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alexbevi
GitHub Repository: alexbevi/BizHawk
 Path: blob/master/libsnes/bsnes/snes/alt/cpu/timing.cpp
2 views
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#ifdef CPU_CPP

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void CPU::queue_event(unsigned id) {

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  switch(id) {

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    case QueueEvent::DramRefresh: return add_clocks(40);

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    case QueueEvent::HdmaRun: return hdma_run();

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  }

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}

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void CPU::last_cycle() {

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  if(status.irq_lock) {

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    status.irq_lock = false;

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    return;

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  }

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  if(status.nmi_transition) {

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    regs.wai = false;

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    status.nmi_transition = false;

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    status.nmi_pending = true;

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  }

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  if(status.irq_transition || regs.irq) {

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    regs.wai = false;

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    status.irq_transition = false;

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    status.irq_pending = !regs.p.i;

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  }

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}

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void CPU::add_clocks(unsigned clocks) {

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  if(status.hirq_enabled) {

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    if(status.virq_enabled) {

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      unsigned cpu_time = vcounter() * 1364 + hcounter();

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      unsigned irq_time = status.vtime * 1364 + status.htime * 4;

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      unsigned framelines = (system.region() == System::Region::NTSC ? 262 : 312) + field();

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      if(cpu_time > irq_time) irq_time += framelines * 1364;

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      bool irq_valid = status.irq_valid;

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      status.irq_valid = cpu_time <= irq_time && cpu_time + clocks > irq_time;

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      if(!irq_valid && status.irq_valid) status.irq_line = true;

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    } else {

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      unsigned irq_time = status.htime * 4;

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      if(hcounter() > irq_time) irq_time += 1364;

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      bool irq_valid = status.irq_valid;

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      status.irq_valid = hcounter() <= irq_time && hcounter() + clocks > irq_time;

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      if(!irq_valid && status.irq_valid) status.irq_line = true;

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    }

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    if(status.irq_line) status.irq_transition = true;

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  } else if(status.virq_enabled) {

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    bool irq_valid = status.irq_valid;

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    status.irq_valid = vcounter() == status.vtime;

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    if(!irq_valid && status.irq_valid) status.irq_line = true;

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    if(status.irq_line) status.irq_transition = true;

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  } else {

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    status.irq_valid = false;

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  }

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  tick(clocks);

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  queue.tick(clocks);

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  step(clocks);

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}

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void CPU::scanline() {

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  synchronize_smp();

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  synchronize_ppu();

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  synchronize_coprocessors();

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  system.scanline();

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  if(vcounter() == 0) hdma_init();

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  queue.enqueue(534, QueueEvent::DramRefresh);

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  if(vcounter() <= (ppu.overscan() == false ? 224 : 239)) {

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    queue.enqueue(1104 + 8, QueueEvent::HdmaRun);

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  }

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  bool nmi_valid = status.nmi_valid;

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  status.nmi_valid = vcounter() >= (ppu.overscan() == false ? 225 : 240);

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  if(!nmi_valid && status.nmi_valid) {

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    status.nmi_line = true;

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    if(status.nmi_enabled) status.nmi_transition = true;

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  } else if(nmi_valid && !status.nmi_valid) {

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    status.nmi_line = false;

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  }

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  if(status.auto_joypad_poll_enabled && vcounter() == (ppu.overscan() == false ? 227 : 242)) {

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    run_auto_joypad_poll();

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  }

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}

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void CPU::run_auto_joypad_poll() {

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  input.port1->latch(1);

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  input.port2->latch(1);

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  input.port1->latch(0);

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  input.port2->latch(0);

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  interface()->inputNotify(1);

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  interface()->inputNotify(0);

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  uint16 joy1 = 0, joy2 = 0, joy3 = 0, joy4 = 0;

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  for(unsigned i = 0; i < 16; i++) {

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    uint8 port0 = input.port1->data();

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    uint8 port1 = input.port2->data();

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    joy1 |= (port0 & 1) ? (0x8000 >> i) : 0;

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    joy2 |= (port1 & 1) ? (0x8000 >> i) : 0;

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    joy3 |= (port0 & 2) ? (0x8000 >> i) : 0;

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    joy4 |= (port1 & 2) ? (0x8000 >> i) : 0;

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  }

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  status.joy1l = joy1;

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  status.joy1h = joy1 >> 8;

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  status.joy2l = joy2;

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  status.joy2h = joy2 >> 8;

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  status.joy3l = joy3;

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  status.joy3h = joy3 >> 8;

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  status.joy4l = joy4;

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  status.joy4h = joy4 >> 8;

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}

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#endif

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