xref: /openbmc/linux/arch/m68k/lib/ashrdi3.c (revision 842ed298)
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);
63