004/life.awk

   1 #! /usr/bin/awk -f
   2
   3
   4 function CHAR_BORDER() {return "-"}
   5 function CHAR_ALIVE()  {return "o"}
   6 function CHAR_DEAD()   {return " "}
   7
   8
   9 function get_random_state() {
  10     return int(2 * rand())
  11 }
  12
  13
  14 function get_init_board(n) {
  15     board = "";
  16
  17     for (i=1; i <= n; i++) {
  18         board = sprintf("%s%d", board, get_random_state())
  19     };
  20
  21     return board
  22 }
  23
  24
  25 function get_char_of_state(state) {
  26     if (state == 1) {
  27         return CHAR_ALIVE()
  28     } else if (state == 0) {
  29         return CHAR_DEAD()
  30     }
  31 }
  32
  33
  34 function do_print_border(x) {
  35     for (i=1; i <= x; i++) {
  36         printf CHAR_BORDER()
  37     };
  38     print
  39 }
  40
  41
  42 function do_print_board(x, n, board) {
  43     do_print_border(x);
  44
  45     for (i=1; i <= n; i++) {
  46         printf "%s", get_char_of_state(substr(board, i, 1));
  47
  48         if (i % x == 0) {
  49             printf "\n"
  50         }
  51     };
  52
  53     do_print_border(x)
  54 }
  55
  56
  57 function get_new_state(state, live_neighbors) {
  58     if (state == 1 && live_neighbors < 2) {
  59         return 0
  60     } else if (state == 1 && live_neighbors < 4) {
  61         return 1
  62     } else if (state == 1 && live_neighbors > 3) {
  63         return 0
  64     } else if (state == 0 && live_neighbors == 3) {
  65         return 1
  66     } else {
  67         return state
  68     }
  69 }
  70
  71
  72 function get_new_generation(x, n, board) {
  73     offsets["N" ] =  - x     ;
  74     offsets["NE"] =  -(x - 1);
  75     offsets["E" ] =        1 ;
  76     offsets["SE"] =    x + 1 ;
  77     offsets["S" ] =    x     ;
  78     offsets["SW"] =    x - 1 ;
  79     offsets["W" ] =      - 1 ;
  80     offsets["NW"] =  -(x + 1);
  81
  82     new_board = "";
  83
  84     for (cell_id=1; cell_id <= n; cell_id++) {
  85         cell_state = substr(board, cell_id, 1);
  86         live_neighbors = 0;
  87
  88         for (direction in offsets) {
  89             neighbor_id = offsets[direction] + cell_id;
  90
  91             # -----------------------------------------------------------------
  92             # Real neighbors within boundaries, ghosts beyond that!
  93             # -----------------------------------------------------------------
  94             if ((neighbor_id >= 1) && (neighbor_id <= n)) {
  95                 neighbor_state = substr(board, neighbor_id, 1)
  96             } else {
  97                 neighbor_state = get_random_state()
  98             };
  99
 100             live_neighbors += neighbor_state
 101         }
 102
 103         new_cell_state = get_new_state(cell_state, live_neighbors);
 104         new_board = sprintf("%s%d", new_board, new_cell_state)
 105     };
 106
 107     return new_board
 108 }
 109
 110
 111 function life() {
 112     "stty size" | getline stty_size_out;
 113     split(stty_size_out, stty_size);
 114
 115     x = stty_size[2];
 116     y = stty_size[1] - 3;  # Minus 1 char for each: border, border, cursor
 117     n = x * y;
 118
 119     board = get_init_board(n);
 120
 121     while (1) {
 122         do_print_board(x, n, board);
 123         board = get_new_generation(x, n, board)
 124     }
 125 }
 126
 127
 128 BEGIN {life()}