xref: /openbsd-src/sys/lib/libkern/lshrti3.c (revision 49f00df61520a457c70db7bca65b2d6bc6acdd2a)
1cb5d789fSjca /* ===-- lshrti3.c - Implement __lshrti3 -----------------------------------===
2cb5d789fSjca  *
3cb5d789fSjca  *                     The LLVM Compiler Infrastructure
4cb5d789fSjca  *
5cb5d789fSjca  * This file is dual licensed under the MIT and the University of Illinois Open
6cb5d789fSjca  * Source Licenses. See LICENSE.TXT for details.
7cb5d789fSjca  *
8cb5d789fSjca  * ===----------------------------------------------------------------------===
9cb5d789fSjca  *
10cb5d789fSjca  * This file implements __lshrti3 for the compiler_rt library.
11cb5d789fSjca  *
12cb5d789fSjca  * ===----------------------------------------------------------------------===
13cb5d789fSjca  */
14cb5d789fSjca 
15*49f00df6Sjca #include "crt_glue.h"
16*49f00df6Sjca 
17cb5d789fSjca /* Returns: logical a >> b */
18cb5d789fSjca 
19cb5d789fSjca /* Precondition:  0 <= b < bits_in_tword */
20cb5d789fSjca 
21cb5d789fSjca ti_int
__lshrti3(ti_int a,si_int b)22cb5d789fSjca __lshrti3(ti_int a, si_int b)
23cb5d789fSjca {
24cb5d789fSjca     const int bits_in_dword = (int)(sizeof(di_int) * CHAR_BIT);
25cb5d789fSjca     utwords input;
26cb5d789fSjca     utwords result;
27cb5d789fSjca     input.all = a;
28cb5d789fSjca     if (b & bits_in_dword)  /* bits_in_dword <= b < bits_in_tword */
29cb5d789fSjca     {
30cb5d789fSjca         result.s.high = 0;
31cb5d789fSjca         result.s.low = input.s.high >> (b - bits_in_dword);
32cb5d789fSjca     }
33cb5d789fSjca     else  /* 0 <= b < bits_in_dword */
34cb5d789fSjca     {
35cb5d789fSjca         if (b == 0)
36cb5d789fSjca             return a;
37cb5d789fSjca         result.s.high  = input.s.high >> b;
38cb5d789fSjca         result.s.low = (input.s.high << (bits_in_dword - b)) | (input.s.low >> b);
39cb5d789fSjca     }
40cb5d789fSjca     return result.all;
41cb5d789fSjca }
42