AxibugEmuOnline/References/virtuanessrc097-master/NES/Mapper/Mapper251.cpp

<EFBFBD><EFBFBD>//////////////////////////////////////////////////////////////////////////
// Mapper251                                                            //
//////////////////////////////////////////////////////////////////////////
void	Mapper251::Reset()
{
	SetPROM_32K_Bank( 0, 1, PROM_8K_SIZE-2, PROM_8K_SIZE-1 );

	SetVRAM_Mirror( VRAM_VMIRROR );

	INT	i;
	for( i = 0; i < 11; i++ )
		reg[i] = 0;
	for( i = 0; i < 4; i++ )
		breg[i] = 0;
}

void	Mapper251::WriteLow( WORD addr, BYTE data )
{
	if( (addr & 0xE001) == 0x6000 ) {
		if( reg[9] ) {
			breg[reg[10]++] = data;
			if( reg[10] == 4 ) {
				reg[10] = 0;
				SetBank();
			}
		}
	}
}

void	Mapper251::Write( WORD addr, BYTE data )
{
	switch( addr & 0xE001 ) {
		case	0x8000:
			reg[8] = data;
			SetBank();
			break;
		case	0x8001:
			reg[reg[8]&0x07] = data;
			SetBank();
			break;
		case	0xA001:
			if( data & 0x80 ) {
				reg[ 9] = 1;
				reg[10] = 0;
			} else {
				reg[ 9] = 0;
			}
			break;
	}
}

void	Mapper251::SetBank()
{
	INT	chr[6];
	INT	prg[4];

	for( INT i = 0; i < 6; i++ ) {
		chr[i] = (reg[i]|(breg[1]<<4)) & ((breg[2]<<4)|0x0F);
	}

	if( reg[8] & 0x80 ) {
		SetVROM_8K_Bank(chr[2],chr[3],chr[4],chr[5],chr[0],chr[0]+1,chr[1],chr[1]+1);
	} else {
		SetVROM_8K_Bank(chr[0],chr[0]+1,chr[1],chr[1]+1,chr[2],chr[3],chr[4],chr[5]);
	}

	prg[0] = (reg[6]&((breg[3]&0x3F)^0x3F))|(breg[1]);
	prg[1] = (reg[7]&((breg[3]&0x3F)^0x3F))|(breg[1]);
	prg[2] = prg[3] =((breg[3]&0x3F)^0x3F)|(breg[1]);
	prg[2] &= PROM_8K_SIZE-1;

	if( reg[8] & 0x40 ) {
		SetPROM_32K_Bank( prg[2],prg[1],prg[0],prg[3] );
	} else {
		SetPROM_32K_Bank( prg[0],prg[1],prg[2],prg[3] );
	}
}

void	Mapper251::SaveState( LPBYTE p )
{
	INT	i;

	for( i = 0; i < 11; i++ ) {
		p[i] = reg[i];
	}
	for( i = 0; i < 4; i++ ) {
		p[i+11] = breg[i];
	}
}

void	Mapper251::LoadState( LPBYTE p )
{
	INT	i;
	for( i = 0; i < 11; i++ ) {
		reg[i] = p[i];
	}
	for( i = 0; i < 4; i++ ) {
		reg[i] = p[i+11];
	}
}