mirror of
https://github.com/golang/go
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54 lines
1.3 KiB
Go
54 lines
1.3 KiB
Go
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// Copyright 2017 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package runtime
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import "unsafe"
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var inf = float64frombits(0x7FF0000000000000)
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// isNaN reports whether f is an IEEE 754 ``not-a-number'' value.
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func isNaN(f float64) (is bool) {
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// IEEE 754 says that only NaNs satisfy f != f.
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return f != f
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}
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// isFinite reports whether f is neither NaN nor an infinity.
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func isFinite(f float64) bool {
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return !isNaN(f - f)
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}
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// isInf reports whether f is an infinity.
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func isInf(f float64) bool {
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return !isNaN(f) && !isFinite(f)
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}
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// Abs returns the absolute value of x.
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//
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// Special cases are:
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// Abs(±Inf) = +Inf
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// Abs(NaN) = NaN
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func abs(x float64) float64 {
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const sign = 1 << 63
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return float64frombits(float64bits(x) &^ sign)
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}
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// copysign returns a value with the magnitude
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// of x and the sign of y.
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func copysign(x, y float64) float64 {
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const sign = 1 << 63
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return float64frombits(float64bits(x)&^sign | float64bits(y)&sign)
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}
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// Float64bits returns the IEEE 754 binary representation of f.
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func float64bits(f float64) uint64 {
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return *(*uint64)(unsafe.Pointer(&f))
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}
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// Float64frombits returns the floating point number corresponding
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// the IEEE 754 binary representation b.
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func float64frombits(b uint64) float64 {
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return *(*float64)(unsafe.Pointer(&b))
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}
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