xref: /aosp_15_r20/external/compiler-rt/lib/builtins/ctzti2.c (revision 7c3d14c8b49c529e04be81a3ce6f5cc23712e4c6)
1*7c3d14c8STreehugger Robot /* ===-- ctzti2.c - Implement __ctzti2 -------------------------------------===
2*7c3d14c8STreehugger Robot  *
3*7c3d14c8STreehugger Robot  *                     The LLVM Compiler Infrastructure
4*7c3d14c8STreehugger Robot  *
5*7c3d14c8STreehugger Robot  * This file is dual licensed under the MIT and the University of Illinois Open
6*7c3d14c8STreehugger Robot  * Source Licenses. See LICENSE.TXT for details.
7*7c3d14c8STreehugger Robot  *
8*7c3d14c8STreehugger Robot  * ===----------------------------------------------------------------------===
9*7c3d14c8STreehugger Robot  *
10*7c3d14c8STreehugger Robot  * This file implements __ctzti2 for the compiler_rt library.
11*7c3d14c8STreehugger Robot  *
12*7c3d14c8STreehugger Robot  * ===----------------------------------------------------------------------===
13*7c3d14c8STreehugger Robot  */
14*7c3d14c8STreehugger Robot 
15*7c3d14c8STreehugger Robot #include "int_lib.h"
16*7c3d14c8STreehugger Robot 
17*7c3d14c8STreehugger Robot #ifdef CRT_HAS_128BIT
18*7c3d14c8STreehugger Robot 
19*7c3d14c8STreehugger Robot /* Returns: the number of trailing 0-bits */
20*7c3d14c8STreehugger Robot 
21*7c3d14c8STreehugger Robot /* Precondition: a != 0 */
22*7c3d14c8STreehugger Robot 
23*7c3d14c8STreehugger Robot COMPILER_RT_ABI si_int
__ctzti2(ti_int a)24*7c3d14c8STreehugger Robot __ctzti2(ti_int a)
25*7c3d14c8STreehugger Robot {
26*7c3d14c8STreehugger Robot     twords x;
27*7c3d14c8STreehugger Robot     x.all = a;
28*7c3d14c8STreehugger Robot     const di_int f = -(x.s.low == 0);
29*7c3d14c8STreehugger Robot     return __builtin_ctzll((x.s.high & f) | (x.s.low & ~f)) +
30*7c3d14c8STreehugger Robot               ((si_int)f & ((si_int)(sizeof(di_int) * CHAR_BIT)));
31*7c3d14c8STreehugger Robot }
32*7c3d14c8STreehugger Robot 
33*7c3d14c8STreehugger Robot #endif /* CRT_HAS_128BIT */
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