1 | /* ===-- ffsdi2.c - Implement __ffsdi2 -------------------------------------=== |
2 | * |
3 | * The LLVM Compiler Infrastructure |
4 | * |
5 | * This file is dual licensed under the MIT and the University of Illinois Open |
6 | * Source Licenses. See LICENSE.TXT for details. |
7 | * |
8 | * ===----------------------------------------------------------------------=== |
9 | * |
10 | * This file implements __ffsdi2 for the compiler_rt library. |
11 | * |
12 | * ===----------------------------------------------------------------------=== |
13 | */ |
14 | |
15 | #include "int_lib.h" |
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 | |
21 | COMPILER_RT_ABI si_int |
22 | __ffsdi2(di_int a) |
23 | { |
24 | dwords x; |
25 | x.all = a; |
26 | if (x.s.low == 0) |
27 | { |
28 | if (x.s.high == 0) |
29 | return 0; |
30 | return __builtin_ctz(x.s.high) + (1 + sizeof(si_int) * CHAR_BIT); |
31 | } |
32 | return __builtin_ctz(x.s.low) + 1; |
33 | } |
34 | |