Return to BSD News archive
Xref: sserve comp.os.386bsd.apps:1030 comp.os.linux.misc:10891 Newsgroups: comp.os.386bsd.apps,comp.os.linux.misc Path: sserve!newshost.anu.edu.au!munnari.oz.au!news.Hawaii.Edu!ames!hookup!news.moneng.mei.com!howland.reston.ans.net!EU.net!sunic!psinntp!psinntp!relay1!rsvl_ns!ernie!ernie.rsvl.unisys.com!markus From: markus@rsvl.unisys.com (Mark K Vallevand) Subject: Re: DOOM for X Sender: news@rsvl.unisys.com (News Admin) Message-ID: <markus.57.00E736E9@rsvl.unisys.com> Date: Fri, 11 Mar 1994 17:42:36 GMT Lines: 31 References: <1994Mar3.131137.27311@infodev.cam.ac.uk> <CM44Lq.78x@seagoon.newcastle.edu.au> <2lkpg5$8hn@Tut.MsState.Edu> <hastyCMEw58.FMr@netcom.com> <2lm9ih$6s5@godot.cc.duq.edu> <glen.763349922@paladine> Nntp-Posting-Host: mkv1 Organization: SO&M X-Newsreader: Trumpet for Windows [Version 1.0 Rev B] In article <glen.763349922@paladine> glen@paladine.ece.jcu.edu.au (Glen Harris) writes: >In <2lm9ih$6s5@godot.cc.duq.edu> mcquill@next.duq.edu (Tod McQuillin) writes: >>Amancio, what effect, if any, do you think the shared memory extentions of X >>have on graphics performance? > What it means is that a bitmap in memory is mapped directly over the >screen, so an access to the array is an access to the screen. After the >mapping is set up, there's no calls to X for the graphics. In effect, >it's exactly as if you were in dos, but there's no 64Kb segment switching >as the system does this transparently. *I* don't know how page flipping >is done, maybe there's a X call to do this, or a fast memcpy during the >refresh? Inquiring minds....... No, no, no. The X shared memory extension simply gives the X app and X server shared access to a piece of memory so that they can exchange data quickly. Instead of sending a huge message through, a tiny message is sent with a reference to the shared memory that has the huge chunk of data. It's not exactly as it is in DOS. Its not that close to what it is in DOS. Get a book about X programming. Read about images and pixmaps. If you can understand that, the shared memory extension is just a way to excelerate image and pixmap operations. Regards. Mark K Vallevand Unisys Corp Roseville, Minnesota markus@rsvl.unisys.com Mail Station 4313, POBox 65942, St Paul, MN 55164 612-635-7880 On the Information SuperHighway, I'm the guy with a hat driving 50 in the fast lane with my blinker on and my seatbelt hanging out the door making sparks.