wartank/vendor/github.com/chewxy/math32/frexp.go

package math32

// Frexp breaks f into a normalized fraction
// and an integral power of two.
// It returns frac and exp satisfying f == frac × 2**exp,
// with the absolute value of frac in the interval [½, 1).
//
// Special cases are:
//	Frexp(±0) = ±0, 0
//	Frexp(±Inf) = ±Inf, 0
//	Frexp(NaN) = NaN, 0
func Frexp(f float32) (frac float32, exp int) {
	return frexp(f)
}

func frexp(f float32) (frac float32, exp int) {
	// special cases
	switch {
	case f == 0:
		return f, 0 // correctly return -0
	case IsInf(f, 0) || IsNaN(f):
		return f, 0
	}
	f, exp = normalize(f)
	x := Float32bits(f)
	exp += int((x>>shift)&mask) - bias + 1
	x &^= mask << shift
	x |= (-1 + bias) << shift
	frac = Float32frombits(x)
	return
}