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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 | |||
1819 | decky | 29 | /** @addtogroup generic |
1702 | cejka | 30 | * @{ |
31 | */ |
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32 | /** @file |
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33 | */ |
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34 | |||
1888 | jermar | 35 | #ifndef KERN_BITOPS_H_ |
36 | #define KERN_BITOPS_H_ |
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771 | palkovsky | 37 | |
38 | #include <typedefs.h> |
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39 | |||
40 | |||
1310 | jermar | 41 | /** Return position of first non-zero bit from left (i.e. [log_2(arg)]). |
771 | palkovsky | 42 | * |
43 | * If number is zero, it returns 0 |
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44 | */ |
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1780 | jermar | 45 | static inline int fnzb32(uint32_t arg) |
771 | palkovsky | 46 | { |
47 | int n = 0; |
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48 | |||
2004 | decky | 49 | if (arg >> 16) { |
50 | arg >>= 16; |
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51 | n += 16; |
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52 | } |
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53 | |||
54 | if (arg >> 8) { |
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55 | arg >>= 8; |
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56 | n += 8; |
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57 | } |
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58 | |||
59 | if (arg >> 4) { |
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60 | arg >>= 4; |
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61 | n += 4; |
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62 | } |
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63 | |||
64 | if (arg >> 2) { |
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65 | arg >>= 2; |
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66 | n += 2; |
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67 | } |
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68 | |||
69 | if (arg >> 1) { |
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70 | arg >>= 1; |
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71 | n += 1; |
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72 | } |
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73 | |||
771 | palkovsky | 74 | return n; |
75 | } |
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76 | |||
1780 | jermar | 77 | static inline int fnzb64(uint64_t arg) |
771 | palkovsky | 78 | { |
79 | int n = 0; |
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80 | |||
2004 | decky | 81 | if (arg >> 32) { |
82 | arg >>= 32; |
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83 | n += 32; |
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84 | } |
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85 | |||
1780 | jermar | 86 | return n + fnzb32((uint32_t) arg); |
771 | palkovsky | 87 | } |
88 | |||
89 | #define fnzb(x) fnzb32(x) |
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90 | |||
91 | #endif |
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1702 | cejka | 92 | |
1819 | decky | 93 | /** @} |
1702 | cejka | 94 | */ |