compiler/mlib/s_tanf.c

   1 /* s_tanf.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 #ifndef lint
  17 static char rcsid[] = "$FreeBSD: src/lib/msun/src/s_tanf.c,v 1.5 1999/08/28 00:06:56 peter Exp $";
  18 #endif
  19
  20 #include "math.h"
  21 #define INLINE_KERNEL_TANDF
  22 #include "math_private.h"
  23 #include "k_tanf.c"
  24
  25 /* Small multiples of pi/2 rounded to double precision. */
  26 static const double
  27 t1pio2 = 1*M_PI_2,                      /* 0x3FF921FB, 0x54442D18 */
  28 t2pio2 = 2*M_PI_2,                      /* 0x400921FB, 0x54442D18 */
  29 t3pio2 = 3*M_PI_2,                      /* 0x4012D97C, 0x7F3321D2 */
  30 t4pio2 = 4*M_PI_2;                      /* 0x401921FB, 0x54442D18 */
  31
  32 float
  33 tanf(float x)
  34 {
  35         float y[2];
  36         int32_t n, hx, ix;
  37
  38         GET_FLOAT_WORD(hx,x);
  39         ix = hx & 0x7fffffff;
  40
  41         if(ix <= 0x3f490fda) {          /* |x| ~<= pi/4 */
  42             if(ix<0x39800000)           /* |x| < 2**-12 */
  43                 if(((int)x)==0) return x;       /* x with inexact if x != 0 */
  44             return __kernel_tandf(x,1);
  45         }
  46         if(ix<=0x407b53d1) {            /* |x| ~<= 5*pi/4 */
  47             if(ix<=0x4016cbe3)          /* |x| ~<= 3pi/4 */
  48                 return __kernel_tandf(x + (hx>0 ? -t1pio2 : t1pio2), -1);
  49             else
  50                 return __kernel_tandf(x + (hx>0 ? -t2pio2 : t2pio2), 1);
  51         }
  52         if(ix<=0x40e231d5) {            /* |x| ~<= 9*pi/4 */
  53             if(ix<=0x40afeddf)          /* |x| ~<= 7*pi/4 */
  54                 return __kernel_tandf(x + (hx>0 ? -t3pio2 : t3pio2), -1);
  55             else
  56                 return __kernel_tandf(x + (hx>0 ? -t4pio2 : t4pio2), 1);
  57         }
  58
  59     /* tan(Inf or NaN) is NaN */
  60         else if (ix>=0x7f800000) return x-x;
  61
  62     /* general argument reduction needed */
  63         else {
  64             n = __ieee754_rem_pio2f(x,y);
  65             /* integer parameter: 1 -- n even; -1 -- n odd */
  66             return __kernel_tandf((double)y[0]+y[1],1-((n&1)<<1));
  67         }
  68 }