Home | History | Annotate | Download | only in builtins
      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