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1702 | - | 1 | /* Copyright (c) 2007, Dmitry Xmelkov |
2 | All rights reserved. |
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3 | |||
4 | Redistribution and use in source and binary forms, with or without |
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5 | modification, are permitted provided that the following conditions are met: |
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6 | |||
7 | * Redistributions of source code must retain the above copyright |
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8 | notice, this list of conditions and the following disclaimer. |
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9 | * Redistributions in binary form must reproduce the above copyright |
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10 | notice, this list of conditions and the following disclaimer in |
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11 | the documentation and/or other materials provided with the |
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12 | distribution. |
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13 | * Neither the name of the copyright holders nor the names of |
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14 | contributors may be used to endorse or promote products derived |
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15 | from this software without specific prior written permission. |
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16 | |||
17 | THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" |
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18 | AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
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19 | IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
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20 | ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE |
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21 | LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
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22 | CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
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23 | SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
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24 | INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
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25 | CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
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26 | ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
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27 | POSSIBILITY OF SUCH DAMAGE. */ |
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28 | |||
29 | /* $Id: ntz.h 1217 2007-02-18 13:18:05Z dmix $ */ |
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30 | |||
31 | #ifndef _NTZ_H |
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32 | #define _NTZ_H |
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33 | |||
34 | /* Number of Tail Zeros: ntz(x)= (ffs(x) ? ffs(x)-1 : 16) |
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35 | It works with all: cpp, gcc and gas expressions. */ |
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36 | #define ntz(x) \ |
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37 | ( (1 & (((x) & 1) == 0)) \ |
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38 | + (1 & (((x) & 3) == 0)) \ |
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39 | + (1 & (((x) & 7) == 0)) \ |
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40 | + (1 & (((x) & 017) == 0)) \ |
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41 | + (1 & (((x) & 037) == 0)) \ |
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42 | + (1 & (((x) & 077) == 0)) \ |
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43 | + (1 & (((x) & 0177) == 0)) \ |
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44 | + (1 & (((x) & 0377) == 0)) \ |
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45 | + (1 & (((x) & 0777) == 0)) \ |
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46 | + (1 & (((x) & 01777) == 0)) \ |
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47 | + (1 & (((x) & 03777) == 0)) \ |
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48 | + (1 & (((x) & 07777) == 0)) \ |
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49 | + (1 & (((x) & 017777) == 0)) \ |
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50 | + (1 & (((x) & 037777) == 0)) \ |
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51 | + (1 & (((x) & 077777) == 0)) \ |
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52 | + (1 & (((x) & 0177777) == 0)) ) |
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53 | |||
54 | #endif /* !_NTZ_H */ |