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
18COMPILER_RT_ABI si_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 __builtin_ctz(x.s.high) + (1 + sizeof(si_int) * CHAR_BIT);
25  }
26  return __builtin_ctz(x.s.low) + 1;
27}
28