From 276870d6e0ff5d22b73feee56e0bad9096f01b22 Mon Sep 17 00:00:00 2001 From: Robert Griesemer Date: Thu, 6 Dec 2018 13:32:50 -0800 Subject: [PATCH] math: document sign bit correspondence for floating-point/bits conversions Fixes #27736. Change-Id: Ibda7da7ec6e731626fc43abf3e8c1190117f7885 Reviewed-on: https://go-review.googlesource.com/c/153057 Reviewed-by: Ian Lance Taylor --- src/math/unsafe.go | 20 ++++++++++++++------ 1 file changed, 14 insertions(+), 6 deletions(-) diff --git a/src/math/unsafe.go b/src/math/unsafe.go index 5ae67420f4..e59f50ca62 100644 --- a/src/math/unsafe.go +++ b/src/math/unsafe.go @@ -6,16 +6,24 @@ package math import "unsafe" -// Float32bits returns the IEEE 754 binary representation of f. +// Float32bits returns the IEEE 754 binary representation of f, +// with the sign bit of f and the result in the same bit position. +// Float32bits(Float32frombits(x)) == x. func Float32bits(f float32) uint32 { return *(*uint32)(unsafe.Pointer(&f)) } -// Float32frombits returns the floating point number corresponding -// to the IEEE 754 binary representation b. +// Float32frombits returns the floating-point number corresponding +// to the IEEE 754 binary representation b, with the sign bit of b +// and the result in the same bit position. +// Float32frombits(Float32bits(x)) == x. func Float32frombits(b uint32) float32 { return *(*float32)(unsafe.Pointer(&b)) } -// Float64bits returns the IEEE 754 binary representation of f. +// Float64bits returns the IEEE 754 binary representation of f, +// with the sign bit of f and the result in the same bit position, +// and Float64bits(Float64frombits(x)) == x. func Float64bits(f float64) uint64 { return *(*uint64)(unsafe.Pointer(&f)) } -// Float64frombits returns the floating point number corresponding -// the IEEE 754 binary representation b. +// Float64frombits returns the floating-point number corresponding +// to the IEEE 754 binary representation b, with the sign bit of b +// and the result in the same bit position. +// Float64frombits(Float64bits(x)) == x. func Float64frombits(b uint64) float64 { return *(*float64)(unsafe.Pointer(&b)) } -- 2.50.0