newlib/libm/math/sf_tan.c

   1 /* sf_tan.c -- float version of s_tan.c.
   2  * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
   3  */
   4
   5 /*
   6  * ====================================================
   7  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
   8  *
   9  * Developed at SunPro, a Sun Microsystems, Inc. business.
  10  * Permission to use, copy, modify, and distribute this
  11  * software is freely granted, provided that this notice
  12  * is preserved.
  13  * ====================================================
  14  */
  15
  16 #include "fdlibm.h"
  17
  18 #ifdef __STDC__
  19         float tanf(float x)
  20 #else
  21         float tanf(x)
  22         float x;
  23 #endif
  24 {
  25         float y[2],z=0.0;
  26         __int32_t n,ix;
  27
  28         GET_FLOAT_WORD(ix,x);
  29
  30     /* |x| ~< pi/4 */
  31         ix &= 0x7fffffff;
  32         if(ix <= 0x3f490fda) return __kernel_tanf(x,z,1);
  33
  34     /* tan(Inf or NaN) is NaN */
  35         else if (!FLT_UWORD_IS_FINITE(ix)) return x-x;          /* NaN */
  36
  37     /* argument reduction needed */
  38         else {
  39             n = __ieee754_rem_pio2f(x,y);
  40             return __kernel_tanf(y[0],y[1],1-((n&1)<<1)); /*   1 -- n even
  41                                                               -1 -- n odd */
  42         }
  43 }
  44
  45 #ifdef _DOUBLE_IS_32BITS
  46
  47 #ifdef __STDC__
  48         double tan(double x)
  49 #else
  50         double tan(x)
  51         double x;
  52 #endif
  53 {
  54         return (double) tanf((float) x);
  55 }
  56
  57 #endif /* defined(_DOUBLE_IS_32BITS) */