sqrtf.c revision 25c28e83beb90e7c80452a7c818c5e6f73a07dc8
/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright 2011 Nexenta Systems, Inc. All rights reserved.
*/
/*
* Copyright 2005 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
#include "libm.h"
#ifdef __INLINE
extern float __inline_sqrtf(float);
float
sqrtf(float x) {
return (__inline_sqrtf(x));
}
#else /* defined(__INLINE) */
float
sqrtf(float x) {
float dz, w;
int *pw = (int *)&w;
int ix, j, r, q, m, n, s, t;
w = x;
if (ix <= 0) {
/* x is <= 0 or nan */
j = ix & 0x7fffffff;
if (j == 0)
return (w);
}
/* x is +inf or nan */
return (w * w);
}
m = ir_ilogb_(&w);
n = -m;
w = r_scalbn_(&w, (int *)&n);
n = m / 2;
if ((n + n) != m) {
m -= 1;
n = m / 2;
}
/* generate sqrt(x) bit by bit */
ix <<= 1;
q = s = 0;
r = 0x01000000;
for (j = 1; j <= 25; j++) {
t = s + r;
if (t <= ix) {
s = t + r;
ix -= t;
q += r;
}
ix <<= 1;
r >>= 1;
}
if (ix == 0)
goto done;
/* raise inexact and determine the ambient rounding mode */
goto done;
q += 1;
q += (q & 1);
done:
return (r_scalbn_(&w, (int *)&n));
}
#endif /* defined(__INLINE) */