| Daniel Dunbar | b3a6901 | 2009-06-26 16:47:03 +0000 | [diff] [blame] | 1 | //===-- ffsdi2.c - Implement __ffsdi2 -------------------------------------===// |
| 2 | // |
| 3 | // The LLVM Compiler Infrastructure |
| 4 | // |
| 5 | // This file is distributed under the University of Illinois Open Source |
| 6 | // License. See LICENSE.TXT for details. |
| 7 | // |
| 8 | //===----------------------------------------------------------------------===// |
| 9 | // |
| 10 | // This file implements __ffsdi2 for the compiler_rt library. |
| 11 | // |
| 12 | //===----------------------------------------------------------------------===// |
| 13 | |
| 14 | #include "int_lib.h" |
| 15 | |
| 16 | // Returns: the index of the least significant 1-bit in a, or |
| 17 | // the value zero if a is zero. The least significant bit is index one. |
| 18 | |
| 19 | si_int |
| 20 | __ffsdi2(di_int a) |
| 21 | { |
| 22 | dwords x; |
| 23 | x.all = a; |
| 24 | if (x.low == 0) |
| 25 | { |
| 26 | if (x.high == 0) |
| 27 | return 0; |
| 28 | return __builtin_ctz(x.high) + (1 + sizeof(si_int) * CHAR_BIT); |
| 29 | } |
| 30 | return __builtin_ctz(x.low) + 1; |
| 31 | } |