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olc2C02.hpp
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#pragma once
#include <iostream>
#include <cstdint>
#include <memory>
#include "olcPixelGameEngine.h"
#include "Cartridge.hpp"
class olc2C02{
public:
olc2C02();
~olc2C02();
private:
uint8_t tblName[2][1024];
uint8_t tblPattern[2][4096];
uint8_t tblPalette[32];
public:
uint8_t cpuRead(uint16_t addr);
void cpuWrite(uint16_t addr, uint8_t data);
uint8_t ppuRead(uint16_t addr);
void ppuWrite(uint16_t addr, uint8_t data);
private:
Cartridge* rom=nullptr;
public:
void ConnectCartridge(Cartridge*);
void clock();
void reset();
bool nmi = false;
private:
olc::Pixel palScreen[0x40];
olc::Sprite sprScreen = olc::Sprite(256, 240);
olc::Sprite sprtblName[2];
olc::Sprite sprPatternTable[2];
public:
// Debugging Utilities
olc::Sprite& GetScreen();
olc::Sprite& GettblName(uint8_t i);
olc::Sprite& GetPatternTable(uint8_t i, uint8_t palette);
olc::Pixel& GetColourFromPaletteRam(uint8_t palette, uint8_t pixel);
bool frame_complete = false;
private:
union
{
struct
{
uint8_t unused : 5;
uint8_t sprite_overflow : 1;
uint8_t sprite_zero_hit : 1;
uint8_t vertical_blank : 1;
};
uint8_t reg;
} status;
union
{
struct
{
uint8_t grayscale : 1;
uint8_t render_background_left : 1;
uint8_t render_sprites_left : 1;
uint8_t render_background : 1;
uint8_t render_sprites : 1;
uint8_t enhance_red : 1;
uint8_t enhance_green : 1;
uint8_t enhance_blue : 1;
};
uint8_t reg;
} mask;
union PPUCTRL
{
struct
{
uint8_t tblName_x : 1;
uint8_t tblName_y : 1;
uint8_t increment_mode : 1;
uint8_t pattern_sprite : 1;
uint8_t pattern_background : 1;
uint8_t sprite_size : 1;
uint8_t slave_mode : 1; // unused
uint8_t enable_nmi : 1;
};
uint8_t reg;
} control;
union loopy_register
{
struct
{
uint16_t coarse_x : 5;
uint16_t coarse_y : 5;
uint16_t tblName_x : 1;
uint16_t tblName_y : 1;
uint16_t fine_y : 3;
uint16_t unused : 1;
};
uint16_t reg = 0x0000;
};
loopy_register vram_addr; // Active "pointer" address into tblName to extract background tile info
loopy_register tram_addr; // Temporary store of information to be "transferred" into "pointer" at various times
// Pixel offset horizontally
uint8_t fine_x = 0x00;
// Internal communications
uint8_t address_latch = 0x00;
uint8_t ppu_data_buffer = 0x00;
// Pixel "dot" position information
int16_t scanline = 0;
int16_t cycle = 0;
// Background rendering =========================================
uint8_t bg_next_tile_id = 0x00;
uint8_t bg_next_tile_attrib = 0x00;
uint8_t bg_next_tile_lsb = 0x00;
uint8_t bg_next_tile_msb = 0x00;
uint16_t bg_shifter_pattern_lo = 0x0000;
uint16_t bg_shifter_pattern_hi = 0x0000;
uint16_t bg_shifter_attrib_lo = 0x0000;
uint16_t bg_shifter_attrib_hi = 0x0000;
// Foreground "Sprite" rendering ================================
// The OAM is an additional memory internal to the PPU. It is
// not connected via the any bus. It stores the locations of
// 64off 8x8 (or 8x16) tiles to be drawn on the next frame.
struct sObjectAttributeEntry
{
uint8_t y; // Y position of sprite
uint8_t id; // ID of tile from pattern memory
uint8_t attribute; // Flags define how sprite should be rendered
uint8_t x; // X position of sprite
} OAM[64];
// A register to store the address when the CPU manually communicates
// with OAM via PPU registers. This is not commonly used because it
// is very slow, and instead a 256-Byte DMA transfer is used. See
// the Bus header for a description of this.
uint8_t oam_addr = 0x00;
sObjectAttributeEntry spriteScanline[8];
uint8_t sprite_count;
uint8_t sprite_shifter_pattern_lo[8];
uint8_t sprite_shifter_pattern_hi[8];
// Sprite Zero Collision Flags
bool bSpriteZeroHitPossible = false;
bool bSpriteZeroBeingRendered = false;
// The OAM is conveniently package above to work with, but the DMA
// mechanism will need access to it for writing one byute at a time
public:
uint8_t* pOAM = (uint8_t*)OAM;
};
olc2C02::olc2C02()
{
sprtblName[0]=olc::Sprite(256, 240);
sprtblName[1]= olc::Sprite(256, 240) ;
//sprPatternTable[0] = olc::Sprite(128, 128);
//sprPatternTable[1]=olc::Sprite(128, 128) ;
palScreen[0x00] = olc::Pixel(84, 84, 84);
palScreen[0x01] = olc::Pixel(0, 30, 116);
palScreen[0x02] = olc::Pixel(8, 16, 144);
palScreen[0x03] = olc::Pixel(48, 0, 136);
palScreen[0x04] = olc::Pixel(68, 0, 100);
palScreen[0x05] = olc::Pixel(92, 0, 48);
palScreen[0x06] = olc::Pixel(84, 4, 0);
palScreen[0x07] = olc::Pixel(60, 24, 0);
palScreen[0x08] = olc::Pixel(32, 42, 0);
palScreen[0x09] = olc::Pixel(8, 58, 0);
palScreen[0x0A] = olc::Pixel(0, 64, 0);
palScreen[0x0B] = olc::Pixel(0, 60, 0);
palScreen[0x0C] = olc::Pixel(0, 50, 60);
palScreen[0x0D] = olc::Pixel(0, 0, 0);
palScreen[0x0E] = olc::Pixel(0, 0, 0);
palScreen[0x0F] = olc::Pixel(0, 0, 0);
palScreen[0x10] = olc::Pixel(152, 150, 152);
palScreen[0x11] = olc::Pixel(8, 76, 196);
palScreen[0x12] = olc::Pixel(48, 50, 236);
palScreen[0x13] = olc::Pixel(92, 30, 228);
palScreen[0x14] = olc::Pixel(136, 20, 176);
palScreen[0x15] = olc::Pixel(160, 20, 100);
palScreen[0x16] = olc::Pixel(152, 34, 32);
palScreen[0x17] = olc::Pixel(120, 60, 0);
palScreen[0x18] = olc::Pixel(84, 90, 0);
palScreen[0x19] = olc::Pixel(40, 114, 0);
palScreen[0x1A] = olc::Pixel(8, 124, 0);
palScreen[0x1B] = olc::Pixel(0, 118, 40);
palScreen[0x1C] = olc::Pixel(0, 102, 120);
palScreen[0x1D] = olc::Pixel(0, 0, 0);
palScreen[0x1E] = olc::Pixel(0, 0, 0);
palScreen[0x1F] = olc::Pixel(0, 0, 0);
palScreen[0x20] = olc::Pixel(236, 238, 236);
palScreen[0x21] = olc::Pixel(76, 154, 236);
palScreen[0x22] = olc::Pixel(120, 124, 236);
palScreen[0x23] = olc::Pixel(176, 98, 236);
palScreen[0x24] = olc::Pixel(228, 84, 236);
palScreen[0x25] = olc::Pixel(236, 88, 180);
palScreen[0x26] = olc::Pixel(236, 106, 100);
palScreen[0x27] = olc::Pixel(212, 136, 32);
palScreen[0x28] = olc::Pixel(160, 170, 0);
palScreen[0x29] = olc::Pixel(116, 196, 0);
palScreen[0x2A] = olc::Pixel(76, 208, 32);
palScreen[0x2B] = olc::Pixel(56, 204, 108);
palScreen[0x2C] = olc::Pixel(56, 180, 204);
palScreen[0x2D] = olc::Pixel(60, 60, 60);
palScreen[0x2E] = olc::Pixel(0, 0, 0);
palScreen[0x2F] = olc::Pixel(0, 0, 0);
palScreen[0x30] = olc::Pixel(236, 238, 236);
palScreen[0x31] = olc::Pixel(168, 204, 236);
palScreen[0x32] = olc::Pixel(188, 188, 236);
palScreen[0x33] = olc::Pixel(212, 178, 236);
palScreen[0x34] = olc::Pixel(236, 174, 236);
palScreen[0x35] = olc::Pixel(236, 174, 212);
palScreen[0x36] = olc::Pixel(236, 180, 176);
palScreen[0x37] = olc::Pixel(228, 196, 144);
palScreen[0x38] = olc::Pixel(204, 210, 120);
palScreen[0x39] = olc::Pixel(180, 222, 120);
palScreen[0x3A] = olc::Pixel(168, 226, 144);
palScreen[0x3B] = olc::Pixel(152, 226, 180);
palScreen[0x3C] = olc::Pixel(160, 214, 228);
palScreen[0x3D] = olc::Pixel(160, 162, 160);
palScreen[0x3E] = olc::Pixel(0, 0, 0);
palScreen[0x3F] = olc::Pixel(0, 0, 0);
}
olc2C02::~olc2C02()
{
}
olc::Sprite& olc2C02::GetScreen()
{
return sprScreen;
}
olc::Sprite & olc2C02::GettblName(uint8_t i)
{
return sprtblName[i];
}
olc::Sprite & olc2C02::GetPatternTable(uint8_t i, uint8_t palette)
{
for (uint16_t nTileY = 0; nTileY < 16; nTileY++)
{
for (uint16_t nTileX = 0; nTileX < 16; nTileX++)
{
uint16_t nOffset = nTileY * 256 + nTileX * 16;
for (uint16_t row = 0; row < 8; row++)
{
uint8_t tile_lsb = ppuRead(i * 0x1000 + nOffset + row + 0x0000);
uint8_t tile_msb = ppuRead(i * 0x1000 + nOffset + row + 0x0008);
for (uint16_t col = 0; col < 8; col++)
{
uint8_t pixel = (tile_lsb & 0x01) << 1 | (tile_msb & 0x01);
tile_lsb >>= 1; tile_msb >>= 1;
sprPatternTable[i].SetPixel
(
nTileX * 8 + (7 - col),
nTileY * 8 + row,
GetColourFromPaletteRam(palette, pixel)
);
}
}
}
}
return sprPatternTable[i];
}
olc::Pixel& olc2C02::GetColourFromPaletteRam(uint8_t palette, uint8_t pixel)
{
return palScreen[ppuRead(0x3F00 + (palette << 2) + pixel) & 0x3F];
}
uint8_t olc2C02::cpuRead(uint16_t addr)
{
uint8_t data = 0x00;
switch (addr)
{
case 0x0000: // Control
break;
case 0x0001: // Mask
break;
case 0x0002: // Status
data = (status.reg & 0xE0) | (ppu_data_buffer & 0x1F);
// Clear the vertical blanking flag
status.vertical_blank = 0;
// Reset Loopy's Address latch flag
address_latch = 0;
break;
case 0x0003: // OAM Address
break;
case 0x0004: // OAM Data
data = pOAM[oam_addr];
break;
case 0x0005: // Scroll
break;
case 0x0006: // PPU Address
break;
case 0x0007: // PPU Data
data = ppu_data_buffer;
ppu_data_buffer = ppuRead(vram_addr.reg);
if (vram_addr.reg >= 0x3F00) data = ppu_data_buffer;
vram_addr.reg += (control.increment_mode ? 32 : 1);
break;
}
return data;
}
void olc2C02::cpuWrite(uint16_t addr, uint8_t data)
{
switch (addr)
{
case 0x0000: // Control
control.reg = data;
tram_addr.tblName_x = control.tblName_x;
tram_addr.tblName_y = control.tblName_y;
break;
case 0x0001: // Mask
mask.reg = data;
break;
case 0x0002: // Status
break;
case 0x0003: // OAM Address
oam_addr = data;
break;
case 0x0004: // OAM Data
pOAM[oam_addr] = data;
break;
case 0x0005: // Scroll
if (address_latch == 0)
{
fine_x = data & 0x07;
tram_addr.coarse_x = data >> 3;
address_latch = 1;
}
else
{
tram_addr.fine_y = data & 0x07;
tram_addr.coarse_y = data >> 3;
address_latch = 0;
}
break;
case 0x0006: // PPU Address
if (address_latch == 0)
{
tram_addr.reg = (uint16_t)((data & 0x3F) << 8) | (tram_addr.reg & 0x00FF);
address_latch = 1;
}
else
{
tram_addr.reg = (tram_addr.reg & 0xFF00) | data;
vram_addr = tram_addr;
address_latch = 0;
}
break;
case 0x0007: // PPU Data
ppuWrite(vram_addr.reg, data);
vram_addr.reg += (control.increment_mode ? 32 : 1);
break;
}
}
uint8_t olc2C02::ppuRead(uint16_t addr)
{
uint8_t data = 0x00;
addr &= 0x3FFF;
if (rom->ppuRead(addr, data))
{
}
else if (addr >= 0x0000 && addr <= 0x1FFF)
{
// If the cartridge cant map the address, have
// a physical location ready here
data = tblPattern[(addr & 0x1000) >> 12][addr & 0x0FFF];
}
else if (addr >= 0x2000 && addr <= 0x3EFF)
{
addr &= 0x0FFF;
if (rom->mirror == Cartridge::MIRROR::VERTICAL)
{
// Vertical
if (addr >= 0x0000 && addr <= 0x03FF)
data = tblName[0][addr & 0x03FF];
if (addr >= 0x0400 && addr <= 0x07FF)
data = tblName[1][addr & 0x03FF];
if (addr >= 0x0800 && addr <= 0x0BFF)
data = tblName[0][addr & 0x03FF];
if (addr >= 0x0C00 && addr <= 0x0FFF)
data = tblName[1][addr & 0x03FF];
}
else if (rom->mirror == Cartridge::MIRROR::HORIZONTAL)
{
// Horizontal
if (addr >= 0x0000 && addr <= 0x03FF)
data = tblName[0][addr & 0x03FF];
if (addr >= 0x0400 && addr <= 0x07FF)
data = tblName[0][addr & 0x03FF];
if (addr >= 0x0800 && addr <= 0x0BFF)
data = tblName[1][addr & 0x03FF];
if (addr >= 0x0C00 && addr <= 0x0FFF)
data = tblName[1][addr & 0x03FF];
}
}
else if (addr >= 0x3F00 && addr <= 0x3FFF)
{
addr &= 0x001F;
if (addr == 0x0010) addr = 0x0000;
if (addr == 0x0014) addr = 0x0004;
if (addr == 0x0018) addr = 0x0008;
if (addr == 0x001C) addr = 0x000C;
data = tblPalette[addr] & (mask.grayscale ? 0x30 : 0x3F);
}
return data;
}
void olc2C02::ppuWrite(uint16_t addr, uint8_t data)
{
addr &= 0x3FFF;
if (rom->ppuWrite(addr, data))
{
}
else if (addr >= 0x0000 && addr <= 0x1FFF)
{
tblPattern[(addr & 0x1000) >> 12][addr & 0x0FFF] = data;
}
else if (addr >= 0x2000 && addr <= 0x3EFF)
{
addr &= 0x0FFF;
if (rom->mirror == Cartridge::MIRROR::VERTICAL)
{
// Vertical
if (addr >= 0x0000 && addr <= 0x03FF)
tblName[0][addr & 0x03FF] = data;
if (addr >= 0x0400 && addr <= 0x07FF)
tblName[1][addr & 0x03FF] = data;
if (addr >= 0x0800 && addr <= 0x0BFF)
tblName[0][addr & 0x03FF] = data;
if (addr >= 0x0C00 && addr <= 0x0FFF)
tblName[1][addr & 0x03FF] = data;
}
else if (rom->mirror == Cartridge::MIRROR::HORIZONTAL)
{
// Horizontal
if (addr >= 0x0000 && addr <= 0x03FF)
tblName[0][addr & 0x03FF] = data;
if (addr >= 0x0400 && addr <= 0x07FF)
tblName[0][addr & 0x03FF] = data;
if (addr >= 0x0800 && addr <= 0x0BFF)
tblName[1][addr & 0x03FF] = data;
if (addr >= 0x0C00 && addr <= 0x0FFF)
tblName[1][addr & 0x03FF] = data;
}
}
else if (addr >= 0x3F00 && addr <= 0x3FFF)
{
addr &= 0x001F;
if (addr == 0x0010) addr = 0x0000;
if (addr == 0x0014) addr = 0x0004;
if (addr == 0x0018) addr = 0x0008;
if (addr == 0x001C) addr = 0x000C;
tblPalette[addr] = data;
}
}
void olc2C02::ConnectCartridge(Cartridge *cart){
this->rom=cart;
}
void olc2C02::reset()
{
fine_x = 0x00;
address_latch = 0x00;
ppu_data_buffer = 0x00;
scanline = 0;
cycle = 0;
bg_next_tile_id = 0x00;
bg_next_tile_attrib = 0x00;
bg_next_tile_lsb = 0x00;
bg_next_tile_msb = 0x00;
bg_shifter_pattern_lo = 0x0000;
bg_shifter_pattern_hi = 0x0000;
bg_shifter_attrib_lo = 0x0000;
bg_shifter_attrib_hi = 0x0000;
status.reg = 0x00;
mask.reg = 0x00;
control.reg = 0x00;
vram_addr.reg = 0x0000;
tram_addr.reg = 0x0000;
}
void olc2C02::clock()
{
auto IncrementScrollX = [&]()
{
if (mask.render_background || mask.render_sprites)
{
if (vram_addr.coarse_x == 31)
{
vram_addr.coarse_x = 0;
vram_addr.tblName_x = ~vram_addr.tblName_x;
}
else
{
vram_addr.coarse_x++;
}
}
};
auto IncrementScrollY = [&]()
{
if (mask.render_background || mask.render_sprites)
{
if (vram_addr.fine_y < 7)
{
vram_addr.fine_y++;
}
else
{
vram_addr.fine_y = 0;
if (vram_addr.coarse_y == 29)
{
vram_addr.coarse_y = 0;
vram_addr.tblName_y = ~vram_addr.tblName_y;
}
else if (vram_addr.coarse_y == 31)
{
vram_addr.coarse_y = 0;
}
else
{
vram_addr.coarse_y++;
}
}
}
};
auto TransferAddressX = [&]()
{
if (mask.render_background || mask.render_sprites)
{
vram_addr.tblName_x = tram_addr.tblName_x;
vram_addr.coarse_x = tram_addr.coarse_x;
}
};
auto TransferAddressY = [&]()
{
if (mask.render_background || mask.render_sprites)
{
vram_addr.fine_y = tram_addr.fine_y;
vram_addr.tblName_y = tram_addr.tblName_y;
vram_addr.coarse_y = tram_addr.coarse_y;
}
};
auto LoadBackgroundShifters = [&]()
{
bg_shifter_pattern_lo = (bg_shifter_pattern_lo & 0xFF00) | bg_next_tile_lsb;
bg_shifter_pattern_hi = (bg_shifter_pattern_hi & 0xFF00) | bg_next_tile_msb;
bg_shifter_attrib_lo = (bg_shifter_attrib_lo & 0xFF00) | ((bg_next_tile_attrib & 0b01) ? 0xFF : 0x00);
bg_shifter_attrib_hi = (bg_shifter_attrib_hi & 0xFF00) | ((bg_next_tile_attrib & 0b10) ? 0xFF : 0x00);
};
auto UpdateShifters = [&]()
{
if (mask.render_background)
{
bg_shifter_pattern_lo <<= 1;
bg_shifter_pattern_hi <<= 1;
bg_shifter_attrib_lo <<= 1;
bg_shifter_attrib_hi <<= 1;
}
if (mask.render_sprites && cycle >= 1 && cycle < 258)
{
for (int i = 0; i < sprite_count; i++)
{
if (spriteScanline[i].x > 0)
{
spriteScanline[i].x--;
}
else
{
sprite_shifter_pattern_lo[i] <<= 1;
sprite_shifter_pattern_hi[i] <<= 1;
}
}
}
};
if (scanline >= -1 && scanline < 240)
{
if (scanline == 0 && cycle == 0)
{
cycle = 1;
}
if (scanline == -1 && cycle == 1)
{
status.vertical_blank = 0;
status.sprite_overflow = 0;
status.sprite_zero_hit = 0;
for (int i = 0; i < 8; i++)
{
sprite_shifter_pattern_lo[i] = 0;
sprite_shifter_pattern_hi[i] = 0;
}
}
if ((cycle >= 2 && cycle < 258) || (cycle >= 321 && cycle < 338))
{
UpdateShifters();
switch ((cycle - 1) % 8)
{
case 0:
LoadBackgroundShifters();
bg_next_tile_id = ppuRead(0x2000 | (vram_addr.reg & 0x0FFF));
break;
case 2:
bg_next_tile_attrib = ppuRead(0x23C0 | (vram_addr.tblName_y << 11)
| (vram_addr.tblName_x << 10)
| ((vram_addr.coarse_y >> 2) << 3)
| (vram_addr.coarse_x >> 2));
if (vram_addr.coarse_y & 0x02) bg_next_tile_attrib >>= 4;
if (vram_addr.coarse_x & 0x02) bg_next_tile_attrib >>= 2;
bg_next_tile_attrib &= 0x03;
break;
case 4:
bg_next_tile_lsb = ppuRead((control.pattern_background << 12)
+ ((uint16_t)bg_next_tile_id << 4)
+ (vram_addr.fine_y) + 0);
break;
case 6:
bg_next_tile_msb = ppuRead((control.pattern_background << 12)
+ ((uint16_t)bg_next_tile_id << 4)
+ (vram_addr.fine_y) + 8);
break;
case 7:
IncrementScrollX();
break;
}
}
if (cycle == 256)
{
IncrementScrollY();
}
if (cycle == 257)
{
LoadBackgroundShifters();
TransferAddressX();
}
if (cycle == 338 || cycle == 340)
{
bg_next_tile_id = ppuRead(0x2000 | (vram_addr.reg & 0x0FFF));
}
if (scanline == -1 && cycle >= 280 && cycle < 305)
{
TransferAddressY();
}
if (cycle == 257 && scanline >= 0)
{
std::memset(spriteScanline, 0xFF, 8 * sizeof(sObjectAttributeEntry));
sprite_count = 0;
for (uint8_t i = 0; i < 8; i++)
{
sprite_shifter_pattern_lo[i] = 0;
sprite_shifter_pattern_hi[i] = 0;
}
uint8_t nOAMEntry = 0;
bSpriteZeroHitPossible = false;
while (nOAMEntry < 64 && sprite_count < 9)
{
int16_t diff = ((int16_t)scanline - (int16_t)OAM[nOAMEntry].y);
if (diff >= 0 && diff < (control.sprite_size ? 16 : 8))
{
if (sprite_count < 8)
{
if (nOAMEntry == 0)
{
bSpriteZeroHitPossible = true;
}
memcpy(&spriteScanline[sprite_count], &OAM[nOAMEntry], sizeof(sObjectAttributeEntry));
sprite_count++;
}
}
nOAMEntry++;
}
status.sprite_overflow = (sprite_count > 8);
}
if (cycle == 340)
{
for (uint8_t i = 0; i < sprite_count; i++)
{
uint8_t sprite_pattern_bits_lo, sprite_pattern_bits_hi;
uint16_t sprite_pattern_addr_lo, sprite_pattern_addr_hi;
if (!control.sprite_size)
{
if (!(spriteScanline[i].attribute & 0x80))
{
sprite_pattern_addr_lo =
(control.pattern_sprite << 12)
| (spriteScanline[i].id << 4)
| (scanline - spriteScanline[i].y);
}
else
{
sprite_pattern_addr_lo =
(control.pattern_sprite << 12)
| (spriteScanline[i].id << 4)
| (7 - (scanline - spriteScanline[i].y));
}
}
else
{
if (!(spriteScanline[i].attribute & 0x80))
{
if (scanline - spriteScanline[i].y < 8)
{
sprite_pattern_addr_lo =
((spriteScanline[i].id & 0x01) << 12)
| ((spriteScanline[i].id & 0xFE) << 4)
| ((scanline - spriteScanline[i].y) & 0x07);
}
else
{
sprite_pattern_addr_lo =
((spriteScanline[i].id & 0x01) << 12)
| (((spriteScanline[i].id & 0xFE) + 1) << 4)
| ((scanline - spriteScanline[i].y) & 0x07);
}
}
else
{
if (scanline - spriteScanline[i].y < 8)
{
sprite_pattern_addr_lo =
((spriteScanline[i].id & 0x01) << 12)
| (((spriteScanline[i].id & 0xFE) + 1) << 4)
| (7 - (scanline - spriteScanline[i].y) & 0x07);
}
else
{
sprite_pattern_addr_lo =
((spriteScanline[i].id & 0x01) << 12)
| ((spriteScanline[i].id & 0xFE) << 4)
| (7 - (scanline - spriteScanline[i].y) & 0x07);
}
}
}
sprite_pattern_addr_hi = sprite_pattern_addr_lo + 8;
sprite_pattern_bits_lo = ppuRead(sprite_pattern_addr_lo);
sprite_pattern_bits_hi = ppuRead(sprite_pattern_addr_hi);
if (spriteScanline[i].attribute & 0x40)
{
auto flipbyte = [](uint8_t b)
{
b = (b & 0xF0) >> 4 | (b & 0x0F) << 4;
b = (b & 0xCC) >> 2 | (b & 0x33) << 2;
b = (b & 0xAA) >> 1 | (b & 0x55) << 1;
return b;
};
sprite_pattern_bits_lo = flipbyte(sprite_pattern_bits_lo);
sprite_pattern_bits_hi = flipbyte(sprite_pattern_bits_hi);
}
sprite_shifter_pattern_lo[i] = sprite_pattern_bits_lo;
sprite_shifter_pattern_hi[i] = sprite_pattern_bits_hi;
}
}
}
if (scanline == 240)
{
}
if (scanline >= 241 && scanline < 261)
{
if (scanline == 241 && cycle == 1)
{
status.vertical_blank = 1;
if (control.enable_nmi)
nmi = true;
}
}
uint8_t bg_pixel = 0x00;
uint8_t bg_palette = 0x00;
if (mask.render_background)
{
uint16_t bit_mux = 0x8000 >> fine_x;
uint8_t p0_pixel = (bg_shifter_pattern_lo & bit_mux) > 0;
uint8_t p1_pixel = (bg_shifter_pattern_hi & bit_mux) > 0;
bg_pixel = (p1_pixel << 1) | p0_pixel;
uint8_t bg_pal0 = (bg_shifter_attrib_lo & bit_mux) > 0;
uint8_t bg_pal1 = (bg_shifter_attrib_hi & bit_mux) > 0;
bg_palette = (bg_pal1 << 1) | bg_pal0;
}
uint8_t fg_pixel = 0x00;
uint8_t fg_palette = 0x00;
uint8_t fg_priority = 0x00;
if (mask.render_sprites)
{
bSpriteZeroBeingRendered = false;
for (uint8_t i = 0; i < sprite_count; i++)
{
if (spriteScanline[i].x == 0)
{
uint8_t fg_pixel_lo = (sprite_shifter_pattern_lo[i] & 0x80) > 0;
uint8_t fg_pixel_hi = (sprite_shifter_pattern_hi[i] & 0x80) > 0;
fg_pixel = (fg_pixel_hi << 1) | fg_pixel_lo;
fg_palette = (spriteScanline[i].attribute & 0x03) + 0x04;
fg_priority = (spriteScanline[i].attribute & 0x20) == 0;
if (fg_pixel != 0)
{
if (i == 0)
{
bSpriteZeroBeingRendered = true;
}
break;
}
}
}
}
uint8_t pixel = 0x00;
uint8_t palette = 0x00;
if (bg_pixel == 0 && fg_pixel == 0)
{
pixel = 0x00;
palette = 0x00;
}
else if (bg_pixel == 0 && fg_pixel > 0)