282 lines
5.3 KiB
C++
282 lines
5.3 KiB
C++
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/////////////////////////////////////////////////////////////////////
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// Mapper 100
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void NES_mapper100::Reset()
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{
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// clear registers FIRST!!!
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for(int i = 0; i < 8; i++) regs[i] = 0x00;
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// set CPU bank pointers
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prg0 = 0;
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prg1 = 1;
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prg2 = num_8k_ROM_banks - 2;
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prg3 = num_8k_ROM_banks - 1;
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MMC3_set_CPU_banks();
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// set VROM banks
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if(num_1k_VROM_banks)
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{
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chr0 = 0;
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chr1 = 1;
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chr2 = 2;
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chr3 = 3;
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chr4 = 4;
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chr5 = 5;
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chr6 = 6;
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chr7 = 7;
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MMC3_set_PPU_banks();
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}
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else
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{
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chr0 = chr2 = chr4 = chr5 = chr6 = chr7 = 0;
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chr1 = chr3 = 1;
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}
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irq_enabled = 0;
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irq_counter = 0;
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irq_latch = 0;
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}
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void NES_mapper100::MemoryWrite(uint32 addr, uint8 data)
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{
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switch(addr & 0xE001)
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{
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case 0x8000:
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{
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regs[0] = data;
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}
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break;
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case 0x8001:
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{
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uint32 bank_num;
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regs[1] = data;
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bank_num = regs[1];
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switch(regs[0] & 0xC7)
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{
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case 0x00:
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{
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if(num_1k_VROM_banks)
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{
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bank_num &= 0xfe;
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chr0 = bank_num;
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chr1 = bank_num + 1;
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MMC3_set_PPU_banks();
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}
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}
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break;
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case 0x01:
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{
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if(num_1k_VROM_banks)
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{
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bank_num &= 0xfe;
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chr2 = bank_num;
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chr3 = bank_num + 1;
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MMC3_set_PPU_banks();
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}
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}
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break;
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case 0x02:
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{
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if(num_1k_VROM_banks)
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{
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chr4 = bank_num;
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MMC3_set_PPU_banks();
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}
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}
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break;
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case 0x03:
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{
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if(num_1k_VROM_banks)
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{
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chr5 = bank_num;
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MMC3_set_PPU_banks();
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}
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}
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break;
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case 0x04:
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{
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if(num_1k_VROM_banks)
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{
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chr6 = bank_num;
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MMC3_set_PPU_banks();
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}
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}
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break;
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case 0x05:
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{
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if(num_1k_VROM_banks)
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{
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chr7 = bank_num;
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MMC3_set_PPU_banks();
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}
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}
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break;
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case 0x06:
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{
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prg0 = bank_num;
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MMC3_set_CPU_banks();
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}
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break;
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case 0x07:
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{
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prg1 = bank_num;
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MMC3_set_CPU_banks();
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}
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break;
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case 0x46:
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{
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prg2 = bank_num;
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MMC3_set_CPU_banks();
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}
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break;
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case 0x47:
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{
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prg3 = bank_num;
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MMC3_set_CPU_banks();
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}
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break;
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case 0x80:
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{
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if(num_1k_VROM_banks)
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{
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bank_num &= 0xfe;
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chr4 = bank_num;
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chr5 = bank_num + 1;
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MMC3_set_PPU_banks();
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}
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}
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break;
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case 0x81:
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{
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if(num_1k_VROM_banks)
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{
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bank_num &= 0xfe;
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chr6 = bank_num;
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chr7 = bank_num + 1;
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MMC3_set_PPU_banks();
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}
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}
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break;
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case 0x82:
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{
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if(num_1k_VROM_banks)
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{
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chr0 = bank_num;
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MMC3_set_PPU_banks();
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}
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}
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break;
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case 0x83:
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{
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if(num_1k_VROM_banks)
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{
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chr1 = bank_num;
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MMC3_set_PPU_banks();
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}
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}
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break;
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case 0x84:
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{
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if(num_1k_VROM_banks)
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{
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chr2 = bank_num;
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MMC3_set_PPU_banks();
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}
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}
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break;
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case 0x85:
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{
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if(num_1k_VROM_banks)
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{
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chr3 = bank_num;
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MMC3_set_PPU_banks();
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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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break;
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case 0xA000:
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{
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regs[2] = data;
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if(parent_NES->ROM->get_mirroring() != NES_PPU::MIRROR_FOUR_SCREEN)
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{
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if(data & 0x01)
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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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}
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break;
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case 0xA001:
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{
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regs[3] = data;
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}
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break;
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case 0xC000:
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regs[4] = data;
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irq_counter = regs[4];
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break;
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case 0xC001:
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regs[5] = data;
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irq_latch = regs[5];
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break;
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case 0xE000:
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regs[6] = data;
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irq_enabled = 0;
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break;
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case 0xE001:
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regs[7] = data;
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irq_enabled = 1;
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break;
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}
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}
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void NES_mapper100::HSync(uint32 scanline)
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{
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if(irq_enabled)
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{
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if((scanline >= 0) && (scanline <= 239))
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{
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if(parent_NES->ppu->spr_enabled() || parent_NES->ppu->bg_enabled())
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{
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if(!(irq_counter--))
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{
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irq_counter = irq_latch;
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parent_NES->cpu->DoIRQ();
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}
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}
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}
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}
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}
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/////////////////////////////////////////////////////////////////////
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