286 lines
10 KiB
C
286 lines
10 KiB
C
|
/*
|
||
|
|
* FreeRTOS Kernel V10.2.1
|
||
|
|
* Copyright (C) 2019 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.
|
||
|
|
*
|
||
|
|
* http://www.FreeRTOS.org
|
||
|
|
* http://aws.amazon.com/freertos
|
||
|
|
*
|
||
|
|
* 1 tab == 4 spaces!
|
||
|
|
*/
|
||
|
|
|
||
|
|
/**
|
||
|
|
* 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. */
|
||
|
|
portBASE_TYPE 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;
|
||
|
|
}
|
||
|
|
|
||
|
|
|