update INIT_RATIO

[lifeboot.git] / prototype.c

diff --git a/prototype.c b/prototype.c
index c0dd9870b58627b7b7b23bb6634895d8af387b6f..c9c2afa8796467d30fceb93c72d64b402d1c2e06 100644 (file)
--- a/prototype.c
+++ b/prototype.c
@@ -1,4 +1,8 @@
 #include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <time.h>
 
 #define COLS 80
 #define ROWS 25
@@ -6,10 +10,14 @@
 #define DEAD ' '
 #define ALIVE '#'
 
+#define INIT_RATIO 4
+
 #define STR(x) _STR(x)
 #define _STR(x) #x
 
-char grid[COLS * ROWS] = { [0 ... (COLS*ROWS-1)] = ALIVE };
+static void clearscr() {
+  printf("\e[1;1H\e[2J");
+}
 
 static void print_row(char row[COLS]) {
   printf("%." STR(COLS) "s\n", row);
@@ -20,13 +28,74 @@ static void print_grid(char grid[COLS * ROWS]) {
     print_row(grid + i * COLS);
 }
 
-static void clearscr() {
-  printf("\e[1;1H\e[2J");
+static void init_grid(char grid[COLS * ROWS]) {
+  for (int i = 0; i < COLS * ROWS; i++) {
+    if (rand() % INIT_RATIO)
+      grid[i] = DEAD;
+    else
+      grid[i] = ALIVE;
+  }
+}
+
+static char get_state(char grid[COLS * ROWS], int row, int col) {
+  if (row < 0 || row >= ROWS || col < 0 || col >= COLS)
+    return DEAD;
+
+  return grid[row * COLS + col];
+}
+
+static int alive_neighbours(char grid[COLS * ROWS], int idx) {
+  int row = idx / COLS;
+  int col = idx % COLS;
+  int neighbours = 0;
+
+  for (int i = -1; i <= 1; i++)
+    for (int j = -1; j <= 1; j++)
+      if (get_state(grid, row + i, col + j) == ALIVE)
+        neighbours++;
+
+  if (get_state(grid, row, col) == ALIVE)
+    neighbours--;
+
+  return neighbours;
+}
+
+static char next_state(char grid[COLS * ROWS], int idx) {
+  int n = alive_neighbours(grid, idx);
+
+  if (get_state(grid, idx / COLS, idx % COLS) == ALIVE) {
+    if (n < 2 || n > 3)
+      return DEAD;
+
+    return ALIVE;
+  }
+
+  if (n == 3)
+    return ALIVE;
+
+  return DEAD;
+}
+
+static void update_grid(char grid[COLS * ROWS]) {
+  char new[COLS * ROWS];
+
+  for (int i = 0; i < COLS * ROWS; i++)
+    new[i] = next_state(grid, i);
+
+  memcpy(grid, new, COLS * ROWS);
 }
 
 int main () {
-  clearscr();
-  print_grid(grid);
+  char grid[COLS * ROWS];
+
+  srand(time(0));
+  init_grid(grid);
+
+  do {
+    clearscr();
+    print_grid(grid);
+    update_grid(grid);
+  } while (getchar() != 'q');
 
   return 0;
 }