lib/libm/src/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  * $NetBSD: s_cosf.c,v 1.8 2002/05/26 22:01:55 wiz Exp $
  16  * $DragonFly: src/lib/libm/src/s_cosf.c,v 1.1 2005/07/26 21:15:20 joerg Exp $
  17  */
  18
  19 #include <math.h>
  20 #include "math_private.h"
  21
  22 float
  23 cosf(float x)
  24 {
  25         float y[2],z=0.0;
  26         int32_t n,ix;
  27
  28         GET_FLOAT_WORD(ix,x);
  29
  30     /* |x| ~< pi/4 */
  31         ix &= 0x7fffffff;
  32         if(ix <= 0x3f490fd8) return __kernel_cosf(x,z);
  33
  34     /* cos(Inf or NaN) is NaN */
  35         else if (ix>=0x7f800000) return x-x;
  36
  37     /* argument reduction needed */
  38         else {
  39             n = __libm_rem_pio2f(x,y);
  40             switch(n&3) {
  41                 case 0: return  __kernel_cosf(y[0],y[1]);
  42                 case 1: return -__kernel_sinf(y[0],y[1],1);
  43                 case 2: return -__kernel_cosf(y[0],y[1]);
  44                 default:
  45                         return  __kernel_sinf(y[0],y[1],1);
  46             }
  47         }
  48 }