From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rolf Offermanns Subject: color map vs. pseudo-palette vs. RAMDAC registers Date: Mon, 24 Oct 2005 09:48:50 +0200 Message-ID: <200510240948.50185.rolf.offermanns@gmx.net> Reply-To: linux-fbdev-devel@lists.sourceforge.net Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Return-path: Received: from sc8-sf-mx2-b.sourceforge.net ([10.3.1.92] helo=mail.sourceforge.net) by sc8-sf-list1.sourceforge.net with esmtp (Exim 4.30) id 1ETx4m-0000sy-3T for linux-fbdev-devel@lists.sourceforge.net; Mon, 24 Oct 2005 00:49:00 -0700 Received: from mail.sysgo.com ([62.8.134.5]) by mail.sourceforge.net with esmtp (Exim 4.44) id 1ETx4k-0001he-Eb for linux-fbdev-devel@lists.sourceforge.net; Mon, 24 Oct 2005 00:49:00 -0700 Received: from localhost (localhost [127.0.0.1]) by mail.sysgo.com (Postfix) with ESMTP id EF4A8FB877 for ; Mon, 24 Oct 2005 09:48:50 +0200 (CEST) Received: from donald.sysgo.com (unknown [172.20.1.30]) by mail.sysgo.com (Postfix) with ESMTP id DD724FB877 for ; Mon, 24 Oct 2005 09:48:50 +0200 (CEST) Received: from kolab.sysgo.com (rof.sysgo.com [172.22.10.10]) by donald.sysgo.com (Postfix) with ESMTP id E98251AE865 for ; Mon, 24 Oct 2005 09:48:48 +0200 (CEST) Content-Disposition: inline Sender: linux-fbdev-devel-admin@lists.sourceforge.net Errors-To: linux-fbdev-devel-admin@lists.sourceforge.net List-Unsubscribe: , List-Id: List-Post: List-Help: List-Subscribe: , List-Archive: Content-Type: text/plain; charset="us-ascii" To: linux-fbdev-devel@lists.sourceforge.net Hi All, I tried to understand the skeletonfb driver code, and I am confused by some= =20 comments in it: I do not understand what the color map and pseudo palette stuff is used for. =46rom the c file: =2D------------------------------------------------------------------- Pseudocolor: * cmap is not used * DAC[X] is programmed to (red, green, blue) =2D------------------------------------------------------------------- Does that mean, I do not need to allocate a color map, if my driver would o= nly=20 support pseudocolor visual? Is pseudocolor always used for 8bpp or are ther= e=20 situations where 16bpp pseudocolor makes sense? =2D------------------------------------------------------------------------= =2D--- Truecolor: * does not use RAMDAC (usually has 3 of them). * var->{color}.offset contains start of bitfield * var->{color}.length contains length of bitfield * cmap is programmed to (red << red.offset) |=20 (green << green.offset) | (blue << blue.offset) |=20 (transp << transp.offset) * RAMDAC does not exist =2D------------------------------------------------------------------------= =2D--- Now I am lost: =2D> does not use RAMDAC.=20 I understand this. It states the same in my chip reference. But what means= =20 "usually has 3 of them" in this context? =2D> cmap is programmed to... In the code that follows this comment, not the cmap is programmed, but the= =20 pseudo palette. 1. Why do I need a pseudo palette and where does its size 16 comes from? 2. What do I need a color map for? =2D> RAMDAC does not exist <-> "usually has 3 of them" ??? Please shed some light on me. Thanks, Rolf ------------------------------------------------------- This SF.Net email is sponsored by the JBoss Inc. Get Certified Today * Register for a JBoss Training Course Free Certification Exam for All Training Attendees Through End of 2005 Visit http://www.jboss.com/services/certification for more information