diff options
author | upstream source tree <ports@midipix.org> | 2015-03-15 20:14:05 -0400 |
---|---|---|
committer | upstream source tree <ports@midipix.org> | 2015-03-15 20:14:05 -0400 |
commit | 554fd8c5195424bdbcabf5de30fdc183aba391bd (patch) | |
tree | 976dc5ab7fddf506dadce60ae936f43f58787092 /libgo/go/math/bits.go | |
download | cbb-gcc-4.6.4-upstream.tar.bz2 cbb-gcc-4.6.4-upstream.tar.xz |
obtained gcc-4.6.4.tar.bz2 from upstream website;upstream
verified gcc-4.6.4.tar.bz2.sig;
imported gcc-4.6.4 source tree from verified upstream tarball.
downloading a git-generated archive based on the 'upstream' tag
should provide you with a source tree that is binary identical
to the one extracted from the above tarball.
if you have obtained the source via the command 'git clone',
however, do note that line-endings of files in your working
directory might differ from line-endings of the respective
files in the upstream repository.
Diffstat (limited to 'libgo/go/math/bits.go')
-rw-r--r-- | libgo/go/math/bits.go | 59 |
1 files changed, 59 insertions, 0 deletions
diff --git a/libgo/go/math/bits.go b/libgo/go/math/bits.go new file mode 100644 index 000000000..a1dca3ed6 --- /dev/null +++ b/libgo/go/math/bits.go @@ -0,0 +1,59 @@ +// 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 + +const ( + uvnan = 0x7FF0000000000001 + uvinf = 0x7FF0000000000000 + uvneginf = 0xFFF0000000000000 + mask = 0x7FF + shift = 64 - 11 - 1 + bias = 1023 +) + +// Inf returns positive infinity if sign >= 0, negative infinity if sign < 0. +func Inf(sign int) float64 { + var v uint64 + if sign >= 0 { + v = uvinf + } else { + v = uvneginf + } + return Float64frombits(v) +} + +// NaN returns an IEEE 754 ``not-a-number'' value. +func NaN() float64 { return Float64frombits(uvnan) } + +// IsNaN returns whether f is an IEEE 754 ``not-a-number'' value. +func IsNaN(f float64) (is bool) { + // IEEE 754 says that only NaNs satisfy f != f. + // To avoid the floating-point hardware, could use: + // x := Float64bits(f); + // return uint32(x>>shift)&mask == mask && x != uvinf && x != uvneginf + return f != f +} + +// IsInf returns whether f is an infinity, according to sign. +// If sign > 0, IsInf returns whether f is positive infinity. +// If sign < 0, IsInf returns whether f is negative infinity. +// If sign == 0, IsInf returns whether f is either infinity. +func IsInf(f float64, sign int) bool { + // Test for infinity by comparing against maximum float. + // To avoid the floating-point hardware, could use: + // x := Float64bits(f); + // return sign >= 0 && x == uvinf || sign <= 0 && x == uvneginf; + return sign >= 0 && f > MaxFloat64 || sign <= 0 && f < -MaxFloat64 +} + +// normalize returns a normal number y and exponent exp +// satisfying x == y × 2**exp. It assumes x is finite and non-zero. +func normalize(x float64) (y float64, exp int) { + const SmallestNormal = 2.2250738585072014e-308 // 2**-1022 + if Fabs(x) < SmallestNormal { + return x * (1 << 52), -52 + } + return x, 0 +} |