libgcc/config/s390/32/_fixdfdi.c

   1 /* Definitions of target machine for GNU compiler, for IBM S/390
   2    Copyright (C) 1999-2013 Free Software Foundation, Inc.
   3    Contributed by Hartmut Penner (hpenner@de.ibm.com) and
   4                   Ulrich Weigand (uweigand@de.ibm.com).
   5
   6 This file is part of GCC.
   7
   8 GCC is free software; you can redistribute it and/or modify it under
   9 the terms of the GNU General Public License as published by the Free
  10 Software Foundation; either version 3, or (at your option) any later
  11 version.
  12
  13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  15 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  16 for more details.
  17
  18 Under Section 7 of GPL version 3, you are granted additional
  19 permissions described in the GCC Runtime Library Exception, version
  20 3.1, as published by the Free Software Foundation.
  21
  22 You should have received a copy of the GNU General Public License and
  23 a copy of the GCC Runtime Library Exception along with this program;
  24 see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  25 <http://www.gnu.org/licenses/>.  */
  26
  27 #define EXPD(fp)        (((fp.l.upper) >> 20) & 0x7FF)
  28 #define EXCESSD         1022
  29 #define SIGNBIT         0x80000000
  30 #define SIGND(fp)       ((fp.l.upper) & SIGNBIT)
  31 #define MANTD_LL(fp)    ((fp.ll & (HIDDEND_LL-1)) | HIDDEND_LL)
  32 #define FRACD_LL(fp)    (fp.ll & (HIDDEND_LL-1))
  33 #define HIDDEND_LL      ((UDItype_x)1 << 52)
  34
  35 typedef int DItype_x __attribute__ ((mode (DI)));
  36 typedef unsigned int UDItype_x __attribute__ ((mode (DI)));
  37 typedef int SItype_x __attribute__ ((mode (SI)));
  38 typedef unsigned int USItype_x __attribute__ ((mode (SI)));
  39
  40 union double_long {
  41     double d;
  42     struct {
  43       SItype_x upper;
  44       USItype_x lower;
  45     } l;
  46     UDItype_x ll;
  47 };
  48
  49 DItype_x __fixdfdi (double a1);
  50
  51 /* convert double to int */
  52 DItype_x
  53 __fixdfdi (double a1)
  54 {
  55     register union double_long dl1;
  56     register int exp;
  57     register DItype_x l;
  58
  59     dl1.d = a1;
  60
  61     /* +/- 0, denormalized */
  62
  63     if (!EXPD (dl1))
  64       return 0;
  65
  66     exp = EXPD (dl1) - EXCESSD - 53;
  67
  68     /* number < 1 */
  69
  70     if (exp < -53)
  71       return 0;
  72
  73     /* NaN */
  74
  75     if ((EXPD(dl1) == 0x7ff) && (FRACD_LL(dl1) != 0)) /* NaN */
  76       return 0x8000000000000000ULL;
  77
  78     /* Number big number & +/- inf */
  79
  80     if (exp >= 11) {
  81         l = (long long)1<<63;
  82         if (!SIGND(dl1))
  83             l--;
  84         return l;
  85     }
  86
  87     l = MANTD_LL(dl1);
  88
  89     /* shift down until exp < 12 or l = 0 */
  90     if (exp > 0)
  91       l <<= exp;
  92     else
  93       l >>= -exp;
  94
  95     return (SIGND (dl1) ? -l : l);
  96 }