contrib/openbsd_libm/src/s_truncf.c

   1 /* @(#)s_floor.c 5.1 93/09/24 */
   2 /*
   3  * ====================================================
   4  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
   5  *
   6  * Developed at SunPro, a Sun Microsystems, Inc. business.
   7  * Permission to use, copy, modify, and distribute this
   8  * software is freely granted, provided that this notice
   9  * is preserved.
  10  * ====================================================
  11  */
  12
  13 /*
  14  * truncf(x)
  15  * Return x rounded toward 0 to integral value
  16  * Method:
  17  *      Bit twiddling.
  18  * Exception:
  19  *      Inexact flag raised if x not equal to truncf(x).
  20  */
  21
  22 #include "math.h"
  23 #include "math_private.h"
  24
  25 static const float huge = 1.0e30F;
  26
  27 float
  28 truncf(float x)
  29 {
  30         int32_t i0,jj0;
  31         u_int32_t i;
  32         GET_FLOAT_WORD(i0,x);
  33         jj0 = ((i0>>23)&0xff)-0x7f;
  34         if(jj0<23) {
  35             if(jj0<0) {         /* raise inexact if x != 0 */
  36                 if(huge+x>0.0F)         /* |x|<1, so return 0*sign(x) */
  37                     i0 &= 0x80000000;
  38             } else {
  39                 i = (0x007fffff)>>jj0;
  40                 if((i0&i)==0) return x; /* x is integral */
  41                 if(huge+x>0.0F)         /* raise inexact flag */
  42                     i0 &= (~i);
  43             }
  44         } else {
  45             if(jj0==0x80) return x+x;   /* inf or NaN */
  46             else return x;              /* x is integral */
  47         }
  48         SET_FLOAT_WORD(x,i0);
  49         return x;
  50 }