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// Modf returns integer and fractional floating-point numbers
8// that sum to f. Both values have the same sign as f.
9//
10// Special cases are:
11//
12//	Modf(±Inf) = ±Inf, NaN
13//	Modf(NaN) = NaN, NaN
14func Modf(f float64) (int float64, frac float64) {
15	if haveArchModf {
16		return archModf(f)
17	}
18	return modf(f)
19}
20
21func modf(f float64) (int float64, frac float64) {
22	if f < 1 {
23		switch {
24		case f < 0:
25			int, frac = Modf(-f)
26			return -int, -frac
27		case f == 0:
28			return f, f // Return -0, -0 when f == -0
29		}
30		return 0, f
31	}
32
33	x := Float64bits(f)
34	e := uint(x>>shift)&mask - bias
35
36	// Keep the top 12+e bits, the integer part; clear the rest.
37	if e < 64-12 {
38		x &^= 1<<(64-12-e) - 1
39	}
40	int = Float64frombits(x)
41	frac = f - int
42	return
43}
44