cgol

commit 7a617e8e9692a496caf878cfdeac038bbf285bc1
parent 532da220dbb29fb0d09cdce2473634074c487812
Author: aabacchus <ben@bvnf.space>
Date:   Tue, 28 Sep 2021 12:35:51 +0100

add option to run until static

Diffstat:
M
cgol.1
 | 
8
+++++++-
M
main.c
 | 
14
++++++++++++++

2 files changed, 21 insertions(+), 1 deletion(-)
diff --git a/cgol.1 b/cgol.1
@@ -6,7 +6,7 @@
 .Nd generate images of the game of life
 .Sh SYNOPSIS
 .Nm
-.Op Ar width height Op Ar gens
+.Op Ar width height Op Ar gens | 0
 .Sh DESCRIPTION
 .Nm
 generates frames of the progression of the game of life as images,
@@ -40,6 +40,12 @@ Options:
 the width and height of the images to be printed, in pixels.
 .It Ar gens
 the number of generations to evolve. Must be 0 < gens <= 999999.
+However, if
+.Ar gens
+is 0,
+.Nm
+will run until there are 4 consecutive generations without a change
+in population.
 .El
 .Ss Creating a video from the images
 Using a tool such as
diff --git a/main.c b/main.c
@@ -30,6 +30,7 @@ int
 main(int argc, char **argv) {
     double width, height;
     int gens;
+    int check_births = 0;
 
     if (argc > 1 && strncmp("-h", *(argv + 1), 2) == 0) {
         fprintf(stderr, "usage: %s [width height [gens]]\nthe defaults are \"800\" \"600\" \"200\"\n", *argv);
@@ -44,6 +45,10 @@ main(int argc, char **argv) {
         if (argc > 3) {
             gens = atoi(*++argv);
             check(gens);
+            if (gens == 0) {
+                gens = 999999;
+                check_births = 1;
+            }
             if (gens < 1 || gens > 999999) {
                 /* the upper limit is to ensure the gen number fits onto the
                  * image filenames */
@@ -86,6 +91,8 @@ main(int argc, char **argv) {
 
     int gen, n_alive;
     char *fn = malloc(12 + 6);
+    int n_alive1, n_alive2, n_alive3;
+    n_alive3 = n_alive2 = n_alive1 = 0;
     for (gen = 0; gen < gens; gen++) {
 #ifdef __TEST
         printf("==> GEN %d <==\r", gen);
@@ -98,6 +105,13 @@ main(int argc, char **argv) {
             return 1;
         }
         n_alive = evolve(&cells[0][0], NCOLS, NROWS);
+        if (check_births) {
+            if (n_alive == n_alive1 && n_alive == n_alive2 && n_alive == n_alive3)
+                break;
+            n_alive3 = n_alive2;
+            n_alive2 = n_alive1;
+            n_alive1 = n_alive;
+        }
 #ifndef __TEST
         printf("%d\n", n_alive);
 #endif