prototype.c

   1 #include <stdio.h>
   2 #include <stdlib.h>
   3 #include <unistd.h>
   4 #include <string.h>
   5 #include <time.h>
   6
   7 #define COLS 80
   8 #define ROWS 25
   9
  10 #define DEAD ' '
  11 #define ALIVE '#'
  12
  13 #define INIT_RATIO 10
  14
  15 #define STR(x) _STR(x)
  16 #define _STR(x) #x
  17
  18 static void clearscr() {
  19   printf("\e[1;1H\e[2J");
  20 }
  21
  22 static void print_row(char row[COLS]) {
  23   printf("%." STR(COLS) "s\n", row);
  24 }
  25
  26 static void print_grid(char grid[COLS * ROWS]) {
  27   for (int i = 0; i < ROWS; i++)
  28     print_row(grid + i * COLS);
  29 }
  30
  31 static void init_grid(char grid[COLS * ROWS]) {
  32   for (int i = 0; i < COLS * ROWS; i++) {
  33     if (rand() % INIT_RATIO)
  34       grid[i] = DEAD;
  35     else
  36       grid[i] = ALIVE;
  37   }
  38 }
  39
  40 static char get_state(char grid[COLS * ROWS], int idx) {
  41   if (idx < 0 || idx >= COLS * ROWS)
  42     return DEAD;
  43
  44   return grid[idx];
  45 }
  46
  47 static int alive_neighbours(char grid[COLS * ROWS], int idx) {
  48   int neighbours = 0;
  49
  50   for (int i = -1; i <= 1; i++) /* row */
  51     for (int j = -1; j <= 1; j++) /* col */
  52       if (get_state(grid, idx + i * COLS + j) == ALIVE)
  53         neighbours++;
  54
  55   if (get_state(grid, idx) == ALIVE)
  56     neighbours--;
  57
  58   return neighbours;
  59 }
  60
  61 static char next_state(char grid[COLS * ROWS], int idx) {
  62   int n = alive_neighbours(grid, idx);
  63
  64   if (get_state(grid, idx) == ALIVE) {
  65     if (n < 2 || n > 3)
  66       return DEAD;
  67
  68     return ALIVE;
  69   }
  70
  71   if (n == 3)
  72     return ALIVE;
  73
  74   return DEAD;
  75 }
  76
  77 static void update_grid(char grid[COLS * ROWS]) {
  78   char new[COLS * ROWS];
  79
  80   for (int i = 0; i < COLS * ROWS; i++)
  81     new[i] = next_state(grid, i);
  82
  83   memcpy(grid, new, COLS * ROWS);
  84 }
  85
  86 int main () {
  87   char grid[COLS * ROWS];
  88
  89   srand(time(0));
  90   init_grid(grid);
  91
  92   for (;;) {
  93     clearscr();
  94     print_grid(grid);
  95     update_grid(grid);
  96     getchar();
  97   }
  98
  99   return 0;
 100 }