src/math/sincosf.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 #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 }