compiler/stdc/math/s_tanl.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_tanl.c,v 1.3 2011/05/30 19:41:28 kargl Exp $";
  29 #endif
  30
  31 #include <float.h>
  32 #include "math.h"
  33
  34 #include "math_private.h"
  35
  36 #if defined(__x86_64__)
  37 #include "x86_64/ieeefp.h"
  38 #elif defined(__i386__)
  39 #include "i386/ieeefp.h"
  40 #endif
  41
  42 #if LDBL_MANT_DIG == 64
  43 #include "ld80/e_rem_pio2l.h"
  44 #elif LDBL_MANT_DIG == 113
  45 #include "ld128/e_rem_pio2l.h"
  46 #else
  47 #error "Unsupported long double format"
  48 #endif
  49
  50 long double
  51 tanl(long double x)
  52 {
  53         union IEEEl2bits z;
  54         int e0, s;
  55         long double y[2];
  56         long double hi, lo;
  57
  58         z.e = x;
  59         s = z.bits.sign;
  60         z.bits.sign = 0;
  61
  62         /* If x = +-0 or x is subnormal, then tan(x) = x. */
  63         if (z.bits.exp == 0)
  64                 return (x);
  65
  66         /* If x = NaN or Inf, then tan(x) = NaN. */
  67         if (z.bits.exp == 32767)
  68                 return ((x - x) / (x - x));
  69
  70         ENTERI();
  71
  72         /* Optimize the case where x is already within range. */
  73         if (z.e < M_PI_4) {
  74                 hi = __kernel_tanl(z.e, 0, 0);
  75                 RETURNI(s ? -hi : hi);
  76         }
  77
  78         e0 = __ieee754_rem_pio2l(x, y);
  79         hi = y[0];
  80         lo = y[1];
  81
  82         switch (e0 & 3) {
  83         case 0:
  84         case 2:
  85             hi = __kernel_tanl(hi, lo, 0);
  86             break;
  87         case 1:
  88         case 3:
  89             hi = __kernel_tanl(hi, lo, 1);
  90             break;
  91         }
  92
  93         RETURNI(hi);
  94 }