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

     1  #include <math.h>
     2  #include <stdint.h>
     3  
     4  double fabs(double x)
     5  {
     6  	union {double f; uint64_t i;} u = {x};
     7  	u.i &= -1ULL/2;
     8  	return u.f;
     9  }