sysdeps/libm-ieee754/s_floorf.c

   1 /* s_floorf.c -- float version of s_floor.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_floorf.c,v 1.4 1995/05/10 20:47:22 jtc Exp $";
  18 #endif
  19
  20 /*
  21  * floorf(x)
  22  * Return x rounded toward -inf to integral value
  23  * Method:
  24  *      Bit twiddling.
  25  * Exception:
  26  *      Inexact flag raised if x not equal to floorf(x).
  27  */
  28
  29 #include "math.h"
  30 #include "math_private.h"
  31
  32 #ifdef __STDC__
  33 static const float huge = 1.0e30;
  34 #else
  35 static float huge = 1.0e30;
  36 #endif
  37
  38 #ifdef __STDC__
  39         float __floorf(float x)
  40 #else
  41         float __floorf(x)
  42         float x;
  43 #endif
  44 {
  45         int32_t i0,j0;
  46         u_int32_t i;
  47         GET_FLOAT_WORD(i0,x);
  48         j0 = ((i0>>23)&0xff)-0x7f;
  49         if(j0<23) {
  50             if(j0<0) {  /* raise inexact if x != 0 */
  51                 if(huge+x>(float)0.0) {/* return 0*sign(x) if |x|<1 */
  52                     if(i0>=0) {i0=0;}
  53                     else if((i0&0x7fffffff)!=0)
  54                         { i0=0xbf800000;}
  55                 }
  56             } else {
  57                 i = (0x007fffff)>>j0;
  58                 if((i0&i)==0) return x; /* x is integral */
  59                 if(huge+x>(float)0.0) { /* raise inexact flag */
  60                     if(i0<0) i0 += (0x00800000)>>j0;
  61                     i0 &= (~i);
  62                 }
  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         return x;
  70 }
  71 weak_alias (__floorf, floorf)