#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <string.h>

#define DEFAULT_NUM 5000
#define PROGNAME "primepattern"

void primetable(long long int maxnumber);

int main(int argc, char *argv[]){
	long long int numprimes = 0;
	if(argc == 1){
		fprintf(stderr, "No number specified, using %i\n", DEFAULT_NUM);
		numprimes = DEFAULT_NUM;
	}else if(argc == 2){
		numprimes = atoll(argv[1]);
		if(numprimes <= 0){
			fprintf(stderr, "Number must be greater than 0\n");
			numprimes = 0;
		}
	}else{
		fprintf(stderr, "Syntax:\n\t%s <amount>\n", PROGNAME);
	}

	if(numprimes){
		primetable(numprimes);
	}

	return (numprimes != 0);
}

void primetable(long long int maxnumber){
	long long int testnum, n, tnsq, delta, pindex;
	unsigned char *isprime;
	int displaynum;

	isprime = (unsigned char *)malloc(maxnumber * sizeof(unsigned char));
	if(isprime != (unsigned char *)NULL){
		memset(isprime, (1 << (8 * sizeof(unsigned char))) - 1, maxnumber * sizeof(unsigned char));
		pindex = 0;
		testnum = 2;
		tnsq = testnum * testnum;
		do{
			printf("[%4lli]", testnum); /* print the prime we're filtering out */
			for(n = 0; n < pindex; n++) printf(" "); /* line up the output */
			delta = 0;
			for(n = tnsq; n < maxnumber; n += testnum){
				if(isprime[n]){
					isprime[n] = 0;
					displaynum = (delta / testnum) % 62;

					if(displaynum < 10)
						printf("%i", displaynum);
					else if(displaynum < 36)
						printf("%c", 'A' + (char)(displaynum - 10));
					else
						printf("%c", 'a' + (char)(displaynum - 36));

					delta = 0;
				}
				delta += testnum;
			}
			printf("\n");
			do testnum++; while(!isprime[testnum] && testnum < maxnumber);
			tnsq = testnum * testnum;
			pindex++;
			fflush(stdout);

		}while(tnsq < maxnumber);
/*
		for(n = 0; n < maxnumber; n++)
			if(isprime[n])
				printf("%lli ", n);
		printf("\n");
*/

		free(isprime);
	}
}