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1 /* ===-- muldi3.c - Implement __muldi3 -------------------------------------===
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 __muldi3 for the compiler_rt library.
11  *
12  * ===----------------------------------------------------------------------===
13  */
14 
15 #include "int_lib.h"
16 
17 /* Returns: a * b */
18 
19 static
20 di_int
__muldsi3(su_int a,su_int b)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 
ARM_EABI_FNALIAS(lmul,muldi3)43 ARM_EABI_FNALIAS(lmul, muldi3)
44 
45 COMPILER_RT_ABI di_int
46 __muldi3(di_int a, di_int b)
47 {
48     dwords x;
49     x.all = a;
50     dwords y;
51     y.all = b;
52     dwords r;
53     r.all = __muldsi3(x.s.low, y.s.low);
54     r.s.high += x.s.high * y.s.low + x.s.low * y.s.high;
55     return r.all;
56 }
57