sysdeps/ieee754/flt-32/s_cosf.c

   1 /* s_cosf.c -- float version of s_cos.c.
   2  * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
   3  */
   4
   5 /*
   6  * ====================================================
   7  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
   8  *
   9  * Developed at SunPro, a Sun Microsystems, Inc. business.
  10  * Permission to use, copy, modify, and distribute this
  11  * software is freely granted, provided that this notice
  12  * is preserved.
  13  * ====================================================
  14  */
  15
  16 #if defined(LIBM_SCCS) && !defined(lint)
  17 static char rcsid[] = "$NetBSD: s_cosf.c,v 1.4 1995/05/10 20:47:03 jtc Exp $";
  18 #endif
  19
  20 #include <errno.h>
  21 #include "math.h"
  22 #include "math_private.h"
  23
  24 #ifdef __STDC__
  25 static const float one=1.0;
  26 #else
  27 static float one=1.0;
  28 #endif
  29
  30 #ifdef __STDC__
  31         float __cosf(float x)
  32 #else
  33         float __cosf(x)
  34         float x;
  35 #endif
  36 {
  37         float y[2],z=0.0;
  38         int32_t n,ix;
  39
  40         GET_FLOAT_WORD(ix,x);
  41
  42     /* |x| ~< pi/4 */
  43         ix &= 0x7fffffff;
  44         if(ix <= 0x3f490fd8) return __kernel_cosf(x,z);
  45
  46     /* cos(Inf or NaN) is NaN */
  47         else if (ix>=0x7f800000) {
  48           if (ix == 0x7f800000)
  49             __set_errno (EDOM);
  50           return x-x;
  51         }
  52
  53     /* argument reduction needed */
  54         else {
  55             n = __ieee754_rem_pio2f(x,y);
  56             switch(n&3) {
  57                 case 0: return  __kernel_cosf(y[0],y[1]);
  58                 case 1: return -__kernel_sinf(y[0],y[1],1);
  59                 case 2: return -__kernel_cosf(y[0],y[1]);
  60                 default:
  61                         return  __kernel_sinf(y[0],y[1],1);
  62             }
  63         }
  64 }
  65 weak_alias (__cosf, cosf)