clzti2.c revision 2d1fdb26e458c4ddc04155c1d421bced3ba90cd0 
1/* ===-- clzti2.c - Implement __clzti2 -------------------------------------===
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 __clzti2 for the compiler_rt library.
11 *
12 * ===----------------------------------------------------------------------===
13 */
14
15#include "int_lib.h"
16
17#ifdef CRT_HAS_128BIT
18
19/* Returns: the number of leading 0-bits */
20
21/* Precondition: a != 0 */
22
23COMPILER_RT_ABI si_int
24__clzti2(ti_int a)
25{
26    twords x;
27    x.all = a;
28    const di_int f = -(x.s.high == 0);
29    return __builtin_clzll((x.s.high & ~f) | (x.s.low & f)) +
30           ((si_int)f & ((si_int)(sizeof(di_int) * CHAR_BIT)));
31}
32
33#endif /* CRT_HAS_128BIT */
34