sysdeps/ieee754/ldbl-128/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 <math.h>
  30 #include <math_private.h>
  31 #include <libm-alias-ldouble.h>
  32
  33 static const _Float128
  34 two114 = L(2.0769187434139310514121985316880384E+34); /* 0x4071000000000000, 0 */
  35
  36 _Float128 __frexpl(_Float128 x, int *eptr)
  37 {
  38         uint64_t hx, lx, ix;
  39         GET_LDOUBLE_WORDS64(hx,lx,x);
  40         ix = 0x7fffffffffffffffULL&hx;
  41         *eptr = 0;
  42         if(ix>=0x7fff000000000000ULL||((ix|lx)==0)) return x + x;/* 0,inf,nan */
  43         if (ix<0x0001000000000000ULL) {         /* subnormal */
  44             x *= two114;
  45             GET_LDOUBLE_MSW64(hx,x);
  46             ix = hx&0x7fffffffffffffffULL;
  47             *eptr = -114;
  48         }
  49         *eptr += (ix>>48)-16382;
  50         hx = (hx&0x8000ffffffffffffULL) | 0x3ffe000000000000ULL;
  51         SET_LDOUBLE_MSW64(x,hx);
  52         return x;
  53 }
  54 libm_alias_ldouble (__frexp, frexp)