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 |
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 | |
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 |