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| Rev | Author | Line No. | Line |
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| 771 | palkovsky | 1 | /* |
| 2071 | jermar | 2 | * Copyright (c) 2006 Ondrej Palkovsky |
| 771 | palkovsky | 3 | * All rights reserved. |
| 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 | |||
| 1310 | jermar | 39 | /** Return position of first non-zero bit from left (i.e. [log_2(arg)]). |
| 771 | palkovsky | 40 | * |
| 41 | * If number is zero, it returns 0 |
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| 42 | */ |
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| 1780 | jermar | 43 | static inline int fnzb32(uint32_t arg) |
| 771 | palkovsky | 44 | { |
| 45 | int n = 0; |
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| 46 | |||
| 2004 | decky | 47 | if (arg >> 16) { |
| 48 | arg >>= 16; |
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| 49 | n += 16; |
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| 50 | } |
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| 51 | |||
| 52 | if (arg >> 8) { |
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| 53 | arg >>= 8; |
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| 54 | n += 8; |
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| 55 | } |
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| 56 | |||
| 57 | if (arg >> 4) { |
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| 58 | arg >>= 4; |
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| 59 | n += 4; |
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| 60 | } |
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| 61 | |||
| 62 | if (arg >> 2) { |
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| 63 | arg >>= 2; |
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| 64 | n += 2; |
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| 65 | } |
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| 66 | |||
| 67 | if (arg >> 1) { |
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| 68 | arg >>= 1; |
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| 69 | n += 1; |
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| 70 | } |
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| 71 | |||
| 771 | palkovsky | 72 | return n; |
| 73 | } |
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| 74 | |||
| 1780 | jermar | 75 | static inline int fnzb64(uint64_t arg) |
| 771 | palkovsky | 76 | { |
| 77 | int n = 0; |
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| 78 | |||
| 2004 | decky | 79 | if (arg >> 32) { |
| 80 | arg >>= 32; |
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| 81 | n += 32; |
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| 82 | } |
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| 83 | |||
| 1780 | jermar | 84 | return n + fnzb32((uint32_t) arg); |
| 771 | palkovsky | 85 | } |
| 86 | |||
| 87 | #define fnzb(x) fnzb32(x) |
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| 88 | |||
| 89 | #endif |
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| 1702 | cejka | 90 | |
| 1819 | decky | 91 | /** @} |
| 1702 | cejka | 92 | */ |