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

   1 /*      $Id: fixunssfdi.c,v 1.1.1.2 2009/09/04 00:27:36 gmcgarry Exp $  */
   2 /*      $NetBSD: fixunssfdi.c,v 1.6 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 float to (unsigned) quad.  We do most of our work in double,
  45  * out of sheer paranoia.
  46  *
  47  * Not sure what to do with negative numbers---for now, anything out
  48  * of range becomes UQUAD_MAX.
  49  */
  50 u_quad_t
  51 __fixunssfdi(float f)
  52 {
  53         double x, toppart;
  54         union uu t;
  55
  56         if (f < 0)
  57                 return (UQUAD_MAX);     /* ??? should be 0?  ERANGE??? */
  58 #ifdef notdef                           /* this falls afoul of a GCC bug */
  59         if (f >= UQUAD_MAX)
  60                 return (UQUAD_MAX);
  61 #else                                   /* so we wire in 2^64-1 instead */
  62         if (f >= 18446744073709551615.0)        /* XXX */
  63                 return (UQUAD_MAX);
  64 #endif
  65         x = f;
  66         /*
  67          * Get the upper part of the result.  Note that the divide
  68          * may round up; we want to avoid this if possible, so we
  69          * subtract `1/2' first.
  70          */
  71         toppart = (x - ONE_HALF) / ONE;
  72         /*
  73          * Now build a u_quad_t out of the top part.  The difference
  74          * between x and this is the bottom part (this may introduce
  75          * a few fuzzy bits, but what the heck).  With any luck this
  76          * difference will be nonnegative: x should wind up in the
  77          * range [0..UINT_MAX].  For paranoia, we assume [INT_MIN..
  78          * 2*UINT_MAX] instead.
  79          */
  80         t.ul[H] = (unsigned int)toppart;
  81         t.ul[L] = 0;
  82         x -= (double)t.uq;
  83         if (x < 0) {
  84                 t.ul[H]--;
  85                 x += UINT_MAX;
  86         }
  87         if (x > UINT_MAX) {
  88                 t.ul[H]++;
  89                 x -= UINT_MAX;
  90         }
  91         t.ul[L] = (unsigned int)x;
  92         return (t.uq);
  93 }