anybody can help?

i'm sorry. i dont know what to do this project. please please help me.


In this project we are going to implement reader-writer problem with circular buffer using various methods.  Consider the following data structure:

typedef struct
{
     int total;
     short len, readPtr, writePtr, buf[BUFSIZE];
} CBuf;

where

Total: is the total number of integers that the writher has ever produced.  In this project let’s use 2000(starting with 1).  You may adjust this number if you like.
len: is the number of integers left in the buffer,
readPtr: indicates the next location in the buffer that eh reader is going to read,
writePtr: is the next location in the buffer where the writer is going to place the number,
buf: is the circular buffer and let’s assume it has the size of 20.

Assignment: For each of the following steps, you will need to use ctime and times functions in the beginning and/or the end of the program to record the time and read and write, please have it run (100,000..110,000) factorial.  For steps 1 and 2, you may use spin lock, busy wait to synchronize the two processes/threads.

STEP 1: Write a c program of two processes using shared memory.  You will need the following functions:

#include<sys/ipc.h>
#include<sys/shm.h>

int shmget(key_t key, int size, int shmflg);
void *shmat(int shmid, const void *shmaddr, int shmflg);
int shmdt(const void *shmaddr);
int shmctl(int shmid, int cmd, struct shmid_ds *buf);

Given below are the proper steps to use these functions:

1. you will need to create or access the shared memory segment by something like following:
     #define SHMKEY ((key_t) 8000)
     if( (shmid = shmget( SHMKEY, sizeof(CBuf), 0666|IPC_CREAT)) < 0)
   or
     if( (shmid = shmget( SHMKEY, sizeof(CBuf), 0)) < 0)

2. you will attach the shared memory segment to your program’s address space by something similar to the following:
     if( (cbuf = (CBuf*) shmat (shmid,(char*) 0,0)) == (CBuf*) - 1)

3. when you are done you will need to have it detached from you program’s address space by something similar to the following:
     if( shmdt(cbuf) < 0)

4. one of the processes needs to destroy the shared memory segment using the following function:
     if( shmctl(shmid, IPC_RMID, NULL) )


STEP 2: Modify step 1 using threads instead of processes.  Since threads share the same address space, so shared memory is not needed here.

STEP 3: Modify step 2 using semaphore to synchronize the two threads.