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// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package math

// 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 float64) (frac float64, exp int) {
        return frexp(f)
}

func frexp(f float64) (frac float64, 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 := Float64bits(f)
        exp += int((x>>shift)&mask) - bias + 1
        x &^= mask << shift
        x |= (-1 + bias) << shift
        frac = Float64frombits(x)
        return
}