#include <Core.hpp>

namespace n64 {
Interpreter::Interpreter(ParallelRDP& parallel, Mem& mem, Registers& regs) : mem(mem), regs(regs) {}

bool Interpreter::ShouldServiceInterrupt() const {
  const bool interrupts_pending = (regs.cop0.status.im & regs.cop0.cause.interruptPending) != 0;
  const bool interrupts_enabled = regs.cop0.status.ie == 1;
  const bool currently_handling_exception = regs.cop0.status.exl == 1;
  const bool currently_handling_error = regs.cop0.status.erl == 1;

  return interrupts_pending && interrupts_enabled && !currently_handling_exception && !currently_handling_error;
}

void Interpreter::CheckCompareInterrupt() {
  regs.cop0.count++;
  regs.cop0.count &= 0x1FFFFFFFF;
  if (regs.cop0.count == static_cast<u64>(regs.cop0.compare) << 1) {
    regs.cop0.cause.ip7 = 1;
    mem.mmio.mi.UpdateInterrupt();
  }
}

int Interpreter::Step() {
  CheckCompareInterrupt();

  regs.prevDelaySlot = regs.delaySlot;
  regs.delaySlot = false;

  if (check_address_error(0b11, u64(regs.pc))) [[unlikely]] {
    regs.cop0.HandleTLBException(regs.pc);
    regs.cop0.FireException(ExceptionCode::AddressErrorLoad, 0, regs.pc);
    return 1;
  }

  u32 paddr = 0;
  if (!regs.cop0.MapVAddr(Cop0::LOAD, regs.pc, paddr)) {
    regs.cop0.HandleTLBException(regs.pc);
    regs.cop0.FireException(Cop0::GetTLBExceptionCode(regs.cop0.tlbError, Cop0::LOAD), 0, regs.pc);
    return 1;
  }

  const u32 instruction = mem.Read<u32>(paddr);

  if (ShouldServiceInterrupt()) {
    regs.cop0.FireException(ExceptionCode::Interrupt, 0, regs.pc);
    return 1;
  }

  regs.oldPC = regs.pc;
  regs.pc = regs.nextPC;
  regs.nextPC += 4;

  Exec(instruction);

  return 1;
}
} // namespace n64