mapper252.cpp

著名的任天堂FC游戏机模拟器VirtuaNes 085版的源码!

//////////////////////////////////////////////////////////////////////////
// Mapper252                                                            //
//////////////////////////////////////////////////////////////////////////
void	Mapper252::Reset()
{
	for( INT i = 0; i < 8; i++ ) {
		reg[i] = i;
	}
	reg[8] = 0;

	irq_enable = 0;
	irq_counter = 0;
	irq_latch = 0;
	irq_clock = 0;
	irq_occur = 0;

	SetPROM_32K_Bank( 0, 1, PROM_8K_SIZE-2, PROM_8K_SIZE-1 );
	SetVROM_8K_Bank( 0 );

	nes->SetRenderMethod( NES::POST_RENDER );
}

void	Mapper252::Write( WORD addr, BYTE data )
{
	if( (addr & 0xF000) == 0x8000 ) {
		SetPROM_8K_Bank( 4, data );
		return;
	}
	if( (addr & 0xF000) == 0xA000 ) {
		SetPROM_8K_Bank( 5, data );
		return;
	}
	switch( addr & 0xF00C ) {
		case 0xB000:
			reg[0] = (reg[0] & 0xF0) | (data & 0x0F);
			SetVROM_1K_Bank( 0, reg[0] );
			break;	
		case 0xB004:
			reg[0] = (reg[0] & 0x0F) | ((data & 0x0F) << 4);
			SetVROM_1K_Bank( 0, reg[0] );
			break;
		case 0xB008:
			reg[1] = (reg[1] & 0xF0) | (data & 0x0F);
			SetVROM_1K_Bank( 1, reg[1] );
			break;
		case 0xB00C:
			reg[1] = (reg[1] & 0x0F) | ((data & 0x0F) << 4);
			SetVROM_1K_Bank( 1, reg[1] );
			break;

		case 0xC000:
			reg[2] = (reg[2] & 0xF0) | (data & 0x0F);
			SetVROM_1K_Bank( 2, reg[2] );
			break;
		case 0xC004:
			reg[2] = (reg[2] & 0x0F) | ((data & 0x0F) << 4);
			SetVROM_1K_Bank( 2, reg[2] );
			break;
		case 0xC008:
			reg[3] = (reg[3] & 0xF0) | (data & 0x0F);
			SetVROM_1K_Bank( 3, reg[3] );
			break;
		case 0xC00C:
			reg[3] = (reg[3] & 0x0F) | ((data & 0x0F) << 4);
			SetVROM_1K_Bank( 3, reg[3] );
			break;

		case 0xD000:
			reg[4] = (reg[4] & 0xF0) | (data & 0x0F);
			SetVROM_1K_Bank( 4, reg[4] );
			break;
		case 0xD004:
			reg[4] = (reg[4] & 0x0F) | ((data & 0x0F) << 4);
			SetVROM_1K_Bank( 4, reg[4] );
			break;
		case 0xD008:
			reg[5] = (reg[5] & 0xF0) | (data & 0x0F);
			SetVROM_1K_Bank( 5, reg[5] );
			break;
		case 0xD00C:
			reg[5] = (reg[5] & 0x0F) | ((data & 0x0F) << 4);
			SetVROM_1K_Bank( 5, reg[5] );
			break;

		case 0xE000:
			reg[6] = (reg[6] & 0xF0) | (data & 0x0F);
			SetVROM_1K_Bank( 6, reg[6] );
			break;
		case 0xE004:
			reg[6] = (reg[6] & 0x0F) | ((data & 0x0F) << 4);
			SetVROM_1K_Bank( 6, reg[6] );
			break;
		case 0xE008:
			reg[7] = (reg[7] & 0xF0) | (data & 0x0F);
			SetVROM_1K_Bank( 7, reg[7] );
			break;
		case 0xE00C:
			reg[7] = (reg[7] & 0x0F) | ((data & 0x0F) << 4);
			SetVROM_1K_Bank( 7, reg[7] );
			break;

		case 0xF000:
			irq_latch = (irq_latch & 0xF0) | (data & 0x0F);
			irq_occur = 0;
			break;
		case 0xF004:
			irq_latch = (irq_latch & 0x0F) | ((data & 0x0F) << 4);
			irq_occur = 0;
			break;

		case 0xF008:
			irq_enable = data & 0x03;
			if( irq_enable & 0x02 ) {
				irq_counter = irq_latch;
				irq_clock = 0;
			}
			irq_occur = 0;
			nes->cpu->ClrIRQ( IRQ_MAPPER );
			break;

		case 0xF00C:
			irq_enable = (irq_enable & 0x01) * 3;
			irq_occur = 0;
			nes->cpu->ClrIRQ( IRQ_MAPPER );
			break;
	}
}

void	Mapper252::Clock( INT cycles )
{
	if( irq_enable & 0x02 ) {
		if( (irq_clock+=cycles) >= 0x72 ) {
			irq_clock -= 0x72;
			if( irq_counter == 0xFF ) {
				irq_occur = 0xFF;
				irq_counter = irq_latch;
				irq_enable = (irq_enable & 0x01) * 3;

				nes->cpu->SetIRQ( IRQ_MAPPER );
			} else {
				irq_counter++;
			}
		}
//		if( irq_occur ) {
//			nes->cpu->IRQ_NotPending();
//		}
	}
}

void	Mapper252::SaveState( LPBYTE p )
{
	for( INT i = 0; i < 9; i++ ) {
		p[i] = reg[i];
	}
	p[ 9] = irq_enable;
	p[10] = irq_counter;
	p[11] = irq_latch;
	*(INT*)&p[12] = irq_clock;
}

void	Mapper252::LoadState( LPBYTE p )
{
	for( INT i = 0; i < 9; i++ ) {
		reg[i] = p[i];
	}
	irq_enable  = p[ 9];
	irq_counter = p[10];
	irq_latch   = p[11];
	irq_clock   = *(INT*)&p[12];
}