ctzdi2.c revision 276789
1276789Sdim/* ===-- ctzdi2.c - Implement __ctzdi2 -------------------------------------=== 2276789Sdim * 3276789Sdim * The LLVM Compiler Infrastructure 4276789Sdim * 5276789Sdim * This file is dual licensed under the MIT and the University of Illinois Open 6276789Sdim * Source Licenses. See LICENSE.TXT for details. 7276789Sdim * 8276789Sdim * ===----------------------------------------------------------------------=== 9276789Sdim * 10276789Sdim * This file implements __ctzdi2 for the compiler_rt library. 11276789Sdim * 12276789Sdim * ===----------------------------------------------------------------------=== 13276789Sdim */ 14276789Sdim 15276789Sdim#include "int_lib.h" 16276789Sdim 17276789Sdim/* Returns: the number of trailing 0-bits */ 18276789Sdim 19276789Sdim/* Precondition: a != 0 */ 20276789Sdim 21276789SdimCOMPILER_RT_ABI si_int 22276789Sdim__ctzdi2(di_int a) 23276789Sdim{ 24276789Sdim dwords x; 25276789Sdim x.all = a; 26276789Sdim const si_int f = -(x.s.low == 0); 27276789Sdim return __builtin_ctz((x.s.high & f) | (x.s.low & ~f)) + 28276789Sdim (f & ((si_int)(sizeof(si_int) * CHAR_BIT))); 29276789Sdim} 30