compiler/stdc/math/s_sin.c

   1 /* @(#)s_sin.c 5.1 93/09/24 */
   2 /*
   3  * ====================================================
   4  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
   5  *
   6  * Developed at SunPro, a Sun Microsystems, Inc. business.
   7  * Permission to use, copy, modify, and distribute this
   8  * software is freely granted, provided that this notice
   9  * is preserved.
  10  * ====================================================
  11  */
  12
  13 #ifndef lint
  14 static char rcsid[] = "$FreeBSD: src/lib/msun/src/s_sin.c,v 1.13 2011/02/10 07:37:50 das Exp $";
  15 #endif
  16
  17 /* sin(x)
  18  * Return sine function of x.
  19  *
  20  * kernel function:
  21  *      __kernel_sin            ... sine function on [-pi/4,pi/4]
  22  *      __kernel_cos            ... cose function on [-pi/4,pi/4]
  23  *      __ieee754_rem_pio2      ... argument reduction routine
  24  *
  25  * Method.
  26  *      Let S,C and T denote the sin, cos and tan respectively on
  27  *      [-PI/4, +PI/4]. Reduce the argument x to y1+y2 = x-k*pi/2
  28  *      in [-pi/4 , +pi/4], and let n = k mod 4.
  29  *      We have
  30  *
  31  *          n        sin(x)      cos(x)        tan(x)
  32  *     ----------------------------------------------------------
  33  *          0          S           C             T
  34  *          1          C          -S            -1/T
  35  *          2         -S          -C             T
  36  *          3         -C           S            -1/T
  37  *     ----------------------------------------------------------
  38  *
  39  * Special cases:
  40  *      Let trig be any of sin, cos, or tan.
  41  *      trig(+-INF)  is NaN, with signals;
  42  *      trig(NaN)    is that NaN;
  43  *
  44  * Accuracy:
  45  *      TRIG(x) returns trig(x) nearly rounded
  46  */
  47
  48 #include <float.h>
  49 #include "math.h"
  50 #define INLINE_REM_PIO2
  51 #include "math_private.h"
  52 #include "e_rem_pio2.c"
  53
  54 double
  55 sin(double x)
  56 {
  57         double y[2],z=0.0;
  58         int32_t n, ix;
  59
  60     /* High word of x. */
  61         GET_HIGH_WORD(ix,x);
  62
  63     /* |x| ~< pi/4 */
  64         ix &= 0x7fffffff;
  65         if(ix <= 0x3fe921fb) {
  66             if(ix<0x3e500000)                   /* |x| < 2**-26 */
  67                {if((int)x==0) return x;}        /* generate inexact */
  68             return __kernel_sin(x,z,0);
  69         }
  70
  71     /* sin(Inf or NaN) is NaN */
  72         else if (ix>=0x7ff00000) return x-x;
  73
  74     /* argument reduction needed */
  75         else {
  76             n = __ieee754_rem_pio2(x,y);
  77             switch(n&3) {
  78                 case 0: return  __kernel_sin(y[0],y[1],1);
  79                 case 1: return  __kernel_cos(y[0],y[1]);
  80                 case 2: return -__kernel_sin(y[0],y[1],1);
  81                 default:
  82                         return -__kernel_cos(y[0],y[1]);
  83             }
  84         }
  85 }
  86
  87 #if (LDBL_MANT_DIG == 53)
  88 AROS_MAKE_ASM_SYM(typeof(sinl), sinl, AROS_CSYM_FROM_ASM_NAME(sinl), AROS_CSYM_FROM_ASM_NAME(sin));
  89 AROS_EXPORT_ASM_SYM(AROS_CSYM_FROM_ASM_NAME(sinl));
  90 #endif