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| 2 | pj | 1 | /* |
| 2 | * Project: S.Ha.R.K. |
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| 3 | * |
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| 4 | * Coordinators: |
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| 5 | * Giorgio Buttazzo <giorgio@sssup.it> |
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| 6 | * Paolo Gai <pj@gandalf.sssup.it> |
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| 7 | * |
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| 8 | * Authors : |
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| 9 | * Paolo Gai <pj@gandalf.sssup.it> |
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| 10 | * Massimiliano Giorgi <massy@gandalf.sssup.it> |
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| 11 | * Luca Abeni <luca@gandalf.sssup.it> |
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| 12 | * (see the web pages for full authors list) |
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| 13 | * |
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| 14 | * ReTiS Lab (Scuola Superiore S.Anna - Pisa - Italy) |
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| 15 | * |
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| 16 | * http://www.sssup.it |
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| 17 | * http://retis.sssup.it |
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| 18 | * http://shark.sssup.it |
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| 19 | */ |
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| 20 | |||
| 21 | |||
| 22 | /** |
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| 23 | ------------ |
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| 24 | CVS : $Id: int_sem.h,v 1.1.1.1 2002-03-29 14:12:51 pj Exp $ |
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| 25 | |||
| 26 | File: $File$ |
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| 27 | Revision: $Revision: 1.1.1.1 $ |
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| 28 | Last update: $Date: 2002-03-29 14:12:51 $ |
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| 29 | ------------ |
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| 30 | |||
| 31 | Internal semaphores. |
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| 32 | |||
| 33 | They are different from the Posix semaphores and the mutexes because: |
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| 34 | - internal_sem_wait is not a cancellation point |
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| 35 | - there are no limits on the semaphores that can be created |
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| 36 | (they works like a mutex_t...) |
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| 37 | - the queuing policy is FIFO |
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| 38 | - Be Careful! |
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| 39 | they are made to be fast... so not so many controls are done!!! |
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| 40 | |||
| 41 | **/ |
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| 42 | |||
| 43 | /* |
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| 44 | * Copyright (C) 2000 Paolo Gai |
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| 45 | * |
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| 46 | * This program is free software; you can redistribute it and/or modify |
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| 47 | * it under the terms of the GNU General Public License as published by |
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| 48 | * the Free Software Foundation; either version 2 of the License, or |
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| 49 | * (at your option) any later version. |
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| 50 | * |
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| 51 | * This program is distributed in the hope that it will be useful, |
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| 52 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
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| 53 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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| 54 | * GNU General Public License for more details. |
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| 55 | * |
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| 56 | * You should have received a copy of the GNU General Public License |
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| 57 | * along with this program; if not, write to the Free Software |
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| 58 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
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| 59 | * |
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| 60 | */ |
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| 61 | |||
| 62 | #ifndef __INT_SEM_H__ |
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| 63 | #define __INT_SEM_H__ |
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| 64 | |||
| 65 | #include <kernel/types.h> |
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| 66 | |||
| 67 | /* this is the structure normally pointed by the opt field in the |
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| 68 | mutex_t structure */ |
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| 69 | typedef struct { |
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| 70 | int count; |
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| 71 | QQUEUE blocked; |
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| 72 | } internal_sem_t; |
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| 73 | |||
| 74 | |||
| 75 | /* this function initializes an internal semaphore */ |
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| 76 | void internal_sem_init(internal_sem_t *s, int value); |
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| 77 | |||
| 78 | /* blocking wait (decrement by 1) */ |
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| 79 | void internal_sem_wait(internal_sem_t *s); |
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| 80 | |||
| 81 | /* return 0 if the counter is decremented, -1 if not */ |
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| 82 | int internal_sem_trywait(internal_sem_t *s); |
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| 83 | |||
| 84 | /* post (increment by 1) */ |
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| 85 | void internal_sem_post(internal_sem_t *s); |
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| 86 | |||
| 87 | /* getvalue (>= 0 if there is noone blocked on it, -1 otherwise) */ |
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| 88 | int internal_sem_getvalue(internal_sem_t *s); |
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| 89 | |||
| 90 | #endif |