#include <stdlib.h>

extern "C" void __cxa_pure_virtual() {
  printk("__cxa_pure_virtual\n");
  abort();
}

extern "C" void* memcpy(void* dstptr, const void* srcptr, const size_t n) {
  auto* dst = static_cast<uint8_t*>(dstptr);
  const auto* src = static_cast<const uint8_t*>(srcptr);
  for (size_t i = 0; i < n; ++i) dst[i] = src[i];
  return dstptr;
}

extern "C" void* memset(void* bufptr, const int value, const size_t n) {
  auto* buf = static_cast<uint8_t*>(bufptr);
  for (size_t i = 0; i < n; ++i) buf[i] = static_cast<uint8_t>(value);
  return bufptr;
}

extern "C" void* memmove(void* dstptr, const void* srcptr, const size_t n) {
  auto* dst = static_cast<uint8_t*>(dstptr);
  const auto* src = static_cast<const uint8_t*>(srcptr);
  if (dst < src) {
    for (size_t i = 0; i < n; ++i) dst[i] = src[i];
  } else {
    for (size_t i = n; i != 0; i--) dst[i - 1] = src[i - 1];
  }
  return dstptr;
}

extern "C" int memcmp(const void* aptr, const void* bptr, const size_t n) {
  const auto* a = static_cast<const uint8_t*>(aptr);
  const auto* b = static_cast<const uint8_t*>(bptr);
  for (size_t i = 0; i < n; ++i) {
    if (a[i] < b[i])
      return -1;
    else if (b[i] < a[i])
      return 1;
  }
  return 0;
}