compiler/stdc/math/s_cosl.c

   1 /*-
   2  * Copyright (c) 2007 Steven G. Kargl
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice unmodified, this list of conditions, and the following
  10  *    disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  *
  15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  16  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  17  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  18  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  19  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  20  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  21  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  22  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  24  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  25  */
  26
  27 #ifndef lint
  28 static char rcsid[] = "$FreeBSD: src/lib/msun/src/s_cosl.c,v 1.3 2011/05/30 19:41:28 kargl Exp $";
  29 #endif
  30
  31 /*
  32  * Limited testing on pseudorandom numbers drawn within [-2e8:4e8] shows
  33  * an accuracy of <= 0.7412 ULP.
  34  */
  35
  36 #include <float.h>
  37 #include "math.h"
  38
  39 #if defined(__x86_64__)
  40 #include "i386/ieeefp.h"
  41 #elif defined(__i386__)
  42 #include "i386/ieeefp.h"
  43 #endif
  44
  45 #include "math_private.h"
  46 #if LDBL_MANT_DIG == 64
  47 #include "ld80/e_rem_pio2l.h"
  48 #elif LDBL_MANT_DIG == 113
  49 #include "ld128/e_rem_pio2l.h"
  50 #else
  51 #error "Unsupported long double format"
  52 #endif
  53
  54 long double
  55 cosl(long double x)
  56 {
  57         union IEEEl2bits z;
  58         int e0;
  59         long double y[2];
  60         long double hi, lo;
  61
  62         z.e = x;
  63         z.bits.sign = 0;
  64
  65         /* If x = +-0 or x is a subnormal number, then cos(x) = 1 */
  66         if (z.bits.exp == 0)
  67                 return (1.0);
  68
  69         /* If x = NaN or Inf, then cos(x) = NaN. */
  70         if (z.bits.exp == 32767)
  71                 return ((x - x) / (x - x));
  72
  73         ENTERI();
  74
  75         /* Optimize the case where x is already within range. */
  76         if (z.e < M_PI_4)
  77                 RETURNI(__kernel_cosl(z.e, 0));
  78
  79         e0 = __ieee754_rem_pio2l(x, y);
  80         hi = y[0];
  81         lo = y[1];
  82
  83         switch (e0 & 3) {
  84         case 0:
  85             hi = __kernel_cosl(hi, lo);
  86             break;
  87         case 1:
  88             hi = - __kernel_sinl(hi, lo, 1);
  89             break;
  90         case 2:
  91             hi = - __kernel_cosl(hi, lo);
  92             break;
  93         case 3:
  94             hi = __kernel_sinl(hi, lo, 1);
  95             break;
  96         }
  97
  98         RETURNI(hi);
  99 }