1#include "libm.h"
2
3double copysign(double x, double y) {
4	union {double f; uint64_t i;} ux={x}, uy={y};
5	ux.i &= -1ULL/2;
6	ux.i |= uy.i & 1ULL<<63;
7	return ux.f;
8}
9