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| 1 | jermar | 1 | /* |
| 2 | * Copyright (C) 2001-2004 Jakub Jermar |
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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 | |||
| 1702 | cejka | 29 | /** @addtogroup sync |
| 30 | * @{ |
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| 31 | */ |
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| 32 | |||
| 1264 | jermar | 33 | /** |
| 1702 | cejka | 34 | * @file |
| 1264 | jermar | 35 | * @brief Semaphores. |
| 36 | */ |
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| 37 | |||
| 1 | jermar | 38 | #include <synch/semaphore.h> |
| 39 | #include <synch/waitq.h> |
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| 40 | #include <synch/spinlock.h> |
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| 384 | jermar | 41 | #include <synch/synch.h> |
| 115 | jermar | 42 | #include <arch/asm.h> |
| 195 | vana | 43 | #include <arch.h> |
| 1 | jermar | 44 | |
| 384 | jermar | 45 | /** Initialize semaphore |
| 46 | * |
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| 47 | * Initialize semaphore. |
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| 48 | * |
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| 49 | * @param s Semaphore. |
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| 50 | * @param val Maximal number of threads allowed to enter critical section. |
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| 51 | */ |
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| 1 | jermar | 52 | void semaphore_initialize(semaphore_t *s, int val) |
| 53 | { |
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| 413 | jermar | 54 | ipl_t ipl; |
| 1 | jermar | 55 | |
| 56 | waitq_initialize(&s->wq); |
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| 57 | |||
| 413 | jermar | 58 | ipl = interrupts_disable(); |
| 1 | jermar | 59 | |
| 60 | spinlock_lock(&s->wq.lock); |
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| 61 | s->wq.missed_wakeups = val; |
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| 62 | spinlock_unlock(&s->wq.lock); |
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| 63 | |||
| 413 | jermar | 64 | interrupts_restore(ipl); |
| 1 | jermar | 65 | } |
| 66 | |||
| 384 | jermar | 67 | /** Semaphore down |
| 68 | * |
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| 69 | * Semaphore down. |
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| 70 | * Conditional mode and mode with timeout can be requested. |
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| 71 | * |
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| 72 | * @param s Semaphore. |
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| 73 | * @param usec Timeout in microseconds. |
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| 1502 | jermar | 74 | * @param flags Select mode of operation. |
| 384 | jermar | 75 | * |
| 76 | * For exact description of possible combinations of |
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| 1502 | jermar | 77 | * usec and flags, see comment for waitq_sleep_timeout(). |
| 384 | jermar | 78 | * |
| 79 | * @return See comment for waitq_sleep_timeout(). |
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| 80 | */ |
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| 1502 | jermar | 81 | int _semaphore_down_timeout(semaphore_t *s, __u32 usec, int flags) |
| 1 | jermar | 82 | { |
| 1502 | jermar | 83 | return waitq_sleep_timeout(&s->wq, usec, flags); |
| 1 | jermar | 84 | } |
| 85 | |||
| 384 | jermar | 86 | /** Semaphore up |
| 87 | * |
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| 88 | * Semaphore up. |
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| 89 | * |
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| 90 | * @param s Semaphore. |
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| 91 | */ |
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| 1 | jermar | 92 | void semaphore_up(semaphore_t *s) |
| 93 | { |
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| 94 | waitq_wakeup(&s->wq, WAKEUP_FIRST); |
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| 95 | } |
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| 1702 | cejka | 96 | |
| 97 | /** @} |
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| 98 | */ |
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| 99 |