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/*
* $Id$
*
* Copyright © 1999 Keith Packard
*
* Permission to use, copy, modify, distribute, and sell this software and its
* documentation for any purpose is hereby granted without fee, provided that
* the above copyright notice appear in all copies and that both that
* copyright notice and this permission notice appear in supporting
* documentation, and that the name of Keith Packard not be used in
* advertising or publicity pertaining to distribution of the software without
* specific, written prior permission. Keith Packard makes no
* representations about the suitability of this software for any purpose. It
* is provided "as is" without express or implied warranty.
*
* KEITH PACKARD DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
* INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
* EVENT SHALL KEITH PACKARD BE LIABLE FOR ANY SPECIAL, INDIRECT OR
* CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
* DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
* TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
* PERFORMANCE OF THIS SOFTWARE.
*/
/* $XFree86: $ */
#include "kdrive.h"
static CARD8 memoryPatterns[] = { 0xff, 0x00, 0x5a, 0xa5, 0xaa, 0x55 };
#define NUM_PATTERNS (sizeof (memoryPatterns) / sizeof (memoryPatterns[0]))
Bool
KdFrameBufferValid (CARD8 *base, int size)
{
volatile CARD8 *b = (volatile CARD8 *) base;
CARD8 save, test, compare;
int i, j;
b = base + (size - 1);
save = *b;
for (i = 0; i < NUM_PATTERNS; i++)
{
test = memoryPatterns[i];
*b = test;
for (j = 0; j < 1000; j++)
{
compare = *b;
if (compare != test)
return FALSE;
}
}
*b = save;
return TRUE;
}
int
KdFrameBufferSize (CARD8 *base, int max)
{
int min, cur;
min = 0;
while (min + 1 < max)
{
cur = (max + min) / 2;
if (KdFrameBufferValid (base, cur))
min = cur;
else
max = cur;
}
if (KdFrameBufferValid (base, max))
return max;
else
return min;
}
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