mirror of https://github.com/bsnes-emu/bsnes.git
147 lines
3.3 KiB
C++
147 lines
3.3 KiB
C++
//Konami VRC7
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//Yamaha YM2413 OPLL audio - not emulated
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struct VRC7 : Chip {
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VRC7(Board& board) : Chip(board) {
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}
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auto main() -> void {
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if(irqEnable) {
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if(irqMode == 0) {
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irqScalar -= 3;
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if(irqScalar <= 0) {
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irqScalar += 341;
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if(irqCounter == 0xff) {
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irqCounter = irqLatch;
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irqLine = 1;
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} else {
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irqCounter++;
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}
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}
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}
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if(irqMode == 1) {
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if(irqCounter == 0xff) {
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irqCounter = irqLatch;
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irqLine = 1;
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} else {
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irqCounter++;
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}
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}
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}
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cpu.irqLine(irqLine);
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tick();
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}
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auto writeIO(uint addr, uint8 data) -> void {
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switch(addr) {
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case 0x8000: prgBank[0] = data; break;
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case 0x8010: prgBank[1] = data; break;
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case 0x9000: prgBank[2] = data; break;
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case 0x9010: break; //APU addr port
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case 0x9030: break; //APU data port
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case 0xa000: chrBank[0] = data; break;
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case 0xa010: chrBank[1] = data; break;
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case 0xb000: chrBank[2] = data; break;
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case 0xb010: chrBank[3] = data; break;
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case 0xc000: chrBank[4] = data; break;
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case 0xc010: chrBank[5] = data; break;
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case 0xd000: chrBank[6] = data; break;
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case 0xd010: chrBank[7] = data; break;
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case 0xe000: mirror = data & 0x03; break;
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case 0xe010:
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irqLatch = data;
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break;
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case 0xf000:
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irqMode = data & 0x04;
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irqEnable = data & 0x02;
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irqAcknowledge = data & 0x01;
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if(irqEnable) {
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irqCounter = irqLatch;
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irqScalar = 341;
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}
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irqLine = 0;
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break;
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case 0xf010:
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irqEnable = irqAcknowledge;
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irqLine = 0;
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break;
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}
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}
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auto addrPRG(uint addr) const -> uint {
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uint bank = 0;
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switch(addr & 0xe000) {
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case 0x8000: bank = prgBank[0]; break;
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case 0xa000: bank = prgBank[1]; break;
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case 0xc000: bank = prgBank[2]; break;
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case 0xe000: bank = 0xff; break;
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}
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return (bank * 0x2000) + (addr & 0x1fff);
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}
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auto addrCHR(uint addr) const -> uint {
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uint bank = chrBank[addr / 0x0400];
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return (bank * 0x0400) + (addr & 0x03ff);
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}
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auto addrCIRAM(uint addr) const -> uint {
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switch(mirror) {
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case 0: return ((addr & 0x0400) >> 0) | (addr & 0x03ff); //vertical mirroring
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case 1: return ((addr & 0x0800) >> 1) | (addr & 0x03ff); //horizontal mirroring
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case 2: return 0x0000 | (addr & 0x03ff); //one-screen mirroring (first)
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case 3: return 0x0400 | (addr & 0x03ff); //one-screen mirroring (second)
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}
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}
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auto power() -> void {
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}
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auto reset() -> void {
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for(auto& n : prgBank) n = 0;
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for(auto& n : chrBank) n = 0;
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mirror = 0;
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irqLatch = 0;
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irqMode = 0;
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irqEnable = 0;
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irqAcknowledge = 0;
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irqCounter = 0;
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irqScalar = 0;
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irqLine = 0;
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}
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auto serialize(serializer& s) -> void {
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s.array(prgBank);
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s.array(chrBank);
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s.integer(mirror);
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s.integer(irqLatch);
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s.integer(irqMode);
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s.integer(irqEnable);
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s.integer(irqAcknowledge);
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s.integer(irqCounter);
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s.integer(irqScalar);
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s.integer(irqLine);
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}
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uint8 prgBank[3];
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uint8 chrBank[8];
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uint2 mirror;
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uint8 irqLatch;
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bool irqMode;
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bool irqEnable;
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bool irqAcknowledge;
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uint8 irqCounter;
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int irqScalar;
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bool irqLine;
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};
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