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/***************************************************************************
* Copyright (c) 2024 Microsoft Corporation
* Copyright (c) 2026-present Eclipse ThreadX contributors
*
* This program and the accompanying materials are made available under the
* terms of the MIT License which is available at
* https://opensource.org/licenses/MIT.
*
* SPDX-License-Identifier: MIT
**************************************************************************/
/**************************************************************************/
/**************************************************************************/
/** */
/** POSIX wrapper for THREADX */
/** */
/** */
/** */
/**************************************************************************/
/**************************************************************************/
/* Include necessary system files. */
#include "tx_api.h" /* Threadx API */
#include "pthread.h" /* Posix API */
#include "px_int.h" /* Posix helper functions */
/**************************************************************************/
/* */
/* FUNCTION RELEASE */
/* */
/* pthread_cond_wait PORTABLE C */
/* 6.1.7 */
/* AUTHOR */
/* */
/* William E. Lamie, Microsoft Corporation */
/* */
/* DESCRIPTION */
/* */
/* This function shall block on a condition variable. They shall be */
/* called with mutex locked by the calling thread or undefined behavior*/
/* results. These functions atomically release the mutex and cause the */
/* calling thread to block on the condition variable cond; atomically */
/* here means atomically with respect to access by another thread to */
/* the mutex and then the request for semaphore. */
/* */
/* Upon successful return, the mutex shall have been locked and shall */
/* be owned by the calling thread. */
/* */
/* When using condition variables there is always a Boolean predicate */
/* involving shared variables associated with each condition wait that */
/* is true if the thread should proceed. Spurious wakeups from the */
/* pthread_cond_timedwait or pthread_cond_wait functions may occur. */
/* Since the return from pthread_cond_timedwait or pthread_cond_wait */
/* does not imply anything about the value of this predicate, the */
/* predicate should be re-evaluated upon such return. The effect of */
/* using more than one mutex for concurrent pthread_cond_timedwait or */
/* pthread_cond_wait operations on the same condition variable is */
/* undefined; that is, a condition variable becomes bound to a unique */
/* mutex when a thread waits on the condition variable, and this */
/* (dynamic) binding shall end when the wait returns. */
/* */
/* INPUT */
/* */
/* cond condition variable */
/* mutex mutex to be associated with condition */
/* variable */
/* */
/* OUTPUT */
/* */
/* OK if succesfull */
/* ERROR in case of any error */
/* */
/* CALLS */
/* */
/* pthread_mutex_unlock unlocks the mutex held by the caller */
/* tx_semaphore_get try to get sempaphore internal to cond */
/* tx_semaphore_prioritize prioritize all suspended pthreads */
/* pthread_mutex_lock lock the mutex */
/* */
/* CALLED BY */
/* */
/* Application Code */
/* */
/**************************************************************************/
INT pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
{
TX_SEMAPHORE *semaphore_ptr;
UINT status;
UINT old_threshold,dummy;
TX_THREAD *thread;
/* Find the current thread. */
thread = tx_thread_identify();
/* Raise its preemption threshold so it does not get descheduled. */
tx_thread_preemption_change(thread,0,&old_threshold);
pthread_mutex_unlock(mutex);
semaphore_ptr = (&( cond->cond_semaphore ));
status = tx_semaphore_get(semaphore_ptr, TX_WAIT_FOREVER);
/* Restore original preemption threshold. */
tx_thread_preemption_change(thread, old_threshold, &dummy);
if ( status != TX_SUCCESS)
{
posix_errno = EINVAL;
posix_set_pthread_errno(EINVAL);
return(EINVAL);
}
status = tx_semaphore_prioritize(semaphore_ptr);
if ( status != TX_SUCCESS)
{
posix_errno = EINVAL;
posix_set_pthread_errno(EINVAL);
return(EINVAL);
}
pthread_mutex_lock(mutex);
return(OK);
}
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