From 3c71286b6df0dab9355c0edffdf64ea37cc1e087 Mon Sep 17 00:00:00 2001
From: Micke Nordin <mik@elnord.in>
Date: Sat, 29 Oct 2016 21:53:26 +0200
Subject: [PATCH] Working 2d cellular automaton in c++

---
 ca.c   |  42 -----------------
 ca.cpp | 142 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 142 insertions(+), 42 deletions(-)
 delete mode 100644 ca.c
 create mode 100644 ca.cpp

diff --git a/ca.c b/ca.c
deleted file mode 100644
index f4d4a1c..0000000
--- a/ca.c
+++ /dev/null
@@ -1,42 +0,0 @@
-# include <iostream>
-# include <cmath>
-# include <bitset>
-
-using namespace std;
-
-const int DIM = 11;
-const int HALF = DIM / 2;
-const int NUM_RULES = 256;
-static const int BITS = floor(log(NUM_RULES)/log(2)) + 1;
-
-string to_bin(int x) {
-	char bits[BITS +1];
-	for (int i = 0; i < BITS; i++) {
-	
-		bits[i] = char (x & (1 << i) ? 1 : 0);
-	}
-	const char* str = bits;
-	string s = str;
-	return s;
-}
-
-int main() {
-	int initial[DIM][DIM];
-	int rules[NUM_RULES];
-	for(int i = 0; i < NUM_RULES; i++) {
-		rules[i] = i;	
-		cout << to_bin(i) << endl;
-	}
-
-	for(int i = 0; i < DIM; i++) {
-		for(int j = 0; j < DIM; j++) {
-			if(i == HALF && j == HALF) {
-				initial[i][j] = 1;
-			} else {
-				initial[i][j] = 0;
-			}
-			
-		}
-	}
-	
-}
diff --git a/ca.cpp b/ca.cpp
new file mode 100644
index 0000000..8141cb1
--- /dev/null
+++ b/ca.cpp
@@ -0,0 +1,142 @@
+# include <iostream>
+# include <cmath>
+# include <cstdlib>
+# include <cstring>
+# include <unistd.h>
+# include<ctime>
+
+using namespace std;
+
+const int DIM = 35;
+const int HALF = DIM / 2;
+
+// Get the number of bits needed to store an int
+int get_bits (int x) {
+	return floor(log(x)/log(2)) + 1;
+}
+
+// Convert an int to a string representation of a binary number
+string to_bin(int x) {
+	if(x == 0) {
+		return "0";
+	} else {
+		int bits = get_bits(x);
+		char buffer[bits];
+		char* p = buffer + bits;
+		do {
+			*--p = '0' + (x & 1);
+		} while (x >>= 1);
+
+		return string(p, buffer + bits);
+	}
+}
+
+// Convert a string representation of a binary number to an integer
+long  to_int(string str) {
+
+	char * ptr;
+	return strtol(str.c_str(), & ptr, 2); 
+} 
+
+// Get the string representation of a rule 
+string get_rule(int rule, int bits = 9) {
+	int length = pow(2, bits);
+	string str = to_bin(rule);
+	int strl = strlen(str.c_str()); 
+	string padding = "";
+	if (strl < length) {
+		for (int i = 0; i < (length - strl); i++) {
+			padding += "0";
+		}	
+	}
+	return string ( str.rbegin(), str.rend() ) +  padding;
+}
+
+// Get the bit that correspons to the int pos of the rule
+int get_val_at_pos(int pos, int rule) {
+	// Minus the ascii value of 0
+	return get_rule(rule).c_str()[pos] - 48;
+}
+
+// Pretty pint a matrix of bits (represented by ints)
+void print_arr(int arr[DIM][DIM]) {
+	for(int i = 0; i < DIM; i++) {
+		for( int j = 0; j < DIM; j++) {
+			int value = arr[i][j];
+			char c;
+			if(value == 1) {
+				c = '#';
+			} else {
+				c = ' ';
+			}
+			cout << c << " ";
+		}
+		cout << endl;
+	}
+	cout << endl;
+} 
+
+
+int main(int argc, char* argv[] ) {
+	// Assume rule 30 and 200 generations if nothing else is stated
+	int rule = 30;
+	int gens = 200;
+	if (argc > 1) {
+		gens = atoi(argv[1]);
+	}
+	if (argc > 2) {
+		rule = atoi(argv[2]);
+	}
+	// Seed the random number generator
+	srand (time(0));
+	
+	// Set up the initial condition
+	int initial[DIM][DIM];
+	for(int i = 0; i < DIM; i++) {
+		for(int j = 0; j < DIM; j++) {
+			// Set up a random initial condition
+			initial[i][j] = rand() % 1;
+			
+		}
+	}
+	
+	// Loop all generations
+	for(int i = 0; i < gens; i++) {
+		// Print the current state
+		print_arr(initial);
+		// Sleep 0.5 seconds
+		usleep(500000);
+		// Clear the screen
+		cout << "\033[2J";
+		cout << "\033[0;0H";
+		
+		// The next state
+		int next[DIM][DIM];
+		// Loop the columns
+		for(int j = 0; j < DIM; j++) {
+			char state[10];
+			// Loop the row
+			for(int k = 0; k < DIM; k++) {
+				state[0] = initial[ (j -1) % DIM ][ (k-1) % DIM ] + 48;
+				state[1] = initial[ (j -1) % DIM ][k] + 48;
+				state[2] = initial[ (j -1) % DIM ][ (k+1) % DIM ] + 48; 
+				state[3] = initial[j][ (k-1) % DIM ] + 48;
+				state[4] = initial[j][k] + 48 ;
+				state[5] = initial[j][ (k+1) % DIM ] + 48; 
+				state[6] = initial[ (j +1) % DIM ][ (k-1) % DIM ] + 48;
+				state[7] = initial[ (j +1) % DIM ][k] + 48;
+				state[8] = initial[ (j +1) % DIM ][ (k+1) % DIM ] + 48; 
+				state[9] = '\0';
+				next[j][k] = get_val_at_pos(to_int(state), rule);
+			}
+		}
+		// Copy the matrix
+		for(int j = 0; j < DIM; j++) {
+			for(int k = 0; k < DIM; k++) {
+				initial[j][k] = next[j][k];
+			}
+		}
+	
+	}
+	
+}