sysdeps/arm/e_sqrt.c

   1 /* Compute square root for double.  ARM version.
   2    Copyright (C) 2016-2018 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #ifdef __SOFTFP__
  20
  21 /* Use architecture-indendent sqrt implementation.  */
  22 # include <sysdeps/ieee754/dbl-64/e_sqrt.c>
  23
  24 #else
  25
  26 /* Use VFP square root instruction.  */
  27 # include <math.h>
  28 # include <sysdep.h>
  29
  30 double
  31 __ieee754_sqrt (double x)
  32 {
  33   double ret;
  34 # if __ARM_ARCH >= 6
  35   asm ("vsqrt.f64 %P0, %P1" : "=w" (ret) : "w" (x));
  36 # else
  37   /* As in GCC, for VFP9 Erratum 760019 avoid overwriting the
  38      input.  */
  39   asm ("vsqrt.f64 %P0, %P1" : "=&w" (ret) : "w" (x));
  40 # endif
  41   return ret;
  42 }
  43 strong_alias (__ieee754_sqrt, __sqrt_finite)
  44
  45 #endif