351 lines
13 KiB
C
351 lines
13 KiB
C
/*
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* FreeRTOS V202212.00
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* Copyright (C) 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved.
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy of
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* this software and associated documentation files (the "Software"), to deal in
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* the Software without restriction, including without limitation the rights to
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* use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
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* the Software, and to permit persons to whom the Software is furnished to do so,
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* subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in all
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* copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
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* FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
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* COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
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* IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*
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* https://www.FreeRTOS.org
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* https://github.com/FreeRTOS
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*
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*/
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/**
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* Creates two tasks that operate on an interrupt driven serial port. A loopback
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* connector should be used so that everything that is transmitted is also received.
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* The serial port does not use any flow control. On a standard 9way 'D' connector
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* pins two and three should be connected together.
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*
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* The first task repeatedly sends a string to a queue, character at a time. The
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* serial port interrupt will empty the queue and transmit the characters. The
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* task blocks for a pseudo random period before resending the string.
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*
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* The second task blocks on a queue waiting for a character to be received.
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* Characters received by the serial port interrupt routine are posted onto the
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* queue - unblocking the task making it ready to execute. If this is then the
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* highest priority task ready to run it will run immediately - with a context
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* switch occurring at the end of the interrupt service routine. The task
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* receiving characters is spawned with a higher priority than the task
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* transmitting the characters.
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*
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* With the loop back connector in place, one task will transmit a string and the
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* other will immediately receive it. The receiving task knows the string it
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* expects to receive so can detect an error.
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*
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* This also creates a third task. This is used to test semaphore usage from an
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* ISR and does nothing interesting.
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*
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* \page ComTestC comtest.c
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* \ingroup DemoFiles
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* <HR>
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*/
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/*
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* Changes from V1.00:
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*
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+ The priority of the Rx task has been lowered. Received characters are
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+ now processed (read from the queue) at the idle priority, allowing low
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+ priority tasks to run evenly at times of a high communications overhead.
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+
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+ Changes from V1.01:
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+
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+ The Tx task now waits a pseudo random time between transmissions.
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+ Previously a fixed period was used but this was not such a good test as
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+ interrupts fired at regular intervals.
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+
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+ Changes From V1.2.0:
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+
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+ Use vSerialPutString() instead of single character puts.
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+ Only stop the check variable incrementing after two consecutive errors.
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+
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+ Changed from V1.2.5
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+
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+ Made the Rx task 2 priorities higher than the Tx task. Previously it was
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+ only 1. This is done to tie in better with the other demo application
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+ tasks.
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+
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+ Changes from V2.0.0
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+
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+ Delay periods are now specified using variables and constants of
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+ TickType_t rather than unsigned long.
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+ Slight modification to task priorities.
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+
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*/
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/* Scheduler include files. */
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#include <stdlib.h>
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#include <string.h>
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#include "FreeRTOS.h"
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#include "task.h"
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/* Demo program include files. */
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#include "serial.h"
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#include "comtest.h"
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#include "print.h"
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/* The Tx task will transmit the sequence of characters at a pseudo random
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* interval. This is the maximum and minimum block time between sends. */
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#define comTX_MAX_BLOCK_TIME ( ( TickType_t ) 0x15e )
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#define comTX_MIN_BLOCK_TIME ( ( TickType_t ) 0xc8 )
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#define comMAX_CONSECUTIVE_ERRORS ( 2 )
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#define comSTACK_SIZE ( ( unsigned short ) 256 )
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#define comRX_RELATIVE_PRIORITY ( 1 )
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/* Handle to the com port used by both tasks. */
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static xComPortHandle xPort;
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/* The transmit function as described at the top of the file. */
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static void vComTxTask( void * pvParameters );
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/* The receive function as described at the top of the file. */
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static void vComRxTask( void * pvParameters );
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/* The semaphore test function as described at the top of the file. */
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static void vSemTestTask( void * pvParameters );
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/* The string that is repeatedly transmitted. */
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const char * const pcMessageToExchange = "Send this message over and over again to check communications interrupts. "
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"0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ\r\n";
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/* Variables that are incremented on each cycle of each task. These are used to
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* check that both tasks are still executing. */
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volatile short sTxCount = 0, sRxCount = 0, sSemCount = 0;
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/* The handle to the semaphore test task. */
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static TaskHandle_t xSemTestTaskHandle = NULL;
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/*-----------------------------------------------------------*/
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void vStartComTestTasks( unsigned portBASE_TYPE uxPriority,
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eCOMPort ePort,
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eBaud eBaudRate )
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{
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const unsigned portBASE_TYPE uxBufferLength = 255;
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/* Initialise the com port then spawn both tasks. */
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xPort = xSerialPortInit( ePort, eBaudRate, serNO_PARITY, serBITS_8, serSTOP_1, uxBufferLength );
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xTaskCreate( vComTxTask, "COMTx", comSTACK_SIZE, NULL, uxPriority, NULL );
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xTaskCreate( vComRxTask, "COMRx", comSTACK_SIZE, NULL, uxPriority + comRX_RELATIVE_PRIORITY, NULL );
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xTaskCreate( vSemTestTask, "ISRSem", comSTACK_SIZE, NULL, tskIDLE_PRIORITY, &xSemTestTaskHandle );
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}
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/*-----------------------------------------------------------*/
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static void vComTxTask( void * pvParameters )
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{
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const char * const pcTaskStartMsg = "COM Tx task started.\r\n";
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TickType_t xTimeToWait;
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/* Stop warnings. */
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( void ) pvParameters;
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/* Queue a message for printing to say the task has started. */
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vPrintDisplayMessage( &pcTaskStartMsg );
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for( ; ; )
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{
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/* Send the string to the serial port. */
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vSerialPutString( xPort, pcMessageToExchange, strlen( pcMessageToExchange ) );
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/* We have posted all the characters in the string - increment the variable
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* used to check that this task is still running, then wait before re-sending
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* the string. */
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sTxCount++;
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xTimeToWait = xTaskGetTickCount();
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/* Make sure we don't wait too long... */
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xTimeToWait %= comTX_MAX_BLOCK_TIME;
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/* ...but we do want to wait. */
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if( xTimeToWait < comTX_MIN_BLOCK_TIME )
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{
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xTimeToWait = comTX_MIN_BLOCK_TIME;
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}
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vTaskDelay( xTimeToWait );
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}
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} /*lint !e715 !e818 pvParameters is required for a task function even if it is not referenced. */
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/*-----------------------------------------------------------*/
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static void vComRxTask( void * pvParameters )
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{
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const char * const pcTaskStartMsg = "COM Rx task started.\r\n";
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const char * const pcTaskErrorMsg = "COM read error\r\n";
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const char * const pcTaskRestartMsg = "COM resynced\r\n";
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const char * const pcTaskTimeoutMsg = "COM Rx timed out\r\n";
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const TickType_t xBlockTime = ( TickType_t ) 0xffff / portTICK_PERIOD_MS;
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const char * pcExpectedChar;
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portBASE_TYPE xGotChar;
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char cRxedChar;
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short sResyncRequired, sConsecutiveErrors, sLatchedError;
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/* Stop warnings. */
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( void ) pvParameters;
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/* Queue a message for printing to say the task has started. */
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vPrintDisplayMessage( &pcTaskStartMsg );
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/* The first expected character is the first character in the string. */
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pcExpectedChar = pcMessageToExchange;
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sResyncRequired = pdFALSE;
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sConsecutiveErrors = 0;
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sLatchedError = pdFALSE;
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for( ; ; )
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{
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/* Receive a message from the com port interrupt routine. If a message is
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* not yet available the call will block the task. */
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xGotChar = xSerialGetChar( xPort, &cRxedChar, xBlockTime );
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if( xGotChar == pdTRUE )
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{
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if( sResyncRequired == pdTRUE )
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{
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/* We got out of sequence and are waiting for the start of the next
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* transmission of the string. */
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if( cRxedChar == '\n' )
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{
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/* This is the end of the message so we can start again - with
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* the first character in the string being the next thing we expect
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* to receive. */
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pcExpectedChar = pcMessageToExchange;
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sResyncRequired = pdFALSE;
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/* Queue a message for printing to say that we are going to try
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* again. */
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vPrintDisplayMessage( &pcTaskRestartMsg );
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/* Stop incrementing the check variable, if consecutive errors occur. */
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sConsecutiveErrors++;
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if( sConsecutiveErrors >= comMAX_CONSECUTIVE_ERRORS )
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{
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sLatchedError = pdTRUE;
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}
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}
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}
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else
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{
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/* We have received a character, but is it the expected character? */
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if( cRxedChar != *pcExpectedChar )
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{
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/* This was not the expected character so post a message for
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* printing to say that an error has occurred. We will then wait
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* to resynchronize. */
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vPrintDisplayMessage( &pcTaskErrorMsg );
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sResyncRequired = pdTRUE;
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}
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else
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{
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/* This was the expected character so next time we will expect
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* the next character in the string. Wrap back to the beginning
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* of the string when the null terminator has been reached. */
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pcExpectedChar++;
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if( *pcExpectedChar == '\0' )
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{
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pcExpectedChar = pcMessageToExchange;
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/* We have got through the entire string without error. */
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sConsecutiveErrors = 0;
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}
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}
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}
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/* Increment the count that is used to check that this task is still
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* running. This is only done if an error has never occurred. */
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if( sLatchedError == pdFALSE )
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{
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sRxCount++;
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}
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}
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else
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{
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vPrintDisplayMessage( &pcTaskTimeoutMsg );
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}
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}
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} /*lint !e715 !e818 pvParameters is required for a task function even if it is not referenced. */
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/*-----------------------------------------------------------*/
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static void vSemTestTask( void * pvParameters )
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{
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const char * const pcTaskStartMsg = "ISR Semaphore test started.\r\n";
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portBASE_TYPE xError = pdFALSE;
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/* Stop warnings. */
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( void ) pvParameters;
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/* Queue a message for printing to say the task has started. */
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vPrintDisplayMessage( &pcTaskStartMsg );
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for( ; ; )
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{
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if( xSerialWaitForSemaphore( xPort ) )
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{
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if( xError == pdFALSE )
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{
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sSemCount++;
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}
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}
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else
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{
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xError = pdTRUE;
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}
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}
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} /*lint !e715 !e830 !e818 pvParameters not used but function prototype must be standard for task function. */
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/*-----------------------------------------------------------*/
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/* This is called to check that all the created tasks are still running. */
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portBASE_TYPE xAreComTestTasksStillRunning( void )
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{
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static short sLastTxCount = 0, sLastRxCount = 0, sLastSemCount = 0;
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portBASE_TYPE xReturn;
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/* Not too worried about mutual exclusion on these variables as they are 16
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* bits and we are only reading them. We also only care to see if they have
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* changed or not. */
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if( ( sTxCount == sLastTxCount ) || ( sRxCount == sLastRxCount ) || ( sSemCount == sLastSemCount ) )
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{
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xReturn = pdFALSE;
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}
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else
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{
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xReturn = pdTRUE;
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}
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sLastTxCount = sTxCount;
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sLastRxCount = sRxCount;
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sLastSemCount = sSemCount;
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return xReturn;
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}
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/*-----------------------------------------------------------*/
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void vComTestUnsuspendTask( void )
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{
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/* The task that is suspended on the semaphore will be referenced from the
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* Suspended list as it is blocking indefinitely. This call just checks that
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* the kernel correctly detects this and does not attempt to unsuspend the
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* task. */
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xTaskResumeFromISR( xSemTestTaskHandle );
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}
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