sysdeps/libm-ieee754/s_rintf.c

   1 /* s_rintf.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 #if defined(LIBM_SCCS) && !defined(lint)
  17 static char rcsid[] = "$NetBSD: s_rintf.c,v 1.4 1995/05/10 20:48:06 jtc Exp $";
  18 #endif
  19
  20 #include "math.h"
  21 #include "math_private.h"
  22
  23 #ifdef __STDC__
  24 static const float
  25 #else
  26 static float
  27 #endif
  28 TWO23[2]={
  29   8.3886080000e+06, /* 0x4b000000 */
  30  -8.3886080000e+06, /* 0xcb000000 */
  31 };
  32
  33 #ifdef __STDC__
  34         float __rintf(float x)
  35 #else
  36         float __rintf(x)
  37         float x;
  38 #endif
  39 {
  40         int32_t i0,j0,sx;
  41         u_int32_t i,i1;
  42         float w,t;
  43         GET_FLOAT_WORD(i0,x);
  44         sx = (i0>>31)&1;
  45         j0 = ((i0>>23)&0xff)-0x7f;
  46         if(j0<23) {
  47             if(j0<0) {
  48                 if((i0&0x7fffffff)==0) return x;
  49                 i1 = (i0&0x07fffff);
  50                 i0 &= 0xfff00000;
  51                 i0 |= ((i1|-i1)>>9)&0x400000;
  52                 SET_FLOAT_WORD(x,i0);
  53                 w = TWO23[sx]+x;
  54                 t =  w-TWO23[sx];
  55                 GET_FLOAT_WORD(i0,t);
  56                 SET_FLOAT_WORD(t,(i0&0x7fffffff)|(sx<<31));
  57                 return t;
  58             } else {
  59                 i = (0x007fffff)>>j0;
  60                 if((i0&i)==0) return x; /* x is integral */
  61                 i>>=1;
  62                 if((i0&i)!=0) i0 = (i0&(~i))|((0x100000)>>j0);
  63             }
  64         } else {
  65             if(j0==0x80) return x+x;    /* inf or NaN */
  66             else return x;              /* x is integral */
  67         }
  68         SET_FLOAT_WORD(x,i0);
  69         w = TWO23[sx]+x;
  70         return w-TWO23[sx];
  71 }
  72 weak_alias (__rintf, rintf)