conway.c - conway

(211 lines)
   1 // A console conway's game of life program by Bruce Hill
   2 // Released under the MIT license, see LICENSE for details.
   3 #include <fcntl.h>
   4 #include <signal.h>
   5 #include <stdio.h>
   6 #include <stdlib.h>
   7 #include <string.h>
   8 #include <sys/ioctl.h>
   9 #include <sys/random.h>
  10 #include <termios.h>
  11 #include <unistd.h>
  12 
  13 #define CELL(cells, x, y) cells[(((y)+H) % H)*W + (((x)+W) % W)]
  14 
  15 static char rules[2][9] = {{0,0,0,1,0,0,0,0,0}, {0,0,1,1,0,0,0,0,0}};
  16 static unsigned int W = 0, H = 0;
  17 static char alive_color[64] = "\033[47m", dead_color[64] = "\033[0m";
  18 int ttyin_fd = -1;
  19 
  20 static void update(FILE *out, const char *cells, char *future_cells)
  21 {
  22     const char *color = NULL;
  23     for (int y = 0; y < H; y++) {
  24         fprintf(out, "\033[%d;1H", y+1);
  25         for (int x = 0; x < W; x++) {
  26             int neighbors =
  27                 CELL(cells,x-1,y-1) + CELL(cells,x,y-1) + CELL(cells,x+1,y-1)
  28                 + CELL(cells,x-1,y) + CELL(cells,x+1,y)
  29                 + CELL(cells,x-1,y+1) + CELL(cells,x,y+1) + CELL(cells,x+1,y+1);
  30             CELL(future_cells, x, y) = rules[CELL(cells, x, y)][neighbors];
  31             if (CELL(future_cells, x, y) && color != alive_color) {
  32                 fputs(alive_color, out);
  33                 color = alive_color;
  34             } else if (!CELL(future_cells, x, y) && color != dead_color) {
  35                 fputs(dead_color, out);
  36                 color = dead_color;
  37             }
  38             fputs("  ", out);
  39         }
  40     }
  41     fputs("\033[0m", out);
  42     fflush(out);
  43 }
  44 
  45 static void update_term_size(int sig)
  46 {
  47     (void)sig;
  48     struct winsize sz = {0};
  49     ioctl(ttyin_fd, TIOCGWINSZ, &sz);
  50     W = sz.ws_col / 2;
  51     H = sz.ws_row;
  52 }
  53 
  54 static int gethexrgb(const char *str, int *r, int *g, int *b)
  55 {
  56     if (str[0] == '#') ++str;
  57     if (strlen(str) == 3) {
  58         if (sscanf(str, "%01X%01X%01X", r, g, b) != 3)
  59             return 0;
  60         *r *= 16; *g *= 16; *b *= 16;
  61         return 3;
  62     } else {
  63         return sscanf(str, "%02X%02X%02X", r, g, b);
  64     }
  65 }
  66 
  67 int main(int argc, char **argv) {
  68     int ret = 0;
  69     for (int i = 1; i < argc; i++) {
  70         if (strcmp(argv[i], "--help") == 0 || strcmp(argv[i], "-h") == 0) {
  71           usage:
  72             fprintf(stderr, "Conway's Game of Life Viewer\n"
  73                    "Usage: conway [-S <survival rules>] [-B <birth rules>] [-A <alive RGB hex>] [-D <dead RGB hex>]\n");
  74             return ret;
  75         } else if (strcmp(argv[i], "-B") == 0) {
  76             if (i + 1 >= argc) goto usage;
  77             memset(rules[0], 0, sizeof(rules[0]));
  78             for (char *p = argv[++i]; *p; p++)
  79                 if ('0' <= *p && *p <= '8')
  80                     rules[0][*p - '0'] = 1;
  81         } else if (strcmp(argv[i], "-S") == 0) {
  82             if (i + 1 >= argc) goto usage;
  83             memset(rules[1], 0, sizeof(rules[1]));
  84             for (char *p = argv[++i]; *p; p++)
  85                 if ('0' <= *p && *p <= '8')
  86                     rules[1][*p - '0'] = 1;
  87         } else if (strcmp(argv[i], "-A") == 0) {
  88             if (i + 1 >= argc) goto usage;
  89             int r,g,b;
  90             if (gethexrgb(argv[++i], &r, &g, &b) != 3) goto usage;
  91             sprintf(alive_color, "\033[48;2;%d;%d;%dm", r,g,b);
  92         } else if (strcmp(argv[i], "-D") == 0) {
  93             int r,g,b;
  94             if (gethexrgb(argv[++i], &r, &g, &b) != 3) goto usage;
  95             sprintf(dead_color, "\033[48;2;%d;%d;%dm", r,g,b);
  96         } else {
  97             goto usage;
  98         }
  99     }
 100 
 101     ttyin_fd = open("/dev/tty", O_RDONLY | O_NONBLOCK);
 102     if (ttyin_fd < 0) {
 103         fprintf(stderr, "Couldn't open terminal input.\n");
 104         return 1;
 105     }
 106     FILE *tty_out = fopen("/dev/tty", "w");
 107     if (!tty_out) {
 108         fprintf(stderr, "Couldn't open terminal output.\n");
 109         return 1;
 110     }
 111 
 112     struct termios orig_termios, termios;
 113     tcgetattr(fileno(tty_out), &orig_termios);
 114     memcpy(&termios, &orig_termios, sizeof(termios));
 115     cfmakeraw(&termios);
 116     termios.c_cc[VMIN] = 10;
 117     termios.c_cc[VTIME] = 1;
 118     if (tcsetattr(fileno(tty_out), TCSAFLUSH, &termios) == -1)
 119         return 1;
 120 
 121     struct winsize wsize = {0};
 122     fputs("\033[?25l" // Hide cursor
 123           "\033[?1049;" // Use alternate screen
 124           "1000;" // Enable mouse x/y on press
 125           "1002;" // Enable mouse dragging
 126           "1006"  // Use mouse SGR mode
 127           "h", tty_out);
 128 
 129     update_term_size(0);
 130     signal(SIGWINCH, update_term_size);
 131 
 132     char *buffers[2];
 133     int flipflop = 0, prev_W = W, prev_H = H;
 134   resize:
 135     // TODO: handle resize in SIGWINCH handler
 136     // Cells are 2 characters wide so they look square
 137     buffers[0] = calloc(W*H, sizeof(char));
 138     buffers[1] = calloc(W*H, sizeof(char));
 139     for (int x = 0; x < W; x++)
 140         for (int y = 0; y < H; y++)
 141             CELL(buffers[flipflop], x, y) = random() % 2;
 142 
 143     int draw_mode = 1, paused = 0;
 144     fputs("\033[2J", tty_out);
 145     while (1) {
 146         if (prev_W != W || prev_H != H) {
 147             prev_W = W, prev_H = H;
 148             free(buffers[0]);
 149             free(buffers[1]);
 150             buffers[0] = calloc(W*H, sizeof(char));
 151             buffers[1] = calloc(W*H, sizeof(char));
 152             goto resize;
 153         }
 154         if (!paused) {
 155             update(tty_out, buffers[flipflop], buffers[!flipflop]);
 156             flipflop = !flipflop;
 157         }
 158       present:
 159         usleep(60000);
 160         int drew = 0;
 161         char key;
 162         while (read(ttyin_fd, &key, 1) == 1) {
 163             switch (key) {
 164             case '\3': ret = 1; goto done; // CTRL-C
 165             case 'q': goto done;
 166             case 'p': paused ^= 1; break;
 167             case 'c': memset(buffers[flipflop], 0, W*H); break;
 168             case 'r':
 169                 getrandom(buffers[flipflop], W*H, 0);
 170                 for (int i = 0; i < W*H; i++)
 171                     buffers[flipflop][i] &= 0x1;
 172                 break;
 173             case ' ': draw_mode ^= 1; break;
 174             case '<': { // Mouse dragging/clicks
 175                 int buttons = 0, x = 0, y = 0;
 176                 char buf;
 177                 while (read(ttyin_fd, &buf, 1) == 1 && '0' <= buf && buf <= '9')
 178                     buttons = buttons * 10 + (buf - '0');
 179                 if (buf != ';') return -1;
 180                 while (read(ttyin_fd, &buf, 1) == 1 && '0' <= buf && buf <= '9')
 181                     x = x * 10 + (buf - '0');
 182                 if (buf != ';') return -1;
 183                 while (read(ttyin_fd, &buf, 1) == 1 && '0' <= buf && buf <= '9')
 184                     y = y * 10 + (buf - '0');
 185                 if (buf != 'm' && buf != 'M') return -1;
 186                 if ((buttons & (~32)) == 0 && ((x-1)/2) < W) {
 187                     CELL(buffers[flipflop], (x-1)/2, y-1) = draw_mode;
 188                     fprintf(tty_out, "\033[%d;%dH%s  \033[0m",
 189                             y, 2*((x-1)/2)+1,
 190                             draw_mode ? alive_color : dead_color);
 191                     fflush(tty_out);
 192                     drew = 1;
 193                 }
 194                 break;
 195             }
 196             }
 197         }
 198         if (drew) goto present;
 199     }
 200   done:
 201     tcsetattr(fileno(tty_out), TCSAFLUSH, &orig_termios);
 202     fputs("\033[?25h" // Show cursor
 203           "\033[?1049;" // Back to normal screen
 204           "1000;" // Disable mouse x/y reporting
 205           "1002;" // Disable mouse dragging
 206           "1006" // Disable mouse SGR mode
 207           "l", tty_out);
 208     fclose(tty_out);
 209     close(ttyin_fd);
 210     return ret;
 211 }