rule110-netpbm.c

/*
 * Cellular automaton I made. Now displayed as .pbm
 * https://en.wikipedia.org/wiki/Rule_110
 * https://en.wikipedia.org/wiki/Netpbm
 * https://github.com/r4v10l1
 */

#include <stdio.h>

// Height must be > width
#define HEIGHT 1000
#define WIDTH 999

int calc_rule(int a, int b, int c, int mode);	// Rule conditionals
int calc_array();

int main() {
    int array_len = calc_array();

    char line[array_len];
    char line_aux[array_len];

    int rule_results;
    int position = 0;

    // Clear the arrays
    for (int n = 0; n <= array_len; n++){
        line[n] = 0;
        line_aux[n] = 0;
    }
    line[1] = 1;

    // Start of the .pbm file
    printf("P1\n"); // Black and white
    printf("# Made with https://github.com/r4v10l1/rule110\n");
    printf("%d %d\n", WIDTH, HEIGHT);

    // Display each line
    for (int y = 1; y <= HEIGHT; y++){	
        for (int x = 1; x <= WIDTH; x++){

            rule_results = calc_rule(line[position], line[position+1], line[position+2], 1);
            putchar(rule_results+48);	

            // Stop printing if the lines are too long
            if (x % 75 == 0) putchar('\n');

            // Write into the aux array instead of the main one while reading
            line_aux[x] = rule_results;

            position++;
        }

        // After reading the array, replace the aux with the main one
        for (int n = 0; n <= array_len; n++){
            line[n] = line_aux[n];
        }

        putchar('\n');
        position = 0;
    }
}

int calc_array() {
    if (HEIGHT >= WIDTH)    return HEIGHT;
    else                    return WIDTH;
}

int calc_rule(int a, int b, int c, int mode) {
    // Vanilla rule110 or mirror
    if (mode == 1) {
        int temp = a;
        a = c;
        c = temp;
    }

    // Made a conditional for each rule so it's more visual
    if (a == 0 && b == 0 && c == 0)         return 0;	// 000
    else if (a == 0 && b == 0 && c == 1)    return 1;	// 001
    else if (a == 0 && b == 1 && c == 0)    return 1;	// 010
    else if (a == 0 && b == 1 && c == 1)    return 1;	// 011
    else if (a == 1 && b == 0 && c == 0)    return 0;	// 100
    else if (a == 1 && b == 0 && c == 1)    return 1;	// 101
    else if (a == 1 && b == 1 && c == 0)    return 1;	// 110
    else if (a == 1 && b == 1 && c == 1)    return 0;	// 111
    else                                    return 0;	// ???
}