cprime/src/main.c

#include "sieve.h"

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

static void printfac(int64_t num, int64_t *buf)
{
	int64_t n;
	int i = 0;
	fprintf(stdout, "%ld = ", num);
	while ((n = buf[i++]) != 0)
	{
		if (i == 1)
			fprintf(stdout, "%ld", n);
		else
			fprintf(stdout, " * %ld", n);
	}
	fprintf(stdout, "\n");
}

static sieve s;

void onTerm(int signal)
{
	sieve_free(&s);
	exit(1);
}

int main(int argc, char **argv)
{
	if (argc != 2)
	{
		printf("Usage: %s <max-num>\n", argv[0]);
		exit(1);
	}

	int64_t maxnum = atol(argv[1]);

	sieve_init(&s, sqrt(maxnum) + 1);

	// Attach signal handler
	struct sigaction sa;
	memset(&sa, 0, sizeof(sa));
	sa.sa_handler = onTerm;
	sigaction(SIGTERM, &sa, NULL);
	sigaction(SIGINT, &sa, NULL);

	// Generate sieve
	fprintf(stderr, "Generating sieve...\n");
	sieve_generate(&s);
	fprintf(stderr, "done\n");
	fflush(stderr);

	int64_t buf[1024];

	// Main loop
	char line[1024];
	while (1)
	{
		// Read line
		int i = 0;
		int c;
		while ((c = getchar()) != EOF)
		{
			if (c == '\n')
				break;

			if (i < sizeof(buf) - 3)
				line[i++] = c;
		}
		line[i++] = 0;

		int64_t num = atol(line);
		if (num > maxnum)
		{
			printf("Number too big. Max size: %ld.\n", maxnum);
		}
		else if (num <= 0)
		{
			printf("Can only factor numbers >= 0.\n");
		}
		else
		{
			// Factor
			sieve_factor(&s, num, buf);

			// Print
			printfac(num, buf);
		}

		fflush(stdout);

		if (c == EOF)
			return 0;
	}

	sieve_free(&s);

	return 0;
}