mirror of
https://github.com/azure-rtos/threadx
synced 2025-02-06 08:08:27 +08:00
135 lines
7.1 KiB
C
135 lines
7.1 KiB
C
/***************************************************************************
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* Copyright (c) 2024 Microsoft Corporation
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*
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* This program and the accompanying materials are made available under the
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* terms of the MIT License which is available at
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* https://opensource.org/licenses/MIT.
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*
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* SPDX-License-Identifier: MIT
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**************************************************************************/
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/**************************************************************************/
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/**************************************************************************/
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/** */
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/** POSIX wrapper for THREADX */
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/** */
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/** */
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/** */
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/**************************************************************************/
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/**************************************************************************/
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/* Include necessary system files. */
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#include "tx_api.h" /* Threadx API */
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#include "pthread.h" /* Posix API */
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#include "px_int.h" /* Posix helper functions */
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/**************************************************************************/
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/* */
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/* FUNCTION RELEASE */
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/* */
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/* pthread_cond_wait PORTABLE C */
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/* 6.1.7 */
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/* AUTHOR */
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/* */
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/* William E. Lamie, Microsoft Corporation */
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/* */
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/* DESCRIPTION */
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/* */
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/* This function shall block on a condition variable. They shall be */
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/* called with mutex locked by the calling thread or undefined behavior*/
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/* results. These functions atomically release the mutex and cause the */
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/* calling thread to block on the condition variable cond; atomically */
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/* here means atomically with respect to access by another thread to */
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/* the mutex and then the request for semaphore. */
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/* */
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/* Upon successful return, the mutex shall have been locked and shall */
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/* be owned by the calling thread. */
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/* */
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/* When using condition variables there is always a Boolean predicate */
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/* involving shared variables associated with each condition wait that */
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/* is true if the thread should proceed. Spurious wakeups from the */
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/* pthread_cond_timedwait or pthread_cond_wait functions may occur. */
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/* Since the return from pthread_cond_timedwait or pthread_cond_wait */
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/* does not imply anything about the value of this predicate, the */
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/* predicate should be re-evaluated upon such return. The effect of */
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/* using more than one mutex for concurrent pthread_cond_timedwait or */
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/* pthread_cond_wait operations on the same condition variable is */
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/* undefined; that is, a condition variable becomes bound to a unique */
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/* mutex when a thread waits on the condition variable, and this */
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/* (dynamic) binding shall end when the wait returns. */
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/* */
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/* INPUT */
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/* */
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/* cond condition variable */
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/* mutex mutex to be associated with condition */
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/* variable */
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/* */
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/* OUTPUT */
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/* */
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/* OK if succesfull */
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/* ERROR in case of any error */
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/* */
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/* CALLS */
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/* */
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/* pthread_mutex_unlock unlocks the mutex held by the caller */
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/* tx_semaphore_get try to get sempaphore internal to cond */
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/* tx_semaphore_prioritize prioritize all suspended pthreads */
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/* pthread_mutex_lock lock the mutex */
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/* */
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/* CALLED BY */
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/* */
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/* Application Code */
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/* */
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/* RELEASE HISTORY */
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/* */
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/* DATE NAME DESCRIPTION */
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/* */
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/* 06-02-2021 William E. Lamie Initial Version 6.1.7 */
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/* */
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/**************************************************************************/
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INT pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
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{
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TX_SEMAPHORE *semaphore_ptr;
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UINT status;
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UINT old_threshold,dummy;
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TX_THREAD *thread;
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/* Find the current thread. */
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thread = tx_thread_identify();
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/* Raise its preemption threshold so it does not get descheduled. */
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tx_thread_preemption_change(thread,0,&old_threshold);
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pthread_mutex_unlock(mutex);
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semaphore_ptr = (&( cond->cond_semaphore ));
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status = tx_semaphore_get(semaphore_ptr, TX_WAIT_FOREVER);
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/* Restore original preemption threshold. */
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tx_thread_preemption_change(thread, old_threshold, &dummy);
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if ( status != TX_SUCCESS)
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{
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posix_errno = EINVAL;
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posix_set_pthread_errno(EINVAL);
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return(EINVAL);
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}
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status = tx_semaphore_prioritize(semaphore_ptr);
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if ( status != TX_SUCCESS)
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{
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posix_errno = EINVAL;
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posix_set_pthread_errno(EINVAL);
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return(EINVAL);
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}
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pthread_mutex_lock(mutex);
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return(OK);
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}
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