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btreg.h revision 1.3 
      1 /*	$NetBSD: btreg.h,v 1.3 2005/12/11 12:19:20 christos Exp $ */
      2 
      3 /*
      4  * Copyright (c) 1993
      5  *	The Regents of the University of California.  All rights reserved.
      6  *
      7  * This software was developed by the Computer Systems Engineering group
      8  * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
      9  * contributed to Berkeley.
     10  *
     11  * All advertising materials mentioning features or use of this software
     12  * must display the following acknowledgement:
     13  *	This product includes software developed by the University of
     14  *	California, Lawrence Berkeley Laboratory.
     15  *
     16  * Redistribution and use in source and binary forms, with or without
     17  * modification, are permitted provided that the following conditions
     18  * are met:
     19  * 1. Redistributions of source code must retain the above copyright
     20  *    notice, this list of conditions and the following disclaimer.
     21  * 2. Redistributions in binary form must reproduce the above copyright
     22  *    notice, this list of conditions and the following disclaimer in the
     23  *    documentation and/or other materials provided with the distribution.
     24  * 3. Neither the name of the University nor the names of its contributors
     25  *    may be used to endorse or promote products derived from this software
     26  *    without specific prior written permission.
     27  *
     28  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     29  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     30  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     31  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     32  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     33  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     34  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     35  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     36  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     37  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     38  * SUCH DAMAGE.
     39  *
     40  *	@(#)btreg.h	8.2 (Berkeley) 1/21/94
     41  */
     42 
     43 /*
     44  * Several Sun color frame buffers use some kind of Brooktree video
     45  * DAC (e.g., the Bt458, -- in any case, Brooktree make the only
     46  * decent color frame buffer chips).
     47  *
     48  * Color map control on these is a bit funky in a SPARCstation.
     49  * To update the color map one would normally do byte writes, but
     50  * the hardware takes longword writes.  Since there are three
     51  * registers for each color map entry (R, then G, then B), we have
     52  * to set color 1 with a write to address 0 (setting 0's R/G/B and
     53  * color 1's R) followed by a second write to address 1 (setting
     54  * color 1's G/B and color 2's R/G).  Software must therefore keep
     55  * a copy of the current map.
     56  *
     57  * The colormap address register increments automatically, so the
     58  * above write is done as:
     59  *
     60  *	bt->bt_addr = 0;
     61  *	bt->bt_cmap = R0G0B0R1;
     62  *	bt->bt_cmap = G1B1R2G2;
     63  *	...
     64  *
     65  * Yow!
     66  *
     67  * Bonus complication: on the cg6, only the top 8 bits of each 32 bit
     68  * register matter, even though the cg3 takes all the bits from all
     69  * bytes written to it.
     70  */
     71 struct bt_regs {
     72 	u_int	bt_addr;		/* map address register */
     73 	u_int	bt_cmap;		/* colormap data register */
     74 	u_int	bt_ctrl;		/* control register */
     75 	u_int	bt_omap;		/* overlay (cursor) map register */
     76 };
     77