lib/libm/src/s_sincosf.c

   1 /*-
   2  * ====================================================
   3  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
   4  *
   5  * Developed at SunPro, a Sun Microsystems, Inc. business.
   6  * Permission to use, copy, modify, and distribute this
   7  * software is freely granted, provided that this notice
   8  * is preserved.
   9  * ====================================================
  10  */
  11
  12 /* s_sincosf.c -- float version of s_sincos.c.
  13  * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
  14  * Optimized by Bruce D. Evans.
  15  * Merged s_sinf.c and s_cosf.c by Steven G. Kargl.
  16  */
  17
  18 #include <float.h>
  19 #include "math.h"
  20
  21 #include "math_private.h"
  22 #include "k_sincosf.h"
  23
  24 /* Small multiples of pi/2 rounded to double precision. */
  25 static const double
  26 p1pio2 = 1*M_PI_2,                      /* 0x3FF921FB, 0x54442D18 */
  27 p2pio2 = 2*M_PI_2,                      /* 0x400921FB, 0x54442D18 */
  28 p3pio2 = 3*M_PI_2,                      /* 0x4012D97C, 0x7F3321D2 */
  29 p4pio2 = 4*M_PI_2;                      /* 0x401921FB, 0x54442D18 */
  30
  31 void
  32 sincosf(float x, float *sn, float *cs)
  33 {
  34         float c, s;
  35         float y[2];
  36         int32_t n, hx, ix;
  37
  38         GET_FLOAT_WORD(hx, x);
  39         ix = hx & 0x7fffffff;
  40
  41         if (ix <= 0x3f490fda) {         /* |x| ~<= pi/4 */
  42                 if (ix < 0x39800000) {  /* |x| < 2**-12 */
  43                         if ((int)x == 0) {
  44                                 *sn = x;        /* x with inexact if x != 0 */
  45                                 *cs = 1;
  46                                 return;
  47                         }
  48                 }
  49                 __kernel_sincosdf(x, sn, cs);
  50                 return;
  51         }
  52
  53         if (ix <= 0x407b53d1) {         /* |x| ~<= 5*pi/4 */
  54                 if (ix <= 0x4016cbe3) { /* |x| ~<= 3pi/4 */
  55                         if (hx > 0) {
  56                                 __kernel_sincosdf(x - p1pio2, cs, sn);
  57                                 *cs = -*cs;
  58                         } else {
  59                                 __kernel_sincosdf(x + p1pio2, cs, sn);
  60                                 *sn = -*sn;
  61                         }
  62                 } else {
  63                         if (hx > 0)
  64                                 __kernel_sincosdf(x - p2pio2, sn, cs);
  65                         else
  66                                 __kernel_sincosdf(x + p2pio2, sn, cs);
  67                         *sn = -*sn;
  68                         *cs = -*cs;
  69                 }
  70                 return;
  71         }
  72
  73         if (ix <= 0x40e231d5) {         /* |x| ~<= 9*pi/4 */
  74                 if (ix <= 0x40afeddf) { /* |x| ~<= 7*pi/4 */
  75                         if (hx > 0) {
  76                                 __kernel_sincosdf(x - p3pio2, cs, sn);
  77                                 *sn = -*sn;
  78                         } else {
  79                                 __kernel_sincosdf(x + p3pio2, cs, sn);
  80                                 *cs = -*cs;
  81                         }
  82                 } else {
  83                         if (hx > 0)
  84                                 __kernel_sincosdf(x - p4pio2, sn, cs);
  85                         else
  86                                 __kernel_sincosdf(x + p4pio2, sn, cs);
  87                 }
  88                 return;
  89         }
  90
  91         /* If x = Inf or NaN, then sin(x) = NaN and cos(x) = NaN. */
  92         if (ix >= 0x7f800000) {
  93                 *sn = x - x;
  94                 *cs = x - x;
  95                 return;
  96         }
  97
  98         /* Argument reduction. */
  99         n = __ieee754_rem_pio2f(x, y);
 100         s = __kernel_sinf(y[0], y[1], 1);
 101         c = __kernel_cosf(y[0], y[1]);
 102
 103         switch(n & 3) {
 104         case 0:
 105                 *sn = s;
 106                 *cs = c;
 107                 break;
 108         case 1:
 109                 *sn = c;
 110                 *cs = -s;
 111                 break;
 112         case 2:
 113                 *sn = -s;
 114                 *cs = -c;
 115                 break;
 116         default:
 117                 *sn = -c;
 118                 *cs = s;
 119         }
 120 }