mapper017.cpp

著名的任天堂FC游戏机模拟器VirtuaNes 085版的源码!

//////////////////////////////////////////////////////////////////////////
// Mapper017  FFE F8xxx                                                 //
//////////////////////////////////////////////////////////////////////////
void	Mapper017::Reset()
{
	SetPROM_32K_Bank( 0, 1, PROM_8K_SIZE-2, PROM_8K_SIZE-1 );

	if( VROM_1K_SIZE ) {
		SetVROM_8K_Bank( 0 );
	}

	irq_enable = 0;
	irq_counter = 0;
	irq_latch = 0;
}

void	Mapper017::WriteLow( WORD addr, BYTE data )
{
	switch( addr ) {
		case	0x42FE:
			if( data&0x10 ) SetVRAM_Mirror( VRAM_MIRROR4H );
			else		SetVRAM_Mirror( VRAM_MIRROR4L );
			break;
		case	0x42FF:
			if( data&0x10 ) SetVRAM_Mirror( VRAM_HMIRROR );
			else		SetVRAM_Mirror( VRAM_VMIRROR );
			break;

		case	0x4501:
			irq_enable = 0;
			nes->cpu->ClrIRQ( IRQ_MAPPER );
			break;
		case	0x4502:
			irq_latch = (irq_latch&0xFF00)|data;
			break;
		case	0x4503:
			irq_latch = (irq_latch&0x00FF)|((INT)data<<8);
			irq_counter = irq_latch;
			irq_enable = 0xFF;
			break;

		case	0x4504:
		case	0x4505:
		case	0x4506:
		case	0x4507:
			SetPROM_8K_Bank( addr&0x07, data );
			break;

		case	0x4510:
		case	0x4511:
		case	0x4512:
		case	0x4513:
		case	0x4514:
		case	0x4515:
		case	0x4516:
		case	0x4517:
			SetVROM_1K_Bank( addr&0x07, data );
			break;

		default:
			Mapper::WriteLow( addr, data );
			break;
	}
}

void	Mapper017::HSync( INT scanline )
{
	if( irq_enable ) {
		if( irq_counter >= 0xFFFF-113 ) {
			nes->cpu->SetIRQ( IRQ_MAPPER );
//			nes->cpu->IRQ();
//			irq_counter = 0;
//			irq_enable = 0;
			irq_counter &= 0xFFFF;
		} else {
			irq_counter += 113;
		}
	}
}

void	Mapper017::SaveState( LPBYTE p )
{
	p[0] = irq_enable;
	*(INT*)&p[1] = irq_counter;
	*(INT*)&p[5] = irq_latch;
}

void	Mapper017::LoadState( LPBYTE p )
{
	irq_enable = p[0];
	irq_counter = *(INT*)&p[1];
	irq_latch   = *(INT*)&p[5];
}