newlib/libm/common/sf_round.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 #include "fdlibm.h"
  13
  14 #ifdef __STDC__
  15         float roundf(float x)
  16 #else
  17         float roundf(x)
  18         float x;
  19 #endif
  20 {
  21   __uint32_t w;
  22   /* Most significant word, least significant word. */
  23   int exponent_less_127;
  24
  25   GET_FLOAT_WORD(w, x);
  26
  27   /* Extract exponent field. */
  28   exponent_less_127 = (int)((w & 0x7f800000) >> 23) - 127;
  29
  30   if (exponent_less_127 < 23)
  31     {
  32       if (exponent_less_127 < 0)
  33         {
  34           w &= 0x80000000;
  35           if (exponent_less_127 == -1)
  36             /* Result is +1.0 or -1.0. */
  37             w |= ((__uint32_t)127 << 23);
  38         }
  39       else
  40         {
  41           unsigned int exponent_mask = 0x007fffff >> exponent_less_127;
  42           if ((w & exponent_mask) == 0)
  43             /* x has an integral value. */
  44             return x;
  45
  46           w += 0x00400000 >> exponent_less_127;
  47           w &= ~exponent_mask;
  48         }
  49     }
  50   else
  51     {
  52       if (exponent_less_127 == 128)
  53         /* x is NaN or infinite. */
  54         return x + x;
  55       else
  56         return x;
  57     }
  58   SET_FLOAT_WORD(x, w);
  59   return x;
  60 }
  61
  62 #ifdef _DOUBLE_IS_32BITS
  63
  64 #ifdef __STDC__
  65         double round(double x)
  66 #else
  67         double round(x)
  68         double x;
  69 #endif
  70 {
  71         return (double) roundf((float) x);
  72 }
  73
  74 #endif /* defined(_DOUBLE_IS_32BITS) */