#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;}