Subversion Repositories Kolibri OS

Rev

Go to most recent revision | Blame | Last modification | View Log | Download | RSS feed

  1. /* ef_acos.c -- float version of e_acos.c.
  2.  * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
  3.  */
  4.  
  5. /*
  6.  * ====================================================
  7.  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
  8.  *
  9.  * Developed at SunPro, a Sun Microsystems, Inc. business.
  10.  * Permission to use, copy, modify, and distribute this
  11.  * software is freely granted, provided that this notice
  12.  * is preserved.
  13.  * ====================================================
  14.  */
  15.  
  16. #include "fdlibm.h"
  17.  
  18. #ifdef __STDC__
  19. static const float
  20. #else
  21. static float
  22. #endif
  23. one =  1.0000000000e+00, /* 0x3F800000 */
  24. pi =  3.1415925026e+00, /* 0x40490fda */
  25. pio2_hi =  1.5707962513e+00, /* 0x3fc90fda */
  26. pio2_lo =  7.5497894159e-08, /* 0x33a22168 */
  27. pS0 =  1.6666667163e-01, /* 0x3e2aaaab */
  28. pS1 = -3.2556581497e-01, /* 0xbea6b090 */
  29. pS2 =  2.0121252537e-01, /* 0x3e4e0aa8 */
  30. pS3 = -4.0055535734e-02, /* 0xbd241146 */
  31. pS4 =  7.9153501429e-04, /* 0x3a4f7f04 */
  32. pS5 =  3.4793309169e-05, /* 0x3811ef08 */
  33. qS1 = -2.4033949375e+00, /* 0xc019d139 */
  34. qS2 =  2.0209457874e+00, /* 0x4001572d */
  35. qS3 = -6.8828397989e-01, /* 0xbf303361 */
  36. qS4 =  7.7038154006e-02; /* 0x3d9dc62e */
  37.  
  38. #ifdef __STDC__
  39.         float __ieee754_acosf(float x)
  40. #else
  41.         float __ieee754_acosf(x)
  42.         float x;
  43. #endif
  44. {
  45.         float z,p,q,r,w,s,c,df;
  46.         __int32_t hx,ix;
  47.         GET_FLOAT_WORD(hx,x);
  48.         ix = hx&0x7fffffff;
  49.         if(ix==0x3f800000) {            /* |x|==1 */
  50.             if(hx>0) return 0.0;        /* acos(1) = 0  */
  51.             else return pi+(float)2.0*pio2_lo;  /* acos(-1)= pi */
  52.         } else if(ix>0x3f800000) {      /* |x| >= 1 */
  53.             return (x-x)/(x-x);         /* acos(|x|>1) is NaN */
  54.         }
  55.         if(ix<0x3f000000) {     /* |x| < 0.5 */
  56.             if(ix<=0x23000000) return pio2_hi+pio2_lo;/*if|x|<2**-57*/
  57.             z = x*x;
  58.             p = z*(pS0+z*(pS1+z*(pS2+z*(pS3+z*(pS4+z*pS5)))));
  59.             q = one+z*(qS1+z*(qS2+z*(qS3+z*qS4)));
  60.             r = p/q;
  61.             return pio2_hi - (x - (pio2_lo-x*r));
  62.         } else  if (hx<0) {             /* x < -0.5 */
  63.             z = (one+x)*(float)0.5;
  64.             p = z*(pS0+z*(pS1+z*(pS2+z*(pS3+z*(pS4+z*pS5)))));
  65.             q = one+z*(qS1+z*(qS2+z*(qS3+z*qS4)));
  66.             s = __ieee754_sqrtf(z);
  67.             r = p/q;
  68.             w = r*s-pio2_lo;
  69.             return pi - (float)2.0*(s+w);
  70.         } else {                        /* x > 0.5 */
  71.             __int32_t idf;
  72.             z = (one-x)*(float)0.5;
  73.             s = __ieee754_sqrtf(z);
  74.             df = s;
  75.             GET_FLOAT_WORD(idf,df);
  76.             SET_FLOAT_WORD(df,idf&0xfffff000);
  77.             c  = (z-df*df)/(s+df);
  78.             p = z*(pS0+z*(pS1+z*(pS2+z*(pS3+z*(pS4+z*pS5)))));
  79.             q = one+z*(qS1+z*(qS2+z*(qS3+z*qS4)));
  80.             r = p/q;
  81.             w = r*s+c;
  82.             return (float)2.0*(df+w);
  83.         }
  84. }
  85.