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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
ffs(unsigned i)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
ffsll(uint64_t val)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