divdi3.c revision 355940
1//===-- divdi3.c - Implement __divdi3 -------------------------------------===//
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 __divdi3 for the compiler_rt library.
10//
11//===----------------------------------------------------------------------===//
12
13#include "int_lib.h"
14
15// Returns: a / b
16
17COMPILER_RT_ABI di_int __divdi3(di_int a, di_int b) {
18  const int bits_in_dword_m1 = (int)(sizeof(di_int) * CHAR_BIT) - 1;
19  di_int s_a = a >> bits_in_dword_m1;                   // s_a = a < 0 ? -1 : 0
20  di_int s_b = b >> bits_in_dword_m1;                   // s_b = b < 0 ? -1 : 0
21  a = (a ^ s_a) - s_a;                                  // negate if s_a == -1
22  b = (b ^ s_b) - s_b;                                  // negate if s_b == -1
23  s_a ^= s_b;                                           // sign of quotient
24  return (__udivmoddi4(a, b, (du_int *)0) ^ s_a) - s_a; // negate if s_a == -1
25}
26