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  * 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  * FreeBSD SVN: 176569 (2008-02-25)
  16  */
  17
  18 #include <math.h>
  19 #define INLINE_KERNEL_COSDF
  20 #define INLINE_KERNEL_SINDF
  21 #define INLINE_REM_PIO2F
  22 #include "math_private.h"
  23 #include "e_rem_pio2f.c"
  24 #include "k_cosf.c"
  25 #include "k_sinf.c"
  26
  27 /* Small multiples of pi/2 rounded to double precision. */
  28 static const double
  29 c1pio2 = 1*M_PI_2,                      /* 0x3FF921FB, 0x54442D18 */
  30 c2pio2 = 2*M_PI_2,                      /* 0x400921FB, 0x54442D18 */
  31 c3pio2 = 3*M_PI_2,                      /* 0x4012D97C, 0x7F3321D2 */
  32 c4pio2 = 4*M_PI_2;                      /* 0x401921FB, 0x54442D18 */
  33
  34 float
  35 cosf(float x)
  36 {
  37         double y;
  38         int32_t n, hx, ix;
  39
  40         GET_FLOAT_WORD(hx,x);
  41         ix = hx & 0x7fffffff;
  42
  43         if(ix <= 0x3f490fda) {          /* |x| ~<= pi/4 */
  44             if(ix<0x39800000)           /* |x| < 2**-12 */
  45                 if(((int)x)==0) return 1.0;     /* 1 with inexact if x != 0 */
  46             return __kernel_cosdf(x);
  47         }
  48         if(ix<=0x407b53d1) {            /* |x| ~<= 5*pi/4 */
  49             if(ix>0x4016cbe3)           /* |x|  ~> 3*pi/4 */
  50                 return -__kernel_cosdf(x + (hx > 0 ? -c2pio2 : c2pio2));
  51             else {
  52                 if(hx>0)
  53                     return __kernel_sindf(c1pio2 - x);
  54                 else
  55                     return __kernel_sindf(x + c1pio2);
  56             }
  57         }
  58         if(ix<=0x40e231d5) {            /* |x| ~<= 9*pi/4 */
  59             if(ix>0x40afeddf)           /* |x|  ~> 7*pi/4 */
  60                 return __kernel_cosdf(x + (hx > 0 ? -c4pio2 : c4pio2));
  61             else {
  62                 if(hx>0)
  63                     return __kernel_sindf(x - c3pio2);
  64                 else
  65                     return __kernel_sindf(-c3pio2 - x);
  66             }
  67         }
  68
  69     /* cos(Inf or NaN) is NaN */
  70         else if (ix>=0x7f800000) return x-x;
  71
  72     /* general argument reduction needed */
  73         else {
  74             n = __libm_rem_pio2f(x,&y);
  75             switch(n&3) {
  76                 case 0: return  __kernel_cosdf(y);
  77                 case 1: return  __kernel_sindf(-y);
  78                 case 2: return -__kernel_cosdf(y);
  79                 default:
  80                         return  __kernel_sindf(y);
  81             }
  82         }
  83 }