| 1 | //===-- multi3.c - Implement __multi3 -------------------------------------===// |
|---|---|
| 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 __multi3 for the compiler_rt library. |
| 10 | // |
| 11 | //===----------------------------------------------------------------------===// |
| 12 | |
| 13 | #include "int_lib.h" |
| 14 | |
| 15 | #ifdef CRT_HAS_128BIT |
| 16 | |
| 17 | // Returns: a * b |
| 18 | |
| 19 | static ti_int __mulddi3(du_int a, du_int b) { |
| 20 | twords r; |
| 21 | const int bits_in_dword_2 = (int)(sizeof(di_int) * CHAR_BIT) / 2; |
| 22 | const du_int lower_mask = (du_int)~0 >> bits_in_dword_2; |
| 23 | r.s.low = (a & lower_mask) * (b & lower_mask); |
| 24 | du_int t = r.s.low >> bits_in_dword_2; |
| 25 | r.s.low &= lower_mask; |
| 26 | t += (a >> bits_in_dword_2) * (b & lower_mask); |
| 27 | r.s.low += (t & lower_mask) << bits_in_dword_2; |
| 28 | r.s.high = t >> bits_in_dword_2; |
| 29 | t = r.s.low >> bits_in_dword_2; |
| 30 | r.s.low &= lower_mask; |
| 31 | t += (b >> bits_in_dword_2) * (a & lower_mask); |
| 32 | r.s.low += (t & lower_mask) << bits_in_dword_2; |
| 33 | r.s.high += t >> bits_in_dword_2; |
| 34 | r.s.high += (a >> bits_in_dword_2) * (b >> bits_in_dword_2); |
| 35 | return r.all; |
| 36 | } |
| 37 | |
| 38 | // Returns: a * b |
| 39 | |
| 40 | COMPILER_RT_ABI ti_int __multi3(ti_int a, ti_int b) { |
| 41 | twords x; |
| 42 | x.all = a; |
| 43 | twords y; |
| 44 | y.all = b; |
| 45 | twords r; |
| 46 | r.all = __mulddi3(a: x.s.low, b: y.s.low); |
| 47 | r.s.high += x.s.high * y.s.low + x.s.low * y.s.high; |
| 48 | return r.all; |
| 49 | } |
| 50 | |
| 51 | #endif // CRT_HAS_128BIT |
| 52 |