220 31506 <3c737844-0d92-3713-7b7d-06130959a877@wanadoo.fr> article Path: news.gmane.org!.POSTED!not-for-mail From: "Vicente J. Botet Escriba" Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Re: compressed std::bitset Date: Wed, 8 Mar 2017 13:44:52 +0100 Lines: 409 Approved: news@gmane.org Message-ID: <3c737844-0d92-3713-7b7d-06130959a877@wanadoo.fr> References: <32cfea0a-7df8-47cf-47fd-549985f12295@wanadoo.fr> <06e829ca-417b-470c-95ca-c661e8752f79@isocpp.org> <4238c4e6-51f5-4a2f-94c8-f61ca415e7e0@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary="------------3A7744E93E813B6D652594CA" X-Trace: blaine.gmane.org 1488977098 21028 195.159.176.226 (8 Mar 2017 12:44:58 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Wed, 8 Mar 2017 12:44:58 +0000 (UTC) User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.11; rv:45.0) Gecko/20100101 Thunderbird/45.7.1 To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBDH67CONY4PBBRXZ77CQKGQEOOBODMQ@isocpp.org Wed Mar 08 13:44:54 2017 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-lf0-f69.google.com ([209.85.215.69]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1claxV-0004VV-42 for gclcip-std-proposals@m.gmane.org; Wed, 08 Mar 2017 13:44:49 +0100 Original-Received: by mail-lf0-f69.google.com with SMTP id a6sf19118009lfa.1 for ; Wed, 08 Mar 2017 04:44:55 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=isocpp-org.20150623.gappssmtp.com; s=20150623; h=subject:to:references:from:message-id:date:user-agent:mime-version :in-reply-to:x-original-sender:x-original-authentication-results :reply-to:precedence:mailing-list:list-id:x-spam-checked-in-group :list-post:list-help:list-archive:list-subscribe:list-unsubscribe; bh=ZPSrVj691FSsVrqkcVPthOjDA+vbAdwI6+njU+oypec=; b=NkumhBjmuSYIcGXueaTHaQy8oY1C2ADQBdFznRSUkfYBUXH6D6Zd472ZohwZQzv0Q9 eazxMfsmg1nWWNW9BSTbVY+OdmppTSDhLFTnrZNzZHCcq2cDFy6CawYqUF8YnIBsHW2s eQr25GhN10N7Ad31xD7eNp/J0aRZbZ3hahM8UpMuvB06A1MrYLVT9VyvNLNXPMPKhwjD jkfhE3F2gmpzMXrkMhsQA2gsV0+FTG8BUlIKPBAmi0mtYa0ZACtUA1HVkuyvf6FnmePh SNCLC1tDDqBcMoyjX0GH5L3GiSARhpmdoiQfzS18+lcme2m0tDmGHu1eSQlCgbm5HMhI s8lA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:references:from:message-id:date :user-agent:mime-version:in-reply-to:x-original-sender :x-original-authentication-results:reply-to:precedence:mailing-list :list-id:x-spam-checked-in-group:list-post:list-help:list-archive :list-subscribe:list-unsubscribe; bh=ZPSrVj691FSsVrqkcVPthOjDA+vbAdwI6+njU+oypec=; b=uHYCbKXormz+eRBiA3nDPBgukr/f5ROv5F2sVbzjPo1hCdGMQhBqfdXzVE5da2egVA Ldp4mS9eQuMpZtb7JbLOmuVDXbwel//u7oDjP25o6TkmuStz5g1D8D+nE0U8u+/QJhLJ rw8MVU2YRMu36p3UyTvUHr6Wv/Wb/ZEItqoSowzqMa6h7a5mMAqsitYMUQK0axtiPIEC bUQBPWKoCriWGeFaLZMQNj7liTD6/iWKnmeXWP2ioWu1AxRA+uL6qr/j0g6nUIS3ms2J gtAYdJTR7ECFOQ/qYWQRBQaBOZAJezy6euowBri0DUHlgBdnAEXr2tSaLyTFMZlGJ0fc CNSw== X-Gm-Message-State: AMke39m9lnsATNPuq3ER1h8HYfO99C+nnK6LIWHDA+fbTNO25jvHoawQLJM64h5FHKX1tg== X-Received: by 10.46.33.82 with SMTP id h79mr1061008ljh.7.1488977095365; Wed, 08 Mar 2017 04:44:55 -0800 (PST) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.28.209.137 with SMTP id i131ls484876wmg.5.gmail; Wed, 08 Mar 2017 04:44:53 -0800 (PST) X-Received: by 10.223.148.35 with SMTP id 32mr5232795wrq.82.1488977093943; Wed, 08 Mar 2017 04:44:53 -0800 (PST) Original-Received: from smtp.smtpout.orange.fr (smtp08.smtpout.orange.fr. [80.12.242.130]) by mx.google.com with ESMTPS id g78si12329375wme.3.2017.03.08.04.44.53 for (version=TLS1 cipher=AES128-SHA bits=128/128); Wed, 08 Mar 2017 04:44:53 -0800 (PST) Received-SPF: neutral (google.com: 80.12.242.130 is neither permitted nor denied by best guess record for domain of vicente.botet@wanadoo.fr) client-ip=80.12.242.130; Original-Received: from imac-de-vicente-botet-escriba.home ([92.139.161.125]) by mwinf5d31 with ME id tQks1u00t2ie32s03QktQ2; Wed, 08 Mar 2017 13:44:53 +0100 X-ME-Helo: imac-de-vicente-botet-escriba.home X-ME-Auth: dmljZW50ZS5ib3RldEB3YW5hZG9vLmZy X-ME-Date: Wed, 08 Mar 2017 13:44:53 +0100 X-ME-IP: 92.139.161.125 In-Reply-To: <4238c4e6-51f5-4a2f-94c8-f61ca415e7e0@isocpp.org> X-Original-Sender: vicente.botet@wanadoo.fr X-Original-Authentication-Results: mx.google.com; spf=neutral (google.com: 80.12.242.130 is neither permitted nor denied by best guess record for domain of vicente.botet@wanadoo.fr) smtp.mailfrom=vicente.botet@wanadoo.fr Precedence: list Mailing-list: list std-proposals@isocpp.org; contact std-proposals+owners@isocpp.org List-ID: X-Google-Group-Id: 399137483710 List-Post: , List-Help: , List-Archive: List-Subscribe: , List-Unsubscribe: , Xref: news.gmane.org gmane.comp.lang.c++.isocpp.proposals:31506 Archived-At: This is a multi-part message in MIME format. --------------3A7744E93E813B6D652594CA Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: quoted-printable Le 08/03/2017 =C3=A0 06:23, 3dw4rd@verizon.net a =C3=A9crit : > > > On Tuesday, February 21, 2017 at 3:40:00 PM UTC-5, ricky6565 wrote: > > Hi Vicente, > > I think the Bitset2 > library by Claas Bontus > provides what you are looking for. It's like std::bitset but with > enhanced functionality. It let's you set the underlying integral > type of the bitset. In fact, it defaults to uint8_t, uint16_t, or > uint32_t if N bits fit into those integers. I would like this > functionality added to std::bitset but, as you said, it would > probably be a breaking change. > > Riccardo > > > I was just thinking something similar. Allow the user to specify the=20 > bitset leaf-type: > > | > template Bits=3Dstd::numeric_limits::digits> > classbit_array > { > // pretty much like bitset except I would add > usingleaf_type =3DLeafTp; > leaf_iterator lbegin()// > leaf_iterator lend();// > }; > > | > > This is flipped relative to Bitset2 in that leaf type comes first and=20 > the template would decide how many leaves based on bits. > > So now you could get these small bitsets: > using bitset16 =3D bit_array; > etc. > I believe that both orders could have have usage (see below), an alias=20 templates should help here to have both. However I don't like the possibility to have bit_array<>. How many bits=20 do we have? If the data function returns a span we don't need the leaf iterator=20 functions. > I've heard people want similar choices for a dynamic_bitset: > | > template > classbit_vector > { > // pretty much like bitset except I would add > usingleaf_type =3DLeafTp; > leaf_iterator lbegin()// > leaf_iterator lend();// > }; > | > > People who do encryption wanted to set the size of the leaf and have=20 > access to leaves. > I chose bit_array and bit_vector to have a similar relationship as=20 > array and vector do. For the names I believe we should stay close to bitset and=20 dynamic_bitset. But we can not use bitset :( I need to think more about your bit_array/bit_vector suggestion, but=20 array/vector don't have set operations. I will go towards bit_set and=20 dynamic_bit_set. In addition bit_array could be misleading as array has a completely different meaning and layout. Do we have 10 int16_t? Vicente --=20 You received this message because you are subscribed to the Google Groups "= ISO C++ Standard - Future Proposals" group. To unsubscribe from this group and stop receiving emails from it, send an e= mail to std-proposals+unsubscribe@isocpp.org. To post to this group, send email to std-proposals@isocpp.org. To view this discussion on the web visit https://groups.google.com/a/isocpp= ..org/d/msgid/std-proposals/3c737844-0d92-3713-7b7d-06130959a877%40wanadoo.f= r. --------------3A7744E93E813B6D652594CA Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
Le 08/03/2017 =C3=A0 06:23, 3dw4rd@verizon.net a =C3=A9crit=C2=A0:


On Tuesday, February 21, 2017 at 3:40:00 PM UTC-5, ricky6565 wrote:
Hi Vicente,

I think the Bitset2 library by Claas Bontus provides what you are looking for. It's like std::bitset but with enhanced functionality. It let's you set the underlying integral type of the bitset. In fact, it=C2=A0defaults to uint8_t, uint16_t, or uint32_t=C2=A0if N=C2=A0bits fit into those integers.=C2=A0I would like this functionality add= ed to std::bitset but, as you said, it would probably be a breaking change.

Riccardo

I was just thinking something similar.=C2=A0 Allow the user to specify the bitset leaf-type:

template<<= /span>typen= ame LeafT= p =3D unsig= ned long<= /span> long<= /span>, std<= /span>::size_= t Bits =3D std<= /span>::numer= ic_limits<<= /span>LeafT= p>:= :digit= s><= /span>
=C2=A0 class bit_array
=C2=A0 {
=C2=A0 =C2=A0 // pretty much like bitset except I would add
=C2=A0 =C2=A0 using leaf_type =3D LeafT= p;
=C2=A0 =C2=A0 leaf_iterator lbegin() //
=C2=A0 =C2=A0 leaf_iterator lend(); //
=C2=A0 };


This is flipped relative to Bitset2 in that leaf type comes first and the template would decide how many leaves based on bits.

So now you could get these small bitsets:
using bitset16 =3D bit_array<uint16_t>;
etc.

I believe that both orders could have have usage (see below), an alias templates should help here to have both.
However I don't like the possibility to have bit_array<>. How many bits do we have?

If the data function returns a span<T,N> we don't need the leaf iterator functions.
=C2=A0

I've heard people want similar choices for a dynamic_bitset:
template<<= /span>typen= ame LeafT= p =3D unsig= ned long<= /span> long<= /span>><= /span>
=C2=A0 class bit_vector
=C2=A0 {
=C2=A0 =C2=A0 // pretty much like bitset except I would add
=C2=A0 =C2=A0 using leaf_type =3D LeafT= p;
=C2=A0 =C2=A0 leaf_iterator lbegin() //
=C2=A0 =C2=A0 leaf_iterator lend(); //
=C2=A0 };

People who do encryption wanted to set the size of the leaf and have access to leaves.
I chose bit_a= rray and bit_vecto= r to have a similar relationship as array and vector do.
For the names I believe we should stay close to bitset and dynamic_bitset. But we can not use bitset :(
I need to think more about your bit_array/bit_vector suggestion, but array/vector don't have set operations. I will go towards bit_set and dynamic_bit_set.
In addition bit_array<int16_t, 10> could be misleading as array<int16_t, 10> has a completely different meaning and layout. Do we have 10 int16_t?

Vicente

--
You received this message because you are subscribed to the Google Groups &= quot;ISO C++ Standard - Future Proposals" group.
To unsubscribe from this group and stop receiving emails from it, send an e= mail to std-proposa= ls+unsubscribe@isocpp.org.
To post to this group, send email to std-proposals@isocpp.org.
To view this discussion on the web visit https://groups.google.= com/a/isocpp.org/d/msgid/std-proposals/3c737844-0d92-3713-7b7d-06130959a877= %40wanadoo.fr.
--------------3A7744E93E813B6D652594CA-- .