mirror of
https://github.com/libretro/Mesen.git
synced 2024-11-24 01:29:41 +00:00
721 lines
21 KiB
C++
721 lines
21 KiB
C++
#include "stdafx.h"
|
|
#include "PPU.h"
|
|
#include "CPU.h"
|
|
#include "../Utilities/PNGWriter.h"
|
|
|
|
PPU* PPU::Instance = nullptr;
|
|
IVideoDevice *PPU::VideoDevice = nullptr;
|
|
|
|
uint32_t PPU_PALETTE_RGB[] = {
|
|
0xFF666666, 0xFF002A88, 0xFF1412A7, 0xFF3B00A4, 0xFF5C007E,
|
|
0xFF6E0040, 0xFF6C0600, 0xFF561D00, 0xFF333500, 0xFF0B4800,
|
|
0xFF005200, 0xFF004F08, 0xFF00404D, 0xFF000000, 0xFF000000,
|
|
0xFF000000, 0xFFADADAD, 0xFF155FD9, 0xFF4240FF, 0xFF7527FE,
|
|
0xFFA01ACC, 0xFFB71E7B, 0xFFB53120, 0xFF994E00, 0xFF6B6D00,
|
|
0xFF388700, 0xFF0C9300, 0xFF008F32, 0xFF007C8D, 0xFF000000,
|
|
0xFF000000, 0xFF000000, 0xFFFFFEFF, 0xFF64B0FF, 0xFF9290FF,
|
|
0xFFC676FF, 0xFFF36AFF, 0xFFFE6ECC, 0xFFFE8170, 0xFFEA9E22,
|
|
0xFFBCBE00, 0xFF88D800, 0xFF5CE430, 0xFF45E082, 0xFF48CDDE,
|
|
0xFF4F4F4F, 0xFF000000, 0xFF000000, 0xFFFFFEFF, 0xFFC0DFFF,
|
|
0xFFD3D2FF, 0xFFE8C8FF, 0xFFFBC2FF, 0xFFFEC4EA, 0xFFFECCC5,
|
|
0xFFF7D8A5, 0xFFE4E594, 0xFFCFEF96, 0xFFBDF4AB, 0xFFB3F3CC,
|
|
0xFFB5EBF2, 0xFFB8B8B8, 0xFF000000, 0xFF000000,
|
|
};
|
|
|
|
PPU::PPU(MemoryManager *memoryManager)
|
|
{
|
|
PPU::Instance = this;
|
|
|
|
_memoryManager = memoryManager;
|
|
_outputBuffer = new uint8_t[256 * 240 * 4];
|
|
|
|
Reset();
|
|
}
|
|
|
|
PPU::~PPU()
|
|
{
|
|
delete[] _outputBuffer;
|
|
}
|
|
|
|
void PPU::Reset()
|
|
{
|
|
_state = {};
|
|
_flags = {};
|
|
_statusFlags = {};
|
|
|
|
_scanline = 0;
|
|
_cycle = 0;
|
|
_frameCount = 0;
|
|
_memoryReadBuffer = 0;
|
|
|
|
memset(_spriteRAM, 0xFF, 0x100);
|
|
}
|
|
|
|
PPUDebugState PPU::GetState()
|
|
{
|
|
PPUDebugState state;
|
|
state.ControlFlags = _flags;
|
|
state.StatusFlags = _statusFlags;
|
|
state.State = _state;
|
|
state.Cycle = _cycle;
|
|
state.Scanline = _scanline;
|
|
return state;
|
|
}
|
|
|
|
void PPU::UpdateVideoRamAddr()
|
|
{
|
|
if(_scanline >= 239 || !IsRenderingEnabled()) {
|
|
_state.VideoRamAddr += _flags.VerticalWrite ? 32 : 1;
|
|
|
|
//Trigger memory read when setting the vram address - needed by MMC3 IRQ counter
|
|
//"Should be clocked when A12 changes to 1 via $2007 read/write"
|
|
_memoryManager->ReadVRAM(_state.VideoRamAddr);
|
|
} else {
|
|
//"During rendering (on the pre-render line and the visible lines 0-239, provided either background or sprite rendering is enabled), "
|
|
//it will update v in an odd way, triggering a coarse X increment and a Y increment simultaneously"
|
|
IncHorizontalScrolling();
|
|
IncVerticalScrolling();
|
|
}
|
|
}
|
|
|
|
uint8_t PPU::ReadRAM(uint16_t addr)
|
|
{
|
|
uint8_t returnValue;
|
|
switch(GetRegisterID(addr)) {
|
|
case PPURegisters::Status:
|
|
_state.WriteToggle = false;
|
|
_flags.IntensifyBlue = false;
|
|
UpdateStatusFlag();
|
|
return _state.Status;
|
|
case PPURegisters::SpriteData:
|
|
return _spriteRAM[_state.SpriteRamAddr];
|
|
case PPURegisters::VideoMemoryData:
|
|
returnValue = _memoryReadBuffer;
|
|
_memoryReadBuffer = _memoryManager->ReadVRAM(_state.VideoRamAddr);
|
|
|
|
if(_state.VideoRamAddr >= 0x3F00) {
|
|
returnValue = ReadPaletteRAM(_state.VideoRamAddr);
|
|
}
|
|
|
|
UpdateVideoRamAddr();
|
|
return returnValue;
|
|
default:
|
|
//other registers are meant to be read-only
|
|
break;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
void PPU::WriteRAM(uint16_t addr, uint8_t value)
|
|
{
|
|
switch(GetRegisterID(addr)) {
|
|
case PPURegisters::Control:
|
|
SetControlRegister(value);
|
|
break;
|
|
case PPURegisters::Mask:
|
|
SetMaskRegister(value);
|
|
break;
|
|
case PPURegisters::SpriteAddr:
|
|
_state.SpriteRamAddr = value;
|
|
break;
|
|
case PPURegisters::SpriteData:
|
|
_spriteRAM[_state.SpriteRamAddr] = value;
|
|
_state.SpriteRamAddr = (_state.SpriteRamAddr + 1) % 0x100;
|
|
break;
|
|
case PPURegisters::ScrollOffsets:
|
|
if(_state.WriteToggle) {
|
|
_state.TmpVideoRamAddr = (_state.TmpVideoRamAddr & ~0x73E0) | ((value & 0xF8) << 2) | ((value & 0x07) << 12);
|
|
} else {
|
|
_state.XScroll = value & 0x07;
|
|
_state.TmpVideoRamAddr = (_state.TmpVideoRamAddr & ~0x001F) | (value >> 3);
|
|
}
|
|
_state.WriteToggle = !_state.WriteToggle;
|
|
break;
|
|
case PPURegisters::VideoMemoryAddr:
|
|
if(_state.WriteToggle) {
|
|
_state.TmpVideoRamAddr = (_state.TmpVideoRamAddr & ~0x00FF) | value;
|
|
_state.VideoRamAddr = _state.TmpVideoRamAddr;
|
|
|
|
//Trigger memory read when setting the vram address - needed by MMC3 IRQ counter
|
|
//"4) Should be clocked when A12 changes to 1 via $2006 write"
|
|
_memoryManager->ReadVRAM(_state.VideoRamAddr);
|
|
} else {
|
|
_state.TmpVideoRamAddr = (_state.TmpVideoRamAddr & ~0xFF00) | ((value & 0x3F) << 8);
|
|
}
|
|
_state.WriteToggle = !_state.WriteToggle;
|
|
break;
|
|
case PPURegisters::VideoMemoryData:
|
|
if(_state.VideoRamAddr >= 0x3F00) {
|
|
WritePaletteRAM(_state.VideoRamAddr, value);
|
|
} else {
|
|
_memoryManager->WriteVRAM(_state.VideoRamAddr, value);
|
|
}
|
|
UpdateVideoRamAddr();
|
|
break;
|
|
case PPURegisters::SpriteDMA:
|
|
CPU::RunDMATransfer(_spriteRAM, _state.SpriteRamAddr, value);
|
|
break;
|
|
}
|
|
}
|
|
|
|
uint8_t PPU::ReadPaletteRAM(uint16_t addr)
|
|
{
|
|
addr &= 0x1F;
|
|
if(addr == 0x10 || addr == 0x14 || addr == 0x18 || addr == 0x1C) {
|
|
addr &= ~0x10;
|
|
}
|
|
return _paletteRAM[addr];
|
|
}
|
|
|
|
void PPU::WritePaletteRAM(uint16_t addr, uint8_t value)
|
|
{
|
|
addr &= 0x1F;
|
|
if(addr == 0x10 || addr == 0x14 || addr == 0x18 || addr == 0x1C) {
|
|
addr &= ~0x10;
|
|
}
|
|
_paletteRAM[addr] = value;
|
|
}
|
|
|
|
uint32_t PPU::GetBGPaletteEntry(uint32_t paletteOffset, uint32_t pixel)
|
|
{
|
|
if(pixel == 0) {
|
|
return ReadPaletteRAM(0x3F00) % 64;
|
|
} else {
|
|
return ReadPaletteRAM(0x3F00 + paletteOffset + pixel) % 64;
|
|
}
|
|
}
|
|
|
|
uint32_t PPU::GetSpritePaletteEntry(uint32_t paletteOffset, uint32_t pixel)
|
|
{
|
|
if(pixel == 0) {
|
|
return ReadPaletteRAM(0x3F00) % 64;
|
|
} else {
|
|
return ReadPaletteRAM(0x3F10 + paletteOffset + pixel) % 64;
|
|
}
|
|
}
|
|
|
|
bool PPU::IsRenderingEnabled()
|
|
{
|
|
return _flags.BackgroundEnabled || _flags.SpritesEnabled;
|
|
}
|
|
|
|
void PPU::SetControlRegister(uint8_t value)
|
|
{
|
|
_state.Control = value;
|
|
|
|
uint8_t nameTable = (_state.Control & 0x03);
|
|
_state.TmpVideoRamAddr = (_state.TmpVideoRamAddr & ~0x0C00) | (nameTable << 10);
|
|
|
|
_flags.VerticalWrite = (_state.Control & 0x04) == 0x04;
|
|
_flags.SpritePatternAddr = ((_state.Control & 0x08) == 0x08) ? 0x1000 : 0x0000;
|
|
_flags.BackgroundPatternAddr = ((_state.Control & 0x10) == 0x10) ? 0x1000 : 0x0000;
|
|
_flags.LargeSprites = (_state.Control & 0x20) == 0x20;
|
|
|
|
//"By toggling NMI_output ($2000 bit 7) during vertical blank without reading $2002, a program can cause /NMI to be pulled low multiple times, causing multiple NMIs to be generated."
|
|
bool originalVBlank = _flags.VBlank;
|
|
_flags.VBlank = (_state.Control & 0x80) == 0x80;
|
|
|
|
if(!originalVBlank && _flags.VBlank && _statusFlags.VerticalBlank) {
|
|
CPU::SetNMIFlag();
|
|
} else if(_scanline == 241 && _cycle < 3 && !_flags.VBlank) {
|
|
CPU::ClearNMIFlag();
|
|
}
|
|
}
|
|
|
|
void PPU::SetMaskRegister(uint8_t value)
|
|
{
|
|
_state.Mask = value;
|
|
_flags.Grayscale = (_state.Mask & 0x01) == 0x01;
|
|
_flags.BackgroundMask = (_state.Mask & 0x02) == 0x02;
|
|
_flags.SpriteMask = (_state.Mask & 0x04) == 0x04;
|
|
_flags.BackgroundEnabled = (_state.Mask & 0x08) == 0x08;
|
|
_flags.SpritesEnabled = (_state.Mask & 0x10) == 0x10;
|
|
_flags.IntensifyRed = (_state.Mask & 0x20) == 0x20;
|
|
_flags.IntensifyGreen = (_state.Mask & 0x40) == 0x40;
|
|
_flags.IntensifyBlue = (_state.Mask & 0x80) == 0x80;
|
|
}
|
|
|
|
void PPU::UpdateStatusFlag()
|
|
{
|
|
_state.Status = ((uint8_t)_statusFlags.SpriteOverflow << 5) |
|
|
((uint8_t)_statusFlags.Sprite0Hit << 6) |
|
|
((uint8_t)_statusFlags.VerticalBlank << 7);
|
|
_statusFlags.VerticalBlank = false;
|
|
|
|
if(_scanline == 241) {
|
|
if(_cycle < 3) {
|
|
CPU::ClearNMIFlag();
|
|
|
|
if(_cycle == 0) {
|
|
_doNotSetVBFlag = true;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
//Taken from http://wiki.nesdev.com/w/index.php/The_skinny_on_NES_scrolling#Wrapping_around
|
|
void PPU::IncVerticalScrolling()
|
|
{
|
|
uint16_t addr = _state.VideoRamAddr;
|
|
|
|
if((addr & 0x7000) != 0x7000) {
|
|
// if fine Y < 7
|
|
addr += 0x1000; // increment fine Y
|
|
} else {
|
|
// fine Y = 0
|
|
addr &= ~0x7000;
|
|
int y = (addr & 0x03E0) >> 5; // let y = coarse Y
|
|
if(y == 29) {
|
|
y = 0; // coarse Y = 0
|
|
addr ^= 0x0800; // switch vertical nametable
|
|
} else if(y == 31){
|
|
y = 0; // coarse Y = 0, nametable not switched
|
|
} else {
|
|
y++; // increment coarse Y
|
|
}
|
|
addr = (addr & ~0x03E0) | (y << 5); // put coarse Y back into v
|
|
}
|
|
_state.VideoRamAddr = addr;
|
|
}
|
|
|
|
//Taken from http://wiki.nesdev.com/w/index.php/The_skinny_on_NES_scrolling#Wrapping_around
|
|
void PPU::IncHorizontalScrolling()
|
|
{
|
|
//Increase coarse X scrolling value.
|
|
uint16_t addr = _state.VideoRamAddr;
|
|
if((addr & 0x001F) == 31) {
|
|
//When the value is 31, wrap around to 0 and switch nametable
|
|
addr = (addr & ~0x001F) ^ 0x0400;
|
|
} else {
|
|
addr++;
|
|
}
|
|
_state.VideoRamAddr = addr;
|
|
}
|
|
|
|
//Taken from http://wiki.nesdev.com/w/index.php/The_skinny_on_NES_scrolling#Tile_and_attribute_fetching
|
|
uint16_t PPU::GetNameTableAddr()
|
|
{
|
|
return 0x2000 | (_state.VideoRamAddr & 0x0FFF);
|
|
}
|
|
|
|
//Taken from http://wiki.nesdev.com/w/index.php/The_skinny_on_NES_scrolling#Tile_and_attribute_fetching
|
|
uint16_t PPU::GetAttributeAddr()
|
|
{
|
|
return 0x23C0 | (_state.VideoRamAddr & 0x0C00) | ((_state.VideoRamAddr >> 4) & 0x38) | ((_state.VideoRamAddr >> 2) & 0x07);
|
|
}
|
|
|
|
void PPU::LoadTileInfo()
|
|
{
|
|
if(IsRenderingEnabled()) {
|
|
_previousTile = _currentTile;
|
|
_currentTile = _nextTile;
|
|
|
|
uint16_t tileIndex = _memoryManager->ReadVRAM(GetNameTableAddr());
|
|
uint16_t tileAddr = (tileIndex << 4) | (_state.VideoRamAddr >> 12) | _flags.BackgroundPatternAddr;
|
|
|
|
uint16_t shift = ((_state.VideoRamAddr >> 4) & 0x04) | (_state.VideoRamAddr & 0x02);
|
|
_nextTile.PaletteOffset = ((_memoryManager->ReadVRAM(GetAttributeAddr()) >> shift) & 0x03) << 2;
|
|
_nextTile.LowByte = _memoryManager->ReadVRAM(tileAddr);
|
|
_nextTile.HighByte = _memoryManager->ReadVRAM(tileAddr + 8);
|
|
}
|
|
}
|
|
|
|
void PPU::LoadSpriteTileInfo(uint8_t spriteIndex)
|
|
{
|
|
if(IsRenderingEnabled()) {
|
|
uint32_t spriteAddr = spriteIndex * 4;
|
|
uint8_t spriteY = _secondarySpriteRAM[spriteAddr];
|
|
uint8_t tileIndex = _secondarySpriteRAM[spriteAddr + 1];
|
|
uint8_t attributes = _secondarySpriteRAM[spriteAddr + 2];
|
|
uint8_t spriteX = _secondarySpriteRAM[spriteAddr + 3];
|
|
bool backgroundPriority = (attributes & 0x20) == 0x20;
|
|
bool horizontalMirror = (attributes & 0x40) == 0x40;
|
|
bool verticalMirror = (attributes & 0x80) == 0x80;
|
|
|
|
uint16_t tileAddr;
|
|
uint8_t lineOffset;
|
|
if(verticalMirror) {
|
|
lineOffset = (_flags.LargeSprites ? 15 : 7) - (_scanline - spriteY);
|
|
} else {
|
|
lineOffset = _scanline - spriteY;
|
|
}
|
|
|
|
if(_flags.LargeSprites) {
|
|
tileAddr = (((tileIndex & 0x01) ? 0x1000 : 0x0000) | ((tileIndex & ~0x01) << 4)) + (lineOffset >= 8 ? lineOffset + 8 : lineOffset);
|
|
} else {
|
|
tileAddr = ((tileIndex << 4) | _flags.SpritePatternAddr) + lineOffset;
|
|
}
|
|
|
|
if(spriteIndex < _spriteCount && spriteY < 240) {
|
|
_spriteX[spriteIndex] = spriteX;
|
|
_spriteTiles[spriteIndex].BackgroundPriority = backgroundPriority;
|
|
_spriteTiles[spriteIndex].HorizontalMirror = horizontalMirror;
|
|
_spriteTiles[spriteIndex].PaletteOffset = (attributes & 0x03) << 2;
|
|
_spriteTiles[spriteIndex].LowByte = _memoryManager->ReadVRAM(tileAddr);
|
|
_spriteTiles[spriteIndex].HighByte = _memoryManager->ReadVRAM(tileAddr + 8);
|
|
} else {
|
|
//Fetches to sprite 0xFF for remaining sprites/hidden - used by MMC3 IRQ counter
|
|
lineOffset = 0;
|
|
tileIndex = 0xFF;
|
|
if(_flags.LargeSprites) {
|
|
tileAddr = (((tileIndex & 0x01) ? 0x1000 : 0x0000) | ((tileIndex & ~0x01) << 4)) + (lineOffset >= 8 ? lineOffset + 8 : lineOffset);
|
|
} else {
|
|
tileAddr = ((tileIndex << 4) | _flags.SpritePatternAddr) + lineOffset;
|
|
}
|
|
|
|
_memoryManager->ReadVRAM(tileAddr);
|
|
_memoryManager->ReadVRAM(tileAddr + 8);
|
|
}
|
|
}
|
|
}
|
|
|
|
void PPU::LoadNextTile()
|
|
{
|
|
_state.LowBitShift |= _nextTile.LowByte;
|
|
_state.HighBitShift |= _nextTile.HighByte;
|
|
}
|
|
|
|
void PPU::InitializeShiftRegisters()
|
|
{
|
|
_state.LowBitShift = (_currentTile.LowByte << 8) | _nextTile.LowByte;
|
|
_state.HighBitShift = (_currentTile.HighByte << 8) | _nextTile.HighByte;
|
|
}
|
|
|
|
void PPU::ShiftTileRegisters()
|
|
{
|
|
_state.LowBitShift <<= 1;
|
|
_state.HighBitShift <<= 1;
|
|
}
|
|
|
|
void PPU::DrawPixel()
|
|
{
|
|
//This is called 3.7 million times per second - needs to be as fast as possible.
|
|
uint8_t offset = _state.XScroll;
|
|
|
|
uint32_t backgroundColor = 0;
|
|
uint32_t &pixel = (((uint32_t*)_outputBuffer)[(_scanline << 8) + _cycle - 1]);
|
|
|
|
if((_cycle > 8 || _flags.BackgroundMask) && _flags.BackgroundEnabled) {
|
|
//BackgroundMask = false: Hide background in leftmost 8 pixels of screen
|
|
backgroundColor = (((_state.LowBitShift << offset) & 0x8000) >> 15) | (((_state.HighBitShift << offset) & 0x8000) >> 14);
|
|
}
|
|
|
|
if((_cycle > 8 || _flags.SpriteMask) && _flags.SpritesEnabled) {
|
|
//SpriteMask = true: Hide sprites in leftmost 8 pixels of screen
|
|
for(uint8_t i = 0; i < _spriteCount; i++) {
|
|
int32_t shift = -((int32_t)_spriteX[i] - (int32_t)_cycle + 1);
|
|
if(shift >= 0 && shift < 8) {
|
|
uint32_t spriteColor;
|
|
if(_spriteTiles[i].HorizontalMirror) {
|
|
spriteColor = ((_spriteTiles[i].LowByte >> shift) & 0x01) | ((_spriteTiles[i].HighByte >> shift) & 0x01) << 1;
|
|
} else {
|
|
spriteColor = ((_spriteTiles[i].LowByte << shift) & 0x80) >> 7 | ((_spriteTiles[i].HighByte << shift) & 0x80) >> 6;
|
|
}
|
|
|
|
if(spriteColor != 0) {
|
|
//First sprite without a 00 color, use it.
|
|
if(backgroundColor == 0 || !_spriteTiles[i].BackgroundPriority) {
|
|
//Check sprite priority
|
|
pixel = PPU_PALETTE_RGB[GetSpritePaletteEntry(_spriteTiles[i].PaletteOffset, spriteColor)];
|
|
}
|
|
|
|
if(i == 0 && backgroundColor != 0 && _sprite0Visible && _cycle != 256 && _flags.BackgroundEnabled) {
|
|
//"The hit condition is basically sprite zero is in range AND the first sprite output unit is outputting a non-zero pixel AND the background drawing unit is outputting a non-zero pixel."
|
|
//"Sprite zero hits do not register at x=255" (cycle 256)
|
|
//"... provided that background and sprite rendering are both enabled"
|
|
//"Should always miss when Y >= 239"
|
|
_statusFlags.Sprite0Hit = true;
|
|
}
|
|
return;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
pixel = PPU_PALETTE_RGB[GetBGPaletteEntry(offset + ((_cycle - 1) % 8) < 8 ? _previousTile.PaletteOffset : _currentTile.PaletteOffset, backgroundColor)];
|
|
}
|
|
|
|
void PPU::ProcessPreVBlankScanline()
|
|
{
|
|
//For pre-render scanline & all visible scanlines
|
|
if(IsRenderingEnabled()) {
|
|
//Update video ram address according to scrolling logic
|
|
if((_cycle > 0 && _cycle < 256 && _cycle % 8 == 0) || _cycle == 328 || _cycle == 336) {
|
|
IncHorizontalScrolling();
|
|
} else if(_cycle == 256) {
|
|
IncVerticalScrolling();
|
|
} else if(_cycle == 257) {
|
|
//copy horizontal scrolling value from t
|
|
_state.VideoRamAddr = (_state.VideoRamAddr & ~0x041F) | (_state.TmpVideoRamAddr & 0x041F);
|
|
}
|
|
}
|
|
|
|
if(_cycle >= 257 && _cycle <= 320) {
|
|
//"OAMADDR is set to 0 during each of ticks 257-320 (the sprite tile loading interval) of the pre-render and visible scanlines."
|
|
_state.SpriteRamAddr = 0;
|
|
}
|
|
}
|
|
|
|
void PPU::ProcessPrerenderScanline()
|
|
{
|
|
ProcessPreVBlankScanline();
|
|
|
|
if(_cycle == 1) {
|
|
_statusFlags.SpriteOverflow = false;
|
|
_statusFlags.Sprite0Hit = false;
|
|
_statusFlags.VerticalBlank = false;
|
|
}
|
|
|
|
if((_cycle - 1) % 8 == 0 && _cycle < 250) {
|
|
LoadTileInfo();
|
|
} else if(_cycle >= 280 && _cycle <= 304) {
|
|
if(IsRenderingEnabled()) {
|
|
//copy vertical scrolling value from t
|
|
_state.VideoRamAddr = (_state.VideoRamAddr & ~0x7BE0) | (_state.TmpVideoRamAddr & 0x7BE0);
|
|
}
|
|
} else if(_cycle == 339 && IsRenderingEnabled() && (_frameCount % 2 == 1)) {
|
|
//"With rendering enabled, each odd PPU frame is one PPU clock shorter than normal" (skip from 339 to 0, going over 340)
|
|
_cycle = -1;
|
|
_scanline = 0;
|
|
} else if(_cycle == 321 || _cycle == 329) {
|
|
LoadTileInfo();
|
|
if(_cycle == 329) {
|
|
InitializeShiftRegisters();
|
|
}
|
|
}
|
|
|
|
if(_cycle >= 261 && (_cycle - 261) % 8 == 0 && _cycle <= 320) {
|
|
//Unused sprite tile fetches, but vital for MMC3 IRQ counter
|
|
uint32_t spriteIndex = (_cycle - 261) / 8;
|
|
LoadSpriteTileInfo(spriteIndex);
|
|
}
|
|
}
|
|
|
|
void PPU::ProcessVisibleScanline()
|
|
{
|
|
if(_cycle > 0 && _cycle <= 256) {
|
|
if((_cycle - 1) % 8 == 0) {
|
|
//Cycle 1, 9, 17, etc.
|
|
if(_cycle != 1) {
|
|
LoadNextTile();
|
|
}
|
|
LoadTileInfo();
|
|
}
|
|
|
|
DrawPixel();
|
|
ShiftTileRegisters();
|
|
|
|
if(IsRenderingEnabled()) {
|
|
CopyOAMData();
|
|
}
|
|
|
|
if(_cycle == 256 && _scanline == 239) {
|
|
//Send frame to GUI once the last pixel has been output
|
|
if(PPU::VideoDevice) {
|
|
PPU::VideoDevice->UpdateFrame(_outputBuffer);
|
|
}
|
|
}
|
|
} else if((_cycle - 261) % 8 == 0 && _cycle <= 320) {
|
|
//Cycle 261, 269, etc.
|
|
uint32_t spriteIndex = (_cycle - 261) / 8;
|
|
LoadSpriteTileInfo(spriteIndex);
|
|
} else if(_cycle == 321 || _cycle == 329) {
|
|
LoadTileInfo();
|
|
if(_cycle == 329) {
|
|
InitializeShiftRegisters();
|
|
}
|
|
}
|
|
|
|
ProcessPreVBlankScanline();
|
|
}
|
|
|
|
void PPU::CopyOAMData()
|
|
{
|
|
if(_cycle < 65) {
|
|
//Clear secondary OAM at between cycle 0 and 64
|
|
_secondarySpriteRAM[_cycle >> 1] = 0xFF;
|
|
} else {
|
|
if(_cycle == 65) {
|
|
_overflowCounter = 0;
|
|
_sprite0Added = false;
|
|
_writeOAMData = false;
|
|
_secondaryOAMAddr = 0;
|
|
} else if(_cycle == 256) {
|
|
_sprite0Visible = _sprite0Added;
|
|
_spriteCount = (_secondaryOAMAddr >> 2);
|
|
}
|
|
|
|
if(_cycle & 0x01) {
|
|
//Read a byte from the primary OAM on odd cycles
|
|
_oamCopybuffer = _spriteRAM[_state.SpriteRamAddr & 0xFF];
|
|
_state.SpriteRamAddr++;
|
|
} else {
|
|
if(!_writeOAMData && _state.SpriteRamAddr < 0x100 && _scanline >= _oamCopybuffer && _scanline < _oamCopybuffer + (_flags.LargeSprites ? 16 : 8)) {
|
|
_writeOAMData = true;
|
|
}
|
|
|
|
if(_secondaryOAMAddr < 0x20) {
|
|
//Copy 1 byte to secondary OAM
|
|
_secondarySpriteRAM[_secondaryOAMAddr] = _oamCopybuffer;
|
|
|
|
if(_writeOAMData) {
|
|
_secondaryOAMAddr++;
|
|
|
|
if(_state.SpriteRamAddr == 0x01) {
|
|
_sprite0Added = true;
|
|
}
|
|
|
|
if((_secondaryOAMAddr & 0x03) == 0) {
|
|
//Done copying
|
|
_writeOAMData = false;
|
|
}
|
|
} else {
|
|
_state.SpriteRamAddr += 3;
|
|
}
|
|
} else {
|
|
//8 sprites have been found, check next sprite for overflow + emulate PPU bug
|
|
//Based on: http://forums.nesdev.com/viewtopic.php?p=85431#p85431
|
|
//Behavior matches: http://forums.nesdev.com/viewtopic.php?p=1387#p1387
|
|
if(!_statusFlags.SpriteOverflow) {
|
|
if(_writeOAMData) {
|
|
//Sprite is visible, consider this to be an overflow
|
|
_statusFlags.SpriteOverflow = true;
|
|
_overflowCounter = 3;
|
|
} else if((_state.SpriteRamAddr & 0x3) != 0) {
|
|
//Sprite isn't on this scanline, trigger sprite evaluation bug
|
|
_state.SpriteRamAddr += 4;
|
|
}
|
|
} else {
|
|
if(_overflowCounter != 0) {
|
|
_overflowCounter--;
|
|
if(_overflowCounter == 0) {
|
|
_state.SpriteRamAddr = (_state.SpriteRamAddr + 3) & 0x0FFC;
|
|
}
|
|
} else {
|
|
_state.SpriteRamAddr = (_state.SpriteRamAddr + 4) & 0x0FFC;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
void PPU::BeginVBlank()
|
|
{
|
|
if(_cycle == 1) {
|
|
if(!_doNotSetVBFlag) {
|
|
_statusFlags.VerticalBlank = true;
|
|
if(_flags.VBlank) {
|
|
CPU::SetNMIFlag();
|
|
}
|
|
}
|
|
_doNotSetVBFlag = false;
|
|
}
|
|
}
|
|
|
|
void PPU::EndVBlank()
|
|
{
|
|
if(_cycle == 340) {
|
|
_frameCount++;
|
|
}
|
|
}
|
|
|
|
void PPU::Exec()
|
|
{
|
|
if(_scanline != -1 && _scanline < 240) {
|
|
ProcessVisibleScanline();
|
|
} else if(_scanline == -1) {
|
|
ProcessPrerenderScanline();
|
|
} else if(_scanline == 241) {
|
|
BeginVBlank();
|
|
} else if(_scanline == 260) {
|
|
EndVBlank();
|
|
}
|
|
|
|
if(_cycle == 340) {
|
|
_cycle = -1;
|
|
_scanline++;
|
|
|
|
if(_scanline == 261) {
|
|
_scanline = -1;
|
|
}
|
|
}
|
|
_cycle++;
|
|
}
|
|
|
|
void PPU::ExecStatic()
|
|
{
|
|
PPU::Instance->Exec();
|
|
PPU::Instance->Exec();
|
|
PPU::Instance->Exec();
|
|
}
|
|
|
|
void PPU::StreamState(bool saving)
|
|
{
|
|
Stream<uint8_t>(_state.Control);
|
|
Stream<uint8_t>(_state.Mask);
|
|
Stream<uint8_t>(_state.Status);
|
|
Stream<uint32_t>(_state.SpriteRamAddr);
|
|
Stream<uint16_t>(_state.VideoRamAddr);
|
|
Stream<uint8_t>(_state.XScroll);
|
|
Stream<uint16_t>(_state.TmpVideoRamAddr);
|
|
Stream<bool>(_state.WriteToggle);
|
|
Stream<uint16_t>(_state.HighBitShift);
|
|
Stream<uint16_t>(_state.LowBitShift);
|
|
|
|
Stream<bool>(_flags.VerticalWrite);
|
|
Stream<uint16_t>(_flags.SpritePatternAddr);
|
|
Stream<uint16_t>(_flags.BackgroundPatternAddr);
|
|
Stream<bool>(_flags.LargeSprites);
|
|
Stream<bool>(_flags.VBlank);
|
|
|
|
Stream<bool>(_flags.Grayscale);
|
|
Stream<bool>(_flags.BackgroundMask);
|
|
Stream<bool>(_flags.SpriteMask);
|
|
Stream<bool>(_flags.BackgroundEnabled);
|
|
Stream<bool>(_flags.SpritesEnabled);
|
|
Stream<bool>(_flags.IntensifyRed);
|
|
Stream<bool>(_flags.IntensifyGreen);
|
|
Stream<bool>(_flags.IntensifyBlue);
|
|
|
|
Stream<bool>(_statusFlags.SpriteOverflow);
|
|
Stream<bool>(_statusFlags.Sprite0Hit);
|
|
Stream<bool>(_statusFlags.VerticalBlank);
|
|
|
|
Stream<int32_t>(_scanline);
|
|
Stream<uint32_t>(_cycle);
|
|
Stream<uint32_t>(_frameCount);
|
|
Stream<uint8_t>(_memoryReadBuffer);
|
|
|
|
StreamArray<uint8_t>(_paletteRAM, 0x100);
|
|
StreamArray<uint8_t>(_spriteRAM, 0x100);
|
|
StreamArray<uint8_t>(_secondarySpriteRAM, 0x20);
|
|
|
|
Stream<uint8_t>(_currentTile.LowByte);
|
|
Stream<uint8_t>(_currentTile.HighByte);
|
|
Stream<uint32_t>(_currentTile.PaletteOffset);
|
|
|
|
Stream<uint8_t>(_nextTile.LowByte);
|
|
Stream<uint8_t>(_nextTile.HighByte);
|
|
Stream<uint32_t>(_nextTile.PaletteOffset);
|
|
|
|
Stream<uint8_t>(_previousTile.LowByte);
|
|
Stream<uint8_t>(_previousTile.HighByte);
|
|
Stream<uint32_t>(_previousTile.PaletteOffset);
|
|
|
|
StreamArray<int32_t>(_spriteX, 0x8);
|
|
for(int i = 0; i < 8; i++) {
|
|
Stream<uint8_t>(_spriteTiles[i].LowByte);
|
|
Stream<uint8_t>(_spriteTiles[i].HighByte);
|
|
Stream<uint32_t>(_spriteTiles[i].PaletteOffset);
|
|
Stream<bool>(_spriteTiles[i].HorizontalMirror);
|
|
Stream<bool>(_spriteTiles[i].BackgroundPriority);
|
|
}
|
|
Stream<uint32_t>(_spriteCount);
|
|
Stream<uint32_t>(_secondaryOAMAddr);
|
|
Stream<bool>(_sprite0Visible);
|
|
|
|
Stream<uint8_t>(_oamCopybuffer);
|
|
Stream<bool>(_writeOAMData);
|
|
Stream<uint32_t>(_overflowCounter);
|
|
Stream<bool>(_sprite0Added);
|
|
} |