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 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