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

     1  #include <math.h>
     2  #include <stdint.h>
     3  
     4  float copysignf(float x, float y)
     5  {
     6  	union {float f; uint32_t i;} ux={x}, uy={y};
     7  	ux.i &= 0x7fffffff;
     8  	ux.i |= uy.i & 0x80000000;
     9  	return ux.f;
    10  }