lib: Add shared copies of some GCC library routines
[muen/linux.git] / lib / muldi3.c
1 /*
2  * This program is free software; you can redistribute it and/or modify
3  * it under the terms of the GNU General Public License as published by
4  * the Free Software Foundation; either version 2 of the License, or
5  * (at your option) any later version.
6  *
7  * This program is distributed in the hope that it will be useful,
8  * but WITHOUT ANY WARRANTY; without even the implied warranty of
9  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
10  * GNU General Public License for more details.
11  *
12  * You should have received a copy of the GNU General Public License
13  * along with this program; if not, see the file COPYING, or write
14  * to the Free Software Foundation, Inc.
15  */
16
17 #include <linux/export.h>
18 #include <lib/libgcc.h>
19
20 #define W_TYPE_SIZE 32
21
22 #define __ll_B ((unsigned long) 1 << (W_TYPE_SIZE / 2))
23 #define __ll_lowpart(t) ((unsigned long) (t) & (__ll_B - 1))
24 #define __ll_highpart(t) ((unsigned long) (t) >> (W_TYPE_SIZE / 2))
25
26 /* If we still don't have umul_ppmm, define it using plain C.  */
27 #if !defined(umul_ppmm)
28 #define umul_ppmm(w1, w0, u, v)                                         \
29         do {                                                            \
30                 unsigned long __x0, __x1, __x2, __x3;                   \
31                 unsigned short __ul, __vl, __uh, __vh;                  \
32                                                                         \
33                 __ul = __ll_lowpart(u);                                 \
34                 __uh = __ll_highpart(u);                                \
35                 __vl = __ll_lowpart(v);                                 \
36                 __vh = __ll_highpart(v);                                \
37                                                                         \
38                 __x0 = (unsigned long) __ul * __vl;                     \
39                 __x1 = (unsigned long) __ul * __vh;                     \
40                 __x2 = (unsigned long) __uh * __vl;                     \
41                 __x3 = (unsigned long) __uh * __vh;                     \
42                                                                         \
43                 __x1 += __ll_highpart(__x0); /* this can't give carry */\
44                 __x1 += __x2; /* but this indeed can */                 \
45                 if (__x1 < __x2) /* did we get it? */                   \
46                 __x3 += __ll_B; /* yes, add it in the proper pos */     \
47                                                                         \
48                 (w1) = __x3 + __ll_highpart(__x1);                      \
49                 (w0) = __ll_lowpart(__x1) * __ll_B + __ll_lowpart(__x0);\
50         } while (0)
51 #endif
52
53 #if !defined(__umulsidi3)
54 #define __umulsidi3(u, v) ({                            \
55         DWunion __w;                                    \
56         umul_ppmm(__w.s.high, __w.s.low, u, v);         \
57         __w.ll;                                         \
58         })
59 #endif
60
61 long long notrace __muldi3(long long u, long long v)
62 {
63         const DWunion uu = {.ll = u};
64         const DWunion vv = {.ll = v};
65         DWunion w = {.ll = __umulsidi3(uu.s.low, vv.s.low)};
66
67         w.s.high += ((unsigned long) uu.s.low * (unsigned long) vv.s.high
68                 + (unsigned long) uu.s.high * (unsigned long) vv.s.low);
69
70         return w.ll;
71 }
72 EXPORT_SYMBOL(__muldi3);