1 /*===-- ashrdi3.c - Implement __ashrdi3 -----------------------------------===
2  *
3  *                     The LLVM Compiler Infrastructure
4  *
5  * This file is dual licensed under the MIT and the University of Illinois Open
6  * Source Licenses. See LICENSE.TXT for details.
7  *
8  * ===----------------------------------------------------------------------===
9  *
10  * This file implements __ashrdi3 for the compiler_rt library.
11  *
12  * ===----------------------------------------------------------------------===
13  */
14 
15 #include "int_lib.h"
16 
17 /* Returns: arithmetic a >> b */
18 
19 /* Precondition:  0 <= b < bits_in_dword */
20 
ARM_EABI_FNALIAS(lasr,ashrdi3)21 ARM_EABI_FNALIAS(lasr, ashrdi3)
22 
23 COMPILER_RT_ABI di_int
24 __ashrdi3(di_int a, si_int b)
25 {
26     const int bits_in_word = (int)(sizeof(si_int) * CHAR_BIT);
27     dwords input;
28     dwords result;
29     input.all = a;
30     if (b & bits_in_word)  /* bits_in_word <= b < bits_in_dword */
31     {
32         /* result.s.high = input.s.high < 0 ? -1 : 0 */
33         result.s.high = input.s.high >> (bits_in_word - 1);
34         result.s.low = input.s.high >> (b - bits_in_word);
35     }
36     else  /* 0 <= b < bits_in_word */
37     {
38         if (b == 0)
39             return a;
40         result.s.high  = input.s.high >> b;
41         result.s.low = (input.s.high << (bits_in_word - b)) | (input.s.low >> b);
42     }
43     return result.all;
44 }
45