From ce3ff4797ebccb4a969c6f0273ec200daf265aa9 Mon Sep 17 00:00:00 2001
From: Bruce Hill <bruce@bruce-hill.com>
Date: Mon, 18 Mar 2019 16:44:35 -0700
Subject: [PATCH] Tidying up

---
 conway.c | 83 +++++++++++++++++++++++++-------------------------------
 1 file changed, 37 insertions(+), 46 deletions(-)

diff --git a/conway.c b/conway.c
index c3c1b7a..6b05a2b 100644
--- a/conway.c
+++ b/conway.c
@@ -1,35 +1,28 @@
 // A console conway's game of life program by Bruce Hill
 // Released under the MIT license, see LICENSE for details.
-// This file contains the main code for the table viewer.
-
 #include <stdio.h>
 #include <string.h>
 #include <stdlib.h>
 #include <termbox.h>
 #include <unistd.h>
 
-static char survive[9] = {0,0,1,1,0,0,0,0,0};
-static char birth[9] =   {0,0,0,1,0,0,0,0,0};
+#define CELL(cells, x, y) cells[((y) % H)*W + ((x) % W)]
+
+static char rules[2][9] = {{0,0,0,1,0,0,0,0,0}, {0,0,1,1,0,0,0,0,0}};
+static int W, H;
 
 static void update(const char *cells, char *future_cells)
 {
-    int W = tb_width()/2, H = tb_height();
     for (int y = 0; y < H; y++) {
         for (int x = 0; x < W; x++) {
-            int neighbors = (
-                cells[(y-1 % H)*W + (x-1 % W)] +
-                cells[(y-1 % H)*W + (x % W)] +
-                cells[(y-1 % H)*W + (x+1 % W)] +
-                cells[y*W + (x-1 % W)] +
-                cells[y*W + (x+1 % W)] +
-                cells[(y+1 % H)*W + (x-1 % W)] +
-                cells[(y+1 % H)*W + (x % W)] +
-                cells[(y+1 % H)*W + (x+1 % W)]
-            );
-            future_cells[y*W + x] = cells[y*W + x] ? survive[neighbors] : birth[neighbors];
-            if (future_cells[y*W + x] != cells[y*W + x]) {
-                tb_change_cell(2*x, y, ' ', 0, future_cells[y*W + x] ? 8 : 0);
-                tb_change_cell(2*x+1, y, ' ', 0, future_cells[y*W + x] ? 8 : 0);
+            int neighbors =
+                CELL(cells,x-1,y-1) + CELL(cells,x,y-1) + CELL(cells,x+1,y-1)
+                + CELL(cells,x-1,y) + CELL(cells,x+1,y)
+                + CELL(cells,x-1,y+1) + CELL(cells,x,y+1) + CELL(cells,x+1,y+1);
+            CELL(future_cells, x, y) = rules[CELL(cells, x, y)][neighbors];
+            if (CELL(future_cells, x, y) != CELL(cells, x, y)) {
+                tb_change_cell(2*x, y, ' ', 0, CELL(future_cells, x, y) ? 8 : 0);
+                tb_change_cell(2*x+1, y, ' ', 0, CELL(future_cells, x, y) ? 8 : 0);
             }
         }
     }
@@ -41,16 +34,16 @@ int main(int argc, char **argv) {
             printf("Conway's Game of Life Viewer\nUsage: conway [-S012345678] [-B012345678]\n");
             return 0;
         } else if (strncmp(argv[i], "-B", 2) == 0) {
-            memset(birth, 0, sizeof(birth));
+            memset(rules[0], 0, sizeof(rules[0]));
             for (char *p = &argv[i][2]; *p; p++) {
                 if ('0' <= *p && *p <= '8')
-                    birth[*p - '0'] = 1;
+                    rules[0][*p - '0'] = 1;
             }
         } else if (strncmp(argv[i], "-S", 2) == 0) {
-            memset(survive, 0, sizeof(survive));
+            memset(rules[1], 0, sizeof(rules[1]));
             for (char *p = &argv[i][2]; *p; p++) {
                 if ('0' <= *p && *p <= '8')
-                    survive[*p - '0'] = 1;
+                    rules[1][*p - '0'] = 1;
             }
         }
     }
@@ -62,54 +55,52 @@ int main(int argc, char **argv) {
     }
     tb_select_input_mode(TB_INPUT_MOUSE);
 
-    int flipflop = 0;
     // Cells are 2 characters wide so they look square
-    int W = tb_width()/2, H = tb_height();
     char *buffers[2];
+    int flipflop = 0;
   resize:
+    W = tb_width()/2, H = tb_height();
     buffers[0] = calloc(W*H, sizeof(char));
     buffers[1] = calloc(W*H, sizeof(char));
-    for (int x = 0; x < W; x++) {
-        for (int y = 0; y < H; y++) {
-            buffers[flipflop][y*W+x] = random() % 2;
-        }
-    }
+    for (int x = 0; x < W; x++)
+        for (int y = 0; y < H; y++)
+            CELL(buffers[flipflop], x, y) = random() % 2;
 
+    int draw_mode = 1;
     tb_clear();
     while (1) {
         update(buffers[flipflop], buffers[!flipflop]);
         flipflop = !flipflop;
+      present:
         tb_present();
         usleep(60000);
         struct tb_event ev;
+        int drew = 0;
         while (tb_peek_event(&ev, 0)) {
             switch (ev.type) {
                 case TB_EVENT_RESIZE:
-                    W = ev.w/2, H = ev.h;
+                    free(buffers[0]);
+                    free(buffers[1]);
                     goto resize;
 
                 case TB_EVENT_KEY:
-                    switch (ev.key) {
-                        case TB_KEY_ESC:
-                            if (tb_peek_event(&ev, 50) == 0)
-                                goto done;
-                            else break;
-                    }
-                    switch (ev.ch) {
-                        case 'q':
-                            goto done;
-                    }
+                    if (ev.key == TB_KEY_ESC && tb_peek_event(&ev, 50) == 0)
+                        goto done;
+                    else if (ev.ch == 'q')
+                        goto done;
+                    else if (ev.key == TB_KEY_SPACE)
+                        draw_mode = !draw_mode;
                     break;
 
                 case TB_EVENT_MOUSE:
-                    buffers[flipflop][ev.y*W + ev.x/2] = !buffers[flipflop][ev.y*W + ev.x/2];
-                    tb_change_cell(2*(ev.x/2), ev.y, ' ', 0, buffers[flipflop][ev.y*W + ev.x/2] ? 8 : 0);
-                    tb_change_cell(2*(ev.x/2)+1, ev.y, ' ', 0, buffers[flipflop][ev.y*W + ev.x/2] ? 8 : 0);
-                    tb_present();
-                    usleep(10000);
+                    CELL(buffers[flipflop], ev.x/2, ev.y) = draw_mode;
+                    tb_change_cell(2*(ev.x/2), ev.y, ' ', 0, draw_mode ? 8 : 0);
+                    tb_change_cell(2*(ev.x/2)+1, ev.y, ' ', 0, draw_mode ? 8 : 0);
+                    drew = 1;
                     break;
             }
         }
+        if (drew) goto present;
     }
   done:
     tb_shutdown();