#include <pthread.h>
#include <semaphore.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#define M_LEN (sizeof(int)+2*sizeof(float))

sem_t *sR;
sem_t *sC[3];
sem_t *sM[3];
float res[3];

int line = 0;

int fin;

void* compute(void* arg) {
	int id = *((int *) arg);
	free(arg);
	int n;
	float c, x;
	while(1) {
		sem_wait(sM[id]);
		sem_wait(sR);
		int r = lseek(fin, (line*3+id)*M_LEN, SEEK_SET);
		if (r == -1) {
			pthread_exit(NULL);
		}
		read(fin, &c, sizeof(float));
		read(fin, &x, sizeof(float));
		read(fin, &n, sizeof(int));
		printf("%d-%d-%d: %f %f %d\n",id,line,r,c,x,n);
		sem_post(sR);

		res[id] = c;
		for (int i = 0; i<n;i++)
			res[id]*=x;

		sem_post(sC[id]);
	}
}

void* merge(void* arg) {
	while (1) {
		float sum = 0;
		for (int i = 0; i < 3; i++) {
			sem_wait(sC[i]);
			sum += res[i];
		}
		printf("%f\n", sum);
		sleep(3);
		line++;
		sem_post(sM[0]);
		sem_post(sM[1]);
		sem_post(sM[2]);
	}
}

int main(int argc, char ** argv) {
	pthread_t t;
	fin = open(argv[1], O_RDONLY);
	if (fin == NULL) exit(1);
	sR = malloc(sizeof(sem_t));
	sem_init(sR,0,1);
	for (int i = 0; i<3;i++) {
		int * arg=malloc(sizeof(int));
		*arg=i;
		sC[i] = malloc(sizeof(sem_t));
		sM[i] = malloc(sizeof(sem_t));
		sem_init(sC[i],0,0);
		sem_init(sM[i],0,1);
		pthread_create(&t,NULL,compute,(void *)arg);
	}

	pthread_create(&t,NULL,merge,NULL);
	pthread_join(t,NULL);
	close(fin);
}