1  /* s_modfl.c -- long double version of s_modf.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  /*
      16   * modfl(long double x, long double *iptr)
      17   * return fraction part of x, and return x's integral part in *iptr.
      18   * Method:
      19   *	Bit twiddling.
      20   *
      21   * Exception:
      22   *	No exception.
      23   */
      24  
      25  #include <math.h>
      26  #include <math_private.h>
      27  #include <libm-alias-ldouble.h>
      28  
      29  static const long double one = 1.0;
      30  
      31  long double
      32  __modfl(long double x, long double *iptr)
      33  {
      34  	int32_t i0,i1,j0;
      35  	uint32_t i,se;
      36  	GET_LDOUBLE_WORDS(se,i0,i1,x);
      37  	j0 = (se&0x7fff)-0x3fff;	/* exponent of x */
      38  	if(j0<32) {			/* integer part in high x */
      39  	    if(j0<0) {			/* |x|<1 */
      40  		SET_LDOUBLE_WORDS(*iptr,se&0x8000,0,0);	/* *iptr = +-0 */
      41  		return x;
      42  	    } else {
      43  		i = (0x7fffffff)>>j0;
      44  		if(((i0&i)|i1)==0) {		/* x is integral */
      45  		    *iptr = x;
      46  		    SET_LDOUBLE_WORDS(x,se&0x8000,0,0);	/* return +-0 */
      47  		    return x;
      48  		} else {
      49  		    SET_LDOUBLE_WORDS(*iptr,se,i0&(~i),0);
      50  		    return x - *iptr;
      51  		}
      52  	    }
      53  	} else if (__builtin_expect(j0>63, 0)) { /* no fraction part */
      54  	    *iptr = x*one;
      55  	    /* We must handle NaNs separately.  */
      56  	    if (j0 == 0x4000 && ((i0 & 0x7fffffff) | i1))
      57  	      return x*one;
      58  	    SET_LDOUBLE_WORDS(x,se&0x8000,0,0);	/* return +-0 */
      59  	    return x;
      60  	} else {			/* fraction part in low x */
      61  	    i = ((uint32_t)(0x7fffffff))>>(j0-32);
      62  	    if((i1&i)==0) { 		/* x is integral */
      63  		*iptr = x;
      64  		SET_LDOUBLE_WORDS(x,se&0x8000,0,0);	/* return +-0 */
      65  		return x;
      66  	    } else {
      67  		SET_LDOUBLE_WORDS(*iptr,se,i0,i1&(~i));
      68  		return x - *iptr;
      69  	    }
      70  	}
      71  }
      72  libm_alias_ldouble (__modf, modf)