/usr/share/sdcc/lib/src/sqrtf.c is in sdcc-libraries 2.9.0-5.
This file is owned by root:root, with mode 0o644.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 | /* sqrtf.c: Computes square root of a 32-bit float as outlined in [1]
Copyright (C) 2001, 2002 Jesus Calvino-Fraga, jesusc@ieee.org
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
/* [1] William James Cody and W. M. Waite. _Software manual for the
elementary functions_, Englewood Cliffs, N.J.:Prentice-Hall, 1980. */
/* Version 1.0 - Initial release */
#include <math.h>
#include <errno.h>
float sqrtf(const float x) _FLOAT_FUNC_REENTRANT
{
float f, y;
int n;
if (x==0.0) return x;
else if (x==1.0) return 1.0;
else if (x<0.0)
{
errno=EDOM;
return 0.0;
}
f=frexpf(x, &n);
y=0.41731+0.59016*f; /*Educated guess*/
/*For a 24 bit mantisa (float), two iterations are sufficient*/
y+=f/y;
y=ldexpf(y, -2) + f/y; /*Faster version of 0.25 * y + f/y*/
if (n&1)
{
y*=0.7071067812;
++n;
}
return ldexpf(y, n/2);
}
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