1 //===-- ffsti2.c - Implement __ffsti2 -------------------------------------===//
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 __ffsti2 for the compiler_rt library.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #include "int_lib.h"
14 
15 #ifdef CRT_HAS_128BIT
16 
17 // Returns: the index of the least significant 1-bit in a, or
18 // the value zero if a is zero. The least significant bit is index one.
19 
__ffsti2(ti_int a)20 COMPILER_RT_ABI int __ffsti2(ti_int a) {
21   twords x;
22   x.all = a;
23   if (x.s.low == 0) {
24     if (x.s.high == 0)
25       return 0;
26     return __builtin_ctzll(x.s.high) + (1 + sizeof(di_int) * CHAR_BIT);
27   }
28   return __builtin_ctzll(x.s.low) + 1;
29 }
30 
31 #endif // CRT_HAS_128BIT
32