1/* ===-- muldi3.c - Implement __muldi3 -------------------------------------===
2 *
3 *                     The LLVM Compiler Infrastructure
4 *
5 * This file is distributed under the University of Illinois Open Source
6 * License. See LICENSE.TXT for details.
7 *
8 * ===----------------------------------------------------------------------===
9 *
10 * This file implements __muldi3 for the compiler_rt library.
11 *
12 * ===----------------------------------------------------------------------===
13 */
14
15#include "int_lib.h"
16
17/* Returns: a * b */
18
19static
20di_int
21__muldsi3(su_int a, su_int b)
22{
23    dwords r;
24    const int bits_in_word_2 = (int)(sizeof(si_int) * CHAR_BIT) / 2;
25    const su_int lower_mask = (su_int)~0 >> bits_in_word_2;
26    r.s.low = (a & lower_mask) * (b & lower_mask);
27    su_int t = r.s.low >> bits_in_word_2;
28    r.s.low &= lower_mask;
29    t += (a >> bits_in_word_2) * (b & lower_mask);
30    r.s.low += (t & lower_mask) << bits_in_word_2;
31    r.s.high = t >> bits_in_word_2;
32    t = r.s.low >> bits_in_word_2;
33    r.s.low &= lower_mask;
34    t += (b >> bits_in_word_2) * (a & lower_mask);
35    r.s.low += (t & lower_mask) << bits_in_word_2;
36    r.s.high += t >> bits_in_word_2;
37    r.s.high += (a >> bits_in_word_2) * (b >> bits_in_word_2);
38    return r.all;
39}
40
41/* Returns: a * b */
42
43di_int
44__muldi3(di_int a, di_int b)
45{
46    dwords x;
47    x.all = a;
48    dwords y;
49    y.all = b;
50    dwords r;
51    r.all = __muldsi3(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}
55