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/**************************************************************************/
/* */
/* Copyright (c) Microsoft Corporation. All rights reserved. */
/* */
/* This software is licensed under the Microsoft Software License */
/* Terms for Microsoft Azure RTOS. Full text of the license can be */
/* found in the LICENSE file at https://aka.ms/AzureRTOS_EULA */
/* and in the root directory of this software. */
/* */
/**************************************************************************/
/**************************************************************************/
/**************************************************************************/
/** */
/** ThreadX Component */
/** */
/** Semaphore */
/** */
/**************************************************************************/
/**************************************************************************/
#define TX_SOURCE_CODE
/* Include necessary system files. */
#include "tx_api.h"
#include "tx_trace.h"
#include "tx_thread.h"
#include "tx_semaphore.h"
/**************************************************************************/
/* */
/* FUNCTION RELEASE */
/* */
/* _tx_semaphore_get PORTABLE C */
/* 6.1 */
/* AUTHOR */
/* */
/* William E. Lamie, Microsoft Corporation */
/* */
/* DESCRIPTION */
/* */
/* This function gets an instance from the specified counting */
/* semaphore. */
/* */
/* INPUT */
/* */
/* semaphore_ptr Pointer to semaphore control block*/
/* wait_option Suspension option */
/* */
/* OUTPUT */
/* */
/* status Completion status */
/* */
/* CALLS */
/* */
/* _tx_thread_system_suspend Suspend thread service */
/* _tx_thread_system_ni_suspend Non-interruptable suspend thread */
/* */
/* CALLED BY */
/* */
/* Application Code */
/* */
/* RELEASE HISTORY */
/* */
/* DATE NAME DESCRIPTION */
/* */
/* 05-19-2020 William E. Lamie Initial Version 6.0 */
/* 09-30-2020 Yuxin Zhou Modified comment(s), */
/* resulting in version 6.1 */
/* */
/**************************************************************************/
UINT _tx_semaphore_get(TX_SEMAPHORE *semaphore_ptr, ULONG wait_option)
{
TX_INTERRUPT_SAVE_AREA
TX_THREAD *thread_ptr;
TX_THREAD *next_thread;
TX_THREAD *previous_thread;
UINT status;
/* Default the status to TX_SUCCESS. */
status = TX_SUCCESS;
/* Disable interrupts to get an instance from the semaphore. */
TX_DISABLE
#ifdef TX_SEMAPHORE_ENABLE_PERFORMANCE_INFO
/* Increment the total semaphore get counter. */
_tx_semaphore_performance_get_count++;
/* Increment the number of attempts to get this semaphore. */
semaphore_ptr -> tx_semaphore_performance_get_count++;
#endif
/* If trace is enabled, insert this event into the trace buffer. */
TX_TRACE_IN_LINE_INSERT(TX_TRACE_SEMAPHORE_GET, semaphore_ptr, wait_option, semaphore_ptr -> tx_semaphore_count, TX_POINTER_TO_ULONG_CONVERT(&thread_ptr), TX_TRACE_SEMAPHORE_EVENTS)
/* Log this kernel call. */
TX_EL_SEMAPHORE_GET_INSERT
/* Determine if there is an instance of the semaphore. */
if (semaphore_ptr -> tx_semaphore_count != ((ULONG) 0))
{
/* Decrement the semaphore count. */
semaphore_ptr -> tx_semaphore_count--;
/* Restore interrupts. */
TX_RESTORE
}
/* Determine if the request specifies suspension. */
else if (wait_option != TX_NO_WAIT)
{
/* Determine if the preempt disable flag is non-zero. */
if (_tx_thread_preempt_disable != ((UINT) 0))
{
/* Restore interrupts. */
TX_RESTORE
/* Suspension is not allowed if the preempt disable flag is non-zero at this point - return error completion. */
status = TX_NO_INSTANCE;
}
else
{
/* Prepare for suspension of this thread. */
#ifdef TX_SEMAPHORE_ENABLE_PERFORMANCE_INFO
/* Increment the total semaphore suspensions counter. */
_tx_semaphore_performance_suspension_count++;
/* Increment the number of suspensions on this semaphore. */
semaphore_ptr -> tx_semaphore_performance_suspension_count++;
#endif
/* Pickup thread pointer. */
TX_THREAD_GET_CURRENT(thread_ptr)
/* Setup cleanup routine pointer. */
thread_ptr -> tx_thread_suspend_cleanup = &(_tx_semaphore_cleanup);
/* Setup cleanup information, i.e. this semaphore control
block. */
thread_ptr -> tx_thread_suspend_control_block = (VOID *) semaphore_ptr;
#ifndef TX_NOT_INTERRUPTABLE
/* Increment the suspension sequence number, which is used to identify
this suspension event. */
thread_ptr -> tx_thread_suspension_sequence++;
#endif
/* Setup suspension list. */
if (semaphore_ptr -> tx_semaphore_suspended_count == TX_NO_SUSPENSIONS)
{
/* No other threads are suspended. Setup the head pointer and
just setup this threads pointers to itself. */
semaphore_ptr -> tx_semaphore_suspension_list = thread_ptr;
thread_ptr -> tx_thread_suspended_next = thread_ptr;
thread_ptr -> tx_thread_suspended_previous = thread_ptr;
}
else
{
/* This list is not NULL, add current thread to the end. */
next_thread = semaphore_ptr -> tx_semaphore_suspension_list;
thread_ptr -> tx_thread_suspended_next = next_thread;
previous_thread = next_thread -> tx_thread_suspended_previous;
thread_ptr -> tx_thread_suspended_previous = previous_thread;
previous_thread -> tx_thread_suspended_next = thread_ptr;
next_thread -> tx_thread_suspended_previous = thread_ptr;
}
/* Increment the number of suspensions. */
semaphore_ptr -> tx_semaphore_suspended_count++;
/* Set the state to suspended. */
thread_ptr -> tx_thread_state = TX_SEMAPHORE_SUSP;
#ifdef TX_NOT_INTERRUPTABLE
/* Call actual non-interruptable thread suspension routine. */
_tx_thread_system_ni_suspend(thread_ptr, wait_option);
/* Restore interrupts. */
TX_RESTORE
#else
/* Set the suspending flag. */
thread_ptr -> tx_thread_suspending = TX_TRUE;
/* Setup the timeout period. */
thread_ptr -> tx_thread_timer.tx_timer_internal_remaining_ticks = wait_option;
/* Temporarily disable preemption. */
_tx_thread_preempt_disable++;
/* Restore interrupts. */
TX_RESTORE
/* Call actual thread suspension routine. */
_tx_thread_system_suspend(thread_ptr);
#endif
/* Return the completion status. */
status = thread_ptr -> tx_thread_suspend_status;
}
}
else
{
/* Restore interrupts. */
TX_RESTORE
/* Immediate return, return error completion. */
status = TX_NO_INSTANCE;
}
/* Return completion status. */
return(status);
}