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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 */
/** */
/** Mutex */
/** */
/**************************************************************************/
/**************************************************************************/
#define TX_SOURCE_CODE
/* Include necessary system files. */
#include "tx_api.h"
#include "tx_thread.h"
#include "tx_mutex.h"
/**************************************************************************/
/* */
/* FUNCTION RELEASE */
/* */
/* _tx_mutex_priority_change PORTABLE C */
/* 6.1.6 */
/* AUTHOR */
/* */
/* William E. Lamie, Microsoft Corporation */
/* */
/* DESCRIPTION */
/* */
/* This function changes the priority of the specified thread for the */
/* priority inheritance option of the mutex service. */
/* */
/* INPUT */
/* */
/* thread_ptr Pointer to thread to suspend */
/* new_priority New thread priority */
/* */
/* OUTPUT */
/* */
/* None */
/* */
/* CALLS */
/* */
/* _tx_thread_system_resume Resume thread */
/* _tx_thread_system_ni_resume Non-interruptable resume thread */
/* _tx_thread_system_suspend Suspend thread */
/* _tx_thread_system_ni_suspend Non-interruptable suspend thread */
/* */
/* CALLED BY */
/* */
/* _tx_mutex_get Inherit priority */
/* _tx_mutex_put Restore previous priority */
/* */
/* RELEASE HISTORY */
/* */
/* DATE NAME DESCRIPTION */
/* */
/* 05-19-2020 William E. Lamie Initial Version 6.0 */
/* 09-30-2020 William E. Lamie Modified comment(s), and */
/* change thread state from */
/* TX_SUSPENDED to */
/* TX_PRIORITY_CHANGE before */
/* calling */
/* _tx_thread_system_suspend, */
/* resulting in version 6.1 */
/* 04-02-2021 Scott Larson Modified comments, fixed */
/* mapping current thread's */
/* priority rather than next, */
/* resulting in version 6.1.6 */
/* */
/**************************************************************************/
VOID _tx_mutex_priority_change(TX_THREAD *thread_ptr, UINT new_priority)
{
#ifndef TX_NOT_INTERRUPTABLE
TX_INTERRUPT_SAVE_AREA
#endif
TX_THREAD *execute_ptr;
TX_THREAD *next_execute_ptr;
UINT original_priority;
#ifndef TX_DISABLE_PREEMPTION_THRESHOLD
ULONG priority_bit;
#if TX_MAX_PRIORITIES > 32
UINT map_index;
#endif
#endif
#ifndef TX_NOT_INTERRUPTABLE
/* Lockout interrupts while the thread is being suspended. */
TX_DISABLE
#endif
/* Determine if this thread is currently ready. */
if (thread_ptr -> tx_thread_state != TX_READY)
{
/* Change thread priority to the new mutex priority-inheritance priority. */
thread_ptr -> tx_thread_priority = new_priority;
/* Determine how to setup the thread's preemption-threshold. */
if (thread_ptr -> tx_thread_user_preempt_threshold < new_priority)
{
/* Change thread preemption-threshold to the user's preemption-threshold. */
thread_ptr -> tx_thread_preempt_threshold = thread_ptr -> tx_thread_user_preempt_threshold;
}
else
{
/* Change the thread preemption-threshold to the new threshold. */
thread_ptr -> tx_thread_preempt_threshold = new_priority;
}
#ifndef TX_NOT_INTERRUPTABLE
/* Restore interrupts. */
TX_RESTORE
#endif
}
else
{
/* Pickup the next thread to execute. */
execute_ptr = _tx_thread_execute_ptr;
/* Save the original priority. */
original_priority = thread_ptr -> tx_thread_priority;
#ifdef TX_NOT_INTERRUPTABLE
/* Increment the preempt disable flag. */
_tx_thread_preempt_disable++;
/* Set the state to priority change. */
thread_ptr -> tx_thread_state = TX_PRIORITY_CHANGE;
/* Call actual non-interruptable thread suspension routine. */
_tx_thread_system_ni_suspend(thread_ptr, ((ULONG) 0));
/* At this point, the preempt disable flag is still set, so we still have
protection against all preemption. */
/* Change thread priority to the new mutex priority-inheritance priority. */
thread_ptr -> tx_thread_priority = new_priority;
/* Determine how to setup the thread's preemption-threshold. */
if (thread_ptr -> tx_thread_user_preempt_threshold < new_priority)
{
/* Change thread preemption-threshold to the user's preemption-threshold. */
thread_ptr -> tx_thread_preempt_threshold = thread_ptr -> tx_thread_user_preempt_threshold;
}
else
{
/* Change the thread preemption-threshold to the new threshold. */
thread_ptr -> tx_thread_preempt_threshold = new_priority;
}
/* Resume the thread with the new priority. */
_tx_thread_system_ni_resume(thread_ptr);
/* Decrement the preempt disable flag. */
_tx_thread_preempt_disable--;
#else
/* Increment the preempt disable flag. */
_tx_thread_preempt_disable = _tx_thread_preempt_disable + ((UINT) 2);
/* Set the state to priority change. */
thread_ptr -> tx_thread_state = TX_PRIORITY_CHANGE;
/* 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 = ((ULONG) 0);
/* Restore interrupts. */
TX_RESTORE
/* The thread is ready and must first be removed from the list. Call the
system suspend function to accomplish this. */
_tx_thread_system_suspend(thread_ptr);
/* Disable interrupts. */
TX_DISABLE
/* At this point, the preempt disable flag is still set, so we still have
protection against all preemption. */
/* Change thread priority to the new mutex priority-inheritance priority. */
thread_ptr -> tx_thread_priority = new_priority;
/* Determine how to setup the thread's preemption-threshold. */
if (thread_ptr -> tx_thread_user_preempt_threshold < new_priority)
{
/* Change thread preemption-threshold to the user's preemption-threshold. */
thread_ptr -> tx_thread_preempt_threshold = thread_ptr -> tx_thread_user_preempt_threshold;
}
else
{
/* Change the thread preemption-threshold to the new threshold. */
thread_ptr -> tx_thread_preempt_threshold = new_priority;
}
/* Restore interrupts. */
TX_RESTORE
/* Resume the thread with the new priority. */
_tx_thread_system_resume(thread_ptr);
#endif
/* Optional processing extension. */
TX_MUTEX_PRIORITY_CHANGE_EXTENSION
#ifndef TX_NOT_INTERRUPTABLE
/* Disable interrupts. */
TX_DISABLE
#endif
/* Pickup the next thread to execute. */
next_execute_ptr = _tx_thread_execute_ptr;
/* Determine if this thread is not the next thread to execute. */
if (thread_ptr != next_execute_ptr)
{
/* Make sure the thread is still ready. */
if (thread_ptr -> tx_thread_state == TX_READY)
{
/* Now check and see if this thread has an equal or higher priority. */
if (thread_ptr -> tx_thread_priority <= next_execute_ptr -> tx_thread_priority)
{
/* Now determine if this thread was the previously executing thread. */
if (thread_ptr == execute_ptr)
{
/* Yes, this thread was previously executing before we temporarily suspended and resumed
it in order to change the priority. A lower or same priority thread cannot be the next thread
to execute in this case since this thread really didn't suspend. Simply reset the execute
pointer to this thread. */
_tx_thread_execute_ptr = thread_ptr;
/* Determine if we moved to a lower priority. If so, move the thread to the front of its priority list. */
if (original_priority < new_priority)
{
/* Ensure that this thread is placed at the front of the priority list. */
_tx_thread_priority_list[thread_ptr -> tx_thread_priority] = thread_ptr;
}
}
}
else
{
/* Now determine if this thread's preemption-threshold needs to be enforced. */
if (thread_ptr -> tx_thread_preempt_threshold < thread_ptr -> tx_thread_priority)
{
/* Yes, preemption-threshold is in force for this thread. */
/* Compare the next thread to execute thread's priority against the thread's preemption-threshold. */
if (thread_ptr -> tx_thread_preempt_threshold <= next_execute_ptr -> tx_thread_priority)
{
/* We must swap execute pointers to enforce the preemption-threshold of a thread coming out of
priority inheritance. */
_tx_thread_execute_ptr = thread_ptr;
/* Determine if we moved to a lower priority. If so, move the thread to the front of its priority list. */
if (original_priority < new_priority)
{
/* Ensure that this thread is placed at the front of the priority list. */
_tx_thread_priority_list[thread_ptr -> tx_thread_priority] = thread_ptr;
}
}
#ifndef TX_DISABLE_PREEMPTION_THRESHOLD
else
{
/* In this case, we need to mark the preempted map to indicate a thread executed above the
preemption-threshold. */
#if TX_MAX_PRIORITIES > 32
/* Calculate the index into the bit map array. */
map_index = (thread_ptr -> tx_thread_priority)/ ((UINT) 32);
/* Set the active bit to remember that the preempt map has something set. */
TX_DIV32_BIT_SET(thread_ptr -> tx_thread_priority, priority_bit)
_tx_thread_preempted_map_active = _tx_thread_preempted_map_active | priority_bit;
#endif
/* Remember that this thread was preempted by a thread above the thread's threshold. */
TX_MOD32_BIT_SET(thread_ptr -> tx_thread_priority, priority_bit)
_tx_thread_preempted_maps[MAP_INDEX] = _tx_thread_preempted_maps[MAP_INDEX] | priority_bit;
}
#endif
}
}
}
}
#ifndef TX_NOT_INTERRUPTABLE
/* Restore interrupts. */
TX_RESTORE
#endif
}
}
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