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 #define BITS_PER_UNIT 8
  17
  18 typedef          int SItype     __attribute__ ((mode (SI)));
  19 typedef unsigned int USItype    __attribute__ ((mode (SI)));
  20 typedef          int DItype     __attribute__ ((mode (DI)));
  21 typedef int word_type __attribute__ ((mode (__word__)));
  22
  23 struct DIstruct {SItype high, low;};
  24
  25 typedef union
  26 {
  27   struct DIstruct s;
  28   DItype ll;
  29 } DIunion;
  30
  31 DItype
  32 __ashrdi3 (DItype u, word_type b)
  33 {
  34   DIunion w;
  35   word_type bm;
  36   DIunion uu;
  37
  38   if (b == 0)
  39     return u;
  40
  41   uu.ll = u;
  42
  43   bm = (sizeof (SItype) * BITS_PER_UNIT) - b;
  44   if (bm <= 0)
  45     {
  46       /* w.s.high = 1..1 or 0..0 */
  47       w.s.high = uu.s.high >> (sizeof (SItype) * BITS_PER_UNIT - 1);
  48       w.s.low = uu.s.high >> -bm;
  49     }
  50   else
  51     {
  52       USItype carries = (USItype)uu.s.high << bm;
  53       w.s.high = uu.s.high >> b;
  54       w.s.low = ((USItype)uu.s.low >> b) | carries;
  55     }
  56
  57   return w.ll;
  58 }