1 //===-- ashrdi3.c - Implement __ashrdi3 -----------------------------------===//
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 __ashrdi3 for the compiler_rt library.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #include "int_lib.h"
14 
15 // Returns: arithmetic a >> b
16 
17 // Precondition:  0 <= b < bits_in_dword
18 
19 COMPILER_RT_ABI di_int __ashrdi3(di_int a, si_int b) {
20   const int bits_in_word = (int)(sizeof(si_int) * CHAR_BIT);
21   dwords input;
22   dwords result;
23   input.all = a;
24   if (b & bits_in_word) /* bits_in_word <= b < bits_in_dword */ {
25     // result.s.high = input.s.high < 0 ? -1 : 0
26     result.s.high = input.s.high >> (bits_in_word - 1);
27     result.s.low = input.s.high >> (b - bits_in_word);
28   } else /* 0 <= b < bits_in_word */ {
29     if (b == 0)
30       return a;
31     result.s.high = input.s.high >> b;
32     result.s.low = (input.s.high << (bits_in_word - b)) | (input.s.low >> b);
33   }
34   return result.all;
35 }
36 
37 #if defined(__ARM_EABI__)
38 COMPILER_RT_ALIAS(__ashrdi3, __aeabi_lasr)
39 #endif
40