sysdeps/ieee754/ldbl-96/s_modfl.c

   1 /* s_modfl.c -- long double version of s_modf.c.
   2  * Conversion to long double by Ulrich Drepper,
   3  * Cygnus Support, drepper@cygnus.com.
   4  */
   5
   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 /*
  18  * modfl(long double x, long double *iptr)
  19  * return fraction part of x, and return x's integral part in *iptr.
  20  * Method:
  21  *      Bit twiddling.
  22  *
  23  * Exception:
  24  *      No exception.
  25  */
  26
  27 #include <math.h>
  28 #include <math_private.h>
  29
  30 static const long double one = 1.0;
  31
  32 long double
  33 __modfl(long double x, long double *iptr)
  34 {
  35         int32_t i0,i1,j0;
  36         u_int32_t i,se;
  37         GET_LDOUBLE_WORDS(se,i0,i1,x);
  38         j0 = (se&0x7fff)-0x3fff;        /* exponent of x */
  39         if(j0<32) {                     /* integer part in high x */
  40             if(j0<0) {                  /* |x|<1 */
  41                 SET_LDOUBLE_WORDS(*iptr,se&0x8000,0,0); /* *iptr = +-0 */
  42                 return x;
  43             } else {
  44                 i = (0x7fffffff)>>j0;
  45                 if(((i0&i)|i1)==0) {            /* x is integral */
  46                     *iptr = x;
  47                     SET_LDOUBLE_WORDS(x,se&0x8000,0,0); /* return +-0 */
  48                     return x;
  49                 } else {
  50                     SET_LDOUBLE_WORDS(*iptr,se,i0&(~i),0);
  51                     return x - *iptr;
  52                 }
  53             }
  54         } else if (__builtin_expect(j0>63, 0)) { /* no fraction part */
  55             *iptr = x*one;
  56             /* We must handle NaNs separately.  */
  57             if (j0 == 0x4000 && ((i0 & 0x7fffffff) | i1))
  58               return x*one;
  59             SET_LDOUBLE_WORDS(x,se&0x8000,0,0); /* return +-0 */
  60             return x;
  61         } else {                        /* fraction part in low x */
  62             i = ((u_int32_t)(0x7fffffff))>>(j0-32);
  63             if((i1&i)==0) {             /* x is integral */
  64                 *iptr = x;
  65                 SET_LDOUBLE_WORDS(x,se&0x8000,0,0);     /* return +-0 */
  66                 return x;
  67             } else {
  68                 SET_LDOUBLE_WORDS(*iptr,se,i0,i1&(~i));
  69                 return x - *iptr;
  70             }
  71         }
  72 }
  73 weak_alias (__modfl, modfl)