github.com/afumu/libc@v0.0.6/musl/src/math/__fpclassifyf.c (about)

     1  #include <math.h>
     2  #include <stdint.h>
     3  
     4  int __fpclassifyf(float x)
     5  {
     6  	union {float f; uint32_t i;} u = {x};
     7  	int e = u.i>>23 & 0xff;
     8  	if (!e) return u.i<<1 ? FP_SUBNORMAL : FP_ZERO;
     9  	if (e==0xff) return u.i<<9 ? FP_NAN : FP_INFINITE;
    10  	return FP_NORMAL;
    11  }