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 #include <linux/compiler.h>
  17 #include <linux/export.h>
  18
  19 #define BITS_PER_UNIT 8
  20
  21 typedef          int SItype     __mode(SI);
  22 typedef unsigned int USItype    __mode(SI);
  23 typedef          int DItype     __mode(DI);
  24 typedef int word_type           __mode(__word__);
  25
  26 struct DIstruct {SItype high, low;};
  27
  28 typedef union
  29 {
  30   struct DIstruct s;
  31   DItype ll;
  32 } DIunion;
  33
  34 DItype
  35 __ashrdi3 (DItype u, word_type b)
  36 {
  37   DIunion w;
  38   word_type bm;
  39   DIunion uu;
  40
  41   if (b == 0)
  42     return u;
  43
  44   uu.ll = u;
  45
  46   bm = (sizeof (SItype) * BITS_PER_UNIT) - b;
  47   if (bm <= 0)
  48     {
  49       /* w.s.high = 1..1 or 0..0 */
  50       w.s.high = uu.s.high >> (sizeof (SItype) * BITS_PER_UNIT - 1);
  51       w.s.low = uu.s.high >> -bm;
  52     }
  53   else
  54     {
  55       USItype carries = (USItype)uu.s.high << bm;
  56       w.s.high = uu.s.high >> b;
  57       w.s.low = ((USItype)uu.s.low >> b) | carries;
  58     }
  59
  60   return w.ll;
  61 }
  62 EXPORT_SYMBOL(__ashrdi3);