xref: /openbsd-src/gnu/llvm/compiler-rt/lib/builtins/lshrti3.c (revision 3cab2bb3f667058bece8e38b12449a63a9d73c4b)
1*3cab2bb3Spatrick //===-- lshrti3.c - Implement __lshrti3 -----------------------------------===//
2*3cab2bb3Spatrick //
3*3cab2bb3Spatrick // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4*3cab2bb3Spatrick // See https://llvm.org/LICENSE.txt for license information.
5*3cab2bb3Spatrick // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6*3cab2bb3Spatrick //
7*3cab2bb3Spatrick //===----------------------------------------------------------------------===//
8*3cab2bb3Spatrick //
9*3cab2bb3Spatrick // This file implements __lshrti3 for the compiler_rt library.
10*3cab2bb3Spatrick //
11*3cab2bb3Spatrick //===----------------------------------------------------------------------===//
12*3cab2bb3Spatrick 
13*3cab2bb3Spatrick #include "int_lib.h"
14*3cab2bb3Spatrick 
15*3cab2bb3Spatrick #ifdef CRT_HAS_128BIT
16*3cab2bb3Spatrick 
17*3cab2bb3Spatrick // Returns: logical a >> b
18*3cab2bb3Spatrick 
19*3cab2bb3Spatrick // Precondition:  0 <= b < bits_in_tword
20*3cab2bb3Spatrick 
__lshrti3(ti_int a,si_int b)21*3cab2bb3Spatrick COMPILER_RT_ABI ti_int __lshrti3(ti_int a, si_int b) {
22*3cab2bb3Spatrick   const int bits_in_dword = (int)(sizeof(di_int) * CHAR_BIT);
23*3cab2bb3Spatrick   utwords input;
24*3cab2bb3Spatrick   utwords result;
25*3cab2bb3Spatrick   input.all = a;
26*3cab2bb3Spatrick   if (b & bits_in_dword) /* bits_in_dword <= b < bits_in_tword */ {
27*3cab2bb3Spatrick     result.s.high = 0;
28*3cab2bb3Spatrick     result.s.low = input.s.high >> (b - bits_in_dword);
29*3cab2bb3Spatrick   } else /* 0 <= b < bits_in_dword */ {
30*3cab2bb3Spatrick     if (b == 0)
31*3cab2bb3Spatrick       return a;
32*3cab2bb3Spatrick     result.s.high = input.s.high >> b;
33*3cab2bb3Spatrick     result.s.low = (input.s.high << (bits_in_dword - b)) | (input.s.low >> b);
34*3cab2bb3Spatrick   }
35*3cab2bb3Spatrick   return result.all;
36*3cab2bb3Spatrick }
37*3cab2bb3Spatrick 
38*3cab2bb3Spatrick #endif // CRT_HAS_128BIT
39