#include "arch/kernel/cpu/msr.hpp"

namespace teachos::arch::memory::cpu
{
  namespace
  {
    auto constexpr IA32_EFER_ADDRESS = 0xC0000080;
  }

  auto read_msr(uint32_t msr) -> uint64_t
  {
    uint32_t low, high;
    asm volatile("rdmsr" : "=a"(low), "=d"(high) : "c"(msr));
    return (static_cast<uint64_t>(high) << 32) | low;
  }

  auto write_msr(uint32_t msr, uint64_t value) -> void
  {
    uint32_t low = value & 0xFFFFFFFF;
    uint32_t high = value >> 32;
    asm volatile("wrmsr"
                 : /* no output from call */
                 : "c"(msr), "a"(low), "d"(high));
  }

  auto set_efer_bit(efer_flags flag) -> void
  {
    auto const efer = read_msr(IA32_EFER_ADDRESS);
    write_msr(IA32_EFER_ADDRESS, static_cast<std::underlying_type<efer_flags>::type>(flag) | efer);
  }
}  // namespace teachos::arch::memory::cpu