sysdeps/libm-ieee754/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 "math.h"
  21 #include "math_private.h"
  22
  23 #ifdef __STDC__
  24 static const float one=1.0;
  25 #else
  26 static float one=1.0;
  27 #endif
  28
  29 #ifdef __STDC__
  30         float __cosf(float x)
  31 #else
  32         float __cosf(x)
  33         float x;
  34 #endif
  35 {
  36         float y[2],z=0.0;
  37         int32_t n,ix;
  38
  39         GET_FLOAT_WORD(ix,x);
  40
  41     /* |x| ~< pi/4 */
  42         ix &= 0x7fffffff;
  43         if(ix <= 0x3f490fd8) return __kernel_cosf(x,z);
  44
  45     /* cos(Inf or NaN) is NaN */
  46         else if (ix>=0x7f800000) return x-x;
  47
  48     /* argument reduction needed */
  49         else {
  50             n = __ieee754_rem_pio2f(x,y);
  51             switch(n&3) {
  52                 case 0: return  __kernel_cosf(y[0],y[1]);
  53                 case 1: return -__kernel_sinf(y[0],y[1],1);
  54                 case 2: return -__kernel_cosf(y[0],y[1]);
  55                 default:
  56                         return  __kernel_sinf(y[0],y[1],1);
  57             }
  58         }
  59 }
  60 weak_alias (__cosf, cosf)