| 1 | /*
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| 2 | * Copyright (c) 2005 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 |
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| 29 | /** @addtogroup generic
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| 30 | * @{
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| 31 | */
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| 32 | /** @file
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| 33 | */
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| 34 |
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| 35 | #ifndef KERN_PREEMPTION_H_
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| 36 | #define KERN_PREEMPTION_H_
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| 37 |
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| 38 | #include <arch.h>
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| 39 | #include <compiler/barrier.h>
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| 40 | #include <debug.h>
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| 41 |
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| 42 | #define PREEMPTION_INC (1 << 1)
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| 43 | #define PREEMPTION_NEEDED_FLAG (1 << 0)
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| 44 | #define PREEMPTION_NEEDED (THE->preemption & PREEMPTION_NEEDED_FLAG)
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| 45 | #define PREEMPTION_DISABLED (PREEMPTION_INC <= THE->preemption)
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| 46 | #define PREEMPTION_ENABLED (!PREEMPTION_DISABLED)
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| 47 |
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| 48 | /** Increment preemption disabled counter. */
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| 49 | #define preemption_disable() \
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| 50 | do { \
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| 51 | THE->preemption += PREEMPTION_INC; \
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| 52 | compiler_barrier(); \
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| 53 | } while (0)
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| 54 |
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| 55 | /** Restores preemption and reschedules if out time slice already elapsed.*/
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| 56 | #define preemption_enable() \
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| 57 | do { \
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| 58 | preemption_enable_noresched(); \
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| 59 | \
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| 60 | if (PREEMPTION_ENABLED && PREEMPTION_NEEDED) { \
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| 61 | preemption_enabled_scheduler(); \
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| 62 | } \
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| 63 | } while (0)
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| 64 |
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| 65 | /** Restores preemption but never reschedules. */
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| 66 | #define preemption_enable_noresched() \
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| 67 | do { \
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| 68 | ASSERT(PREEMPTION_DISABLED); \
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| 69 | compiler_barrier(); \
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| 70 | THE->preemption -= PREEMPTION_INC; \
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| 71 | } while (0)
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| 72 |
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| 73 |
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| 74 | extern void preemption_enabled_scheduler(void);
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| 75 | extern void preemption_set_needed(void);
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| 76 | extern void preemption_clear_needed(void);
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| 77 |
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| 78 | #endif
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| 79 |
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| 80 | /** @}
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| 81 | */
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