mirror of https://github.com/bsnes-emu/bsnes.git
101 lines
2.1 KiB
C++
101 lines
2.1 KiB
C++
struct VRC3 : Chip {
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uint4 prg_bank;
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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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uint16 irq_latch;
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struct {
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union {
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uint16 w;
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struct { uint8 order_lsb2(l, h); };
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};
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} irq_counter;
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bool irq_line;
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void main() {
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while(true) {
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if(scheduler.sync == Scheduler::SynchronizeMode::All) {
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scheduler.exit(Scheduler::ExitReason::SynchronizeEvent);
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}
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if(irq_enable) {
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if(irq_mode == 0) { //16-bit
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if(++irq_counter.w == 0) {
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irq_line = 1;
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irq_enable = irq_acknowledge;
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irq_counter.w = irq_latch;
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}
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}
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if(irq_mode == 1) { //8-bit
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if(++irq_counter.l == 0) {
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irq_line = 1;
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irq_enable = irq_acknowledge;
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irq_counter.l = irq_latch;
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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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}
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unsigned prg_addr(unsigned addr) const {
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unsigned bank = (addr < 0xc000 ? (unsigned)prg_bank : 0x0f);
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return (bank * 0x4000) + (addr & 0x3fff);
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}
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void reg_write(unsigned addr, uint8 data) {
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switch(addr & 0xf000) {
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case 0x8000: irq_latch = (irq_latch & 0xfff0) | ((data & 0x0f) << 0); break;
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case 0x9000: irq_latch = (irq_latch & 0xff0f) | ((data & 0x0f) << 4); break;
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case 0xa000: irq_latch = (irq_latch & 0xf0ff) | ((data & 0x0f) << 8); break;
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case 0xb000: irq_latch = (irq_latch & 0x0fff) | ((data & 0x0f) << 12); break;
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case 0xc000:
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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) irq_counter.w = irq_latch;
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break;
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case 0xd000:
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irq_line = 0;
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irq_enable = irq_acknowledge;
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break;
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case 0xf000:
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prg_bank = data & 0x0f;
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break;
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}
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}
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void power() {
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}
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void reset() {
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prg_bank = 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_latch = 0;
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irq_counter.w = 0;
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irq_line = 0;
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}
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void serialize(serializer& s) {
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s.integer(prg_bank);
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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_latch);
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s.integer(irq_counter.w);
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s.integer(irq_line);
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}
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VRC3(Board& board) : Chip(board) {
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}
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};
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