/* includes */
#include "vxWorks.h"
#include "taskLib.h"
#include "msgQLib.h"
#include "sysLib.h"
#include "stdio.h"
/* globals */
#define CONSUMER_TASK_PRI 99 /* Priority of the consumer task */
#define PRODUCER_TASK_PRI 98 /* Priority of the producer task */
#define TASK_STACK_SIZE 5000 /* stack size for spawned tasks */
struct msg /* data structure for msg passing */
{
int tid; /* task id */
int value; /* msg value */
};
LOCAL MSG_Q_ID msgQId; /* message queue id */
LOCAL int numMsg = 8; /* number of messages */
LOCAL BOOL notDone; /* Flag to indicate the completion of this demo */
/* function prototypes */
LOCAL STATUS producerTask (); /* producer task */
LOCAL STATUS consumerTask (); /* consumer task */
/* user entry */
STATUS msgQDemo()
{
notDone = TRUE; /* initialize the global flag */
/* Create the message queue*/
if ((msgQId = msgQCreate (numMsg, sizeof (struct msg), MSG_Q_FIFO))
== NULL)
{
perror ("Error in creating msgQ");
return (ERROR);
}
/* Spwan the producerTask task */
if (taskSpawn ("tProducerTask", PRODUCER_TASK_PRI, 0, TASK_STACK_SIZE,
(FUNCPTR) producerTask, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0)
== ERROR)
{
perror ("producerTask: Error in spawning demoTask");
return (ERROR);
}
/* Spwan the consumerTask task */
if (taskSpawn ("tConsumerTask", CONSUMER_TASK_PRI, 0, TASK_STACK_SIZE,
(FUNCPTR) consumerTask, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0)
== ERROR)
{
perror ("consumerTask: Error in spawning demoTask");
return (ERROR);
}
/* polling is not recommended. But used to make this demonstration simple*/
while (notDone)
taskDelay (sysClkRateGet ());
if (msgQDelete (msgQId) == ERROR)
{
perror ("Error in deleting msgQ");
return (ERROR);
}
return (OK);
}
/* producerTask :发送消息给consumerTask */
STATUS producerTask (void)
{
int count;
int value;
struct msg producedItem; /* producer item - produced data */
printf ("producerTask started: task id = %#x \n", taskIdSelf ());
/* Produce numMsg number of messages and send these messages */
for (count = 1; count <= numMsg; count++)
{
value = count * 10; /* produce a value */
/* Fill in the data structure for message passing */
producedItem.tid = taskIdSelf ();
producedItem.value = value;
/* Send Messages */
if ((msgQSend (msgQId, (char *) &producedItem, sizeof (producedItem),
WAIT_FOREVER, MSG_PRI_NORMAL)) == ERROR)
{
perror ("Error in sending the message");
return (ERROR);
}
else
printf ("ProducerTask: tid = %#x, produced value = %d \n",
taskIdSelf (), value);
}
return (OK);
}
/* consumerTask:获取(消费)消息 */
STATUS consumerTask (void)
{
int count;
struct msg consumedItem; /* consumer item - consumed data */
printf ("\n\nConsumerTask: Started - task id = %#x\n", taskIdSelf());
/* consume numMsg number of messages */
for (count = 1; count <= numMsg; count++)
{
/* Receive messages */
if ((msgQReceive (msgQId, (char *) &consumedItem,
sizeof (consumedItem), WAIT_FOREVER)) == ERROR)
{
perror ("Error in receiving the message");
return (ERROR);
}
else
printf ("ConsumerTask: Consuming msg of value %d from tid = %#x\n",
consumedItem.value, consumedItem.tid);
}
notDone = FALSE; /* set the global flag to FALSE to indicate completion*/
return (OK);
}
程序运行输出:
producerTask started: task id = 0x1010f20
ProducerTask: tid = 0x1010f20, produced value = 10
ProducerTask: tid = 0x1010f20, produced value = 20
ProducerTask: tid = 0x1010f20, produced value = 30
ProducerTask: tid = 0x1010f20, produced value = 40
ProducerTask: tid = 0x1010f20, produced value = 50
ProducerTask: tid = 0x1010f20, produced value = 60
ProducerTask: tid = 0x1010f20, produced value = 70
ProducerTask: tid = 0x1010f20, produced value = 80
ConsumerTask: Started - task id = 0x100c840
ConsumerTask: Consuming msg of value 10 from tid = 0x1010f20
ConsumerTask: Consuming msg of value 20 from tid = 0x1010f20
ConsumerTask: Consuming msg of value 30 from tid = 0x1010f20
ConsumerTask: Consuming msg of value 40 from tid = 0x1010f20
ConsumerTask: Consuming msg of value 50 from tid = 0x1010f20
ConsumerTask: Consuming msg of value 60 from tid = 0x1010f20
ConsumerTask: Consuming msg of value 70 from tid = 0x1010f20
ConsumerTask: Consuming msg of value 80 from tid = 0x1010f20
VxWorks主要提供如下API进行消息队列的创建、读取和传递:
msgQCreate( ):创建斌初始化一个消息队列,函数原型为:
MSG_Q_ID msgQCreate
(
int maxMsgs, /*队列所能容纳的最大消息数目*/
int maxMsgLength, /*每一消息的最大长度*/
int options /*消息入列方式*/
);
msgQDelete( ):终止并释放一个消息队列,函数原型为:
STATUS msgQDelete
(
MSG_Q_ID msgQId /*要删除的消息队列ID号*/
);
msgQSend( ):发送一个消息到消息队列,函数原型为:
STATUS msgQSend
(
MSG_Q_ID msgQId, /*所发向的消息队列名*/
char * buffer, /*消息包所在缓冲区指针*/
UINT nBytes, /*消息包长度*/
int timeout, /*等待的时间长度*/
int priority /*优先级*/
);
msgQReceive( ):从消息队列接受一个消息,函数原型为:
int msgQReceive
(
MSG_Q_ID msgQId, /*接收消息的消息队列ID号*/
char * buffer, /*接收消息的缓冲区指针*/
UINT maxNBytes, /*缓冲区长度*/
int timeout /*等待时间*/
);
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