third_party/ulib/musl/src/math/copysignf.c

#include <math.h>
#include <stdint.h>

float copysignf(float x, float y) {
    union {
        float f;
        uint32_t i;
    } ux = {x}, uy = {y};
    ux.i &= 0x7fffffff;
    ux.i |= uy.i & 0x80000000;
    return ux.f;
}