| Daniel Dunbar | fd08999 | 2009-06-26 16:47:03 +0000 | [diff] [blame] | 1 | //===-- ctzdi2.c - Implement __ctzdi2 -------------------------------------===// |
| 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 __ctzdi2 for the compiler_rt library. |
| 11 | // |
| 12 | //===----------------------------------------------------------------------===// |
| 13 | |
| 14 | #include "int_lib.h" |
| 15 | |
| 16 | // Returns: the number of trailing 0-bits |
| 17 | |
| 18 | // Precondition: a != 0 |
| 19 | |
| 20 | si_int |
| 21 | __ctzdi2(di_int a) |
| 22 | { |
| 23 | dwords x; |
| 24 | x.all = a; |
| 25 | const si_int f = -(x.low == 0); |
| 26 | return __builtin_ctz((x.high & f) | (x.low & ~f)) + |
| 27 | (f & ((si_int)(sizeof(si_int) * CHAR_BIT))); |
| 28 | } |