mirror of https://github.com/gohugoio/hugo
63 lines
1.4 KiB
Go
63 lines
1.4 KiB
Go
// 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.
|
|
|
|
// According to https://github.com/golang/go/issues/20100, the Go stdlib will
|
|
// include math.Round beginning with Go 1.10.
|
|
//
|
|
// The following implementation was taken from https://golang.org/cl/43652.
|
|
|
|
package math
|
|
|
|
import "math"
|
|
|
|
const (
|
|
mask = 0x7FF
|
|
shift = 64 - 11 - 1
|
|
bias = 1023
|
|
)
|
|
|
|
// Round returns the nearest integer, rounding half away from zero.
|
|
//
|
|
// Special cases are:
|
|
//
|
|
// Round(±0) = ±0
|
|
// Round(±Inf) = ±Inf
|
|
// Round(NaN) = NaN
|
|
func _round(x float64) float64 {
|
|
// Round is a faster implementation of:
|
|
//
|
|
// func Round(x float64) float64 {
|
|
// t := Trunc(x)
|
|
// if Abs(x-t) >= 0.5 {
|
|
// return t + Copysign(1, x)
|
|
// }
|
|
// return t
|
|
// }
|
|
const (
|
|
signMask = 1 << 63
|
|
fracMask = 1<<shift - 1
|
|
half = 1 << (shift - 1)
|
|
one = bias << shift
|
|
)
|
|
|
|
bits := math.Float64bits(x)
|
|
e := uint(bits>>shift) & mask
|
|
if e < bias {
|
|
// Round abs(x) < 1 including denormals.
|
|
bits &= signMask // +-0
|
|
if e == bias-1 {
|
|
bits |= one // +-1
|
|
}
|
|
} else if e < bias+shift {
|
|
// Round any abs(x) >= 1 containing a fractional component [0,1).
|
|
//
|
|
// Numbers with larger exponents are returned unchanged since they
|
|
// must be either an integer, infinity, or NaN.
|
|
e -= bias
|
|
bits += half >> e
|
|
bits &^= fracMask >> e
|
|
}
|
|
return math.Float64frombits(bits)
|
|
}
|