Date: Tue, 8 Nov 2011 09:12:16 -0500 From: Rich Felker <dalias@...ifal.cx> To: musl@...ts.openwall.com Subject: Re: Undefined behavior in atoi() On Tue, Nov 08, 2011 at 06:43:45AM +0100, Pascal Cuoq wrote: > On Tue, Nov 8, 2011 at 4:44 AM, Rich Felker <dalias@...ifal.cx> wrote: > > > On Sun, Nov 06, 2011 at 11:28:41PM +0100, Pascal Cuoq wrote: > > > > > I was looking at implementations for strtod() (long story for another > > time) > > > > It should be noted that the current implementation is not correct. > > There's lots of loss-of-precision. > > > > So I have seen, but if it's possible to do better for the objectives of > musl, > I do not know how. David M. Gay's code is efficient but it's not portable, > and the other implementation I found (provided as part of Tcl and Ruby > for instance) is only to a few ULPs too. > > I am going to write my own, with multi-precision integers (that I already > rely on for other things). I am hoping that by letting ldexp take care > of denormals and infinites, it will be simple. I believe it's possible using a method similar to what's in vfprintf.c, but in reverse. In principle this amounts to using high-precision floats, but with only a couple operations permitted on them and fixed-size buffers, the code simplifies down to a managable level. Actually that's why mentioning it came to mind.. Rich
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