rdblab.c

Vxworks的培训教程,大家分享下啊,

/* rdbLab.c - Using CrossWind, nyuk, nyuk, nyuk! */

#include "vxWorks.h"
#include "stdio.h"
#include "stdlib.h"
#include "taskLib.h"
#include "semLib.h"

typedef struct stoogeStruct 
    {
    char *name;
    struct stoogeStruct *next;
    } STOOGE, *STOOGE_LIST;

#define NUM_STOOGES 4 

/* global variables */
char *stoogeName[NUM_STOOGES] = {"Larry", "Moe", "Curly", "Shempf"};
volatile int number = 0;
SEM_ID mutex = NULL;	/* mutual exclusion semaphore for number */

/* foward declarations */
STOOGE_LIST stoogeMakeList (void);
void stoogeTalk (STOOGE_LIST stoogeList);
void stoogeFreeList (STOOGE_LIST stoogeList);
void stoogeNumberInc (void);
void stoogeMutex (void);

/*******************************************************************************
*
* stoogeStart - do the stooge thing.
*
* This routine creates a linked list of stooges. Each stooge in turn says
* "Nyuk, nyuk, nyuk". The list is then freed up.
*
* RETURNS: VOID
*/

void stoogeStart (void)
    {
    STOOGE_LIST stoogeList;

    if (mutex == NULL)		/* first time through, create mutex */
	stoogeMutex ();

    stoogeList = stoogeMakeList ();
    printf("\n%5s (%2d) : Oh, a wise guy, eh?\n", taskName(0), number);
    stoogeTalk (stoogeList);
    stoogeFreeList (stoogeList);
    }

/*************************************************************************
*
* stoogeMutex - create mutex for <number>
*
* This routine creates a mutual exclusion semaphore <mutex> guarding
* access to the global integer <number>. 
* 
* Semaphores will be covered in detail in a later chapter.
*/

void stoogeMutex (void)
    {
    if ( (mutex = semMCreate (SEM_Q_PRIORITY | 
		 	      SEM_INVERSION_SAFE |
			      SEM_DELETE_SAFE))
	 == NULL)
	{
	printf ("stoogeInit: Creation of mutex failed. Exiting.\n");
	exit(0);
	}
    }


/*******************************************************************************
*
* stoogeMakeList - make a linked list of stooges.
*
* RETURNS: a pointer to this list.
*/

STOOGE_LIST stoogeMakeList (void)
    {
    STOOGE *oldStooge = NULL;
    STOOGE *newStooge;
    int i;

    for (i=0; i<NUM_STOOGES; i++)
		{
		newStooge = (STOOGE *)malloc(sizeof(STOOGE));
		newStooge->next = oldStooge;
		newStooge->name = stoogeName[NUM_STOOGES - i - 1];

		oldStooge = newStooge;
		}

    stoogeNumberInc ();
    return (newStooge);
    }
    


/*******************************************************************************
*
* stoogeTalk - let each stooge say "Nyuk, nyuk, nyuk"
*
* RETURNS: VOID
*/

void stoogeTalk
    (
    STOOGE_LIST stoogeList
    )
    {
    STOOGE *stooge = stoogeList;

    while (stooge != NULL)
		{
		printf("%10s : Nyuk, nyuk, nyuk\n", stooge->name);
		stooge = stooge->next;
		}


    stoogeNumberInc ();
    }



/*******************************************************************************
* stoogeFreeList - free the linked list of stooges.
*
* RETURNS: VOID
*/

void stoogeFreeList
    (
    STOOGE_LIST stoogeList
    )
    {
    STOOGE *stooge, *nextStooge;
    stooge = stoogeList;
    
    while (stooge!=NULL)
		{
		nextStooge = stooge->next;
		free (stooge);
		stooge = nextStooge;
		}

    stoogeNumberInc ();
    }


/*******************************************************************************
* stoogeListSize - find out the size of the stoogeList.
*
* RETURNS: the size of the linked list.
*/

int stoogeListSize
    (
    STOOGE_LIST stoogeList
    )
    {
    int i=0;
    STOOGE *stooge = stoogeList;

    while(stooge!=NULL)
		{
		i++;
		stooge = stooge->next;
		}

    return(i);
    }

/**************************************************************************
*
* stoogeNumberInc - increment ye olde number, modulo ye olde 100
*
* The increment is done within a mutual exclusion critical region
* to avoid a possible race condition when more than one task executes
* this program concurrently. Mutual exclusion issues will be discussed
* in a later chapter.
*/

void stoogeNumberInc (void)
    {
    if (semTake (mutex, WAIT_FOREVER) != OK)
	return;

    if (++number == 100)
	number = 0;

    semGive (mutex);
    }