kc3-lang/libquadmath/math/remainderq.c

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• Hash : 4f659ab9
  Author : Thomas de Grivel
  Date : 2025-11-02T19:33:45
  

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• math/remainderq.c

• /* e_fmodl.c -- long double version of e_fmod.c.
   * Conversion to IEEE quad long double by Jakub Jelinek, jj@ultra.linux.cz.
   */
  /*
   * ====================================================
   * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
   *
   * Developed at SunPro, a Sun Microsystems, Inc. business.
   * Permission to use, copy, modify, and distribute this
   * software is freely granted, provided that this notice
   * is preserved.
   * ====================================================
   */
  
  /* remainderq(x,p)
   * Return :
   *	returns  x REM p  =  x - [x/p]*p as if in infinite
   *	precise arithmetic, where [x/p] is the (infinite bit)
   *	integer nearest x/p (in half way case choose the even one).
   * Method :
   *	Based on fmodl() return x-[x/p]chopped*p exactlp.
   */
  
  #include "quadmath-imp.h"
  
  static const __float128 zero = 0;
  
  
  __float128
  remainderq(__float128 x, __float128 p)
  {
  	int64_t hx,hp;
  	uint64_t sx,lx,lp;
  	__float128 p_half;
  
  	GET_FLT128_WORDS64(hx,lx,x);
  	GET_FLT128_WORDS64(hp,lp,p);
  	sx = hx&0x8000000000000000ULL;
  	hp &= 0x7fffffffffffffffLL;
  	hx &= 0x7fffffffffffffffLL;
  
      /* purge off exception values */
  	if((hp|lp)==0) return (x*p)/(x*p);	/* p = 0 */
  	if((hx>=0x7fff000000000000LL)||			/* x not finite */
  	  ((hp>=0x7fff000000000000LL)&&			/* p is NaN */
  	  (((hp-0x7fff000000000000LL)|lp)!=0)))
  	    return (x*p)/(x*p);
  
  
  	if (hp<=0x7ffdffffffffffffLL) x = fmodq(x,p+p);	/* now x < 2p */
  	if (((hx-hp)|(lx-lp))==0) return zero*x;
  	x  = fabsq(x);
  	p  = fabsq(p);
  	if (hp<0x0002000000000000LL) {
  	    if(x+x>p) {
  		x-=p;
  		if(x+x>=p) x -= p;
  	    }
  	} else {
  	    p_half = 0.5Q*p;
  	    if(x>p_half) {
  		x-=p;
  		if(x>=p_half) x -= p;
  	    }
  	}
  	GET_FLT128_MSW64(hx,x);
  	SET_FLT128_MSW64(x,hx^sx);
  	return x;
  }
  

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