#if __has_include(<sys/auxv.h>)
#include <sys/auxv.h>
#else
#include <sys/param.h>
#include <sys/sysctl.h>
#include <elf.h>
#include <errno.h>
#include <unistd.h>

static unsigned long getauxval(unsigned long type) {
  Elf_Auxinfo auxv[AT_COUNT];
  size_t len = sizeof(auxv);
  int mib[] = {
    CTL_KERN,
    KERN_PROC,
    KERN_PROC_AUXV,
    getpid(),
  };

  if (sysctl(mib, nitems(mib), auxv, &len, NULL, 0) != -1) {
    for (size_t i = 0; i < nitems(auxv); i++)
      if ((unsigned long)auxv[i].a_type == type)
        return auxv[i].a_un.a_val;

    errno = ENOENT;
  }
  return 0;
}
#endif

#if defined __FreeBSD__
#define AT_HWCAP        25
#else
#define AT_HWCAP        16
#endif

#ifndef HWCAP_NEON
#define HWCAP_NEON (1 << 12)
#endif

#include <stdio.h>

int main() {
  printf("NEON: %s supported\n", getauxval(AT_HWCAP) & HWCAP_NEON ? "" : "not");

  return 0;
}