[RaspberryPi] Thread & Shared Memory & USB Serial Data

[Description]

- Thread 를 3개 생성함

- 하나의 Thread는 Shared Memory를 지속적으로 읽으면서 데이터가 있으면 출력

- 또 하나의 Thread는 USB를 통한 데이터를 지속적으로 출력

- 또 하나는 그냥 Printf 하는 단순 작업

 

[MakeFile]

CC = gcc
TARGET = main
LDFLAGS = -pthread -lwiringPi
 
OBJS = main.o SharedMemory.o
main : $(OBJS)
    $(CC) -o $(TARGET) $(LDFLAGS) $(OBJS)
main.o: main.c SharedMemory.h
    $(CC) -c main.c
SharedMemory.o: SharedMemory.c SharedMemory.h
    $(CC) -c main.c SharedMemory.c

[SharedMemory.c Code]

#include "SharedMemory.h"
 
int shmid;
 
int SHM_create()
{
    shmid = shmget((key_t)SHARED_MEMORY_KEY, MEMORY_SIZE, 0666|IPC_CREAT);
    
    if(shmid == -1)
    {
        perror("shmget failed: ");
        return -1;
    }
    return shmid;
}
 
int SHM_delete()
{
    if(shmctl(shmid, IPC_RMID, 0) == -1)
    {
        perror("shmctl failed: ");
        return -1;
    }
    return 1;
}

[SharedMemory.h Code]

#include <stdio.h>
#include <stdlib.h>
 
#include <sys/shm.h>
#include <unistd.h>
 
#define SHARED_MEMORY_KEY 1111
#define MEMORY_SIZE 1024
 
int SHM_create();
int SHM_delete();

[Main.c Code]

#include <stdio.h>
#include <pthread.h>
#include <stdlib.h>
#include <unistd.h>
#include <signal.h>
#include <string.h>
#include <errno.h> //error output
#include <stdint.h> //uint8_t definitions
 
//wiring Pi
#include <wiringPi.h>
#include <wiringSerial.h>
 
#include "SharedMemory.h"
 
#define READ_CLIENT_FLAG 0
#define READ_SERVER_FLAG 1
#define PRINT_CLIENT_FLAG 2
 
char device[]= "/dev/ttyACM0";
// filedescriptor
int fd;
unsigned long baud = 9600;
//unsigned long time=0;
 
void signal_handler(int signo)
{
    printf("terminate Process\n");
    SHM_delete();
    exit(0);
}
 
void *t_function(void *data)
{
    printf("Test");
    pid_t pid;
    pthread_t tid;
    
    pid = getpid();
    tid = pthread_self();
    
    char* thread_name = (char*)data;
    int i = 0;
    
    while(i<3)
    {
        printf("[%s] pid:%u, tid:%x --- %d\n",
            thread_name, (unsigned int)pid, (unsigned int)tid, i);
        i++;
        sleep(1);
    }
}
 
void *t_buffer()
{
    int shmid;
    shmid = SHM_create();
    
    char *buffer;
    char *string;
    
    buffer = shmat(shmid, (void *)0, 0);
    if(buffer == (void *)-1)
    {
        perror("shmat failed: ");
    }
    
    buffer[0] = READ_CLIENT_FLAG;
    string = buffer + 1;    
    
    while(1)
    {
        if(buffer[0] == READ_SERVER_FLAG)
        {
            puts(string);
            strcat(string, "by server");
            buffer[0] = PRINT_CLIENT_FLAG;
        }
        printf("wait data\n");
        sleep(1);
    }
}
 
void setup(){
 
  printf("%s \n", "Raspberry Startup!");
  fflush(stdout);
 
  //get filedescriptor
  if ((fd = serialOpen (device, baud)) < 0){
    fprintf (stderr, "Unable to open serial device: %s\n", strerror (errno)) ;
    exit(1); //error
  }
 
  //setup GPIO in wiringPi mode
  if (wiringPiSetup () == -1){
    fprintf (stdout, "Unable to start wiringPi: %s\n", strerror (errno)) ;
    exit(1); //error
  }
 
}
 
void loop()
{ 
  // read signal
  if(serialDataAvail (fd)){
    char newChar = serialGetchar (fd);
    printf("%c", newChar);
    fflush(stdout);
  }
 
}
 
void *t_usb_comm()
{
    setup();
  while(1) loop();
}
 
int main()
{
    signal(SIGINT, signal_handler);
 
    pthread_t p_thread[3];
    
    int thr_id;
    int status;
    
    char p1[] = "thread_1";
    char p2[] = "thread_2";
    char pM[] = "thread_m";
    
    sleep(1);
    
    thr_id = pthread_create(&p_thread[0], NULL, t_buffer, NULL);
    
    if(thr_id < 0)
    {
        perror("thread create error:1 ");
        exit(0);
    }
    
    thr_id = pthread_create(&p_thread[1], NULL, t_usb_comm, NULL);
    
    if(thr_id < 0)
    {
        perror("thread create error: ");
        exit(0);
    }
    
    thr_id = pthread_create(&p_thread[2], NULL, t_function, (void*)p2);
    
    if(thr_id < 0)
    {
        perror("thread create error: ");
        exit(0);
    }
    
    t_function((void *)pM);
    
    pthread_join(p_thread[0], (void **)&status);
    pthread_join(p_thread[1], (void **)&status);
    pthread_join(p_thread[2], (void **)&status);
    
    printf("when terminal\n");
    
    return 0;
}