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
  16 #include <sys/cdefs.h>
  17 #if defined(LIBM_SCCS) && !defined(lint)
  18 __RCSID("$NetBSD: s_frexpf.c,v 1.10 2007/08/21 20:12:27 drochner Exp $");
  19 #endif
  20
  21 #include "math.h"
  22 #include "math_private.h"
  23
  24 static const float
  25 two25 =  3.3554432000e+07; /* 0x4c000000 */
  26
  27 float
  28 frexpf(float x, int *eptr)
  29 {
  30         int32_t hx,ix;
  31         GET_FLOAT_WORD(hx,x);
  32         ix = 0x7fffffff&hx;
  33         *eptr = 0;
  34         if(ix>=0x7f800000||(ix==0)) return x;   /* 0,inf,nan */
  35         if (ix<0x00800000) {            /* subnormal */
  36             x *= two25;
  37             GET_FLOAT_WORD(hx,x);
  38             ix = hx&0x7fffffff;
  39             *eptr = -25;
  40         }
  41         *eptr += (ix>>23)-126;
  42         hx = (hx&0x807fffff)|0x3f000000;
  43         SET_FLOAT_WORD(x,hx);
  44         return x;
  45 }