lib/msun/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  * Optimized by Bruce D. Evans.
   4  */
   5
   6 /*
   7  * ====================================================
   8  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
   9  *
  10  * Developed at SunPro, a Sun Microsystems, Inc. business.
  11  * Permission to use, copy, modify, and distribute this
  12  * software is freely granted, provided that this notice
  13  * is preserved.
  14  * ====================================================
  15  */
  16
  17 #ifndef lint
  18 static char rcsid[] = "$FreeBSD$";
  19 #endif
  20
  21 #include "math.h"
  22 #define INLINE_KERNEL_COSDF
  23 #define INLINE_KERNEL_SINDF
  24 #include "math_private.h"
  25 #include "k_cosf.c"
  26 #include "k_sinf.c"
  27
  28 /* Small multiples of pi/2 rounded to double precision. */
  29 static const double
  30 c1pio2 = 1*M_PI_2,                      /* 0x3FF921FB, 0x54442D18 */
  31 c2pio2 = 2*M_PI_2,                      /* 0x400921FB, 0x54442D18 */
  32 c3pio2 = 3*M_PI_2,                      /* 0x4012D97C, 0x7F3321D2 */
  33 c4pio2 = 4*M_PI_2;                      /* 0x401921FB, 0x54442D18 */
  34
  35 float
  36 cosf(float x)
  37 {
  38         float y[2];
  39         int32_t n, hx, ix;
  40
  41         GET_FLOAT_WORD(hx,x);
  42         ix = hx & 0x7fffffff;
  43
  44         if(ix <= 0x3f490fda) {          /* |x| ~<= pi/4 */
  45             if(ix<0x39800000)           /* |x| < 2**-12 */
  46                 if(((int)x)==0) return 1.0;     /* 1 with inexact if x != 0 */
  47             return __kernel_cosdf(x);
  48         }
  49         if(ix<=0x407b53d1) {            /* |x| ~<= 5*pi/4 */
  50             if(ix>0x4016cbe3)           /* |x|  ~> 3*pi/4 */
  51                 return -__kernel_cosdf(x + (hx > 0 ? -c2pio2 : c2pio2));
  52             else {
  53                 if(hx>0)
  54                     return __kernel_sindf(c1pio2 - x);
  55                 else
  56                     return __kernel_sindf(x + c1pio2);
  57             }
  58         }
  59         if(ix<=0x40e231d5) {            /* |x| ~<= 9*pi/4 */
  60             if(ix>0x40afeddf)           /* |x|  ~> 7*pi/4 */
  61                 return __kernel_cosdf(x + (hx > 0 ? -c4pio2 : c4pio2));
  62             else {
  63                 if(hx>0)
  64                     return __kernel_sindf(x - c3pio2);
  65                 else
  66                     return __kernel_sindf(-c3pio2 - x);
  67             }
  68         }
  69
  70     /* cos(Inf or NaN) is NaN */
  71         else if (ix>=0x7f800000) return x-x;
  72
  73     /* general argument reduction needed */
  74         else {
  75             n = __ieee754_rem_pio2f(x,y);
  76             switch(n&3) {
  77                 case 0: return  __kernel_cosdf((double)y[0]+y[1]);
  78                 case 1: return  __kernel_sindf(-(double)y[0]-y[1]);
  79                 case 2: return -__kernel_cosdf((double)y[0]+y[1]);
  80                 default:
  81                         return  __kernel_sindf((double)y[0]+y[1]);
  82             }
  83         }
  84 }