sysdeps/powerpc/fpu/s_cosf.c

   1 /* s_cosf.c -- float version of s_cos.c.
   2    Copyright (C) 2011-2014 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Adhemerval Zanella <azanella@br.ibm.com>, 2011
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Library General Public License as
   8    published by the Free Software Foundation; either version 2 of the
   9    License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Library General Public License for more details.
  15
  16    You should have received a copy of the GNU Library General Public
  17    License along with the GNU C Library; see the file COPYING.LIB.  If
  18    not, see <http://www.gnu.org/licenses/>.  */
  19
  20 #include <errno.h>
  21 #include <math.h>
  22 #include <math_private.h>
  23
  24 static const float one  = 1.0;
  25 static const float pio4 = 7.8539801e-1;
  26
  27 float
  28 __cosf (float x)
  29 {
  30   float y[2], z = 0.0;
  31   float ix;
  32   int32_t n;
  33
  34   ix = __builtin_fabsf (x);
  35
  36   /* |x| ~< pi/4 */
  37   if (ix <= pio4)
  38     {
  39       return __kernel_cosf (x, z);
  40       /* cos(Inf or NaN) is NaN */
  41     }
  42   else if (isnanf (ix))
  43     {
  44       return x - x;
  45     }
  46   else if (isinff (ix))
  47     {
  48       __set_errno (EDOM);
  49       return x - x;
  50     }
  51
  52   /* argument reduction needed */
  53   else
  54     {
  55       n = __ieee754_rem_pio2f (x, y);
  56       switch (n & 3)
  57         {
  58         case 0:
  59           return __kernel_cosf (y[0], y[1]);
  60         case 1:
  61           return -__kernel_sinf (y[0], y[1], 1);
  62         case 2:
  63           return -__kernel_cosf (y[0], y[1]);
  64         default:
  65           return __kernel_sinf (y[0], y[1], 1);
  66         }
  67     }
  68 }
  69
  70 weak_alias (__cosf, cosf)