lib/libm/src/s_frexpf.c

   1 /* s_frexpf.c -- float version of s_frexp.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  * $NetBSD: s_frexpf.c,v 1.9 2002/12/05 16:03:42 scw Exp $
  16  * $DragonFly: src/lib/libm/src/s_frexpf.c,v 1.1 2005/07/26 21:15:20 joerg Exp $
  17  */
  18
  19 #include <math.h>
  20 #include "math_private.h"
  21
  22 static const float
  23 two25 =  3.3554432000e+07; /* 0x4c000000 */
  24
  25 float
  26 frexpf(float x, int *eptr)
  27 {
  28         int32_t hx,ix;
  29         GET_FLOAT_WORD(hx,x);
  30         ix = 0x7fffffff&hx;
  31         *eptr = 0;
  32         if(ix>=0x7f800000||(ix==0)) return x;   /* 0,inf,nan */
  33         if (ix<0x00800000) {            /* subnormal */
  34             x *= two25;
  35             GET_FLOAT_WORD(hx,x);
  36             ix = hx&0x7fffffff;
  37             *eptr = -25;
  38         }
  39         *eptr += (ix>>23)-126;
  40         hx = (hx&0x807fffff)|0x3f000000;
  41         *(int*)(void*)&x = hx;
  42         return x;
  43 }