341 lines
6.4 KiB
C++
341 lines
6.4 KiB
C++
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/////////////////////////////////////////////////////////////////////
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// Mapper 90
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void NES_mapper90::Reset()
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{
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// set CPU bank pointers
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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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irq_counter = 0;
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irq_latch = 0;
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irq_enabled = 0;
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for(uint8 i = 0; i < 4; i++)
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{
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prg_reg[i] = num_8k_ROM_banks-4+i;
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nam_low_reg[i] = 0;
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nam_high_reg[i] = 0;
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chr_low_reg[i] = i;
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chr_high_reg[i] = 0;
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chr_low_reg[i+4] = i+4;
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chr_high_reg[i+4] = 0;
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}
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}
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uint8 NES_mapper90::MemoryReadLow(uint32 addr)
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{
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if(addr == 0x5000)
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{
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return (uint8)(value1*value2 & 0x00FF);
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}
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else
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{
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return (uint8)(addr >> 8);
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}
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}
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void NES_mapper90::MemoryWriteLow(uint32 addr, uint8 data)
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{
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if(addr == 0x5000)
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{
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value1 = data;
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}
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else if(addr == 0x5001)
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{
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value2 = data;
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}
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}
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void NES_mapper90::MemoryWrite(uint32 addr, uint8 data)
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{
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switch(addr)
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{
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case 0x8000:
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case 0x8001:
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case 0x8002:
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case 0x8003:
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{
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prg_reg[addr & 0x03] = data;
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Sync_Prg_Banks();
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}
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break;
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case 0x9000:
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case 0x9001:
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case 0x9002:
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case 0x9003:
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case 0x9004:
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case 0x9005:
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case 0x9006:
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case 0x9007:
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{
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chr_low_reg[addr & 0x07] = data;
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Sync_Chr_Banks();
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}
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break;
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case 0xA000:
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case 0xA001:
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case 0xA002:
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case 0xA003:
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case 0xA004:
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case 0xA005:
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case 0xA006:
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case 0xA007:
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{
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chr_high_reg[addr & 0x07] = data;
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Sync_Chr_Banks();
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}
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break;
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case 0xB000:
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case 0xB001:
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case 0xB002:
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case 0xB003:
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{
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nam_low_reg[addr & 0x03] = data;
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Sync_Mirror();
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}
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break;
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case 0xB004:
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case 0xB005:
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case 0xB006:
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case 0xB007:
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{
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nam_high_reg[addr & 0x03] = data;
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Sync_Mirror();
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}
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break;
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case 0xC002:
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{
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irq_enabled = 0;
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}
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break;
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case 0xC003:
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case 0xC004:
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{
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if(irq_enabled == 0)
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{
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irq_enabled = 1;
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irq_counter = irq_latch;
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}
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}
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break;
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case 0xC005:
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{
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irq_counter = data;
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irq_latch = data;
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}
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break;
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case 0xD000:
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{
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prg_bank_6000 = data & 0x80;
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prg_bank_e000 = data & 0x04;
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prg_bank_size = data & 0x03;
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chr_bank_size = (data & 0x18) >> 3;
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mirror_mode = data & 0x20;
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Sync_Prg_Banks();
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Sync_Chr_Banks();
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Sync_Mirror();
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}
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break;
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case 0xD001:
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{
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mirror_type = data & 0x03;
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Sync_Mirror();
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}
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break;
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case 0xD003:
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{
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// bank page
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}
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break;
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}
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}
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void NES_mapper90::HSync(uint32 scanline)
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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 == 0)
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{
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if(irq_enabled)
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{
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parent_NES->cpu->DoIRQ();
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}
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irq_latch = 0;
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irq_enabled = 0;
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}
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else
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{
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irq_counter--;
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}
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}
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}
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}
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void NES_mapper90::Sync_Mirror()
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{
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uint8 i;
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uint32 nam_bank[4];
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for(i = 0; i < 4; i++)
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{
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nam_bank[i] = ((uint32)nam_high_reg[i] << 8) | (uint32)nam_low_reg[i];
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}
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if(mirror_mode)
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{
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for(i = 0; i < 4; i++)
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{
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if(!nam_high_reg[i] && (nam_low_reg[i] == i))
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{
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mirror_mode = 0;
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}
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}
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if(mirror_mode)
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{
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set_PPU_bank8(nam_bank[0]);
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set_PPU_bank9(nam_bank[1]);
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set_PPU_bank10(nam_bank[2]);
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set_PPU_bank11(nam_bank[3]);
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}
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}
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else
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{
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if(mirror_type == 0)
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{
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set_mirroring(NES_PPU::MIRROR_VERT);
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}
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else if(mirror_type == 1)
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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(0,0,0,0);
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}
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}
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}
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void NES_mapper90::Sync_Chr_Banks()
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{
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uint8 i;
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uint32 chr_bank[8];
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for(i = 0; i < 8; i++)
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{
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chr_bank[i] = ((uint32)chr_high_reg[i] << 8) | (uint32)chr_low_reg[i];
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}
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if(chr_bank_size == 0)
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{
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set_PPU_bank0(chr_bank[0]*8+0);
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set_PPU_bank1(chr_bank[0]*8+1);
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set_PPU_bank2(chr_bank[0]*8+2);
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set_PPU_bank3(chr_bank[0]*8+3);
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set_PPU_bank4(chr_bank[0]*8+4);
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set_PPU_bank5(chr_bank[0]*8+5);
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set_PPU_bank6(chr_bank[0]*8+6);
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set_PPU_bank7(chr_bank[0]*8+7);
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}
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else if(chr_bank_size == 1)
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{
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set_PPU_bank0(chr_bank[0]*4+0);
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set_PPU_bank1(chr_bank[0]*4+1);
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set_PPU_bank2(chr_bank[0]*4+2);
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set_PPU_bank3(chr_bank[0]*4+3);
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set_PPU_bank4(chr_bank[4]*4+0);
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set_PPU_bank5(chr_bank[4]*4+1);
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set_PPU_bank6(chr_bank[4]*4+2);
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set_PPU_bank7(chr_bank[4]*4+3);
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}
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else if(chr_bank_size == 2)
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{
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set_PPU_bank0(chr_bank[0]*2+0);
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set_PPU_bank1(chr_bank[0]*2+1);
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set_PPU_bank2(chr_bank[2]*2+0);
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set_PPU_bank3(chr_bank[2]*2+1);
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set_PPU_bank4(chr_bank[4]*2+0);
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set_PPU_bank5(chr_bank[4]*2+1);
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set_PPU_bank6(chr_bank[6]*2+0);
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set_PPU_bank7(chr_bank[6]*2+1);
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}
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else
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{
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set_PPU_bank0(chr_bank[0]);
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set_PPU_bank1(chr_bank[1]);
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set_PPU_bank2(chr_bank[2]);
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set_PPU_bank3(chr_bank[3]);
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set_PPU_bank4(chr_bank[4]);
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set_PPU_bank5(chr_bank[5]);
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set_PPU_bank6(chr_bank[6]);
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set_PPU_bank7(chr_bank[7]);
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}
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}
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void NES_mapper90::Sync_Prg_Banks()
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{
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if(prg_bank_size == 0)
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{
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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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}
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else if(prg_bank_size == 1)
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{
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set_CPU_bank4(prg_reg[1]*2);
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set_CPU_bank5(prg_reg[1]*2+1);
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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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}
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else if(prg_bank_size == 2)
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{
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if(prg_bank_e000)
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{
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set_CPU_bank4(prg_reg[0]);
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set_CPU_bank5(prg_reg[1]);
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set_CPU_bank6(prg_reg[2]);
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set_CPU_bank7(prg_reg[3]);
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}
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else
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{
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if(prg_bank_6000)
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{
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set_CPU_bank3(prg_reg[3]);
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}
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set_CPU_bank4(prg_reg[0]);
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set_CPU_bank5(prg_reg[1]);
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set_CPU_bank6(prg_reg[2]);
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set_CPU_bank7(num_8k_ROM_banks-1);
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}
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}
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else
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{
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// 8k in reverse mode?
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set_CPU_bank4(prg_reg[3]);
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set_CPU_bank5(prg_reg[2]);
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set_CPU_bank6(prg_reg[1]);
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set_CPU_bank7(prg_reg[0]);
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}
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}
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/////////////////////////////////////////////////////////////////////
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