root / prex-0.9.0 / bsp / drv / lib / queue.c @ 03e9c04a
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| 1 | 03e9c04a | Brad Neuman | /*-
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| 2 | * Copyright (c) 2005, Kohsuke Ohtani
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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 | * 1. Redistributions of source code must retain the above copyright
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| 9 | * notice, this list of conditions and the following disclaimer.
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| 10 | * 2. Redistributions in binary form must reproduce the above copyright
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| 11 | * notice, this list of conditions and the following disclaimer in the
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| 12 | * documentation and/or other materials provided with the distribution.
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| 13 | * 3. Neither the name of the author nor the names of any co-contributors
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| 14 | * may be used to endorse or promote products derived from this software
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| 15 | * without specific prior written permission.
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| 16 | *
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| 17 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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| 18 | * 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 AUTHOR OR CONTRIBUTORS BE LIABLE
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| 21 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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| 22 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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| 23 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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| 24 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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| 25 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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| 26 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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| 27 | * SUCH DAMAGE.
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| 28 | */
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| 29 | |||
| 30 | /*
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| 31 | * queue.c - generic queue management library
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| 32 | */
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| 33 | #include <sys/queue.h> |
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| 34 | |||
| 35 | /*
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| 36 | * Insert element at tail of queue
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| 37 | */
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| 38 | void
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| 39 | enqueue(queue_t head, queue_t item) |
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| 40 | {
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| 41 | item->next = head; |
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| 42 | item->prev = head->prev; |
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| 43 | item->prev->next = item; |
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| 44 | head->prev = item; |
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| 45 | } |
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| 46 | |||
| 47 | /*
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| 48 | * Remove and return element of head of queue
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| 49 | */
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| 50 | queue_t |
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| 51 | dequeue(queue_t head) |
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| 52 | {
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| 53 | queue_t item; |
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| 54 | |||
| 55 | if (head->next == head)
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| 56 | return ((queue_t)0); |
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| 57 | item = head->next; |
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| 58 | item->next->prev = head; |
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| 59 | head->next = item->next; |
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| 60 | return item;
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| 61 | } |
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| 62 | |||
| 63 | /*
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| 64 | * Insert element after specified element
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| 65 | */
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| 66 | void
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| 67 | queue_insert(queue_t prev, queue_t item) |
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| 68 | {
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| 69 | item->prev = prev; |
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| 70 | item->next = prev->next; |
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| 71 | prev->next->prev = item; |
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| 72 | prev->next = item; |
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| 73 | } |
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| 74 | |||
| 75 | /*
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| 76 | * Remove specified element from queue
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| 77 | */
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| 78 | void
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| 79 | queue_remove(queue_t item) |
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| 80 | {
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| 81 | item->prev->next = item->next; |
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| 82 | item->next->prev = item->prev; |
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| 83 | } |