lib/libc/quad/fixunsdfdi.c

   1 /*      $NetBSD: fixunsdfdi.c,v 1.6 2002/10/20 10:15:47 scw Exp $       */
   2
   3 /*-
   4  * Copyright (c) 1992, 1993
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * This software was developed by the Computer Systems Engineering group
   8  * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
   9  * contributed to Berkeley.
  10  *
  11  * Redistribution and use in source and binary forms, with or without
  12  * modification, are permitted provided that the following conditions
  13  * are met:
  14  * 1. Redistributions of source code must retain the above copyright
  15  *    notice, this list of conditions and the following disclaimer.
  16  * 2. Redistributions in binary form must reproduce the above copyright
  17  *    notice, this list of conditions and the following disclaimer in the
  18  *    documentation and/or other materials provided with the distribution.
  19  * 3. Neither the name of the University nor the names of its contributors
  20  *    may be used to endorse or promote products derived from this software
  21  *    without specific prior written permission.
  22  *
  23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  33  * SUCH DAMAGE.
  34  */
  35
  36 #include <sys/cdefs.h>
  37 #if defined(LIBC_SCCS) && !defined(lint)
  38 #if 0
  39 static char sccsid[] = "@(#)fixunsdfdi.c        8.1 (Berkeley) 6/4/93";
  40 #else
  41 __RCSID("$NetBSD: fixunsdfdi.c,v 1.6 2002/10/20 10:15:47 scw Exp $");
  42 #endif
  43 #endif /* LIBC_SCCS and not lint */
  44
  45 #include "quad.h"
  46
  47 #define ONE_FOURTH      ((int)1 << (INT_BITS - 2))
  48 #define ONE_HALF        (ONE_FOURTH * 2.0)
  49 #define ONE             (ONE_FOURTH * 4.0)
  50
  51 /*
  52  * Convert double to (unsigned) quad.
  53  * Not sure what to do with negative numbers---for now, anything out
  54  * of range becomes UQUAD_MAX.
  55  */
  56 u_quad_t
  57 __fixunsdfdi(x)
  58         double x;
  59 {
  60         union uu t;
  61         unsigned int tmp;
  62
  63         if (x < 0)
  64                 return (UQUAD_MAX);     /* ??? should be 0?  ERANGE??? */
  65 #ifdef notdef                           /* this falls afoul of a GCC bug */
  66         if (x >= UQUAD_MAX)
  67                 return (UQUAD_MAX);
  68 #else                                   /* so we wire in 2^64-1 instead */
  69         if (x >= 18446744073709551615.0)        /* XXX */
  70                 return (UQUAD_MAX);
  71 #endif
  72         /*
  73          * Now we know that 0 <= x <= 18446744073709549568.  The upper
  74          * limit is one ulp less than 18446744073709551615 tested for above.
  75          * Dividing this by 2^32 will *not* round irrespective of any
  76          * rounding modes (except if the result is an IEEE denorm).
  77          * Furthermore, the quotient will fit into a 32-bit integer.
  78          */
  79         tmp = x / ONE;
  80         t.ul[L] = (unsigned int) (x - tmp * ONE);
  81         t.ul[H] = tmp;
  82         return (t.uq);
  83 }