Enrico Fraccaroli
35 lines
992 B
C
35 lines
992 B
C
/// MentOS, The Mentoring Operating system project
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/// @file mutex.c
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/// @brief
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/// @copyright (c) 2014-2021 This file is distributed under the MIT License.
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/// See LICENSE.md for details.
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#include "mutex.h"
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#include "debug.h"
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void mutex_lock(mutex_t *mutex, uint32_t owner)
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{
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pr_debug("[%d] Trying to lock mutex...\n", owner);
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int failure = 1;
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while (mutex->state == 0 || failure || mutex->owner != owner) {
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failure = 1;
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if (mutex->state == 0) {
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asm("movl $0x01,%%eax\n\t" // move 1 to eax
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"xchg %%eax,%0\n\t" // try to set the lock bit
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"mov %%eax,%1\n\t" // export our result to a test var
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: "=m"(mutex->state), "=r"(failure)
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: "m"(mutex->state)
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: "%eax");
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}
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if (failure == 0) {
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mutex->owner = owner; //test to see if we got the lock bit
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}
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}
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}
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void mutex_unlock(mutex_t *mutex)
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{
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mutex->state = 0;
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}
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