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 "int_lib.h" |
16 | |
17 | #ifdef CRT_HAS_128BIT |
18 | |
19 | /* Returns: a * b */ |
20 | |
21 | static |
22 | ti_int |
23 | __mulddi3(du_int a, du_int b) |
24 | { |
25 | twords r; |
26 | const int bits_in_dword_2 = (int)(sizeof(di_int) * CHAR_BIT) / 2; |
27 | const du_int lower_mask = (du_int)~0 >> bits_in_dword_2; |
28 | r.s.low = (a & lower_mask) * (b & lower_mask); |
29 | du_int t = r.s.low >> bits_in_dword_2; |
30 | r.s.low &= lower_mask; |
31 | t += (a >> bits_in_dword_2) * (b & lower_mask); |
32 | r.s.low += (t & lower_mask) << bits_in_dword_2; |
33 | r.s.high = t >> bits_in_dword_2; |
34 | t = r.s.low >> bits_in_dword_2; |
35 | r.s.low &= lower_mask; |
36 | t += (b >> bits_in_dword_2) * (a & lower_mask); |
37 | r.s.low += (t & lower_mask) << bits_in_dword_2; |
38 | r.s.high += t >> bits_in_dword_2; |
39 | r.s.high += (a >> bits_in_dword_2) * (b >> bits_in_dword_2); |
40 | return r.all; |
41 | } |
42 | |
43 | /* Returns: a * b */ |
44 | |
45 | COMPILER_RT_ABI ti_int |
46 | __multi3(ti_int a, ti_int b) |
47 | { |
48 | twords x; |
49 | x.all = a; |
50 | twords y; |
51 | y.all = b; |
52 | twords r; |
53 | r.all = __mulddi3(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 | |
58 | #endif /* CRT_HAS_128BIT */ |
59 |