mirror of https://github.com/bsnes-emu/bsnes.git
147 lines
3.4 KiB
C++
147 lines
3.4 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(irq_enable) {
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if(irq_mode == 0) {
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irq_scalar -= 3;
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if(irq_scalar <= 0) {
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irq_scalar += 341;
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if(irq_counter == 0xff) {
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irq_counter = irq_latch;
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irq_line = 1;
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} else {
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irq_counter++;
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}
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}
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}
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if(irq_mode == 1) {
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if(irq_counter == 0xff) {
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irq_counter = irq_latch;
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irq_line = 1;
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} else {
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irq_counter++;
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}
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}
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}
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cpu.set_irq_line(irq_line);
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tick();
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}
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auto reg_write(uint addr, uint8 data) -> void {
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switch(addr) {
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case 0x8000: prg_bank[0] = data; break;
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case 0x8010: prg_bank[1] = data; break;
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case 0x9000: prg_bank[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: chr_bank[0] = data; break;
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case 0xa010: chr_bank[1] = data; break;
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case 0xb000: chr_bank[2] = data; break;
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case 0xb010: chr_bank[3] = data; break;
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case 0xc000: chr_bank[4] = data; break;
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case 0xc010: chr_bank[5] = data; break;
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case 0xd000: chr_bank[6] = data; break;
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case 0xd010: chr_bank[7] = data; break;
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case 0xe000: mirror = data & 0x03; break;
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case 0xe010:
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irq_latch = data;
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break;
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case 0xf000:
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irq_mode = data & 0x04;
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irq_enable = data & 0x02;
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irq_acknowledge = data & 0x01;
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if(irq_enable) {
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irq_counter = irq_latch;
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irq_scalar = 341;
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}
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irq_line = 0;
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break;
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case 0xf010:
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irq_enable = irq_acknowledge;
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irq_line = 0;
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break;
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}
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}
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auto prg_addr(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 = prg_bank[0]; break;
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case 0xa000: bank = prg_bank[1]; break;
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case 0xc000: bank = prg_bank[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 chr_addr(uint addr) const -> uint {
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uint bank = chr_bank[addr / 0x0400];
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return (bank * 0x0400) + (addr & 0x03ff);
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}
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auto ciram_addr(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 : prg_bank) n = 0;
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for(auto& n : chr_bank) n = 0;
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mirror = 0;
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irq_latch = 0;
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irq_mode = 0;
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irq_enable = 0;
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irq_acknowledge = 0;
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irq_counter = 0;
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irq_scalar = 0;
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irq_line = 0;
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}
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auto serialize(serializer& s) -> void {
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s.array(prg_bank);
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s.array(chr_bank);
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s.integer(mirror);
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s.integer(irq_latch);
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s.integer(irq_mode);
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s.integer(irq_enable);
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s.integer(irq_acknowledge);
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s.integer(irq_counter);
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s.integer(irq_scalar);
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s.integer(irq_line);
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}
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uint8 prg_bank[3];
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uint8 chr_bank[8];
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uint2 mirror;
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uint8 irq_latch;
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bool irq_mode;
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bool irq_enable;
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bool irq_acknowledge;
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uint8 irq_counter;
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int irq_scalar;
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bool irq_line;
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};
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