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      1 /**************************************************************************
      2  *
      3  * Copyright 2008 VMware, Inc.
      4  * All Rights Reserved.
      5  *
      6  * Permission is hereby granted, free of charge, to any person obtaining a
      7  * copy of this software and associated documentation files (the
      8  * "Software"), to deal in the Software without restriction, including
      9  * without limitation the rights to use, copy, modify, merge, publish,
     10  * distribute, sub license, and/or sell copies of the Software, and to
     11  * permit persons to whom the Software is furnished to do so, subject to
     12  * the following conditions:
     13  *
     14  * The above copyright notice and this permission notice (including the
     15  * next paragraph) shall be included in all copies or substantial portions
     16  * of the Software.
     17  *
     18  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
     19  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
     20  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
     21  * IN NO EVENT SHALL VMWARE AND/OR ITS SUPPLIERS BE LIABLE FOR
     22  * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
     23  * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
     24  * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
     25  *
     26  **************************************************************************/
     27 
     28 
     29 #include "bitscan.h"
     30 
     31 #ifdef HAVE___BUILTIN_FFS
     32 #elif defined(_MSC_VER) && (_M_IX86 || _M_ARM || _M_AMD64 || _M_IA64)
     33 #else
     34 int
     35 ffs(unsigned i)
     36 {
     37    int bit = 0;
     38    if (!i)
     39       return bit;
     40    if (!(i & 0xffff)) {
     41       bit += 16;
     42       i >>= 16;
     43    }
     44    if (!(i & 0xff)) {
     45       bit += 8;
     46       i >>= 8;
     47    }
     48    if (!(i & 0xf)) {
     49       bit += 4;
     50       i >>= 4;
     51    }
     52    if (!(i & 0x3)) {
     53       bit += 2;
     54       i >>= 2;
     55    }
     56    if (!(i & 0x1))
     57       bit += 1;
     58    return bit + 1;
     59 }
     60 #endif
     61 
     62 #ifdef HAVE___BUILTIN_FFSLL
     63 #elif defined(_MSC_VER) && (_M_AMD64 || _M_ARM || _M_IA64)
     64 #else
     65 int
     66 ffsll(uint64_t val)
     67 {
     68    int bit;
     69 
     70    bit = ffs((unsigned) (val & 0xffffffff));
     71    if (bit != 0)
     72       return bit;
     73 
     74    bit = ffs((unsigned) (val >> 32));
     75    if (bit != 0)
     76       return 32 + bit;
     77 
     78    return 0;
     79 }
     80 #endif
     81