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1/* ===-- multi3.c - Implement __multi3 -------------------------------------===
2 *
3 * The LLVM Compiler Infrastructure
4 *
5 * This file is dual licensed under the MIT and the University of Illinois Open
6 * Source Licenses. See LICENSE.TXT for details.
7 *
8 * ===----------------------------------------------------------------------===
9
10 * This file implements __multi3 for the compiler_rt library.
11 *
12 * ===----------------------------------------------------------------------===
13 */
14
15#include "crt_glue.h"
16
17/* Returns: a * b */
18
19static
20ti_int
21__mulddi3(du_int a, du_int b)
22{
23 twords r;
24 const int bits_in_dword_2 = (int)(sizeof(di_int) * CHAR_BIT) / 2;
25 const du_int lower_mask = (du_int)~0 >> bits_in_dword_2;
26 r.s.low = (a & lower_mask) * (b & lower_mask);
27 du_int t = r.s.low >> bits_in_dword_2;
28 r.s.low &= lower_mask;
29 t += (a >> bits_in_dword_2) * (b & lower_mask);
30 r.s.low += (t & lower_mask) << bits_in_dword_2;
31 r.s.high = t >> bits_in_dword_2;
32 t = r.s.low >> bits_in_dword_2;
33 r.s.low &= lower_mask;
34 t += (b >> bits_in_dword_2) * (a & lower_mask);
35 r.s.low += (t & lower_mask) << bits_in_dword_2;
36 r.s.high += t >> bits_in_dword_2;
37 r.s.high += (a >> bits_in_dword_2) * (b >> bits_in_dword_2);
38 return r.all;
39}
40
41/* Returns: a * b */
42
43ti_int
44__multi3(ti_int a, ti_int b)
45{
46 twords x;
47 x.all = a;
48 twords y;
49 y.all = b;
50 twords r;
51 r.all = __mulddi3(x.s.low, y.s.low);
52 r.s.high += x.s.high * y.s.low + x.s.low * y.s.high;
53 return r.all;
54}