<= 1)
{
bkg_pixels[bkg_pos] = (bkg_fetch_attr << 2 & 12) | (bkg_fetch_bit0 >> 7 & 1) | (bkg_fetch_bit1 >> 6 & 2);
}
break;
}
}
#endregion
#region Render Pixel
if (VClock < 240)
{
if (!bkg_enabled || (bkg_clipped && HClock < 8))
{
bkgPixel = 0x3F00;
}
else
{
bkgPixel = 0x3F00 | bkg_pixels[HClock + vram_fine];
}
if (!spr_enabled || (spr_clipped && HClock < 8))
{
sprPixel = 0x3F10;
}
else
{
sprPixel = 0x3F10 | spr_pixels[HClock];
}
current_pixel = 0;
//Priority *******************************
if ((sprPixel & 0x8000) != 0)
{
current_pixel = sprPixel;
}
else
{
current_pixel = bkgPixel;
}
//****************************************
// Transparency **************************
if ((bkgPixel & 0x03) == 0)
{
current_pixel = sprPixel;
goto render;
}
if ((sprPixel & 0x03) == 0)
{
current_pixel = bkgPixel;
goto render;
}
//****************************************
//Sprite 0 Hit
if ((sprPixel & 0x4000) != 0 & HClock < 255)
{
spr_0Hit = true;
}
render:
if (!screenPointerMode)
{
screen[(VClock * 256) + HClock] = palette[paletteIndexes[palettes_bank[current_pixel & ((current_pixel & 0x03) == 0 ? 0x0C : 0x1F)]
& (grayscale | emphasis)]];
}
else
{
screenPointerPos = (VClock * 256) + HClock;
if (screenPointerPos >= screenPointerStart && screenPointerPos < screenPointerSize)
{
screenPointer[screenPointerPos - screenPointerStart] = palette[paletteIndexes[palettes_bank[current_pixel & ((current_pixel & 0x03) == 0 ? 0x0C : 0x1F)]
& (grayscale | emphasis)]];
}
}
}
#endregion
#region OAM EVALUATION
switch (HClock & 1)
{
case 0:
{
if (!oam_fetch_mode)
{
oam_fetch_data = 0xFF;
}
else
{
oam_fetch_data = oam_ram[oam_address];
}
break;
}
case 1:
{
switch (oam_phase_index)
{
case 0:
{
if (HClock <= 64)
{
switch (HClock >> 1 & 0x03)
{
case 0: oam_secondary[((HClock >> 3) * 4) + 0] = 0xFF; break;
case 1: oam_secondary[((HClock >> 3) * 4) + 1] = 0xFF; break;
case 2: oam_secondary[((HClock >> 3) * 4) + 2] = 0xFF; break;
case 3:
{
oam_secondary[((HClock >> 3) * 4) + 3] = 0xFF;
spr_zero_buffer[HClock >> 3 & 7] = false;
break;
}
}
}
break;
}
case 1:
{
if (VClock == vbl_vclock_End)
{
break;
}
oam_evaluate_count++;
temp_comparator = (VClock - oam_fetch_data) & int.MaxValue;
if (temp_comparator >= spr_size16)
{
if (oam_evaluate_count != 64)
{
oam_address = (byte)(oam_evaluate_count != 2 ? oam_address + 4 : 8);
}
else
{
oam_address = 0;
oam_phase_index = 9;
}
}
else
{
oam_address++;
oam_phase_index = 2;
oam_secondary[oam_evaluate_slot * 4] = oam_fetch_data;
spr_zero_buffer[oam_evaluate_slot] = (oam_evaluate_count == 1);
}
break;
}
case 2:
{
oam_address++;
oam_phase_index = 3;
oam_secondary[(oam_evaluate_slot * 4) + 1] = oam_fetch_data;
break;
}
case 3:
{
oam_address++;
oam_phase_index = 4;
oam_secondary[(oam_evaluate_slot * 4) + 2] = oam_fetch_data;
break;
}
case 4:
{
oam_secondary[(oam_evaluate_slot * 4) + 3] = oam_fetch_data;
oam_evaluate_slot++;
if (oam_evaluate_count != 64)
{
oam_phase_index = (byte)((oam_evaluate_slot != 8) ? 1 : 5);
if (oam_evaluate_count != 2)
{
oam_address++;
}
else
{
oam_address = 8;
}
}
else
{
oam_address = 0;
oam_phase_index = 9;
}
break;
}
case 5:
{
if (VClock == vbl_vclock_End)
{
break;
}
temp_comparator = (VClock - oam_fetch_data) & int.MaxValue;
if (temp_comparator >= spr_size16)
{
oam_address = (byte)(((oam_address + 4) & 0xFC) +
((oam_address + 1) & 0x03));
if (oam_address <= 5)
{
oam_phase_index = 9;
oam_address &= 0xFC;
}
}
else
{
oam_phase_index = 6;
oam_address += (0x01) & 0xFF;
spr_overflow = true;
}
break;
}
case 6:
{
oam_phase_index = 7;
oam_address += (0x01);
break;
}
case 7:
{
oam_phase_index = 8;
oam_address += (0x01);
break;
}
case 8:
{
oam_phase_index = 9;
oam_address += (0x01);
if ((oam_address & 0x03) == 0x03)
{
oam_address += (0x01);
}
oam_address &= 0xFC;
break;
}
case 9:
{
oam_address += 0x4;
break;
}
}
break;
}
}
if (HClock == 63)
{//Evaluation Begin
oam_fetch_mode = true;
oam_phase_index = 1;
oam_evaluate_slot = 0;
oam_evaluate_count = 0;
}
if (HClock == 255)
{
// Evaluation Reset
oam_fetch_mode = false;
oam_phase_index = 0;
oam_evaluate_slot = 0;
oam_address = 0;
oam_evaluate_count = 0;
//spr_pixels = new int[256];
for (spr_evaluation_i = 0; spr_evaluation_i < 256; spr_evaluation_i++)
{
spr_pixels[spr_evaluation_i] = 0;
}
}
#endregion
}
else if (HClock < 320)
{
#region SPRITE FETCHES + GARBAGE BKG FETCHES 256 - 319
switch (HClock & 7)
{
case 0:
{
// Fetch address of nametable
bkg_fetch_address = 0x2000 | (vram_address & 0x0FFF);
board.OnPPUAddressUpdate(ref bkg_fetch_address);
break;
}
case 1: bkg_fetch_nametable = board.ReadNMT(ref bkg_fetch_address); break;
case 2:
{
// Fetch address for attr byte
bkg_fetch_address = 0x23C0 | (vram_address & 0xC00) | (vram_address >> 4 & 0x38) | (vram_address >> 2 & 0x7);
board.OnPPUAddressUpdate(ref bkg_fetch_address);
break;
}
case 3: bkg_fetch_attr = (byte)(board.ReadNMT(ref bkg_fetch_address) >> ((vram_address >> 4 & 0x04) | (vram_address & 0x02))); break;
case 4:
{
temp = HClock >> 3 & 7;
temp_comparator = (VClock - oam_secondary[temp * 4]) ^ ((oam_secondary[(temp * 4) + 2] & 0x80) != 0 ? 0x0F : 0x00);
if (spr_size16 == 0x10)
{
spr_fetch_address = (oam_secondary[(temp * 4) + 1] << 0x0C & 0x1000) | (oam_secondary[(temp * 4) + 1] << 0x04 & 0x0FE0) |
(temp_comparator << 0x01 & 0x0010) | (temp_comparator & 0x0007);
}
else
{
spr_fetch_address = spr_patternAddress | (oam_secondary[(temp * 4) + 1] << 0x04) | (temp_comparator & 0x0007);
}
board.OnPPUAddressUpdate(ref spr_fetch_address);
break;
}
case 5:
{
spr_fetch_bit0 = board.ReadCHR(ref spr_fetch_address, true);
if ((oam_secondary[((HClock >> 3 & 7) * 4) + 2] & 0x40) != 0)
{
spr_fetch_bit0 = reverseLookup[spr_fetch_bit0];
}
break;
}
case 6:
{
spr_fetch_address = spr_fetch_address | 0x08;
board.OnPPUAddressUpdate(ref spr_fetch_address);
break;
}
case 7:
{
spr_fetch_bit1 = board.ReadCHR(ref spr_fetch_address, true);
if ((oam_secondary[((HClock >> 3 & 7) * 4) + 2] & 0x40) != 0)
{
spr_fetch_bit1 = reverseLookup[spr_fetch_bit1];
}
spr_fetch_attr = oam_secondary[((HClock >> 3 & 7) * 4) + 2];
// Render SPR tile
temp = HClock >> 3 & 7;
if (oam_secondary[(temp * 4) + 3] == 255)
{
break;
}
spr_pos = oam_secondary[(temp * 4) + 3];
object0 = spr_zero_buffer[temp] ? 0x4000 : 0x0000;
infront = ((oam_secondary[(temp * 4) + 2] & 0x20) == 0) ? 0x8000 : 0x0000;
for (spr_render_i = 0; spr_render_i < 8 && spr_pos < 256; spr_render_i++, spr_pos++, spr_fetch_bit0 <<= 1, spr_fetch_bit1 <<= 1)
{
if (spr_pos > 255)
{
break;
}
spr_render_temp_pixel = (spr_fetch_attr << 2 & 12) | (spr_fetch_bit0 >> 7 & 1) | (spr_fetch_bit1 >> 6 & 2) | object0 | infront;
if ((spr_pixels[spr_pos] & 0x03) == 0 && (spr_render_temp_pixel & 0x03) != 0)
{
spr_pixels[spr_pos] = spr_render_temp_pixel;
}
}
break;
}
}
#endregion
if (HClock == 256)// 257 in the Ntsc_timing diagram
{
vram_address = (vram_address & 0x7BE0) | (vram_temp & 0x041F);
}
// 280-304 in the Ntsc_timing diagram
if (VClock == vbl_vclock_End && HClock >= 279 && HClock <= 303)
{
vram_address = (vram_address & 0x041F) | (vram_temp & 0x7BE0);
}
}
else if (HClock < 336)
{
#region FIRST 2 BKG TILES FOR 1ST SCANLINE 320 - 335
switch (HClock & 7)
{
case 0:
{
// Fetch address of nametable
bkg_fetch_address = 0x2000 | (vram_address & 0x0FFF);
board.OnPPUAddressUpdate(ref bkg_fetch_address);
break;
}
case 1: bkg_fetch_nametable = board.ReadNMT(ref bkg_fetch_address); break;
case 2:
{
// Fetch address for attr byte
bkg_fetch_address = 0x23C0 | (vram_address & 0xC00) | (vram_address >> 4 & 0x38) | (vram_address >> 2 & 0x7);
board.OnPPUAddressUpdate(ref bkg_fetch_address);
break;
}
case 3: bkg_fetch_attr = (byte)(board.ReadNMT(ref bkg_fetch_address) >> ((vram_address >> 4 & 0x04) | (vram_address & 0x02))); break;
case 4:
{
// Fetch bit 0 address
bkg_fetch_address = bkg_patternAddress | (bkg_fetch_nametable << 4) | 0 | (vram_address >> 12 & 7);
board.OnPPUAddressUpdate(ref bkg_fetch_address);
break;
}
case 5: bkg_fetch_bit0 = board.ReadCHR(ref bkg_fetch_address, false); break;
case 6:
{
// Fetch bit 1 address
bkg_fetch_address = bkg_patternAddress | (bkg_fetch_nametable << 4) | 8 | (vram_address >> 12 & 7);
board.OnPPUAddressUpdate(ref bkg_fetch_address);
break;
}
case 7:
{
bkg_fetch_bit1 = board.ReadCHR(ref bkg_fetch_address, false);
// Increment X
if ((vram_address & 0x001F) == 0x001F)
{
vram_address ^= 0x041F;
}
else
{
vram_address++;
}
// Render BKG tile
bkg_pos = (HClock + 9) % 336;
for (bkg_render_i = 0; bkg_render_i < 8 && bkg_pos < 272; bkg_render_i++, bkg_pos++, bkg_fetch_bit0 <<= 1, bkg_fetch_bit1 <<= 1)
{
bkg_pixels[bkg_pos] = (bkg_fetch_attr << 2 & 12) | (bkg_fetch_bit0 >> 7 & 1) | (bkg_fetch_bit1 >> 6 & 2);
}
break;
}
}
#endregion
}
else if (HClock < 340)
{
#region DUMMY FETCHES 336 - 339
switch (HClock & 7)
{
case 0:
{
// Fetch address of nametable
bkg_fetch_address = 0x2000 | (vram_address & 0x0FFF);
board.OnPPUAddressUpdate(ref bkg_fetch_address);
break;
}
case 1:
{
bkg_fetch_nametable = board.ReadNMT(ref bkg_fetch_address);
break;
}
}
#endregion
}
else
{
// Idle cycle
}
}
else
{
#region Rendering is off, draw color at vram address if it in range 0x3F00 - 0x3FFF
if (HClock < 255 & VClock < 240)
{
if ((vram_address & 0x3F00) == 0x3F00)
{
if (!screenPointerMode)
{
screen[(VClock * 256) + HClock] = palette[paletteIndexes[palettes_bank[vram_address & ((vram_address & 0x03) == 0 ? 0x0C : 0x1F)]
& (grayscale | emphasis)]];
}
else
{
screenPointerPos = (VClock * 256) + HClock;
if (screenPointerPos >= screenPointerStart && screenPointerPos < screenPointerSize)
{
screenPointer[screenPointerPos - screenPointerStart] = palette[paletteIndexes[palettes_bank[vram_address & ((vram_address & 0x03) == 0 ? 0x0C : 0x1F)]
& (grayscale | emphasis)]];
}
}
}
else
{
if (!screenPointerMode)
{
screen[(VClock * 256) + HClock] = palette[paletteIndexes[palettes_bank[0] & (grayscale | emphasis)]];
}
else
{
screenPointerPos = (VClock * 256) + HClock;
if (screenPointerPos >= screenPointerStart && screenPointerPos < screenPointerSize)
{
screenPointer[screenPointerPos - screenPointerStart] = palette[paletteIndexes[palettes_bank[0] & (grayscale | emphasis)]];
}
}
}
}
#endregion
}
}
// Clock Horz
HClock++;
// Update vbl flag from latch
vbl_flag = vbl_flag_temp;
// Check for nmi
if ((VClock == vbl_vclock_Start) && (HClock <= 3))
{
NMI_Current = (vbl_flag_temp & nmi_enabled);
}
#region odd frame in the idle cycle
if (UseOddFrame)
{
if (HClock == 338 && VClock == vbl_vclock_End)
{
oddSwap = !oddSwap;
if (!oddSwap & bkg_enabled)
{
HClock++;
}
}
}
#endregion
#region VBLANK, NMI and frame end
if (HClock == 341)
{
board.OnPPUScanlineTick();
HClock = 0;
VClock++;
//set vbl
if (VClock == vbl_vclock_Start)
{
vbl_flag_temp = true;
}
//clear vbl
else if (VClock == vbl_vclock_End)
{
spr_0Hit = false;
vbl_flag_temp = false;
spr_overflow = false;
}
else if (VClock == frameEnd)
{
VClock = 0;
#region Render
if (FrameSkipEnabled)
{
if (FrameSkipTimer == 0)
{
if (!screenPointerMode)
{
videoOut.SubmitBuffer(ref screen);
}
else
{
videoOut.OnFrameFinished();
}
}
if (FrameSkipTimer > 0)
{
FrameSkipTimer--;
}
else
{
FrameSkipTimer = FrameSkipReload;
}
}
else
{
if (!screenPointerMode)
{
videoOut.SubmitBuffer(ref screen);
}
else
{
videoOut.OnFrameFinished();
}
}
OnFinishFrame();
#endregion
}
}
#endregion
}