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 #include <sys/cdefs.h>
  18 __FBSDID("$FreeBSD$");
  19
  20 #include <float.h>
  21
  22 #include "math.h"
  23 #define INLINE_KERNEL_COSDF
  24 #define INLINE_KERNEL_SINDF
  25 #define INLINE_REM_PIO2F
  26 #include "math_private.h"
  27 #include "e_rem_pio2f.c"
  28 #include "k_cosf.c"
  29 #include "k_sinf.c"
  30
  31 /* Small multiples of pi/2 rounded to double precision. */
  32 static const double
  33 c1pio2 = 1*M_PI_2,                      /* 0x3FF921FB, 0x54442D18 */
  34 c2pio2 = 2*M_PI_2,                      /* 0x400921FB, 0x54442D18 */
  35 c3pio2 = 3*M_PI_2,                      /* 0x4012D97C, 0x7F3321D2 */
  36 c4pio2 = 4*M_PI_2;                      /* 0x401921FB, 0x54442D18 */
  37
  38 float
  39 cosf(float x)
  40 {
  41         double y;
  42         int32_t n, hx, ix;
  43
  44         GET_FLOAT_WORD(hx,x);
  45         ix = hx & 0x7fffffff;
  46
  47         if(ix <= 0x3f490fda) {          /* |x| ~<= pi/4 */
  48             if(ix<0x39800000)           /* |x| < 2**-12 */
  49                 if(((int)x)==0) return 1.0;     /* 1 with inexact if x != 0 */
  50             return __kernel_cosdf(x);
  51         }
  52         if(ix<=0x407b53d1) {            /* |x| ~<= 5*pi/4 */
  53             if(ix>0x4016cbe3)           /* |x|  ~> 3*pi/4 */
  54                 return -__kernel_cosdf(x + (hx > 0 ? -c2pio2 : c2pio2));
  55             else {
  56                 if(hx>0)
  57                     return __kernel_sindf(c1pio2 - x);
  58                 else
  59                     return __kernel_sindf(x + c1pio2);
  60             }
  61         }
  62         if(ix<=0x40e231d5) {            /* |x| ~<= 9*pi/4 */
  63             if(ix>0x40afeddf)           /* |x|  ~> 7*pi/4 */
  64                 return __kernel_cosdf(x + (hx > 0 ? -c4pio2 : c4pio2));
  65             else {
  66                 if(hx>0)
  67                     return __kernel_sindf(x - c3pio2);
  68                 else
  69                     return __kernel_sindf(-c3pio2 - x);
  70             }
  71         }
  72
  73     /* cos(Inf or NaN) is NaN */
  74         else if (ix>=0x7f800000) return x-x;
  75
  76     /* general argument reduction needed */
  77         else {
  78             n = __ieee754_rem_pio2f(x,&y);
  79             switch(n&3) {
  80                 case 0: return  __kernel_cosdf(y);
  81                 case 1: return  __kernel_sindf(-y);
  82                 case 2: return -__kernel_cosdf(y);
  83                 default:
  84                         return  __kernel_sindf(y);
  85             }
  86         }
  87 }