/* | |
* FreeRTOS Kernel V10.1.0 | |
* Copyright (C) 2017 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 | |
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* 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. | |
* | |
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* | |
* http://www.FreeRTOS.org | |
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* 1 tab == 4 spaces! | |
*/ | |
/* | |
* Simple demonstration of the usage of counting semaphore. | |
*/ | |
/* Scheduler include files. */ | |
#include "FreeRTOS.h" | |
#include "task.h" | |
#include "semphr.h" | |
/* Demo program include files. */ | |
#include "countsem.h" | |
/* The maximum count value that the semaphore used for the demo can hold. */ | |
#define countMAX_COUNT_VALUE ( 200 ) | |
/* Constants used to indicate whether or not the semaphore should have been | |
created with its maximum count value, or its minimum count value. These | |
numbers are used to ensure that the pointers passed in as the task parameters | |
are valid. */ | |
#define countSTART_AT_MAX_COUNT ( 0xaa ) | |
#define countSTART_AT_ZERO ( 0x55 ) | |
/* Two tasks are created for the test. One uses a semaphore created with its | |
count value set to the maximum, and one with the count value set to zero. */ | |
#define countNUM_TEST_TASKS ( 2 ) | |
#define countDONT_BLOCK ( 0 ) | |
/*-----------------------------------------------------------*/ | |
/* Flag that will be latched to pdTRUE should any unexpected behaviour be | |
detected in any of the tasks. */ | |
static volatile BaseType_t xErrorDetected = pdFALSE; | |
/*-----------------------------------------------------------*/ | |
/* | |
* The demo task. This simply counts the semaphore up to its maximum value, | |
* the counts it back down again. The result of each semaphore 'give' and | |
* 'take' is inspected, with an error being flagged if it is found not to be | |
* the expected result. | |
*/ | |
static void prvCountingSemaphoreTask( void *pvParameters ); | |
/* | |
* Utility function to increment the semaphore count value up from zero to | |
* countMAX_COUNT_VALUE. | |
*/ | |
static void prvIncrementSemaphoreCount( SemaphoreHandle_t xSemaphore, volatile UBaseType_t *puxLoopCounter ); | |
/* | |
* Utility function to decrement the semaphore count value up from | |
* countMAX_COUNT_VALUE to zero. | |
*/ | |
static void prvDecrementSemaphoreCount( SemaphoreHandle_t xSemaphore, volatile UBaseType_t *puxLoopCounter ); | |
/*-----------------------------------------------------------*/ | |
/* The structure that is passed into the task as the task parameter. */ | |
typedef struct COUNT_SEM_STRUCT | |
{ | |
/* The semaphore to be used for the demo. */ | |
SemaphoreHandle_t xSemaphore; | |
/* Set to countSTART_AT_MAX_COUNT if the semaphore should be created with | |
its count value set to its max count value, or countSTART_AT_ZERO if it | |
should have been created with its count value set to 0. */ | |
UBaseType_t uxExpectedStartCount; | |
/* Incremented on each cycle of the demo task. Used to detect a stalled | |
task. */ | |
volatile UBaseType_t uxLoopCounter; | |
} xCountSemStruct; | |
/* Two structures are defined, one is passed to each test task. */ | |
static xCountSemStruct xParameters[ countNUM_TEST_TASKS ]; | |
/*-----------------------------------------------------------*/ | |
void vStartCountingSemaphoreTasks( void ) | |
{ | |
/* Create the semaphores that we are going to use for the test/demo. The | |
first should be created such that it starts at its maximum count value, | |
the second should be created such that it starts with a count value of zero. */ | |
xParameters[ 0 ].xSemaphore = xSemaphoreCreateCounting( countMAX_COUNT_VALUE, countMAX_COUNT_VALUE ); | |
xParameters[ 0 ].uxExpectedStartCount = countSTART_AT_MAX_COUNT; | |
xParameters[ 0 ].uxLoopCounter = 0; | |
xParameters[ 1 ].xSemaphore = xSemaphoreCreateCounting( countMAX_COUNT_VALUE, 0 ); | |
xParameters[ 1 ].uxExpectedStartCount = 0; | |
xParameters[ 1 ].uxLoopCounter = 0; | |
/* Were the semaphores created? */ | |
if( ( xParameters[ 0 ].xSemaphore != NULL ) || ( xParameters[ 1 ].xSemaphore != NULL ) ) | |
{ | |
/* vQueueAddToRegistry() adds the semaphore to the registry, if one is | |
in use. The registry is provided as a means for kernel aware | |
debuggers to locate semaphores and has no purpose if a kernel aware | |
debugger is not being used. The call to vQueueAddToRegistry() will be | |
removed by the pre-processor if configQUEUE_REGISTRY_SIZE is not | |
defined or is defined to be less than 1. */ | |
vQueueAddToRegistry( ( QueueHandle_t ) xParameters[ 0 ].xSemaphore, "Counting_Sem_1" ); | |
vQueueAddToRegistry( ( QueueHandle_t ) xParameters[ 1 ].xSemaphore, "Counting_Sem_2" ); | |
/* Create the demo tasks, passing in the semaphore to use as the parameter. */ | |
xTaskCreate( prvCountingSemaphoreTask, "CNT1", configMINIMAL_STACK_SIZE, ( void * ) &( xParameters[ 0 ] ), tskIDLE_PRIORITY, NULL ); | |
xTaskCreate( prvCountingSemaphoreTask, "CNT2", configMINIMAL_STACK_SIZE, ( void * ) &( xParameters[ 1 ] ), tskIDLE_PRIORITY, NULL ); | |
} | |
} | |
/*-----------------------------------------------------------*/ | |
static void prvDecrementSemaphoreCount( SemaphoreHandle_t xSemaphore, volatile UBaseType_t *puxLoopCounter ) | |
{ | |
UBaseType_t ux; | |
/* If the semaphore count is at its maximum then we should not be able to | |
'give' the semaphore. */ | |
if( xSemaphoreGive( xSemaphore ) == pdPASS ) | |
{ | |
xErrorDetected = pdTRUE; | |
} | |
/* We should be able to 'take' the semaphore countMAX_COUNT_VALUE times. */ | |
for( ux = 0; ux < countMAX_COUNT_VALUE; ux++ ) | |
{ | |
configASSERT( uxSemaphoreGetCount( xSemaphore ) == ( countMAX_COUNT_VALUE - ux ) ); | |
if( xSemaphoreTake( xSemaphore, countDONT_BLOCK ) != pdPASS ) | |
{ | |
/* We expected to be able to take the semaphore. */ | |
xErrorDetected = pdTRUE; | |
} | |
( *puxLoopCounter )++; | |
} | |
#if configUSE_PREEMPTION == 0 | |
taskYIELD(); | |
#endif | |
/* If the semaphore count is zero then we should not be able to 'take' | |
the semaphore. */ | |
configASSERT( uxSemaphoreGetCount( xSemaphore ) == 0 ); | |
if( xSemaphoreTake( xSemaphore, countDONT_BLOCK ) == pdPASS ) | |
{ | |
xErrorDetected = pdTRUE; | |
} | |
} | |
/*-----------------------------------------------------------*/ | |
static void prvIncrementSemaphoreCount( SemaphoreHandle_t xSemaphore, volatile UBaseType_t *puxLoopCounter ) | |
{ | |
UBaseType_t ux; | |
/* If the semaphore count is zero then we should not be able to 'take' | |
the semaphore. */ | |
if( xSemaphoreTake( xSemaphore, countDONT_BLOCK ) == pdPASS ) | |
{ | |
xErrorDetected = pdTRUE; | |
} | |
/* We should be able to 'give' the semaphore countMAX_COUNT_VALUE times. */ | |
for( ux = 0; ux < countMAX_COUNT_VALUE; ux++ ) | |
{ | |
configASSERT( uxSemaphoreGetCount( xSemaphore ) == ux ); | |
if( xSemaphoreGive( xSemaphore ) != pdPASS ) | |
{ | |
/* We expected to be able to take the semaphore. */ | |
xErrorDetected = pdTRUE; | |
} | |
( *puxLoopCounter )++; | |
} | |
#if configUSE_PREEMPTION == 0 | |
taskYIELD(); | |
#endif | |
/* If the semaphore count is at its maximum then we should not be able to | |
'give' the semaphore. */ | |
if( xSemaphoreGive( xSemaphore ) == pdPASS ) | |
{ | |
xErrorDetected = pdTRUE; | |
} | |
} | |
/*-----------------------------------------------------------*/ | |
static void prvCountingSemaphoreTask( void *pvParameters ) | |
{ | |
xCountSemStruct *pxParameter; | |
#ifdef USE_STDIO | |
void vPrintDisplayMessage( const char * const * ppcMessageToSend ); | |
const char * const pcTaskStartMsg = "Counting semaphore demo started.\r\n"; | |
/* Queue a message for printing to say the task has started. */ | |
vPrintDisplayMessage( &pcTaskStartMsg ); | |
#endif | |
/* The semaphore to be used was passed as the parameter. */ | |
pxParameter = ( xCountSemStruct * ) pvParameters; | |
/* Did we expect to find the semaphore already at its max count value, or | |
at zero? */ | |
if( pxParameter->uxExpectedStartCount == countSTART_AT_MAX_COUNT ) | |
{ | |
prvDecrementSemaphoreCount( pxParameter->xSemaphore, &( pxParameter->uxLoopCounter ) ); | |
} | |
/* Now we expect the semaphore count to be 0, so this time there is an | |
error if we can take the semaphore. */ | |
if( xSemaphoreTake( pxParameter->xSemaphore, 0 ) == pdPASS ) | |
{ | |
xErrorDetected = pdTRUE; | |
} | |
for( ;; ) | |
{ | |
prvIncrementSemaphoreCount( pxParameter->xSemaphore, &( pxParameter->uxLoopCounter ) ); | |
prvDecrementSemaphoreCount( pxParameter->xSemaphore, &( pxParameter->uxLoopCounter ) ); | |
} | |
} | |
/*-----------------------------------------------------------*/ | |
BaseType_t xAreCountingSemaphoreTasksStillRunning( void ) | |
{ | |
static UBaseType_t uxLastCount0 = 0, uxLastCount1 = 0; | |
BaseType_t xReturn = pdPASS; | |
/* Return fail if any 'give' or 'take' did not result in the expected | |
behaviour. */ | |
if( xErrorDetected != pdFALSE ) | |
{ | |
xReturn = pdFAIL; | |
} | |
/* Return fail if either task is not still incrementing its loop counter. */ | |
if( uxLastCount0 == xParameters[ 0 ].uxLoopCounter ) | |
{ | |
xReturn = pdFAIL; | |
} | |
else | |
{ | |
uxLastCount0 = xParameters[ 0 ].uxLoopCounter; | |
} | |
if( uxLastCount1 == xParameters[ 1 ].uxLoopCounter ) | |
{ | |
xReturn = pdFAIL; | |
} | |
else | |
{ | |
uxLastCount1 = xParameters[ 1 ].uxLoopCounter; | |
} | |
return xReturn; | |
} | |