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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

}