sysdeps/ieee754/ldbl-96/s_frexpl.c

   1 /* s_frexpl.c -- long double version of s_frexp.c.
   2  */
   3
   4 /*
   5  * ====================================================
   6  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
   7  *
   8  * Developed at SunPro, a Sun Microsystems, Inc. business.
   9  * Permission to use, copy, modify, and distribute this
  10  * software is freely granted, provided that this notice
  11  * is preserved.
  12  * ====================================================
  13  */
  14
  15 #if defined(LIBM_SCCS) && !defined(lint)
  16 static char rcsid[] = "$NetBSD: $";
  17 #endif
  18
  19 /*
  20  * for non-zero x
  21  *      x = frexpl(arg,&exp);
  22  * return a long double fp quantity x such that 0.5 <= |x| <1.0
  23  * and the corresponding binary exponent "exp". That is
  24  *      arg = x*2^exp.
  25  * If arg is inf, 0.0, or NaN, then frexpl(arg,&exp) returns arg
  26  * with *exp=0.
  27  */
  28
  29 #include <float.h>
  30 #include <math.h>
  31 #include <math_private.h>
  32 #include <libm-alias-ldouble.h>
  33
  34 static const long double
  35 #if LDBL_MANT_DIG == 64
  36 two65 =  3.68934881474191032320e+19L; /* 0x4040, 0x80000000, 0x00000000 */
  37 #else
  38 # error "Cannot handle this MANT_DIG"
  39 #endif
  40
  41
  42 long double __frexpl(long double x, int *eptr)
  43 {
  44         uint32_t se, hx, ix, lx;
  45         GET_LDOUBLE_WORDS(se,hx,lx,x);
  46         ix = 0x7fff&se;
  47         *eptr = 0;
  48         if(ix==0x7fff||((ix|hx|lx)==0)) return x + x;   /* 0,inf,nan */
  49         if (ix==0x0000) {               /* subnormal */
  50             x *= two65;
  51             GET_LDOUBLE_EXP(se,x);
  52             ix = se&0x7fff;
  53             *eptr = -65;
  54         }
  55         *eptr += ix-16382;
  56         se = (se & 0x8000) | 0x3ffe;
  57         SET_LDOUBLE_EXP(x,se);
  58         return x;
  59 }
  60 libm_alias_ldouble (__frexp, frexp)