#pragma once

#include <stdint.h>
#include <byteswap.h>

static inline uint64_t reverse64_n(uint64_t x, const uint8_t n)
{
  x = bswap_64(x);
  x = ((x & UINT64_C(0x0f0f0f0f0f0f0f0f)) << 4) |
    ((x & UINT64_C(0xf0f0f0f0f0f0f0f0)) >> 4);
  x = ((x & UINT64_C(0x3333333333333333)) << 2) |
    ((x & UINT64_C(0xcccccccccccccccc)) >> 2);
  x = ((x & UINT64_C(0x5555555555555555)) << 1) |
    ((x & UINT64_C(0xaaaaaaaaaaaaaaaa)) >> 1);
  return x >> (64 - n);
}

static inline uint64_t reverse64(uint64_t x)
{
  return reverse64_n(x, 64);
}