newlib/libm/common/sf_rint.c

   1 /* sf_rint.c -- float version of s_rint.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 TWO23[2]={
  24   8.3886080000e+06, /* 0x4b000000 */
  25  -8.3886080000e+06, /* 0xcb000000 */
  26 };
  27
  28 #ifdef __STDC__
  29         float rintf(float x)
  30 #else
  31         float rintf(x)
  32         float x;
  33 #endif
  34 {
  35         __int32_t i0,j0,sx;
  36         __uint32_t i,i1,ix;
  37         float t;
  38         volatile float w;
  39         GET_FLOAT_WORD(i0,x);
  40         sx = (i0>>31)&1;
  41         ix = (i0&0x7fffffff);
  42         j0 = (ix>>23)-0x7f;
  43         if(j0<23) {
  44             if(FLT_UWORD_IS_ZERO(ix))
  45                 return x;
  46             if(j0<0) {
  47                 i1 = (i0&0x07fffff);
  48                 i0 &= 0xfff00000;
  49                 i0 |= ((i1|-i1)>>9)&0x400000;
  50                 SET_FLOAT_WORD(x,i0);
  51                 w = TWO23[sx]+x;
  52                 t =  w-TWO23[sx];
  53                 GET_FLOAT_WORD(i0,t);
  54                 SET_FLOAT_WORD(t,(i0&0x7fffffff)|(sx<<31));
  55                 return t;
  56             } else {
  57                 i = (0x007fffff)>>j0;
  58                 if((i0&i)==0) return x; /* x is integral */
  59                 i>>=1;
  60                 if((i0&i)!=0) i0 = (i0&(~i))|((0x200000)>>j0);
  61             }
  62         } else {
  63             if(!FLT_UWORD_IS_FINITE(ix)) return x+x; /* inf or NaN */
  64             else
  65               return x;         /* x is integral */
  66         }
  67         SET_FLOAT_WORD(x,i0);
  68         w = TWO23[sx]+x;
  69         return w-TWO23[sx];
  70 }
  71
  72 #ifdef _DOUBLE_IS_32BITS
  73
  74 #ifdef __STDC__
  75         double rint(double x)
  76 #else
  77         double rint(x)
  78         double x;
  79 #endif
  80 {
  81         return (double) rintf((float) x);
  82 }
  83
  84 #endif /* defined(_DOUBLE_IS_32BITS) */