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