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//Copyright Paul Reiche, Fred Ford. 1992-2002
/*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
#include "mthintrn.h"
COUNT
square_root (DWORD value)
{
UWORD sig_word, mask;
COUNT result, shift;
if ((sig_word = HIWORD (value)) > 0)
{
DWORD mask_squared, result_shift;
for (mask = 1 << 15, shift = 31;
!(mask & sig_word); mask >>= 1, --shift)
;
shift >>= 1;
mask = 1 << shift;
result = mask;
mask_squared = result_shift = (DWORD)mask << shift;
value -= mask_squared;
while (mask >>= 1)
{
DWORD remainder;
mask_squared >>= 1;
mask_squared >>= 1;
if ((remainder = result_shift + mask_squared) > value)
result_shift >>= 1;
else
{
value -= remainder;
result_shift = (result_shift >> 1) + mask_squared;
result |= mask;
}
}
return (result);
}
else if ((sig_word = LOWORD (value)) > 0)
{
UWORD mask_squared, result_shift;
for (mask = 1 << 15, shift = 15;
!(mask & sig_word); mask >>= 1, --shift)
;
shift >>= 1;
mask = 1 << shift;
result = mask;
mask_squared = result_shift = mask << shift;
sig_word -= mask_squared;
while (mask >>= 1)
{
UWORD remainder;
mask_squared >>= 1;
mask_squared >>= 1;
if ((remainder = result_shift + mask_squared) > sig_word)
result_shift >>= 1;
else
{
sig_word -= remainder;
result_shift = (result_shift >> 1) + mask_squared;
result |= mask;
}
}
return (result);
}
return (0);
}
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