#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <pthread.h>
#include <sys/time.h>
#include <sys/ioctl.h>
#include <linux/rtc.h>
#include <unistd.h>
#include <fcntl.h>
#include <stdio.h>

#define PACKETS 50000

int sock;
struct timeval start;
FILE *logfile;

struct ts_pkt {
    struct timeval tv;
    char rsvd[32 - sizeof(struct timeval)];
};

static inline double delta(struct timeval a, struct timeval b)
{
      if (a.tv_usec & b.tv_usec)  {
              a.tv_sec--;
              a.tv_usec += 1000000;
      }
      return a.tv_sec-b.tv_sec + (a.tv_usec-b.tv_usec)/1000000.0;
}

void *receiverThread(void *arg) {
    struct ts_pkt ts;
    struct timeval tv;
    float delay;
    while(1) {
        pthread_testcancel();
        if(recv(sock, &ts, sizeof(ts), 0) == -1)
            perror("recv");
        gettimeofday(&tv, NULL);
        fprintf(logfile, "%f %f\n", delta(tv, start), delta(tv, ts.tv));
    }
}

void *senderThread(void *arg) {
    int rtc;
    unsigned long ticks;
    int i = PACKETS;
    struct ts_pkt ts;
    
    rtc = open("/dev/rtc", O_RDONLY);
    if(rtc == -1) {
        perror("/dev/rtc");
        pthread_exit(NULL);
    }
    ticks = 64;
    ioctl(rtc, RTC_PIE_ON, 0);
    if(ioctl(rtc, RTC_IRQP_SET, ticks) == -1) {
        perror("/dev/rtc");
        pthread_exit(NULL);
    }
    while(i--) {
        read(rtc, &ticks, sizeof(ticks));
        ticks >>=8;
        while(ticks--) {
            gettimeofday(&ts.tv, NULL);
            send(sock, &ts, sizeof(ts), 0);
        }
    }
    ioctl(rtc, RTC_PIE_OFF, 0);
    close(rtc);
}

int main(int argc, char **argv) {
    struct sockaddr_in sa;
    pthread_t receiver, sender;
    FILE *gnuplot;
    
    if(argc < 3) {
      printf("Syntax: udp-send [ip] [file]\n");
      exit(0);
    }

    memset(&sa, 0, sizeof(sa));
    logfile = fopen(argv[2], "w");
    sock = socket(PF_INET, SOCK_DGRAM, 0);
    sa.sin_port = htons(12388);
    sa.sin_family = PF_INET;
    sa.sin_addr.s_addr = inet_addr(argv[1]);
    connect(sock, (struct sockaddr *)&sa, sizeof(sa));
    
    gettimeofday(&start, NULL);
    pthread_create(&receiver, 0, receiverThread, 0);
    pthread_create(&sender, 0, senderThread, 0);
    pthread_join(sender, 0);
    sleep(3);
    pthread_cancel(receiver);
    fclose(logfile);

    gnuplot = popen("/usr/bin/gnuplot", "w");
    fprintf(gnuplot, "set terminal png large size 1280,1024\n");
    fprintf(gnuplot, "set output '%s.png'\n", argv[2]);
    fprintf(gnuplot, "set title 'UDP RTT Timing at 64pps'\n");
    fprintf(gnuplot, "set xlabel 'Time in Seconds'\n");
    fprintf(gnuplot, "set ylabel 'UDP Response in Seconds'\n");
    fprintf(gnuplot, "plot '%s' title 'UDP Response Time'\n", argv[2]);
    fflush(gnuplot);
    pclose(gnuplot);
}