sincosf.c raw

   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  #define _GNU_SOURCE
  18  #include "libm.h"
  19  
  20  /* Small multiples of pi/2 rounded to double precision. */
  21  static const double
  22  s1pio2 = 1*M_PI_2, /* 0x3FF921FB, 0x54442D18 */
  23  s2pio2 = 2*M_PI_2, /* 0x400921FB, 0x54442D18 */
  24  s3pio2 = 3*M_PI_2, /* 0x4012D97C, 0x7F3321D2 */
  25  s4pio2 = 4*M_PI_2; /* 0x401921FB, 0x54442D18 */
  26  
  27  void sincosf(float x, float *sin, float *cos)
  28  {
  29  	double y;
  30  	float_t s, c;
  31  	uint32_t ix;
  32  	unsigned n, sign;
  33  
  34  	GET_FLOAT_WORD(ix, x);
  35  	sign = ix >> 31;
  36  	ix &= 0x7fffffff;
  37  
  38  	/* |x| ~<= pi/4 */
  39  	if (ix <= 0x3f490fda) {
  40  		/* |x| < 2**-12 */
  41  		if (ix < 0x39800000) {
  42  			/* raise inexact if x!=0 and underflow if subnormal */
  43  			FORCE_EVAL(ix < 0x00100000 ? x/0x1p120f : x+0x1p120f);
  44  			*sin = x;
  45  			*cos = 1.0f;
  46  			return;
  47  		}
  48  		*sin = __sindf(x);
  49  		*cos = __cosdf(x);
  50  		return;
  51  	}
  52  
  53  	/* |x| ~<= 5*pi/4 */
  54  	if (ix <= 0x407b53d1) {
  55  		if (ix <= 0x4016cbe3) {  /* |x| ~<= 3pi/4 */
  56  			if (sign) {
  57  				*sin = -__cosdf(x + s1pio2);
  58  				*cos = __sindf(x + s1pio2);
  59  			} else {
  60  				*sin = __cosdf(s1pio2 - x);
  61  				*cos = __sindf(s1pio2 - x);
  62  			}
  63  			return;
  64  		}
  65  		/* -sin(x+c) is not correct if x+c could be 0: -0 vs +0 */
  66  		*sin = -__sindf(sign ? x + s2pio2 : x - s2pio2);
  67  		*cos = -__cosdf(sign ? x + s2pio2 : x - s2pio2);
  68  		return;
  69  	}
  70  
  71  	/* |x| ~<= 9*pi/4 */
  72  	if (ix <= 0x40e231d5) {
  73  		if (ix <= 0x40afeddf) {  /* |x| ~<= 7*pi/4 */
  74  			if (sign) {
  75  				*sin = __cosdf(x + s3pio2);
  76  				*cos = -__sindf(x + s3pio2);
  77  			} else {
  78  				*sin = -__cosdf(x - s3pio2);
  79  				*cos = __sindf(x - s3pio2);
  80  			}
  81  			return;
  82  		}
  83  		*sin = __sindf(sign ? x + s4pio2 : x - s4pio2);
  84  		*cos = __cosdf(sign ? x + s4pio2 : x - s4pio2);
  85  		return;
  86  	}
  87  
  88  	/* sin(Inf or NaN) is NaN */
  89  	if (ix >= 0x7f800000) {
  90  		*sin = *cos = x - x;
  91  		return;
  92  	}
  93  
  94  	/* general argument reduction needed */
  95  	n = __rem_pio2f(x, &y);
  96  	s = __sindf(y);
  97  	c = __cosdf(y);
  98  	switch (n&3) {
  99  	case 0:
 100  		*sin = s;
 101  		*cos = c;
 102  		break;
 103  	case 1:
 104  		*sin = c;
 105  		*cos = -s;
 106  		break;
 107  	case 2:
 108  		*sin = -s;
 109  		*cos = -c;
 110  		break;
 111  	case 3:
 112  	default:
 113  		*sin = -c;
 114  		*cos = s;
 115  		break;
 116  	}
 117  }
 118