1 //===-- ffsdi2.c - Implement __ffsdi2 -------------------------------------===// 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 __ffsdi2 for the compiler_rt library. 10 // 11 //===----------------------------------------------------------------------===// 12 13 #include "int_lib.h" 14 15 // Returns: the index of the least significant 1-bit in a, or 16 // the value zero if a is zero. The least significant bit is index one. 17 18 COMPILER_RT_ABI int __ffsdi2(di_int a) { 19 dwords x; 20 x.all = a; 21 if (x.s.low == 0) { 22 if (x.s.high == 0) 23 return 0; 24 return ctzsi(x.s.high) + (1 + sizeof(si_int) * CHAR_BIT); 25 } 26 return ctzsi(x.s.low) + 1; 27 } 28