1// Copyright 2009 The Go Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style
3// license that can be found in the LICENSE file.
4
5package math
6
7// Frexp breaks f into a normalized fraction
8// and an integral power of two.
9// It returns frac and exp satisfying f == frac × 2**exp,
10// with the absolute value of frac in the interval [½, 1).
11//
12// Special cases are:
13//
14//	Frexp(±0) = ±0, 0
15//	Frexp(±Inf) = ±Inf, 0
16//	Frexp(NaN) = NaN, 0
17func Frexp(f float64) (frac float64, exp int) {
18	if haveArchFrexp {
19		return archFrexp(f)
20	}
21	return frexp(f)
22}
23
24func frexp(f float64) (frac float64, exp int) {
25	// special cases
26	switch {
27	case f == 0:
28		return f, 0 // correctly return -0
29	case IsInf(f, 0) || IsNaN(f):
30		return f, 0
31	}
32	f, exp = normalize(f)
33	x := Float64bits(f)
34	exp += int((x>>shift)&mask) - bias + 1
35	x &^= mask << shift
36	x |= (-1 + bias) << shift
37	frac = Float64frombits(x)
38	return
39}
40