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771 | palkovsky | 1 | /* |
2 | * Copyright (C) 2006 Ondrej Palkovsky |
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3 | * All rights reserved. |
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4 | * |
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5 | * Redistribution and use in source and binary forms, with or without |
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6 | * modification, are permitted provided that the following conditions |
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7 | * are met: |
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8 | * |
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9 | * - Redistributions of source code must retain the above copyright |
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10 | * notice, this list of conditions and the following disclaimer. |
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11 | * - Redistributions in binary form must reproduce the above copyright |
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12 | * notice, this list of conditions and the following disclaimer in the |
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13 | * documentation and/or other materials provided with the distribution. |
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14 | * - The name of the author may not be used to endorse or promote products |
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15 | * derived from this software without specific prior written permission. |
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16 | * |
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17 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
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18 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
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19 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
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20 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
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21 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
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22 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
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23 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
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24 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
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25 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
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26 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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27 | */ |
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28 | |||
29 | #ifndef _BITOPS_H_ |
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30 | #define _BITOPS_H_ |
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31 | |||
32 | #include <typedefs.h> |
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33 | |||
34 | |||
35 | /** Return position of first non-zero bit from left. |
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36 | * |
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37 | * If number is zero, it returns 0 |
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38 | */ |
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39 | static inline int fnzb32(__u32 arg) |
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40 | { |
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41 | int n = 0; |
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42 | |||
43 | if (arg & 0xffff0000) { arg >>= 16;n += 16;} |
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44 | if (arg & 0xff00) { arg >>= 8; n += 8;} |
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45 | if (arg & 0xf0) { arg >>= 4; n += 4;} |
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46 | if (arg & 0xc) { arg >>= 2; n+=2;} |
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47 | if (arg & 0x2) { arg >>= 1; n+=1;} |
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48 | return n; |
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49 | } |
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50 | |||
51 | static inline int fnzb64(__u64 arg) |
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52 | { |
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53 | int n = 0; |
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54 | |||
55 | /* This is because mips complains about big numbers, |
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56 | * other platforms should optimize it out */ |
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57 | __u64 oper = 0xffffffff; |
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58 | oper <<= 32; |
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59 | |||
60 | if (arg & oper) { arg >>= 32;n += 32;} |
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61 | return n + fnzb32((__u32) arg); |
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62 | } |
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63 | |||
64 | #define fnzb(x) fnzb32(x) |
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65 | |||
66 | #endif |