libquadmath/math/modfq.c

   1 /* modfq.c -- __float128 version of s_modf.c.
   2  * Conversion to IEEE quad long double by Jakub Jelinek, jj@ultra.linux.cz.
   3  */
   4
   5 /*
   6  * ====================================================
   7  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
   8  *
   9  * Developed at SunPro, a Sun Microsystems, Inc. business.
  10  * Permission to use, copy, modify, and distribute this
  11  * software is freely granted, provided that this notice
  12  * is preserved.
  13  * ====================================================
  14  */
  15
  16 #include "quadmath-imp.h"
  17
  18 static const __float128 one = 1.0;
  19
  20 __float128
  21 modfq (__float128 x, __float128 *iptr)
  22 {
  23         int64_t i0,i1,j0;
  24         uint64_t i;
  25         GET_FLT128_WORDS64(i0,i1,x);
  26         j0 = ((i0>>48)&0x7fff)-0x3fff;  /* exponent of x */
  27         if(j0<48) {                     /* integer part in high x */
  28             if(j0<0) {                  /* |x|<1 */
  29                 /* *iptr = +-0 */
  30                 SET_FLT128_WORDS64(*iptr,i0&0x8000000000000000ULL,0);
  31                 return x;
  32             } else {
  33                 i = (0x0000ffffffffffffLL)>>j0;
  34                 if(((i0&i)|i1)==0) {            /* x is integral */
  35                     *iptr = x;
  36                     /* return +-0 */
  37                     SET_FLT128_WORDS64(x,i0&0x8000000000000000ULL,0);
  38                     return x;
  39                 } else {
  40                     SET_FLT128_WORDS64(*iptr,i0&(~i),0);
  41                     return x - *iptr;
  42                 }
  43             }
  44         } else if (j0>111) {            /* no fraction part */
  45             *iptr = x*one;
  46             /* We must handle NaNs separately.  */
  47             if (j0 == 0x4000 && ((i0 & 0x0000ffffffffffffLL) | i1))
  48               return x*one;
  49             /* return +-0 */
  50             SET_FLT128_WORDS64(x,i0&0x8000000000000000ULL,0);
  51             return x;
  52         } else {                        /* fraction part in low x */
  53             i = -1ULL>>(j0-48);
  54             if((i1&i)==0) {             /* x is integral */
  55                 *iptr = x;
  56                 /* return +-0 */
  57                 SET_FLT128_WORDS64(x,i0&0x8000000000000000ULL,0);
  58                 return x;
  59             } else {
  60                 SET_FLT128_WORDS64(*iptr,i0,i1&(~i));
  61                 return x - *iptr;
  62             }
  63         }
  64 }