Date: Wed, 9 Jan 2019 12:00:29 -0800 From: Devin Teske <dteske@FreeBSD.org> To: Gavin Howard <gavin.d.howard@gmail.com> Cc: Devin Teske <dteske@FreeBSD.org>, "freebsd-arch@freebsd.org" <freebsd-arch@freebsd.org>, cem@freebsd.org Subject: Re: GNU-compatible, BSD-licensed bc Message-ID: <A3D7BF6D-2696-45CC-936C-E2D6841840F0@FreeBSD.org> In-Reply-To: <CAF=dzROC1P=44D58hY0RcQW-3nwWeXvQ_5s4BNPG3AE=OzCZqQ@mail.gmail.com> References: <CAF=dzRNnurahLBOaKgq8_bDXNuM8biYPFbj6F2vp0t58Ejp8bg@mail.gmail.com> <8FFA4578-0BAE-4F9F-8A06-AE83283BDEA4@FreeBSD.org> <CAG6CVpXam0bJD9B7n0xDQiRF=ZTeH0hN7wd8f8fDGyMSsCwh0w@mail.gmail.com> <CAF=dzRNYxYf7P8q7mZo=Tc6a%2BfTYsARGpG0=ZTvBP1ESLPBLOg@mail.gmail.com> <61F802DC-2E59-4E0A-955D-899EBD7874A1@FreeBSD.org> <CAF=dzROC1P=44D58hY0RcQW-3nwWeXvQ_5s4BNPG3AE=OzCZqQ@mail.gmail.com>
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> On Jan 7, 2019, at 11:45 PM, Gavin Howard <gavin.d.howard@gmail.com> = wrote: >=20 > On Mon, Jan 7, 2019 at 10:57 PM Devin Teske <dteske@freebsd.org = <mailto:dteske@freebsd.org>> wrote: >>=20 >>=20 >>=20 >>> On Jan 7, 2019, at 4:42 PM, Gavin Howard <gavin.d.howard@gmail.com> = wrote: >>>=20 >>> On Mon, Jan 7, 2019 at 5:38 PM Conrad Meyer <cem@freebsd.org> wrote: >>>>=20 >>>> On Mon, Jan 7, 2019 at 4:00 PM Devin Teske <dteske@freebsd.org> = wrote: >>>>> How do you handle arbitrary arithmetic precision? >>>>=20 >>>> Looks like https://github.com/gavinhoward/bc/blob/master/src/num.c = . >>>=20 >>> That is correct. Because this bc is meant to help bootstrap the = Linux >>> kernel and have no dependencies other than POSIX 2008, I wrote my = own. >>=20 >> Impressive. It might be worth turning this into a library itself. >=20 > Eh...it is completely tuned for bc. And it won't be fast, > unfortunately. See below. >=20 >>> Also, the POSIX bc standard mandates doing math in decimal. OpenSSL >>> would not be smart if they did that. >>=20 >> Not sure I understand what you mean here. >=20 > Well, for starters, OpenSSL's BIGNUM is integer only. Yes, those > integers can be any size, but they are only integers. That is not good > enough for bc; it has to allow arbitrary precision, including > non-integers, and its fractional part can be any size, up to a certain > limit, which you can get from my bc by typing "limits" at the prompt > and looking for the value of BC_NUM_MAX (which is actually the maximum > number of decimal digits, period). >=20 Thanks for explaining that further. [snip] >>> There are also a few >>> peculiarities with the POSIX bc standard that (more or less) require = a >>> standalone implementation. >>>=20 >>=20 >> How hard would it be to convert a bn(3)-based library to use your = code? >> Would there be any performance impact -- I've benchmarked bn(3) to >> be pretty fast. >=20 > It would not be terribly hard, but as I said above, it would not be > fast at all, at least compared to a well-written hardware-based, > binary bignum implementation. But if you want to, go ahead; I would > appreciate the credit (though the license does not even require that). >=20 Well, unfortunately, my needs are purely whole-integer arithmetic but speed is paramount. My application of OpenSSL bn(3) is here: https://reviews.freebsd.org/D16132 <https://reviews.freebsd.org/D16132>; Though worth noting that I haven't updated the review since November. Since then, I have made many changes which can be seen on GitHub: https://FrauBSD.org/libcmb <https://fraubsd.org/libcmb>; >>> Also, right now I am working on getting a release candidate out that >>> will enable me to make a quick port that Stefan could use as a = jumping >>> off point. My build system changed between 1.0 and now, and I would >>> like to be able to test it. >>>=20 >>=20 >> Cool. Looking forward to it. >=20 > It's out. It works great. The Makefile that I sent to the mailing list > a few messages back does the job well enough, though I was told in a > private message not to use the GNU bc port's pkg-descr file, since it > might be under the GPL. >=20 > However, note that this is not the final 1.1 release; it is just for > testing, even though it is high quality. >=20 I'm wondering why you chose to write your own configure.sh instead of leveraging autotools. Also, it looks like you have a high number of build-time options. I also notice that you're into writing tests for your software. It might be = interesting to apply my tool for combining all possible combinations of build = options. Seen here: = https://github.com/FrauBSD/pkgcenter/blob/master/depend/libcmb/release/Mak= efile = <https://github.com/FrauBSD/pkgcenter/blob/master/depend/libcmb/release/Ma= kefile> It's a great way to make sure all the various build options work = together. --=20 Cheers, Devin=
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