github.com/twelsh-aw/go/src@v0.0.0-20230516233729-a56fe86a7c81/math/modf.go (about)

     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  
     5  package 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
    14  func Modf(f float64) (int float64, frac float64) {
    15  	if haveArchModf {
    16  		return archModf(f)
    17  	}
    18  	return modf(f)
    19  }
    20  
    21  func 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  }