ashrdi3.c revision 222656 
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#include "abi.h"
15
16#include "int_lib.h"
17
18/* Returns: arithmetic a >> b */
19
20/* Precondition:  0 <= b < bits_in_dword */
21
22ARM_EABI_FNALIAS(lasr, ashrdi3);
23
24COMPILER_RT_ABI di_int
25__ashrdi3(di_int a, si_int b)
26{
27    const int bits_in_word = (int)(sizeof(si_int) * CHAR_BIT);
28    dwords input;
29    dwords result;
30    input.all = a;
31    if (b & bits_in_word)  /* bits_in_word <= b < bits_in_dword */
32    {
33        /* result.s.high = input.s.high < 0 ? -1 : 0 */
34        result.s.high = input.s.high >> (bits_in_word - 1);
35        result.s.low = input.s.high >> (b - bits_in_word);
36    }
37    else  /* 0 <= b < bits_in_word */
38    {
39        if (b == 0)
40            return a;
41        result.s.high  = input.s.high >> b;
42        result.s.low = (input.s.high << (bits_in_word - b)) | (input.s.low >> b);
43    }
44    return result.all;
45}
46