1 /* ===-- ffsdi2.c - Implement __ffsdi2 -------------------------------------=== 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 __ffsdi2 for the compiler_rt library. 11 * 12 * ===----------------------------------------------------------------------=== 13 */ 14 15 #include "int_lib.h" 16 17 /* Returns: the index of the least significant 1-bit in a, or 18 * the value zero if a is zero. The least significant bit is index one. 19 */ 20 21 COMPILER_RT_ABI si_int 22 __ffsdi2(di_int a) 23 { 24 dwords x; 25 x.all = a; 26 if (x.s.low == 0) 27 { 28 if (x.s.high == 0) 29 return 0; 30 return __builtin_ctz(x.s.high) + (1 + sizeof(si_int) * CHAR_BIT); 31 } 32 return __builtin_ctz(x.s.low) + 1; 33 } 34
