1#include <math.h>
2#include <stdint.h>
3
4float copysignf(float x, float y) {
5    union {
6        float f;
7        uint32_t i;
8    } ux = {x}, uy = {y};
9    ux.i &= 0x7fffffff;
10    ux.i |= uy.i & 0x80000000;
11    return ux.f;
12}
13