libgcc-math/flt-32/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_private.h"
  30
  31 #ifdef __STDC__
  32 static const float huge = 1.0e30;
  33 #else
  34 static float huge = 1.0e30;
  35 #endif
  36
  37 #ifdef __STDC__
  38         float __floorf(float x)
  39 #else
  40         float __floorf(x)
  41         float x;
  42 #endif
  43 {
  44         int32_t i0,j0;
  45         uint32_t i;
  46         GET_FLOAT_WORD(i0,x);
  47         j0 = ((i0>>23)&0xff)-0x7f;
  48         if(j0<23) {
  49             if(j0<0) {  /* raise inexact if x != 0 */
  50                 if(huge+x>(float)0.0) {/* return 0*sign(x) if |x|<1 */
  51                     if(i0>=0) {i0=0;}
  52                     else if((i0&0x7fffffff)!=0)
  53                         { i0=0xbf800000;}
  54                 }
  55             } else {
  56                 i = (0x007fffff)>>j0;
  57                 if((i0&i)==0) return x; /* x is integral */
  58                 if(huge+x>(float)0.0) { /* raise inexact flag */
  59                     if(i0<0) i0 += (0x00800000)>>j0;
  60                     i0 &= (~i);
  61                 }
  62             }
  63         } else {
  64             if(j0==0x80) return x+x;    /* inf or NaN */
  65             else return x;              /* x is integral */
  66         }
  67         SET_FLOAT_WORD(x,i0);
  68         return x;
  69 }
  70 weak_alias (__floorf, floorf)