1 /* ===-- ctzdi2.c - Implement __ctzdi2 -------------------------------------=== 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 __ctzdi2 for the compiler_rt library. 11 * 12 * ===----------------------------------------------------------------------=== 13 */ 14 15 #include "int_lib.h" 16 17 /* Returns: the number of trailing 0-bits */ 18 19 /* Precondition: a != 0 */ 20 21 COMPILER_RT_ABI si_int __ctzdi2(di_int a)22__ctzdi2(di_int a) 23 { 24 dwords x; 25 x.all = a; 26 const si_int f = -(x.s.low == 0); 27 return __builtin_ctz((x.s.high & f) | (x.s.low & ~f)) + 28 (f & ((si_int)(sizeof(si_int) * CHAR_BIT))); 29 } 30