toolchain/gcc/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   int signbit;
  22   int w;
  23   /* Most significant word, least significant word. */
  24   int exponent_less_127;
  25
  26   GET_FLOAT_WORD(w, x);
  27
  28   /* Extract sign bit. */
  29   signbit = w & 0x80000000;
  30
  31   /* Extract exponent field. */
  32   exponent_less_127 = ((w & 0x7f800000) >> 23) - 127;
  33
  34   if (exponent_less_127 < 23)
  35     {
  36       if (exponent_less_127 < 0)
  37         {
  38           w &= 0x80000000;
  39           if (exponent_less_127 == -1)
  40             /* Result is +1.0 or -1.0. */
  41             w |= (127 << 23);
  42         }
  43       else
  44         {
  45           unsigned int exponent_mask = 0x007fffff >> exponent_less_127;
  46           if ((w & exponent_mask) == 0)
  47             /* x has an integral value. */
  48             return x;
  49
  50           w += 0x00400000 >> exponent_less_127;
  51           w &= ~exponent_mask;
  52         }
  53     }
  54   else
  55     {
  56       if (exponent_less_127 == 128)
  57         /* x is NaN or infinite. */
  58         return x + x;
  59       else
  60         return x;
  61     }
  62   SET_FLOAT_WORD(x, w);
  63   return x;
  64 }
  65
  66 #ifdef _DOUBLE_IS_32BITS
  67
  68 #ifdef __STDC__
  69         double round(double x)
  70 #else
  71         double round(x)
  72         double x;
  73 #endif
  74 {
  75         return (double) roundf((float) x);
  76 }
  77
  78 #endif /* defined(_DOUBLE_IS_32BITS) */