//

// proj-4.c

// proj-4

//

// Created by Sean C Bennett on 10/12/15.

// Created by Shane T. Nelson on 10/12/15.

// Copyright © 2015 Sean C Bennett. All rights reserved.

//

#include <stdio.h>

#include <stdlib.h>

#include "sem.h"

sem_t mutex;

sem_t rsem;

sem_t wsem;

unsigned int rwc = 0;

unsigned int wwc = 0;

unsigned int rc = 0;

unsigned int wc = 0;

// Reader CASE 3

void reader(void){

sleep(1);

printf("Entering reader\n");

while(1)

{

//Reader Entry

P(&mutex);

printf("Reader Entry\n");

if((wwc > 0) || (wc > 0))

{

rwc++;

V(&mutex);

P(&rsem);

V(&mutex);

rwc--;

}

rc++;

V(&mutex);

//READ

printf("Reading resource: Reader # %d \n", rc);

sleep(1);

//Reader Exit

P(&mutex);

printf("Reader Exit\n");

rc--;

if((rc == 0) && (wwc > 0))

{

V(&wsem);

}

V(&mutex);

}

return;

}

// Writer CASE 3

void writer(void) {

int i;

sleep(1);

printf("Entering writer\n");

while(1){

//Writer Entry

P(&mutex);

printf("Writer Entry\n");

if((rc > 0) || (wc > 0) || (rwc > 0) || (wwc > 0))

{

wwc++;

V(&mutex);

P(&wsem);

P(&mutex);

wwc--;

}

wc++;

V(&mutex);

//WRITE

printf("Writing to resource: Writer # %d \n", wc);

sleep(1);

//Writer Exit

P(&mutex);

printf("Writer Exit\n");

wc--;

if(rwc > 0)

{

for(i = 0; i <= rwc; i++)

{

V(&rsem);

}

}

else if(wwc > 0)

{

V(&wsem);

}

V(&mutex);

}

return;

}

// Main function

int main() {

int ret1, ret2, ret3;

TCB_t *RunQ = 0;

InitQueue(&RunQ);

ret1 = InitSem(&mutex, 1);

if(ret1 < 0)

{

printf("Error initializing access semaphore");

}

ret2 = InitSem(&rsem, 1);

if(ret2 < 0)

{

printf("Error initializing reader semaphore");

}

ret3 = InitSem(&wsem, 1);

if(ret3 < 0)

{

printf("Error initializing order semaphore");

}

start_thread(reader);

start_thread(reader);

start_thread(reader);

start_thread(writer);

start_thread(writer);

run();

return 0;

}