external/bsd/pcc/dist/pcc-libs/libpcc/fixunsdfdi.c

   1 /*      $Id: fixunsdfdi.c,v 1.1.1.2 2009/09/04 00:27:36 gmcgarry Exp $  */
   2 /*      $NetBSD: fixunsdfdi.c,v 1.7 2003/08/07 16:43:16 agc Exp $       */
   3
   4 /*-
   5  * Copyright (c) 1992, 1993
   6  *      The Regents of the University of California.  All rights reserved.
   7  *
   8  * This software was developed by the Computer Systems Engineering group
   9  * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
  10  * contributed to Berkeley.
  11  *
  12  * Redistribution and use in source and binary forms, with or without
  13  * modification, are permitted provided that the following conditions
  14  * are met:
  15  * 1. Redistributions of source code must retain the above copyright
  16  *    notice, this list of conditions and the following disclaimer.
  17  * 2. Redistributions in binary form must reproduce the above copyright
  18  *    notice, this list of conditions and the following disclaimer in the
  19  *    documentation and/or other materials provided with the distribution.
  20  * 3. Neither the name of the University nor the names of its contributors
  21  *    may be used to endorse or promote products derived from this software
  22  *    without specific prior written permission.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  34  * SUCH DAMAGE.
  35  */
  36
  37 #include "quad.h"
  38
  39 #define ONE_FOURTH      ((int)1 << (INT_BITS - 2))
  40 #define ONE_HALF        (ONE_FOURTH * 2.0)
  41 #define ONE             (ONE_FOURTH * 4.0)
  42
  43 /*
  44  * Convert double to (unsigned) quad.
  45  * Not sure what to do with negative numbers---for now, anything out
  46  * of range becomes UQUAD_MAX.
  47  */
  48 u_quad_t
  49 __fixunsdfdi(double x)
  50 {
  51         union uu t;
  52         unsigned int tmp;
  53
  54         if (x < 0)
  55                 return (UQUAD_MAX);     /* ??? should be 0?  ERANGE??? */
  56 #ifdef notdef                           /* this falls afoul of a GCC bug */
  57         if (x >= UQUAD_MAX)
  58                 return (UQUAD_MAX);
  59 #else                                   /* so we wire in 2^64-1 instead */
  60         if (x >= 18446744073709551615.0)        /* XXX */
  61                 return (UQUAD_MAX);
  62 #endif
  63         /*
  64          * Now we know that 0 <= x <= 18446744073709549568.  The upper
  65          * limit is one ulp less than 18446744073709551615 tested for above.
  66          * Dividing this by 2^32 will *not* round irrespective of any
  67          * rounding modes (except if the result is an IEEE denorm).
  68          * Furthermore, the quotient will fit into a 32-bit integer.
  69          */
  70         tmp = x / ONE;
  71         t.ul[L] = (unsigned int) (x - tmp * ONE);
  72         t.ul[H] = tmp;
  73         return (t.uq);
  74 }