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
  16 #include <sys/cdefs.h>
  17 #if defined(LIBM_SCCS) && !defined(lint)
  18 __RCSID("$NetBSD: s_cosf.c,v 1.9 2007/08/20 16:01:39 drochner Exp $");
  19 #endif
  20
  21 #include "namespace.h"
  22 #include "math.h"
  23 #include "math_private.h"
  24
  25 #if 0 /* notyet */
  26 #ifdef __weak_alias
  27 __weak_alias(cosf, _cosf)
  28 #endif
  29 #endif
  30
  31 #if 0
  32 static const float one=1.0;
  33 #endif
  34
  35 float
  36 cosf(float x)
  37 {
  38         float y[2],z=0.0;
  39         int32_t n,ix;
  40
  41         GET_FLOAT_WORD(ix,x);
  42
  43     /* |x| ~< pi/4 */
  44         ix &= 0x7fffffff;
  45         if(ix <= 0x3f490fd8) return __kernel_cosf(x,z);
  46
  47     /* cos(Inf or NaN) is NaN */
  48         else if (ix>=0x7f800000) return x-x;
  49
  50     /* argument reduction needed */
  51         else {
  52             n = __ieee754_rem_pio2f(x,y);
  53             switch(n&3) {
  54                 case 0: return  __kernel_cosf(y[0],y[1]);
  55                 case 1: return -__kernel_sinf(y[0],y[1],1);
  56                 case 2: return -__kernel_cosf(y[0],y[1]);
  57                 default:
  58                         return  __kernel_sinf(y[0],y[1],1);
  59             }
  60         }
  61 }