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