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MMU.cs
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using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace GBEmu
{
static class MMU
{
// Flag to indicate the bios is mapped
// BIOS is unmapped with the first instruction above 0x00FF
private static bool inBios = true;
// Memory regions
private static byte[] bios;
private static byte[] rom;
private static byte[] wram;
private static byte[] eram;
private static byte[] zram;
public enum HardwareRegisters
{
// Name, Address, Usage
P1 = 0xFF00, // Joypad information
SB = 0xFF01, // Serial Transfer Data
SC = 0xFF02, // Serial I/O Control
DIV = 0xFF04, // Timer Divider
TIMA = 0xFF05, // Timer Counter
TMA = 0xFF06, // Timer Modulo
TAC = 0xFF07, // Timer Control
IF = 0xFF0F, // Interrupt Flag
NR10 = 0xFF10, // Sound Mode 1, Sweep
NR11 = 0xFF11, // Sound Mode 1, Sound length/Wave pattern duty
NR12 = 0xFF12, // Sound Mode 1, Envelope
NR13 = 0xFF13, // Sound Mode 1, Frequency Low
NR14 = 0xFF14, // Sound Mode 1, Frequency High
NR21 = 0xFF16, // Sound Mode 2, Sound length/Wave pattern duty
NR22 = 0xFF17, // Sound Mode 2, Envelope
NR23 = 0xFF18, // Sound Mode 2, Frequency Low
NR24 = 0xFF19, // Sound Mode 2, Frequency High
NR30 = 0xFF1A, // Sound Mode 3, Sound on/off
NR31 = 0xFF1B, // Sound Mode 3, Sound length
NR32 = 0xFF1C, // Sound Mode 3, Select output level
NR33 = 0xFF1D, // Sound Mode 3, Frequency Low
NR34 = 0xFF1E, // Sound Mode 3, Frequency High
NR41 = 0xFF20, // Sound Mode 4, Sound length
NR42 = 0xFF21, // Sound Mode 4, Envelope
NR43 = 0xFF22, // Sound Mode 4, Polynomial counter
NR44 = 0xFF23, // Sound Mode 4, Counter/Consecutive, Initial
NR50 = 0xFF24, // Sound Mode 5, Channel Control, On/Off, Volume
NR51 = 0xFF25, // Sound Mode 5, Select of sound output terminal
NR52 = 0xFF26, // Sound Mode 5, Sound On/Off
WAV00 = 0xFF30, // Wave pattern RAM 16bytes
WAV01 = 0xFF31,
WAV02 = 0xFF32,
WAV03 = 0xFF33,
WAV04 = 0xFF34,
WAV05 = 0xFF35,
WAV06 = 0xFF36,
WAV07 = 0xFF37,
WAV08 = 0xFF38,
WAV09 = 0xFF39,
WAV10 = 0xFF3A,
WAV11 = 0xFF3B,
WAV12 = 0xFF3C,
WAV13 = 0xFF3D,
WAV14 = 0xFF3E,
WAV15 = 0xFF3F,
LCDC = 0xFF40, // LCD Control
STAT = 0xFF41, // LCD Status
SCY = 0xFF42, // Scroll Screen Y
SCX = 0xFF43, // Scroll Screen X
LY = 0xFF44, // LCDC Y-Coord
LYC = 0xFF45, // LY Compare
DMA = 0xFF46, // DMA Transfer
BGP = 0xFF47, // Background Palette Data
OBP0 = 0xFF48, // Object Palette 0 Data
OBP1 = 0xFF49, // Object Palette 1 Data
WY = 0xFF4A, // Window Y Position
WX = 0xFF4B, // Window X Position
// Some GBC only registers, ignored here (at least now...)
IE = 0xFFFF // Interrupt enable
}
static MMU()
{
MMU.bios = new byte[] {
0x31, 0xFE, 0xFF, 0xAF, 0x21, 0xFF, 0x9F, 0x32, 0xCB, 0x7C, 0x20, 0xFB, 0x21, 0x26, 0xFF, 0x0E,
0x11, 0x3E, 0x80, 0x32, 0xE2, 0x0C, 0x3E, 0xF3, 0xE2, 0x32, 0x3E, 0x77, 0x77, 0x3E, 0xFC, 0xE0,
0x47, 0x11, 0x04, 0x01, 0x21, 0x10, 0x80, 0x1A, 0xCD, 0x95, 0x00, 0xCD, 0x96, 0x00, 0x13, 0x7B,
0xFE, 0x34, 0x20, 0xF3, 0x11, 0xD8, 0x00, 0x06, 0x08, 0x1A, 0x13, 0x22, 0x23, 0x05, 0x20, 0xF9,
0x3E, 0x19, 0xEA, 0x10, 0x99, 0x21, 0x2F, 0x99, 0x0E, 0x0C, 0x3D, 0x28, 0x08, 0x32, 0x0D, 0x20,
0xF9, 0x2E, 0x0F, 0x18, 0xF3, 0x67, 0x3E, 0x64, 0x57, 0xE0, 0x42, 0x3E, 0x91, 0xE0, 0x40, 0x04,
0x1E, 0x02, 0x0E, 0x0C, 0xF0, 0x44, 0xFE, 0x90, 0x20, 0xFA, 0x0D, 0x20, 0xF7, 0x1D, 0x20, 0xF2,
0x0E, 0x13, 0x24, 0x7C, 0x1E, 0x83, 0xFE, 0x62, 0x28, 0x06, 0x1E, 0xC1, 0xFE, 0x64, 0x20, 0x06,
0x7B, 0xE2, 0x0C, 0x3E, 0x87, 0xF2, 0xF0, 0x42, 0x90, 0xE0, 0x42, 0x15, 0x20, 0xD2, 0x05, 0x20,
0x4F, 0x16, 0x20, 0x18, 0xCB, 0x4F, 0x06, 0x04, 0xC5, 0xCB, 0x11, 0x17, 0xC1, 0xCB, 0x11, 0x17,
0x05, 0x20, 0xF5, 0x22, 0x23, 0x22, 0x23, 0xC9, 0xCE, 0xED, 0x66, 0x66, 0xCC, 0x0D, 0x00, 0x0B,
0x03, 0x73, 0x00, 0x83, 0x00, 0x0C, 0x00, 0x0D, 0x00, 0x08, 0x11, 0x1F, 0x88, 0x89, 0x00, 0x0E,
0xDC, 0xCC, 0x6E, 0xE6, 0xDD, 0xDD, 0xD9, 0x99, 0xBB, 0xBB, 0x67, 0x63, 0x6E, 0x0E, 0xEC, 0xCC,
0xDD, 0xDC, 0x99, 0x9F, 0xBB, 0xB9, 0x33, 0x3E, 0x3c, 0x42, 0xB9, 0xA5, 0xB9, 0xA5, 0x42, 0x4C,
0x21, 0x04, 0x01, 0x11, 0xA8, 0x00, 0x1A, 0x13, 0xBE, 0x20, 0xFE, 0x23, 0x7D, 0xFE, 0x34, 0x20,
0xF5, 0x06, 0x19, 0x78, 0x86, 0x23, 0x05, 0x20, 0xFB, 0x86, 0x20, 0xFE, 0x3E, 0x01, 0xE0, 0x50
};
MMU.rom = new byte[0x8000];
MMU.wram = new byte[0x2000];
MMU.eram = new byte[0x2000];
MMU.zram = new byte[0xFF];
MMU.reset();
}
public static void load(String pathToRom)
{
MMU.rom = System.IO.File.ReadAllBytes(pathToRom);
}
public static void reset()
{
// CLEAR ALL THE RAMS
if (MMU.rom == null)
{
}
for (int i=0; i < 0x2000; i++)
{
MMU.wram[i] = 0;
MMU.eram[i] = 0;
}
for (int i = 0; i < 127; i++)
{
MMU.zram[i] = 0;
}
MMU.inBios = true;
}
public static byte readByte(UInt16 addr)
{
switch (addr & 0xF000)
{
// BIOS (256b)/ROM0
case 0x0000:
if (MMU.inBios)
{
if (addr < 0x0100)
{
return MMU.bios[addr];
}
else if (addr == 0x0100)
{
MMU.inBios = false;
}
}
return MMU.rom[addr];
// ROM 0 (16k)
case 0x1000: goto case 0x3000;
case 0x2000: goto case 0x3000;
case 0x3000:
return MMU.rom[addr];
// ROM 1 (switchable) (16k)
case 0x4000: goto case 0x7000;
case 0x5000: goto case 0x7000;
case 0x6000: goto case 0x7000;
case 0x7000:
return MMU.rom[addr];
// Video/Graphics RAM
case 0x8000: goto case 0x9000;
case 0x9000:
return GPU.vram[addr & 0x1FFF];
// External RAM
case 0xA000: goto case 0xB000;
case 0xB000:
return eram[addr & 0x1FFF];
// Working RAM
case 0xC000: goto case 0xD000;
case 0xD000:
return wram[addr & 0x1FFF];
// Working RAM shadow
case 0xE000:
return wram[addr & 0x1FFF];
// Working RAM shadow, graphics sprite info, memory mapped IO and Zero-page RAM
case 0xF000:
switch (addr & 0x0F00)
{
// Working RAM shadow
case 0x100: goto case 0xD00;
case 0x200: goto case 0xD00;
case 0x300: goto case 0xD00;
case 0x400: goto case 0xD00;
case 0x500: goto case 0xD00;
case 0x600: goto case 0xD00;
case 0x700: goto case 0xD00;
case 0x800: goto case 0xD00;
case 0x900: goto case 0xD00;
case 0xA00: goto case 0xD00;
case 0xB00: goto case 0xD00;
case 0xC00: goto case 0xD00;
case 0xD00:
return wram[addr & 0x1FFF];
// Graphics sprite information, object attribute memory
// 160 bytes long, remaining bytes read as 0
case 0xE00:
if (addr < 0xFEA0)
{
return GPU.oam[addr - 0xFE00];
}
else
{
return 0;
}
// Zero page / Memory mapped IO
case 0xF00:
if (addr >= 0xFF80)
{
return MMU.zram[addr & 0x7F];
}
else
{
// Memory Mapped IO
switch (addr & 0x00F0)
{
// GPU (64 registers)
case 0x40: goto case 0x70;
case 0x50: goto case 0x70;
case 0x60: goto case 0x70;
case 0x70:
return GPU.readByte(addr);
}
return 0;
}
// No match found, return 0
default:
return 0;
}
default:
return 0;
}
}
public static UInt16 readWord(UInt16 addr)
{
return (UInt16)(MMU.readByte(addr) + (MMU.readByte((UInt16)(addr + 1)) << 8));
}
public static void writeByte(UInt16 addr, byte val)
{
switch (addr & 0xF000)
{
// BIOS (256b)/ROM0
case 0x0000:
if (MMU.inBios && addr <= 0x0100) return;
break;
// Fall through, you don't write to the ROM... YET
case 0x1000: goto case 0x3000;
case 0x2000: goto case 0x3000;
case 0x3000:
break;
// ROM 1 (switchable) (16k)
case 0x4000: goto case 0x7000;
case 0x5000: goto case 0x7000;
case 0x6000: goto case 0x7000;
case 0x7000:
break;
// Video/Graphics RAM
case 0x8000: goto case 0x9000;
case 0x9000:
GPU.vram[addr & 0x1FFF] = val;
break;
// External RAM
case 0xA000: goto case 0xB000;
case 0xB000:
MMU.eram[addr & 0x1FFF] = val;
break;
// Working RAM
case 0xC000: goto case 0xD000;
case 0xD000:
MMU.wram[addr & 0x1FFF] = val;
break;
// Working RAM shadow
case 0xE000:
MMU.wram[addr & 0x1FFF] = val;
break;
// Working RAM shadow, graphics sprite info, memory mapped IO and Zero-page RAM
case 0xF000:
switch (addr & 0x0F00)
{
// Working RAM shadow
case 0x100: goto case 0xD00;
case 0x200: goto case 0xD00;
case 0x300: goto case 0xD00;
case 0x400: goto case 0xD00;
case 0x500: goto case 0xD00;
case 0x600: goto case 0xD00;
case 0x700: goto case 0xD00;
case 0x800: goto case 0xD00;
case 0x900: goto case 0xD00;
case 0xA00: goto case 0xD00;
case 0xB00: goto case 0xD00;
case 0xC00: goto case 0xD00;
case 0xD00:
MMU.wram[addr & 0x1FFF] = val;
break;
// Graphics sprite information, object attribute memory
// 160 bytes long, remaining bytes read as 0
case 0xE00:
if (addr < 0xFEA0)
{
GPU.oam[addr - 0xFE00] = val;
}
break;
// Zero page / Memory mapped IO
case 0xF00:
if (addr >= 0xFF80)
{
MMU.zram[addr & 0x7F] = val;
break;
}
else
{
// Memory Mapped IO
switch (addr & 0x00F0)
{
// GPU (64 registers)
case 0x40: goto case 0x70;
case 0x50: goto case 0x70;
case 0x60: goto case 0x70;
case 0x70:
GPU.writeByte(addr, val);
break;
}
break;
}
// No match found, return 0
default:
break;
}
break;
default:
break;
}
}
public static void writeWord(UInt16 addr, UInt16 val)
{
MMU.writeByte(addr, (byte)(val & 0x00FF));
MMU.writeByte((UInt16)(addr + 1), (byte)(val >> 8));
}
}
}