ffsti2.c revision 214152
1/* ===-- ffsti2.c - Implement __ffsti2 -------------------------------------=== 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 __ffsti2 for the compiler_rt library. 11 * 12 * ===----------------------------------------------------------------------=== 13 */ 14 15#if __x86_64 16 17#include "int_lib.h" 18 19/* Returns: the index of the least significant 1-bit in a, or 20 * the value zero if a is zero. The least significant bit is index one. 21 */ 22 23si_int 24__ffsti2(ti_int a) 25{ 26 twords x; 27 x.all = a; 28 if (x.s.low == 0) 29 { 30 if (x.s.high == 0) 31 return 0; 32 return __builtin_ctzll(x.s.high) + (1 + sizeof(di_int) * CHAR_BIT); 33 } 34 return __builtin_ctzll(x.s.low) + 1; 35} 36 37#endif /* __x86_64 */ 38