EBIKE-FreeRTOS/Common/Full/semtest.c
2024-04-14 18:38:39 +08:00

286 lines
11 KiB
C

/*
* FreeRTOS V202212.00
* Copyright (C) 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy of
* this software and associated documentation files (the "Software"), to deal in
* the Software without restriction, including without limitation the rights to
* use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
* the Software, and to permit persons to whom the Software is furnished to do so,
* subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
* FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
* COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
* IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*
* https://www.FreeRTOS.org
* https://github.com/FreeRTOS
*
*/
/**
* Creates two sets of two tasks. The tasks within a set share a variable, access
* to which is guarded by a semaphore.
*
* Each task starts by attempting to obtain the semaphore. On obtaining a
* semaphore a task checks to ensure that the guarded variable has an expected
* value. It then clears the variable to zero before counting it back up to the
* expected value in increments of 1. After each increment the variable is checked
* to ensure it contains the value to which it was just set. When the starting
* value is again reached the task releases the semaphore giving the other task in
* the set a chance to do exactly the same thing. The starting value is high
* enough to ensure that a tick is likely to occur during the incrementing loop.
*
* An error is flagged if at any time during the process a shared variable is
* found to have a value other than that expected. Such an occurrence would
* suggest an error in the mutual exclusion mechanism by which access to the
* variable is restricted.
*
* The first set of two tasks poll their semaphore. The second set use blocking
* calls.
*
* \page SemTestC semtest.c
* \ingroup DemoFiles
* <HR>
*/
/*
* Changes from V1.2.0:
*
+ The tasks that operate at the idle priority now use a lower expected
+ count than those running at a higher priority. This prevents the low
+ priority tasks from signaling an error because they have not been
+ scheduled enough time for each of them to count the shared variable to
+ the high value.
+
+ Changes from V2.0.0
+
+ Delay periods are now specified using variables and constants of
+ TickType_t rather than unsigned long.
+
+ Changes from V2.1.1
+
+ The stack size now uses configMINIMAL_STACK_SIZE.
+ String constants made file scope to decrease stack depth on 8051 port.
*/
#include <stdlib.h>
/* Scheduler include files. */
#include "FreeRTOS.h"
#include "task.h"
#include "semphr.h"
/* Demo app include files. */
#include "semtest.h"
#include "print.h"
/* The value to which the shared variables are counted. */
#define semtstBLOCKING_EXPECTED_VALUE ( ( unsigned long ) 0xfff )
#define semtstNON_BLOCKING_EXPECTED_VALUE ( ( unsigned long ) 0xff )
#define semtstSTACK_SIZE configMINIMAL_STACK_SIZE
#define semtstNUM_TASKS ( 4 )
#define semtstDELAY_FACTOR ( ( TickType_t ) 10 )
/* The task function as described at the top of the file. */
static void prvSemaphoreTest( void * pvParameters );
/* Structure used to pass parameters to each task. */
typedef struct SEMAPHORE_PARAMETERS
{
SemaphoreHandle_t xSemaphore;
volatile unsigned long * pulSharedVariable;
TickType_t xBlockTime;
} xSemaphoreParameters;
/* Variables used to check that all the tasks are still running without errors. */
static volatile short sCheckVariables[ semtstNUM_TASKS ] = { 0 };
static volatile short sNextCheckVariable = 0;
/* Strings to print if USE_STDIO is defined. */
const char * const pcPollingSemaphoreTaskError = "Guarded shared variable in unexpected state.\r\n";
const char * const pcSemaphoreTaskStart = "Guarded shared variable task started.\r\n";
/*-----------------------------------------------------------*/
void vStartSemaphoreTasks( unsigned portBASE_TYPE uxPriority )
{
xSemaphoreParameters * pxFirstSemaphoreParameters, * pxSecondSemaphoreParameters;
const TickType_t xBlockTime = ( TickType_t ) 100;
/* Create the structure used to pass parameters to the first two tasks. */
pxFirstSemaphoreParameters = ( xSemaphoreParameters * ) pvPortMalloc( sizeof( xSemaphoreParameters ) );
if( pxFirstSemaphoreParameters != NULL )
{
/* Create the semaphore used by the first two tasks. */
vSemaphoreCreateBinary( pxFirstSemaphoreParameters->xSemaphore );
if( pxFirstSemaphoreParameters->xSemaphore != NULL )
{
/* Create the variable which is to be shared by the first two tasks. */
pxFirstSemaphoreParameters->pulSharedVariable = ( unsigned long * ) pvPortMalloc( sizeof( unsigned long ) );
/* Initialise the share variable to the value the tasks expect. */
*( pxFirstSemaphoreParameters->pulSharedVariable ) = semtstNON_BLOCKING_EXPECTED_VALUE;
/* The first two tasks do not block on semaphore calls. */
pxFirstSemaphoreParameters->xBlockTime = ( TickType_t ) 0;
/* Spawn the first two tasks. As they poll they operate at the idle priority. */
xTaskCreate( prvSemaphoreTest, "PolSEM1", semtstSTACK_SIZE, ( void * ) pxFirstSemaphoreParameters, tskIDLE_PRIORITY, ( TaskHandle_t * ) NULL );
xTaskCreate( prvSemaphoreTest, "PolSEM2", semtstSTACK_SIZE, ( void * ) pxFirstSemaphoreParameters, tskIDLE_PRIORITY, ( TaskHandle_t * ) NULL );
}
}
/* Do exactly the same to create the second set of tasks, only this time
* provide a block time for the semaphore calls. */
pxSecondSemaphoreParameters = ( xSemaphoreParameters * ) pvPortMalloc( sizeof( xSemaphoreParameters ) );
if( pxSecondSemaphoreParameters != NULL )
{
vSemaphoreCreateBinary( pxSecondSemaphoreParameters->xSemaphore );
if( pxSecondSemaphoreParameters->xSemaphore != NULL )
{
pxSecondSemaphoreParameters->pulSharedVariable = ( unsigned long * ) pvPortMalloc( sizeof( unsigned long ) );
*( pxSecondSemaphoreParameters->pulSharedVariable ) = semtstBLOCKING_EXPECTED_VALUE;
pxSecondSemaphoreParameters->xBlockTime = xBlockTime / portTICK_PERIOD_MS;
xTaskCreate( prvSemaphoreTest, "BlkSEM1", semtstSTACK_SIZE, ( void * ) pxSecondSemaphoreParameters, uxPriority, ( TaskHandle_t * ) NULL );
xTaskCreate( prvSemaphoreTest, "BlkSEM2", semtstSTACK_SIZE, ( void * ) pxSecondSemaphoreParameters, uxPriority, ( TaskHandle_t * ) NULL );
}
}
}
/*-----------------------------------------------------------*/
static void prvSemaphoreTest( void * pvParameters )
{
xSemaphoreParameters * pxParameters;
volatile unsigned long * pulSharedVariable, ulExpectedValue;
unsigned long ulCounter;
short sError = pdFALSE, sCheckVariableToUse;
/* See which check variable to use. sNextCheckVariable is not semaphore
* protected! */
portENTER_CRITICAL();
sCheckVariableToUse = sNextCheckVariable;
sNextCheckVariable++;
portEXIT_CRITICAL();
/* Queue a message for printing to say the task has started. */
vPrintDisplayMessage( &pcSemaphoreTaskStart );
/* A structure is passed in as the parameter. This contains the shared
* variable being guarded. */
pxParameters = ( xSemaphoreParameters * ) pvParameters;
pulSharedVariable = pxParameters->pulSharedVariable;
/* If we are blocking we use a much higher count to ensure loads of context
* switches occur during the count. */
if( pxParameters->xBlockTime > ( TickType_t ) 0 )
{
ulExpectedValue = semtstBLOCKING_EXPECTED_VALUE;
}
else
{
ulExpectedValue = semtstNON_BLOCKING_EXPECTED_VALUE;
}
for( ; ; )
{
/* Try to obtain the semaphore. */
if( xSemaphoreTake( pxParameters->xSemaphore, pxParameters->xBlockTime ) == pdPASS )
{
/* We have the semaphore and so expect any other tasks using the
* shared variable to have left it in the state we expect to find
* it. */
if( *pulSharedVariable != ulExpectedValue )
{
vPrintDisplayMessage( &pcPollingSemaphoreTaskError );
sError = pdTRUE;
}
/* Clear the variable, then count it back up to the expected value
* before releasing the semaphore. Would expect a context switch or
* two during this time. */
for( ulCounter = ( unsigned long ) 0; ulCounter <= ulExpectedValue; ulCounter++ )
{
*pulSharedVariable = ulCounter;
if( *pulSharedVariable != ulCounter )
{
if( sError == pdFALSE )
{
vPrintDisplayMessage( &pcPollingSemaphoreTaskError );
}
sError = pdTRUE;
}
}
/* Release the semaphore, and if no errors have occurred increment the check
* variable. */
if( xSemaphoreGive( pxParameters->xSemaphore ) == pdFALSE )
{
vPrintDisplayMessage( &pcPollingSemaphoreTaskError );
sError = pdTRUE;
}
if( sError == pdFALSE )
{
if( sCheckVariableToUse < semtstNUM_TASKS )
{
( sCheckVariables[ sCheckVariableToUse ] )++;
}
}
/* If we have a block time then we are running at a priority higher
* than the idle priority. This task takes a long time to complete
* a cycle (deliberately so to test the guarding) so will be starving
* out lower priority tasks. Block for some time to allow give lower
* priority tasks some processor time. */
vTaskDelay( pxParameters->xBlockTime * semtstDELAY_FACTOR );
}
else
{
if( pxParameters->xBlockTime == ( TickType_t ) 0 )
{
/* We have not got the semaphore yet, so no point using the
* processor. We are not blocking when attempting to obtain the
* semaphore. */
taskYIELD();
}
}
}
}
/*-----------------------------------------------------------*/
/* This is called to check that all the created tasks are still running. */
BaseType_t xAreSemaphoreTasksStillRunning( void )
{
static short sLastCheckVariables[ semtstNUM_TASKS ] = { 0 };
portBASE_TYPE xTask, xReturn = pdTRUE;
for( xTask = 0; xTask < semtstNUM_TASKS; xTask++ )
{
if( sLastCheckVariables[ xTask ] == sCheckVariables[ xTask ] )
{
xReturn = pdFALSE;
}
sLastCheckVariables[ xTask ] = sCheckVariables[ xTask ];
}
return xReturn;
}