src/math/sinf.c

   1 /* origin: FreeBSD /usr/src/lib/msun/src/s_sinf.c */
   2 /*
   3  * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
   4  * Optimized by Bruce D. Evans.
   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 #include "libm.h"
  18
  19 /* Small multiples of pi/2 rounded to double precision. */
  20 static const double
  21 s1pio2 = 1*M_PI_2, /* 0x3FF921FB, 0x54442D18 */
  22 s2pio2 = 2*M_PI_2, /* 0x400921FB, 0x54442D18 */
  23 s3pio2 = 3*M_PI_2, /* 0x4012D97C, 0x7F3321D2 */
  24 s4pio2 = 4*M_PI_2; /* 0x401921FB, 0x54442D18 */
  25
  26 float sinf(float x)
  27 {
  28         double y;
  29         uint32_t ix;
  30         int n, sign;
  31
  32         GET_FLOAT_WORD(ix, x);
  33         sign = ix >> 31;
  34         ix &= 0x7fffffff;
  35
  36         if (ix <= 0x3f490fda) {  /* |x| ~<= pi/4 */
  37                 if (ix < 0x39800000) {  /* |x| < 2**-12 */
  38                         /* raise inexact if x!=0 and underflow if subnormal */
  39                         FORCE_EVAL(ix < 0x00800000 ? x/0x1p120f : x+0x1p120f);
  40                         return x;
  41                 }
  42                 return __sindf(x);
  43         }
  44         if (ix <= 0x407b53d1) {  /* |x| ~<= 5*pi/4 */
  45                 if (ix <= 0x4016cbe3) {  /* |x| ~<= 3pi/4 */
  46                         if (sign)
  47                                 return -__cosdf(x + s1pio2);
  48                         else
  49                                 return __cosdf(x - s1pio2);
  50                 }
  51                 return __sindf(sign ? -(x + s2pio2) : -(x - s2pio2));
  52         }
  53         if (ix <= 0x40e231d5) {  /* |x| ~<= 9*pi/4 */
  54                 if (ix <= 0x40afeddf) {  /* |x| ~<= 7*pi/4 */
  55                         if (sign)
  56                                 return __cosdf(x + s3pio2);
  57                         else
  58                                 return -__cosdf(x - s3pio2);
  59                 }
  60                 return __sindf(sign ? x + s4pio2 : x - s4pio2);
  61         }
  62
  63         /* sin(Inf or NaN) is NaN */
  64         if (ix >= 0x7f800000)
  65                 return x - x;
  66
  67         /* general argument reduction needed */
  68         n = __rem_pio2f(x, &y);
  69         switch (n&3) {
  70         case 0: return  __sindf(y);
  71         case 1: return  __cosdf(y);
  72         case 2: return  __sindf(-y);
  73         default:
  74                 return -__cosdf(y);
  75         }
  76 }