arch/m68k/lib/ashrdi3.c

   1 /* ashrdi3.c extracted from gcc-2.7.2/libgcc2.c which is: */
   2 /* Copyright (C) 1989, 1992, 1993, 1994, 1995 Free Software Foundation, Inc.
   3
   4 This file is part of GNU CC.
   5
   6 GNU CC is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2, or (at your option)
   9 any later version.
  10
  11 GNU CC is distributed in the hope that it will be useful,
  12 but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 GNU General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GNU CC; see the file COPYING.  If not, write to
  18 the Free Software Foundation, 59 Temple Place - Suite 330,
  19 Boston, MA 02111-1307, USA.  */
  20
  21 #define BITS_PER_UNIT 8
  22
  23 typedef          int SItype     __attribute__ ((mode (SI)));
  24 typedef unsigned int USItype    __attribute__ ((mode (SI)));
  25 typedef          int DItype     __attribute__ ((mode (DI)));
  26 typedef int word_type __attribute__ ((mode (__word__)));
  27
  28 struct DIstruct {SItype high, low;};
  29
  30 typedef union
  31 {
  32   struct DIstruct s;
  33   DItype ll;
  34 } DIunion;
  35
  36 DItype
  37 __ashrdi3 (DItype u, word_type b)
  38 {
  39   DIunion w;
  40   word_type bm;
  41   DIunion uu;
  42
  43   if (b == 0)
  44     return u;
  45
  46   uu.ll = u;
  47
  48   bm = (sizeof (SItype) * BITS_PER_UNIT) - b;
  49   if (bm <= 0)
  50     {
  51       /* w.s.high = 1..1 or 0..0 */
  52       w.s.high = uu.s.high >> (sizeof (SItype) * BITS_PER_UNIT - 1);
  53       w.s.low = uu.s.high >> -bm;
  54     }
  55   else
  56     {
  57       USItype carries = (USItype)uu.s.high << bm;
  58       w.s.high = uu.s.high >> b;
  59       w.s.low = ((USItype)uu.s.low >> b) | carries;
  60     }
  61
  62   return w.ll;
  63 }