From: "Ulises Hernandez" Newsgroups: comp.arch.fpga Subject: RBT versus BIT file Date: Tue, 13 Aug 2002 09:33:07 +0100 Organization: ECS Technology Ltd. Lines: 22 Message-ID: <1029227596.880081@cswreg.cos.agilent.com> Reply-To: "Ulises Hernandez" NNTP-Posting-Host: cswreg.cos.agilent.com X-Trace: cswtrans.cos.agilent.com 1029227597 22833 130.29.154.45 (13 Aug 2002 08:33:17 GMT) X-Complaints-To: usenet@cswtrans.cos.agilent.com NNTP-Posting-Date: Tue, 13 Aug 2002 08:33:17 +0000 (UTC) X-Priority: 3 X-MSMail-Priority: Normal X-Newsreader: Microsoft Outlook Express 5.50.4133.2400 X-MimeOLE: Produced By Microsoft MimeOLE V5.50.4133.2400 Cache-Post-Path: cswreg.cos.agilent.com!unknown@sqf3448.britain.agilent.com X-Cache: nntpcache 2.3.3 (see http://www.nntpcache.org/) Path: chonsp.franklin.ch!pfaff.ethz.ch!news-zh.switch.ch!news.imp.ch!news.imp.ch!news-spur1.maxwell.syr.edu!news.maxwell.syr.edu!newsfeed.stanford.edu!news.isc.org!agilent.com!not-for-mail Xref: chonsp.franklin.ch comp.arch.fpga:20061 Hello, I am trying to chose some memory to store configuration files for Xilinx FPGAs and I've noticed that in previous designs when I created an FPGA configuration file, the RBT was usually 8 or 9 times bigger than the BIT file. In theory as Xilinx mentions in http://support.xilinx.com/xlnx/xil_ans_display.jsp?iLanguageID=1&iCountryID= 1&getPagePath=14468 the RBT is a 'An ASCII version of the bit file'. Is the size different only because the compression algorithm is different? In that case what are the benefits of using RBT files if you need a bigger memory to store them? Is just that the header is readable with a simple editor? Thank you very much. -- Ulises Hernandez ###### From: hmurray@suespammers.org (Hal Murray) Newsgroups: comp.arch.fpga Subject: Re: RBT versus BIT file Date: Tue, 13 Aug 2002 16:14:45 -0000 Message-ID: X-Newsreader: xrn 9.02 Sender: murray@glypnod (Hal Murray) References: <1029227596.880081@cswreg.cos.agilent.com> X-Complaints-To: newsabuse@supernews.com Lines: 18 Path: chonsp.franklin.ch!pfaff.ethz.ch!news-zh.switch.ch!news.mailgate.org!newsfeed.icl.net!newsfeed.fjserv.net!opentransit.net!wanadoo.fr!freenix!sn-xit-05!sn-xit-06!sn-post-01!supernews.com!corp.supernews.com!glypnod!hmurray Xref: chonsp.franklin.ch comp.arch.fpga:20060 Last time I checked, an RBT file was 1 bit per byte. It was an ASCII "0" or "1". I wouldn't call the BIT file "compressed", just a better encoding. You can do better still if you do real compression. I've always assumed the main advantage of the RBT file format is that you didn't have to worry about which end of the byte the first bit was stored in. If you are writing your own code to wiggle the configuration signals, just read the RBT file with a preprocessing program to make whatever internal format you like. -- The suespammers.org mail server is located in California. So are all my other mailboxes. Please do not send unsolicited bulk e-mail or unsolicited commercial e-mail to my suespammers.org address or any of my other addresses. These are my opinions, not necessarily my employer's. I hate spam. ###### Path: chonsp.franklin.ch!not-for-mail From: Neil Franklin Newsgroups: comp.arch.fpga Subject: Re: RBT versus BIT file Date: 14 Aug 2002 00:56:08 +0200 Organization: My own Private Self Lines: 27 Message-ID: <6ur8h2bc6v.fsf@chonsp.franklin.ch> References: <1029227596.880081@cswreg.cos.agilent.com> NNTP-Posting-Host: chonsp.franklin.ch X-Trace: chonsp.franklin.ch 1029279369 325 10.0.3.2 (13 Aug 2002 22:56:09 GMT) X-Complaints-To: news@chonsp.franklin.ch NNTP-Posting-Date: 13 Aug 2002 22:56:09 GMT X-Newsreader: Gnus v5.7/Emacs 20.4 Xref: chonsp.franklin.ch comp.arch.fpga:20080 hmurray@suespammers.org (Hal Murray) writes: > I wouldn't call the BIT file > "compressed", just a better encoding. Yes. Binary instead of ASCII. > You can do better > still if you do real compression. Yes. Massively (for XCV300): neil@chonsp 0:53:44 ~> ls -al pdp10.bit -rw-r--r-- 1 neil franklin 219047 Jul 10 15:20 pdp10.bit neil@chonsp 0:53:51 ~> gzip pdp10.bit neil@chonsp 0:53:55 ~> ls -al pdp10.bit.gz -rw-r--r-- 1 neil franklin 21243 Jul 10 15:20 pdp10.bit.gz neil@chonsp 0:53:57 ~> It is seldom to see files compress by factor 10. -- Neil Franklin, neil@franklin.ch.remove http://neil.franklin.ch/ Hacker, Unix Guru, El Eng HTL/BSc, Programmer, Archer, Roleplayer - Make your code truely free: put it into the public domain