xorg-server-1.4/hw/kdrive/src/ktest.c

   1 /*
   2  * Copyright © 1999 Keith Packard
   3  *
   4  * Permission to use, copy, modify, distribute, and sell this software and its
   5  * documentation for any purpose is hereby granted without fee, provided that
   6  * the above copyright notice appear in all copies and that both that
   7  * copyright notice and this permission notice appear in supporting
   8  * documentation, and that the name of Keith Packard not be used in
   9  * advertising or publicity pertaining to distribution of the software without
  10  * specific, written prior permission.  Keith Packard makes no
  11  * representations about the suitability of this software for any purpose.  It
  12  * is provided "as is" without express or implied warranty.
  13  *
  14  * KEITH PACKARD DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
  15  * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
  16  * EVENT SHALL KEITH PACKARD BE LIABLE FOR ANY SPECIAL, INDIRECT OR
  17  * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
  18  * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
  19  * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
  20  * PERFORMANCE OF THIS SOFTWARE.
  21  */
  22
  23 #ifdef HAVE_CONFIG_H
  24 #include <kdrive-config.h>
  25 #endif
  26 #include "kdrive.h"
  27
  28
  29 static CARD8    memoryPatterns[] = { 0xff, 0x00, 0x5a, 0xa5, 0xaa, 0x55 };
  30
  31 #define NUM_PATTERNS    (sizeof (memoryPatterns) / sizeof (memoryPatterns[0]))
  32
  33 Bool
  34 KdFrameBufferValid (CARD8 *base, int size)
  35 {
  36     volatile CARD8  *b = (volatile CARD8 *) base;
  37     CARD8           save, test, compare;
  38     int             i, j;
  39
  40     b = base + (size - 1);
  41     save = *b;
  42
  43     for (i = 0; i < NUM_PATTERNS; i++)
  44     {
  45         test = memoryPatterns[i];
  46         *b = test;
  47         for (j = 0; j < 1000; j++)
  48         {
  49             compare = *b;
  50             if (compare != test)
  51                 return FALSE;
  52         }
  53     }
  54     *b = save;
  55     return TRUE;
  56 }
  57
  58 int
  59 KdFrameBufferSize (CARD8 *base, int max)
  60 {
  61     int min, cur;
  62
  63     min = 0;
  64     while (min + 1 < max)
  65     {
  66         cur = (max + min) / 2;
  67         if (KdFrameBufferValid (base, cur))
  68             min = cur;
  69         else
  70             max = cur;
  71     }
  72     if (KdFrameBufferValid (base, max))
  73         return max;
  74     else
  75         return min;
  76 }