1  /* s_scalblnl.c -- long double version of s_scalbn.c.
       2   * Conversion to IEEE quad long double by Jakub Jelinek, jj@ultra.linux.cz.
       3   */
       4  
       5  /* @(#)s_scalbn.c 5.1 93/09/24 */
       6  /*
       7   * ====================================================
       8   * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
       9   *
      10   * Developed at SunPro, a Sun Microsystems, Inc. business.
      11   * Permission to use, copy, modify, and distribute this
      12   * software is freely granted, provided that this notice
      13   * is preserved.
      14   * ====================================================
      15   */
      16  
      17  #if defined(LIBM_SCCS) && !defined(lint)
      18  static char rcsid[] = "$NetBSD: $";
      19  #endif
      20  
      21  /*
      22   * scalblnl (long double x, long int n)
      23   * scalblnl(x,n) returns x* 2**n  computed by  exponent
      24   * manipulation rather than by actually performing an
      25   * exponentiation or a multiplication.
      26   */
      27  
      28  #include "quadmath-imp.h"
      29  
      30  static const __float128
      31  two114 = 2.0769187434139310514121985316880384E+34Q, /* 0x4071000000000000, 0 */
      32  twom114 = 4.8148248609680896326399448564623183E-35Q, /* 0x3F8D000000000000, 0 */
      33  huge   = 1.0E+4900Q,
      34  tiny   = 1.0E-4900Q;
      35  
      36  __float128 scalblnq (__float128 x, long int n)
      37  {
      38  	int64_t k,hx,lx;
      39  	GET_FLT128_WORDS64(hx,lx,x);
      40          k = (hx>>48)&0x7fff;		/* extract exponent */
      41          if (k==0) {				/* 0 or subnormal x */
      42              if ((lx|(hx&0x7fffffffffffffffULL))==0) return x; /* +-0 */
      43  	    x *= two114;
      44  	    GET_FLT128_MSW64(hx,x);
      45  	    k = ((hx>>48)&0x7fff) - 114;
      46  	}
      47          if (k==0x7fff) return x+x;		/* NaN or Inf */
      48  	if (n< -50000) return tiny*copysignq(tiny,x); /*underflow*/
      49          if (n> 50000 || k+n > 0x7ffe)
      50  	  return huge*copysignq(huge,x); /* overflow  */
      51  	/* Now k and n are bounded we know that k = k+n does not
      52  	   overflow.  */
      53          k = k+n;
      54          if (k > 0) 				/* normal result */
      55  	    {SET_FLT128_MSW64(x,(hx&0x8000ffffffffffffULL)|(k<<48)); return x;}
      56          if (k <= -114)
      57  	  return tiny*copysignq(tiny,x); 	/*underflow*/
      58          k += 114;				/* subnormal result */
      59  	SET_FLT128_MSW64(x,(hx&0x8000ffffffffffffULL)|(k<<48));
      60          return x*twom114;
      61  }