1//===-- muldi3.c - Implement __muldi3 -------------------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file implements __muldi3 for the compiler_rt library.
10//
11//===----------------------------------------------------------------------===//
12
13#include "int_lib.h"
14
15// Returns: a * b
16
17static di_int __muldsi3(su_int a, su_int b) {
18  dwords r;
19  const int bits_in_word_2 = (int)(sizeof(si_int) * CHAR_BIT) / 2;
20  const su_int lower_mask = (su_int)~0 >> bits_in_word_2;
21  r.s.low = (a & lower_mask) * (b & lower_mask);
22  su_int t = r.s.low >> bits_in_word_2;
23  r.s.low &= lower_mask;
24  t += (a >> bits_in_word_2) * (b & lower_mask);
25  r.s.low += (t & lower_mask) << bits_in_word_2;
26  r.s.high = t >> bits_in_word_2;
27  t = r.s.low >> bits_in_word_2;
28  r.s.low &= lower_mask;
29  t += (b >> bits_in_word_2) * (a & lower_mask);
30  r.s.low += (t & lower_mask) << bits_in_word_2;
31  r.s.high += t >> bits_in_word_2;
32  r.s.high += (a >> bits_in_word_2) * (b >> bits_in_word_2);
33  return r.all;
34}
35
36// Returns: a * b
37
38COMPILER_RT_ABI di_int __muldi3(di_int a, di_int b) {
39  dwords x;
40  x.all = a;
41  dwords y;
42  y.all = b;
43  dwords r;
44  r.all = __muldsi3(x.s.low, y.s.low);
45  r.s.high += x.s.high * y.s.low + x.s.low * y.s.high;
46  return r.all;
47}
48
49#if defined(__ARM_EABI__)
50COMPILER_RT_ALIAS(__muldi3, __aeabi_lmul)
51#endif
52