73 lines
1.2 KiB
C++
73 lines
1.2 KiB
C++
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/////////////////////////////////////////////////////////////////////
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// Mapper 42
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void NES_mapper42::Reset()
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{
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// set CPU bank pointers
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set_CPU_bank3(0);
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set_CPU_bank4(num_8k_ROM_banks-4);
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set_CPU_bank5(num_8k_ROM_banks-3);
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set_CPU_bank6(num_8k_ROM_banks-2);
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set_CPU_bank7(num_8k_ROM_banks-1);
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// set PPU bank pointers
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set_PPU_banks(0,1,2,3,4,5,6,7);
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}
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void NES_mapper42::MemoryWrite(uint32 addr, uint8 data)
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{
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switch(addr & 0xE003)
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{
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case 0xE000:
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{
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set_CPU_bank3(data & 0x0F);
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}
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break;
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case 0xE001:
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{
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if(data & 0x08)
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{
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set_mirroring(NES_PPU::MIRROR_HORIZ);
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}
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else
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{
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set_mirroring(NES_PPU::MIRROR_VERT);
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}
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}
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break;
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case 0xE002:
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{
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if(data & 0x02)
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{
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irq_enabled = 1;
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}
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else
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{
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irq_enabled = 0;
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irq_counter = 0;
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}
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}
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break;
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}
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}
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void NES_mapper42::HSync(uint32 scanline)
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{
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if(irq_enabled)
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{
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if(irq_counter < 215)
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{
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irq_counter++;
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}
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if(irq_counter == 215)
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{
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parent_NES->cpu->DoIRQ();
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irq_enabled = 0;
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}
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}
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}
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/////////////////////////////////////////////////////////////////////
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