zircon/third_party/ulib/musl/src/math/__fpclassify.c

#include <math.h>
#include <stdint.h>

int __fpclassify(double x) {
  union {
    double f;
    uint64_t i;
  } u = {x};
  int e = u.i >> 52 & 0x7ff;
  if (!e)
    return u.i << 1 ? FP_SUBNORMAL : FP_ZERO;
  if (e == 0x7ff)
    return u.i << 12 ? FP_NAN : FP_INFINITE;
  return FP_NORMAL;
}