modules/fdlibm/src/s_truncf.cpp

   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 //#include <sys/cdefs.h>
  14 //__FBSDID("$FreeBSD$");
  15
  16 /*
  17  * truncf(x)
  18  * Return x rounded toward 0 to integral value
  19  * Method:
  20  *      Bit twiddling.
  21  * Exception:
  22  *      Inexact flag raised if x not equal to truncf(x).
  23  */
  24
  25 #include "math_private.h"
  26
  27 static const float huge = 1.0e30F;
  28
  29 float
  30 truncf(float x)
  31 {
  32         int32_t i0,j0;
  33         u_int32_t i;
  34         GET_FLOAT_WORD(i0,x);
  35         j0 = ((i0>>23)&0xff)-0x7f;
  36         if(j0<23) {
  37             if(j0<0) {  /* raise inexact if x != 0 */
  38                 if(huge+x>0.0F)         /* |x|<1, so return 0*sign(x) */
  39                     i0 &= 0x80000000;
  40             } else {
  41                 i = (0x007fffff)>>j0;
  42                 if((i0&i)==0) return x; /* x is integral */
  43                 if(huge+x>0.0F)         /* raise inexact flag */
  44                     i0 &= (~i);
  45             }
  46         } else {
  47             if(j0==0x80) return x+x;    /* inf or NaN */
  48             else return x;              /* x is integral */
  49         }
  50         SET_FLOAT_WORD(x,i0);
  51         return x;
  52 }