private Instruction InterruptHandler(Interrupts interrupt)
{
// Handle interrupt with a CALL instruction to the interrupt handler
Instruction instruction = new Instruction();
instruction.OpCode = 0xCD; // CALL!
byte lowOpcode = (byte)instruction.OpCode;
instruction.Length = CPUInstructionLengths.Get(lowOpcode);
instruction.Literal = this.interruptHandlers[(Interrupts)interrupt];
instruction.Ticks = CPUInstructionPreClocks.Get(lowOpcode);
instruction.Name = CPUInstructionNames.Get(lowOpcode);
instruction.Description = CPUInstructionDescriptions.Get(lowOpcode);
// Disable interrupts during interrupt handling and clear the current one
this._interruptController.InterruptMasterEnable = false;
byte IF = this._memory.LowLevelRead((ushort)MMR.IF);
IF &= (byte)~(byte)interrupt;
this._memory.LowLevelWrite((ushort)MMR.IF, IF);
return instruction;
}
/// <summary>
/// Sets the initial values for the cpu registers and memory mapped registers.
/// This is the equivalent to run the BIOS rom.
/// </summary>
internal void Reset()
{
// Reset the clock state
_state.Clock = 0;
_state.Halted = false;
_state.HaltLoad = false;
_state.Stopped = false;
// Magic CPU initial values (after bios execution).
_state.Registers.A = 1;
_state.Registers.BC = 0x0013;
_state.Registers.DE = 0x00D8;
_state.Registers.HL = 0x014D;
_state.Registers.PC = 0x0100;
_state.Registers.SP = 0xFFFE;
// We restart the timer
_state.DivCounter = 0xABFF;
_state.TimaCounter = 0;
_state.TacCounter = 0;
_state.TacMask = 0;
_state.TmaValue = 0;
// Initialize memory mapped registers
this._memory.LowLevelWrite(0xFF04, 0xAB); // DIV
this._memory.LowLevelWrite(0xFF05, 0x00); // TIMA
this._memory.LowLevelWrite(0xFF06, 0x00); // TMA
this._memory.LowLevelWrite(0xFF07, 0x00); // TAC
this._memory.LowLevelWrite(0xFF10, 0x80); // NR10
this._memory.LowLevelWrite(0xFF11, 0xBF); // NR11
this._memory.LowLevelWrite(0xFF12, 0xF3); // NR12
this._memory.LowLevelWrite(0xFF14, 0xBF); // NR14
this._memory.LowLevelWrite(0xFF16, 0x3F); // NR21
this._memory.LowLevelWrite(0xFF17, 0x00); // NR22
this._memory.LowLevelWrite(0xFF19, 0xBF); // NR24
this._memory.LowLevelWrite(0xFF1A, 0x7F); // NR30
this._memory.LowLevelWrite(0xFF1B, 0xFF); // NR31
this._memory.LowLevelWrite(0xFF1C, 0x9F); // NR32
this._memory.LowLevelWrite(0xFF1E, 0xBF); // NR33
this._memory.LowLevelWrite(0xFF20, 0xFF); // NR41
this._memory.LowLevelWrite(0xFF21, 0x00); // NR42
this._memory.LowLevelWrite(0xFF22, 0x00); // NR43
this._memory.LowLevelWrite(0xFF23, 0xBF); // NR30
this._memory.LowLevelWrite(0xFF24, 0x77); // NR50
this._memory.LowLevelWrite(0xFF25, 0xF3); // NR51
this._memory.LowLevelWrite(0xFF26, 0xF1); // NR52 GB: 0xF1, SGB: 0xF0
this._memory.LowLevelWrite(0xFF40, 0x91); // LCDC
this._memory.LowLevelWrite(0xFF42, 0x00); // SCY
this._memory.LowLevelWrite(0xFF43, 0x00); // SCX
this._memory.LowLevelWrite(0xFF45, 0x00); // LYC
this._memory.LowLevelWrite(0xFF47, 0xFC); // BGP
this._memory.LowLevelWrite(0xFF48, 0xFF); // OBP0
this._memory.LowLevelWrite(0xFF49, 0xFF); // OBP1
this._memory.LowLevelWrite(0xFF4A, 0x00); // WY
this._memory.LowLevelWrite(0xFF4B, 0x00); // WX
this._memory.LowLevelWrite(0xFFFF, 0x00); // IE
_state.CurrentInstruction = new Instruction();
_exportInstruction = new Instruction();
}
internal void Reset()
{
_disInstructions = new List<IInstruction>();
_disVisitedAddresses = new HashSet<ushort>();
_disAddressToVisit = new Stack<ushort>();
_disassembledMatrix = new byte[0xFFFF][];
for (int i = 0; i < 0xFFFF; ++i)
{
_disassembledMatrix[i] = new byte[5];
}
_tempInstruction = new Instruction();
}
/// <summary>
/// Fetches and Decodes an instruction
/// </summary>
/// <param name="instruction">
/// As FetchAndDecode gets called *several* times a frame (and many times during
/// disassembly), it is better to have a pre-allocated instruction and to replace
/// the values, instead of getting the overhead of allocating a new Instrucion
/// everytime.
/// </param>
/// <param name="instructionAddress"></param>
/// <param name="haltLoad"></param>
/// <returns></returns>
internal Instruction FetchAndDecode(ref Instruction instruction,
ushort instructionAddress, bool haltLoad = false)
{
instruction.Address = instructionAddress;
byte opcode = this._memory.LowLevelRead(instructionAddress);
instruction.OpCode = opcode;
if (instruction.OpCode != 0xCB)
{
instruction.CB = false;
byte lowOpcode = (byte)instruction.OpCode;
if (_instructionHistogram[lowOpcode] < ushort.MaxValue)
_instructionHistogram[lowOpcode]++;
// Normal instructions
instruction.Length = CPUInstructionLengths.Get(lowOpcode);
// Extract literal
if (instruction.Length == 2)
{
// 8 bit literal
instruction.Operands[0] = this._memory.LowLevelRead((ushort)(instructionAddress + 1));
if (haltLoad)
{
instruction.Operands[0] = opcode;
}
instruction.Literal = (byte)instruction.Operands[0];
}
else if (instruction.Length == 3)
{
// 16 bit literal, little endian
instruction.Operands[0] = this._memory.LowLevelRead((ushort)(instructionAddress + 2));
instruction.Operands[1] = this._memory.LowLevelRead((ushort)(instructionAddress + 1));
if (haltLoad)
{
instruction.Operands[1] = instruction.Operands[0];
instruction.Operands[0] = opcode;
}
instruction.Literal = (byte)instruction.Operands[1];
instruction.Literal += (ushort)(instruction.Operands[0] << 8);
}
instruction.Ticks = CPUInstructionPreClocks.Get(lowOpcode);
instruction.Name = CPUInstructionNames.Get(lowOpcode);
instruction.Description = CPUInstructionDescriptions.Get(lowOpcode);
}
else
{
instruction.CB = true;
// CB instructions block
instruction.OpCode <<= 8;
if (!haltLoad)
{
instruction.OpCode += this._memory.LowLevelRead((ushort)(instructionAddress + 1));
}
else
{
instruction.OpCode += 0xCB; // The first byte is duplicated
}
byte lowOpcode = (byte)instruction.OpCode;
if (_cbInstructionHistogram[lowOpcode] < ushort.MaxValue)
{
_cbInstructionHistogram[lowOpcode]++;
}
instruction.Length = CPUCBInstructionLengths.Get(lowOpcode);
// There is no literal in CB instructions!
//instruction.Lambda = this.CBInstructionLambdas[lowOpcode];
instruction.Ticks = CPUCBInstructionPreClocks.Get(lowOpcode);
instruction.Name = CPUCBInstructionNames.Get(lowOpcode);
instruction.Description = CPUCBInstructionDescriptions.Get(lowOpcode);
}
// NOTE(Cristian): On haltLoad (HALT with IME disabled), the next byte after the HALT opcode
// is "duplicated". This is a hardware bug.
if (haltLoad)
{
instruction.Length--;
}
return instruction;
}
public IInstruction FetchAndDecode(ushort address)
{
Instruction inst = new Instruction();
_cpu.FetchAndDecode(ref inst, address);
return inst;
}