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/*===================================================================*/
/* */
/* Mapper 73 (Konami VRC 3) */
/* */
/*===================================================================*/
BYTE Map73_IRQ_Enable;
DWORD Map73_IRQ_Cnt;
/*-------------------------------------------------------------------*/
/* Initialize Mapper 73 */
/*-------------------------------------------------------------------*/
void Map73_Init()
{
/* Initialize Mapper */
MapperInit = Map73_Init;
/* Write to Mapper */
MapperWrite = Map73_Write;
/* Write to SRAM */
MapperSram = Map0_Sram;
/* Write to APU */
MapperApu = Map0_Apu;
/* Read from APU */
MapperReadApu = Map0_ReadApu;
/* Callback at VSync */
MapperVSync = Map0_VSync;
/* Callback at HSync */
MapperHSync = Map73_HSync;
/* Callback at PPU */
MapperPPU = Map0_PPU;
/* Callback at Rendering Screen ( 1:BG, 0:Sprite ) */
MapperRenderScreen = Map0_RenderScreen;
/* Set SRAM Banks */
SRAMBANK = SRAM;
/* Set ROM Banks */
ROMBANK0 = ROMPAGE( 0 );
ROMBANK1 = ROMPAGE( 1 );
ROMBANK2 = ROMLASTPAGE( 1 );
ROMBANK3 = ROMLASTPAGE( 0 );
/* Initialize IRQ Registers */
Map73_IRQ_Enable = 0;
Map73_IRQ_Cnt = 0;
/* Set up wiring of the interrupt pin */
K6502_Set_Int_Wiring( 1, 1 );
}
/*-------------------------------------------------------------------*/
/* Mapper 73 Write Function */
/*-------------------------------------------------------------------*/
void Map73_Write( WORD wAddr, BYTE byData )
{
switch ( wAddr )
{
case 0x8000:
Map73_IRQ_Cnt = ( Map73_IRQ_Cnt & 0xfff0 ) | ( byData & 0x0f );
break;
case 0x9000:
Map73_IRQ_Cnt = ( Map73_IRQ_Cnt & 0xff0f ) | ( ( byData & 0x0f ) << 4 );
break;
case 0xa000:
Map73_IRQ_Cnt = ( Map73_IRQ_Cnt & 0xf0ff ) | ( ( byData & 0x0f ) << 8 );
break;
case 0xb000:
Map73_IRQ_Cnt = ( Map73_IRQ_Cnt & 0x0fff ) | ( ( byData & 0x0f ) << 12 );
break;
case 0xc000:
Map73_IRQ_Enable = byData;
break;
/* Set ROM Banks */
case 0xf000:
byData <<= 1;
byData %= ( NesHeader.byRomSize << 1 );
ROMBANK0 = ROMPAGE( byData );
ROMBANK1 = ROMPAGE( byData + 1 );
break;
}
}
/*-------------------------------------------------------------------*/
/* Mapper 73 H-Sync Function */
/*-------------------------------------------------------------------*/
void Map73_HSync()
{
/*
* Callback at HSync
*
*/
#if 1
if ( Map73_IRQ_Enable & 0x02 )
{
if ( ( Map73_IRQ_Cnt += STEP_PER_SCANLINE ) > 0xffff )
{
Map73_IRQ_Cnt &= 0xffff;
IRQ_REQ;
Map73_IRQ_Enable = 0;
}
}
#else
if ( Map73_IRQ_Enable )
{
if ( Map73_IRQ_Cnt > 0xffff - 114 )
{
IRQ_REQ;
Map73_IRQ_Enable = 0;
} else {
Map73_IRQ_Cnt += 114;
}
}
#endif
}
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