1  /* e_fmodl.c -- long double version of e_fmod.c.
       2   */
       3  /*
       4   * ====================================================
       5   * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
       6   *
       7   * Developed at SunPro, a Sun Microsystems, Inc. business.
       8   * Permission to use, copy, modify, and distribute this
       9   * software is freely granted, provided that this notice
      10   * is preserved.
      11   * ====================================================
      12   */
      13  
      14  /* __ieee754_remainderl(x,p)
      15   * Return :
      16   *	returns  x REM p  =  x - [x/p]*p as if in infinite
      17   *	precise arithmetic, where [x/p] is the (infinite bit)
      18   *	integer nearest x/p (in half way case choose the even one).
      19   * Method :
      20   *	Based on fmodl() return x-[x/p]chopped*p exactlp.
      21   */
      22  
      23  #include <math.h>
      24  #include <math_private.h>
      25  #include <libm-alias-finite.h>
      26  
      27  static const _Float128 zero = 0;
      28  
      29  
      30  _Float128
      31  __ieee754_remainderl(_Float128 x, _Float128 p)
      32  {
      33  	int64_t hx,hp;
      34  	uint64_t sx,lx,lp;
      35  	_Float128 p_half;
      36  
      37  	GET_LDOUBLE_WORDS64(hx,lx,x);
      38  	GET_LDOUBLE_WORDS64(hp,lp,p);
      39  	sx = hx&0x8000000000000000ULL;
      40  	hp &= 0x7fffffffffffffffLL;
      41  	hx &= 0x7fffffffffffffffLL;
      42  
      43      /* purge off exception values */
      44  	if((hp|lp)==0) return (x*p)/(x*p);	/* p = 0 */
      45  	if((hx>=0x7fff000000000000LL)||			/* x not finite */
      46  	  ((hp>=0x7fff000000000000LL)&&			/* p is NaN */
      47  	  (((hp-0x7fff000000000000LL)|lp)!=0)))
      48  	    return (x*p)/(x*p);
      49  
      50  
      51  	if (hp<=0x7ffdffffffffffffLL) x = __ieee754_fmodl(x,p+p);	/* now x < 2p */
      52  	if (((hx-hp)|(lx-lp))==0) return zero*x;
      53  	x  = fabsl(x);
      54  	p  = fabsl(p);
      55  	if (hp<0x0002000000000000LL) {
      56  	    if(x+x>p) {
      57  		x-=p;
      58  		if(x+x>=p) x -= p;
      59  	    }
      60  	} else {
      61  	    p_half = L(0.5)*p;
      62  	    if(x>p_half) {
      63  		x-=p;
      64  		if(x>=p_half) x -= p;
      65  	    }
      66  	}
      67  	GET_LDOUBLE_MSW64(hx,x);
      68  	SET_LDOUBLE_MSW64(x,hx^sx);
      69  	return x;
      70  }
      71  libm_alias_finite (__ieee754_remainderl, __remainderl)