compiler/stdc/math/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  * 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 #ifndef lint
  18 static char rcsid[] = "$FreeBSD: src/lib/msun/src/s_tanf.c,v 1.14 2005/11/28 05:35:32 bde Exp $";
  19 #endif
  20
  21 #include "math.h"
  22 #define INLINE_KERNEL_TANDF
  23 #define INLINE_REM_PIO2F
  24 #include "math_private.h"
  25 #include "e_rem_pio2f.c"
  26 #include "k_tanf.c"
  27
  28 /* Small multiples of pi/2 rounded to double precision. */
  29 static const double
  30 t1pio2 = 1*M_PI_2,                      /* 0x3FF921FB, 0x54442D18 */
  31 t2pio2 = 2*M_PI_2,                      /* 0x400921FB, 0x54442D18 */
  32 t3pio2 = 3*M_PI_2,                      /* 0x4012D97C, 0x7F3321D2 */
  33 t4pio2 = 4*M_PI_2;                      /* 0x401921FB, 0x54442D18 */
  34
  35 float
  36 tanf(float x)
  37 {
  38         float y[2];
  39         int32_t n, hx, ix;
  40
  41         GET_FLOAT_WORD(hx,x);
  42         ix = hx & 0x7fffffff;
  43
  44         if(ix <= 0x3f490fda) {          /* |x| ~<= pi/4 */
  45             if(ix<0x39800000)           /* |x| < 2**-12 */
  46                 if(((int)x)==0) return x;       /* x with inexact if x != 0 */
  47             return __kernel_tandf(x,1);
  48         }
  49         if(ix<=0x407b53d1) {            /* |x| ~<= 5*pi/4 */
  50             if(ix<=0x4016cbe3)          /* |x| ~<= 3pi/4 */
  51                 return __kernel_tandf(x + (hx>0 ? -t1pio2 : t1pio2), -1);
  52             else
  53                 return __kernel_tandf(x + (hx>0 ? -t2pio2 : t2pio2), 1);
  54         }
  55         if(ix<=0x40e231d5) {            /* |x| ~<= 9*pi/4 */
  56             if(ix<=0x40afeddf)          /* |x| ~<= 7*pi/4 */
  57                 return __kernel_tandf(x + (hx>0 ? -t3pio2 : t3pio2), -1);
  58             else
  59                 return __kernel_tandf(x + (hx>0 ? -t4pio2 : t4pio2), 1);
  60         }
  61
  62     /* tan(Inf or NaN) is NaN */
  63         else if (ix>=0x7f800000) return x-x;
  64
  65     /* general argument reduction needed */
  66         else {
  67             n = __ieee754_rem_pio2f(x,y);
  68             /* integer parameter: 1 -- n even; -1 -- n odd */
  69             return __kernel_tandf((double)y[0]+y[1],1-((n&1)<<1));
  70         }
  71 }