52 lines · c
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-exception6//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_128BIT16 17// Returns: a * b18 19static 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 * b39 40COMPILER_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(x.s.low, 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_128BIT52