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https://github.com/libretro/Mesen.git
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509 lines
14 KiB
C++
509 lines
14 KiB
C++
#include "stdafx.h"
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#include "PPU.h"
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#include "CPU.h"
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uint32_t PPU_PALETTE_RGB[] = {
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0x666666, 0x002A88, 0x1412A7, 0x3B00A4, 0x5C007E,
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0x6E0040, 0x6C0600, 0x561D00, 0x333500, 0x0B4800,
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0x005200, 0x004F08, 0x00404D, 0x000000, 0x000000,
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0x000000, 0xADADAD, 0x155FD9, 0x4240FF, 0x7527FE,
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0xA01ACC, 0xB71E7B, 0xB53120, 0x994E00, 0x6B6D00,
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0x388700, 0x0C9300, 0x008F32, 0x007C8D, 0x000000,
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0x000000, 0x000000, 0xFFFEFF, 0x64B0FF, 0x9290FF,
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0xC676FF, 0xF36AFF, 0xFE6ECC, 0xFE8170, 0xEA9E22,
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0xBCBE00, 0x88D800, 0x5CE430, 0x45E082, 0x48CDDE,
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0x4F4F4F, 0x000000, 0x000000, 0xFFFEFF, 0xC0DFFF,
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0xD3D2FF, 0xE8C8FF, 0xFBC2FF, 0xFEC4EA, 0xFECCC5,
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0xF7D8A5, 0xE4E594, 0xCFEF96, 0xBDF4AB, 0xB3F3CC,
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0xB5EBF2, 0xB8B8B8, 0x000000, 0x000000,
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};
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uint8_t *PPU::FrameBuffer = new uint8_t[256*240*4];
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atomic<int> PPU::WaitCounter = 0;
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PPU::PPU(MemoryManager *memoryManager)
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{
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_memoryManager = memoryManager;
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_state = {};
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_flags = {};
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_statusFlags = {};
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_outputBuffer = new uint8_t[256 * 240 * 4];
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}
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PPU::~PPU()
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{
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delete[] _outputBuffer;
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}
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bool PPU::CheckFlag(PPUControlFlags flag)
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{
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return false;
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}
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uint8_t PPU::ReadRAM(uint16_t addr)
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{
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uint8_t returnValue;
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switch(GetRegisterID(addr)) {
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case PPURegisters::Status:
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_state.WriteToggle = false;
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_flags.IntensifyBlue = false;
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UpdateStatusFlag();
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return _state.Status;
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case PPURegisters::SpriteData:
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return _spriteRAM[_state.SpriteRamAddr];
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case PPURegisters::VideoMemoryData:
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returnValue = _memoryReadBuffer;
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_memoryReadBuffer = _memoryManager->ReadVRAM(_state.VideoRamAddr);
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_state.VideoRamAddr += _flags.VerticalWrite ? 32 : 1;
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if(_state.VideoRamAddr >= 0x3F00) {
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//No buffer for palette
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//TODO: Update read buffer when reading palette (See: http://wiki.nesdev.com/w/index.php/PPU_registers#The_PPUDATA_read_buffer_.28post-fetch.29)
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return _memoryReadBuffer;
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} else {
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return returnValue;
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}
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default:
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//other registers are meant to be read-only
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break;
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}
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return 0;
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}
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void PPU::WriteRAM(uint16_t addr, uint8_t value)
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{
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static int counter = 0;
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switch(GetRegisterID(addr)) {
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case PPURegisters::Control:
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_state.Control = value;
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UpdateFlags();
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break;
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case PPURegisters::Control2:
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_state.Control2 = value;
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UpdateFlags();
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break;
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case PPURegisters::SpriteAddr:
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_state.SpriteRamAddr = value;
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break;
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case PPURegisters::SpriteData:
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_spriteRAM[_state.SpriteRamAddr] = value;
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_state.SpriteRamAddr++;
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break;
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case PPURegisters::ScrollOffsets:
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if(_state.WriteToggle) {
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_state.TmpVideoRamAddr = (_state.TmpVideoRamAddr & ~0x73E0) | ((value & 0xF8) << 2) | ((value & 0x07) << 12);
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} else {
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_state.XScroll = value & 0x07;
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_state.TmpVideoRamAddr = (_state.TmpVideoRamAddr & ~0x001F) | (value >> 3);
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}
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_state.WriteToggle = !_state.WriteToggle;
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break;
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case PPURegisters::VideoMemoryAddr:
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if(counter < 50) {
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std::cout << "=> " << std::hex << (short)value << std::endl;
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}
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if(_state.WriteToggle) {
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_state.TmpVideoRamAddr = (_state.TmpVideoRamAddr & ~0x00FF) | value;
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_state.VideoRamAddr = _state.TmpVideoRamAddr;
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if(counter < 50) {
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std::cout << std::hex << _state.VideoRamAddr << std::endl;
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}
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counter++;
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} else {
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_state.TmpVideoRamAddr = (_state.TmpVideoRamAddr & ~0xFF00) | ((value & 0x3F) << 8);
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}
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_state.WriteToggle = !_state.WriteToggle;
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break;
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case PPURegisters::VideoMemoryData:
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if(_state.VideoRamAddr == 0x2001 || _state.VideoRamAddr == 0x2401 || _state.VideoRamAddr == 0x2801 || _state.VideoRamAddr == 0x2C01) {
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//std::cout << "test";
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}
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_memoryManager->WriteVRAM(_state.VideoRamAddr, value);
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_state.VideoRamAddr += _flags.VerticalWrite ? 32 : 1;
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break;
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}
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}
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bool PPU::IsRenderingEnabled()
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{
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return _flags.BackgroundEnabled || _flags.SpritesEnabled;
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}
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void PPU::UpdateFlags()
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{
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uint8_t nameTable = (_state.Control & 0x03);
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switch(nameTable) {
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case 0: _flags.NameTableAddr = 0x2000; break;
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case 1: _flags.NameTableAddr = 0x2400; break;
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case 2: _flags.NameTableAddr = 0x2800; break;
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case 3: _flags.NameTableAddr = 0x2C00; break;
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}
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_state.TmpVideoRamAddr = (_state.TmpVideoRamAddr & ~0xC0000) | (nameTable << 10);
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_flags.VerticalWrite = (_state.Control & 0x04) == 0x04;
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_flags.SpritePatternAddr = ((_state.Control & 0x08) == 0x08) ? 0x1000 : 0x0000;
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_flags.BackgroundPatternAddr = ((_state.Control & 0x10) == 0x10) ? 0x1000 : 0x0000;
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_flags.LargeSprites = (_state.Control & 0x20) == 0x20;
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_flags.VBlank = (_state.Control & 0x80) == 0x80;
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_flags.Grayscale = (_state.Control2 & 0x01) == 0x01;
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_flags.BackgroundMask = (_state.Control2 & 0x02) == 0x02;
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_flags.SpriteMask = (_state.Control2 & 0x04) == 0x04;
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_flags.BackgroundEnabled = (_state.Control2 & 0x08) == 0x08;
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_flags.SpritesEnabled = (_state.Control2 & 0x10) == 0x10;
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_flags.IntensifyRed = (_state.Control2 & 0x20) == 0x20;
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_flags.IntensifyGreen = (_state.Control2 & 0x40) == 0x40;
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_flags.IntensifyBlue = (_state.Control2 & 0x80) == 0x80;
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}
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void PPU::UpdateStatusFlag()
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{
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_state.Status = ((uint8_t)_statusFlags.SpriteOverflow << 5) |
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((uint8_t)_statusFlags.Sprite0Hit << 6) |
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((uint8_t)_statusFlags.VerticalBlank << 7);
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_statusFlags.VerticalBlank = false;
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}
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//Taken from http://wiki.nesdev.com/w/index.php/The_skinny_on_NES_scrolling#Wrapping_around
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void PPU::IncVerticalScrolling()
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{
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uint16_t addr = _state.VideoRamAddr;
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if((addr & 0x7000) != 0x7000) {
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// if fine Y < 7
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addr += 0x1000; // increment fine Y
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} else {
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// fine Y = 0
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addr &= ~0x7000;
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int y = (addr & 0x03E0) >> 5; // let y = coarse Y
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if(y == 29) {
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y = 0; // coarse Y = 0
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addr ^= 0x0800; // switch vertical nametable
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} else if(y == 31){
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y = 0; // coarse Y = 0, nametable not switched
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} else {
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y += 1; // increment coarse Y
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}
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addr = (addr & ~0x03E0) | (y << 5); // put coarse Y back into v
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//std::cout << std::endl;
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}
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_state.VideoRamAddr = addr;
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}
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//Taken from http://wiki.nesdev.com/w/index.php/The_skinny_on_NES_scrolling#Wrapping_around
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void PPU::IncHorizontalScrolling()
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{
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//Increase coarse X scrolling value.
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//When the value is 31, wrap around to 0 and switch nametable
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uint16_t addr = _state.VideoRamAddr;
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if((addr & 0x001F) == 31) {
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addr &= ~0x001F;
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addr ^= 0x0400; // switch horizontal nametable
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} else {
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addr += 1;
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}
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_state.VideoRamAddr = addr;
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}
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//Take from http://wiki.nesdev.com/w/index.php/The_skinny_on_NES_scrolling#Tile_and_attribute_fetching
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uint16_t PPU::GetTileAddr()
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{
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return 0x2000 | (_state.VideoRamAddr & 0x0FFF);
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}
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//Take from http://wiki.nesdev.com/w/index.php/The_skinny_on_NES_scrolling#Tile_and_attribute_fetching
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uint16_t PPU::GetAttributeAddr()
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{
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return 0x23C0 | (_state.VideoRamAddr & 0x0C00) | ((_state.VideoRamAddr >> 4) & 0x38) | ((_state.VideoRamAddr >> 2) & 0x07);
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}
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void PPU::UpdateScrolling()
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{
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//For pre-render scanline & all visible scanlines
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if(_cycle == 256) {
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IncVerticalScrolling();
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} else if(_cycle == 257) {
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//copy horizontal scrolling value from t
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_state.VideoRamAddr = (_state.VideoRamAddr & ~0x041F) | (_state.TmpVideoRamAddr & 0x041F);
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} else if((_cycle % 8 == 0 && _cycle > 0 && _cycle < 256) || _cycle == 328 || _cycle == 336) {
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IncHorizontalScrolling();
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}
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}
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void PPU::ProcessPrerenderScanline()
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{
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if(IsRenderingEnabled()) {
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UpdateScrolling();
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}
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if(_cycle == 1) {
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_statusFlags.SpriteOverflow = false;
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_statusFlags.Sprite0Hit = false;
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_statusFlags.VerticalBlank = false;
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} else if(_cycle >= 280 && _cycle <= 304) {
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if(IsRenderingEnabled()) {
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//copy vertical scrolling value from t
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_state.VideoRamAddr = (_state.VideoRamAddr & ~0x7BF0) | (_state.TmpVideoRamAddr & 0x7BF0);
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}
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} else if(_cycle == 340 && _flags.BackgroundEnabled && (_frameCount % 2 == 1)) {
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//Skip a cycle for odd frames, if background drawing is enabled
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_cycle = 0;
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_scanline = 0;
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} else if(_cycle == 321 || _cycle == 329) {
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LoadTileInfo();
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LoadShiftRegisters();
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}
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}
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void PPU::LoadTileInfo()
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{
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_currentTile = _nextTile;
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uint16_t tileIndex = _memoryManager->ReadVRAM(GetTileAddr());
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uint16_t tileAddr = (tileIndex << 4) | (_state.VideoRamAddr >> 12) | _flags.BackgroundPatternAddr;
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uint16_t shift = _state.VideoRamAddr&0x3FF;
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_nextTile.Attributes = ((_memoryManager->ReadVRAM(GetAttributeAddr()) >> shift) & 0x03) << 2;
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_nextTile.LowByte = _memoryManager->ReadVRAM(tileAddr);
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_nextTile.HighByte = _memoryManager->ReadVRAM(tileAddr + 8);
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}
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void PPU::LoadShiftRegisters()
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{
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_state.LowBitShift = (_state.LowBitShift << 8) | _nextTile.LowByte;
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_state.HighBitShift = (_state.HighBitShift << 8) | _nextTile.HighByte;
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}
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void PPU::DrawPixel()
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{
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uint8_t palette = 0;
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uint8_t tileXPixel = (_cycle - 1) % 8;
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uint32_t bufferPosition = _scanline * 256 + _cycle;
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uint8_t fineXScroll = _state.XScroll;
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uint8_t offset = (15 - tileXPixel - fineXScroll);
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uint8_t pixelColor = ((_state.LowBitShift >> offset) & 0x01) | (((_state.HighBitShift >> offset) & 0x01) << 1);
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// If we're grabbing the pixel from the high part of the shift register, use the buffered palette, not the current one
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if(offset < 8) {
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palette = GetBGPaletteEntry(_nextTile.Attributes, pixelColor);
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} else {
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palette = GetBGPaletteEntry(_currentTile.Attributes, pixelColor);
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}
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/*
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if(p->palettebuffer[fbRow].value != 0) {
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// Pixel is already rendered and priority
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// 1 means show behind background
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continue;
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}*/
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//p->palettebuffer[fbRow].color = PPU_PALETTE_RGB[palette % 64];
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((uint32_t*)_outputBuffer)[bufferPosition] = PPU_PALETTE_RGB[palette % 64] | (0xFF << 24);
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//p->palettebuffer[fbRow].value = pixel;
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//p->palettebuffer[fbRow].pindex = -1;
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}
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void PPU::ProcessVisibleScanline()
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{
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if((_cycle - 1) % 8 == 0 && _cycle <= 250) {
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LoadShiftRegisters();
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LoadTileInfo();
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} else if(_cycle == 321 || _cycle == 329) {
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LoadShiftRegisters();
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LoadTileInfo();
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}
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if(_cycle > 0 && _cycle <= 255) {
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DrawPixel();
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}
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if(IsRenderingEnabled()) {
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UpdateScrolling();
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}
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if(_cycle == 254) {
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//DrawScanline();
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if(_scanline == 239) {
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CopyFrame();
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//std::cout << std::endl << std::endl << std::endl;
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}
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if(_flags.BackgroundEnabled) {
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//Ppu_renderTileRow(p);
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}
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if(_flags.SpritesEnabled) {
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//Ppu_evaluateScanlineSprites(p, p->scanline);
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}
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}
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}
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void PPU::DrawScanline()
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{
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// Generates each tile, one scanline at a time and applies the palette
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// Move first tile into shift registers
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//PpuTileAttributes tileAttrs;
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//FetchTileAttributes(&tileAttrs);
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/* _state.LowBitShift = tileAttrs.low;
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_state.HighBitShift = tileAttrs.high;
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uint8_t attr = tileAttrs.attr;
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FetchTileAttributes(&tileAttrs);
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// Get second tile, move the pixels into the right side of
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// shift registers
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_state.LowBitShift = (_state.LowBitShift << 8) | tileAttrs.low;
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_state.HighBitShift = (_state.HighBitShift << 8) | tileAttrs.high;
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// Current tile to render is attrBuf
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uint8_t attrBuf = tileAttrs.attr;
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for(int x = 0; x < 32; x++) {
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int palette = 0;
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for(unsigned int b = 0; b < 8; b++) {
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int intB = b;
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int fbRow = _scanline * 256 + ((x * 8) + intB);
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unsigned int uintFineX = _state.XScroll;
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uint16_t pixel = (_state.LowBitShift >> (15 - b - uintFineX)) & 0x01;
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pixel += ((_state.HighBitShift >> (15 - b - uintFineX) & 0x01) << 1);
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// If we're grabbing the pixel from the high
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// part of the shift register, use the buffered
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// palette, not the current one
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if((15 - b - uintFineX) < 8) {
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palette = GetBGPaletteEntry(attrBuf, pixel);
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} else {
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palette = GetBGPaletteEntry(attr, pixel);
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}
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if(p->palettebuffer[fbRow].value != 0) {
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// Pixel is already rendered and priority
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// 1 means show behind background
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continue;
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}
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//p->palettebuffer[fbRow].color = PPU_PALETTE_RGB[palette % 64];
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_outputBuffer[fbRow] = PPU_PALETTE_RGB[palette % 64];
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//p->palettebuffer[fbRow].value = pixel;
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//p->palettebuffer[fbRow].pindex = -1;
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}
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// xcoord = p->registers.vramAddress & 0x1F
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attr = attrBuf;
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// Shift the first tile out, bring the new tile in
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FetchTileAttributes(&tileAttrs);
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_state.LowBitShift = (_state.LowBitShift << 8) | tileAttrs.low;
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_state.HighBitShift = (_state.HighBitShift << 8) | tileAttrs.high;
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attrBuf = tileAttrs.attr;
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}*/
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}
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uint8_t PPU::GetBGPaletteEntry(uint8_t a, uint16_t pix)
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{
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uint16_t baseAddr = 0x3F00;
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if(pix == 0x0) {
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return _memoryManager->ReadVRAM(baseAddr);
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}
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switch(a) {
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case 0x0:
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return _memoryManager->ReadVRAM(baseAddr + pix);
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case 0x4:
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return _memoryManager->ReadVRAM(baseAddr + 0x04 + pix);
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case 0x8:
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return _memoryManager->ReadVRAM(baseAddr + 0x08 + pix);
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case 0xC:
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return _memoryManager->ReadVRAM(baseAddr + 0x0C + pix);
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}
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return 0;
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}
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void PPU::CopyFrame()
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{
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int counter = PPU::WaitCounter.fetch_add(1);
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if(counter != 0) {
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//We weren't the first thread to increment the value, wait until other locks are released
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while(PPU::WaitCounter > 1) {}
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}
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memcpy(PPU::FrameBuffer, _outputBuffer, 256 * 240 * 4);
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PPU::WaitCounter--;
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}
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uint8_t* PPU::GetFrame()
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{
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uint8_t *copyBuffer = new uint8_t[256 * 240 * 4];
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int counter = PPU::WaitCounter.fetch_add(1);
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if(counter != 0) {
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//We weren't the first thread to increment the value, wait until other locks are released
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while(PPU::WaitCounter > 1) {}
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}
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memcpy(copyBuffer, PPU::FrameBuffer, 256 * 240 * 4);
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PPU::WaitCounter--;
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return copyBuffer;
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}
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void PPU::BeginVBlank()
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{
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if(_cycle == 1) {
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_statusFlags.VerticalBlank = true;
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/*if(!_suppressVBlank) {
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// We're in VBlank
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Ppu_setStatus(p, STATUS_VBLANK_STARTED);
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p->cycleCount = 0;
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}*/
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if(_flags.VBlank) {
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CPU::SetNMIFlag();
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}
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//Ppu_raster(p);
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|
}
|
|
}
|
|
|
|
void PPU::EndVBlank()
|
|
{
|
|
if(_cycle == 340) {
|
|
_frameCount++;
|
|
//std::cout << _frameCount << std::endl;
|
|
}
|
|
}
|
|
|
|
void PPU::Exec()
|
|
{
|
|
uint64_t equivalentCycleCount = CPU::GetCycleCount() * 3;
|
|
while(_cycleCount < equivalentCycleCount) {
|
|
if(_scanline == -1) {
|
|
ProcessPrerenderScanline();
|
|
} else if(_scanline < 240) {
|
|
ProcessVisibleScanline();
|
|
} else if(_scanline == 241) {
|
|
BeginVBlank();
|
|
} else if(_scanline == 260) {
|
|
EndVBlank();
|
|
}
|
|
|
|
if(_cycle == 340) {
|
|
_cycle = 0;
|
|
_scanline++;
|
|
|
|
if(_scanline == 261) {
|
|
_scanline = -1;
|
|
}
|
|
} else {
|
|
_cycle++;
|
|
}
|
|
|
|
_cycleCount++;
|
|
}
|
|
} |