kc3-lang/SDL/src/libm/s_sin.c

Branch : - branch - v2.28 - tag -

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  Commit

• Author : Ryan C. Gordon
  Date : 2015-04-20 12:22:44
  Hash : b72938c8
  Message : Windows: Always set the system timer resolution to 1ms by default. An existing hint lets apps that don't need the timer resolution changed avoid this, to save battery, etc, but this fixes several problems in timing, audio callbacks not firing fast enough, etc. Fixes Bugzilla #2944.

• src/libm/s_sin.c

• /* @(#)s_sin.c 5.1 93/09/24 */
  /*
   * ====================================================
   * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
   *
   * Developed at SunPro, a Sun Microsystems, Inc. business.
   * Permission to use, copy, modify, and distribute this
   * software is freely granted, provided that this notice
   * is preserved.
   * ====================================================
   */
  
  #if defined(LIBM_SCCS) && !defined(lint)
  static const char rcsid[] =
      "$NetBSD: s_sin.c,v 1.7 1995/05/10 20:48:15 jtc Exp $";
  #endif
  
  /* sin(x)
   * Return sine function of x.
   *
   * kernel function:
   *	__kernel_sin		... sine function on [-pi/4,pi/4]
   *	__kernel_cos		... cose function on [-pi/4,pi/4]
   *	__ieee754_rem_pio2	... argument reduction routine
   *
   * Method.
   *      Let S,C and T denote the sin, cos and tan respectively on
   *	[-PI/4, +PI/4]. Reduce the argument x to y1+y2 = x-k*pi/2
   *	in [-pi/4 , +pi/4], and let n = k mod 4.
   *	We have
   *
   *          n        sin(x)      cos(x)        tan(x)
   *     ----------------------------------------------------------
   *	    0	       S	   C		 T
   *	    1	       C	  -S		-1/T
   *	    2	      -S	  -C		 T
   *	    3	      -C	   S		-1/T
   *     ----------------------------------------------------------
   *
   * Special cases:
   *      Let trig be any of sin, cos, or tan.
   *      trig(+-INF)  is NaN, with signals;
   *      trig(NaN)    is that NaN;
   *
   * Accuracy:
   *	TRIG(x) returns trig(x) nearly rounded
   */
  
  #include "math_libm.h"
  #include "math_private.h"
  
  libm_hidden_proto(sin)
  #ifdef __STDC__
       double sin(double x)
  #else
       double sin(x)
       double x;
  #endif
  {
      double y[2], z = 0.0;
      int32_t n, ix;
  
      /* High word of x. */
      GET_HIGH_WORD(ix, x);
  
      /* |x| ~< pi/4 */
      ix &= 0x7fffffff;
      if (ix <= 0x3fe921fb)
          return __kernel_sin(x, z, 0);
  
      /* sin(Inf or NaN) is NaN */
      else if (ix >= 0x7ff00000)
          return x - x;
  
      /* argument reduction needed */
      else {
          n = __ieee754_rem_pio2(x, y);
          switch (n & 3) {
          case 0:
              return __kernel_sin(y[0], y[1], 1);
          case 1:
              return __kernel_cos(y[0], y[1]);
          case 2:
              return -__kernel_sin(y[0], y[1], 1);
          default:
              return -__kernel_cos(y[0], y[1]);
          }
      }
  }
  
  libm_hidden_def(sin)