kc3-lang/libquadmath/math/modfq.c

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

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• math/modfq.c

• /* s_modfl.c -- long double version of s_modf.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.
   * ====================================================
   */
  
  #if defined(LIBM_SCCS) && !defined(lint)
  static char rcsid[] = "$NetBSD: $";
  #endif
  
  /*
   * modfq(long double x, long double *iptr)
   * return fraction part of x, and return x's integral part in *iptr.
   * Method:
   *	Bit twiddling.
   *
   * Exception:
   *	No exception.
   */
  
  #include "quadmath-imp.h"
  
  static const __float128 one = 1.0;
  
  __float128 modfq(__float128 x, __float128 *iptr)
  {
  	int64_t i0,i1,j0;
  	uint64_t i;
  	GET_FLT128_WORDS64(i0,i1,x);
  	j0 = ((i0>>48)&0x7fff)-0x3fff;	/* exponent of x */
  	if(j0<48) {			/* integer part in high x */
  	    if(j0<0) {			/* |x|<1 */
  		/* *iptr = +-0 */
  	        SET_FLT128_WORDS64(*iptr,i0&0x8000000000000000ULL,0);
  		return x;
  	    } else {
  		i = (0x0000ffffffffffffLL)>>j0;
  		if(((i0&i)|i1)==0) {		/* x is integral */
  		    *iptr = x;
  		    /* return +-0 */
  		    SET_FLT128_WORDS64(x,i0&0x8000000000000000ULL,0);
  		    return x;
  		} else {
  		    SET_FLT128_WORDS64(*iptr,i0&(~i),0);
  		    return x - *iptr;
  		}
  	    }
  	} else if (j0>111) {		/* no fraction part */
  	    *iptr = x*one;
  	    /* We must handle NaNs separately.  */
  	    if (j0 == 0x4000 && ((i0 & 0x0000ffffffffffffLL) | i1))
  	      return x*one;
  	    /* return +-0 */
  	    SET_FLT128_WORDS64(x,i0&0x8000000000000000ULL,0);
  	    return x;
  	} else {			/* fraction part in low x */
  	    i = -1ULL>>(j0-48);
  	    if((i1&i)==0) { 		/* x is integral */
  		*iptr = x;
  		/* return +-0 */
  		SET_FLT128_WORDS64(x,i0&0x8000000000000000ULL,0);
  		return x;
  	    } else {
  		SET_FLT128_WORDS64(*iptr,i0,i1&(~i));
  		return x - *iptr;
  	    }
  	}
  }
  

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