viiper.c

   1 /*******************************************************************************
   2  viiper 0.1
   3  By Tobias Girstmair, 2018
   4
   5  ./viiper 40x25
   6  (see ./viiper -h for full list of options)
   7
   8  KEYBINDINGS:  - hjkl to move
   9                - p to pause and resume
  10                - r to restart
  11                - q to quit
  12                - (see `./minesviiper -h' for all keybindings)
  13
  14  GNU GPL v3, see LICENSE or https://www.gnu.org/licenses/gpl-3.0.txt
  15 *******************************************************************************/
  16
  17
  18 #define _POSIX_C_SOURCE 2 /*for getopt and sigaction in c99, sigsetjmp*/
  19 #include <setjmp.h>
  20 #include <signal.h>
  21 #include <stdio.h>
  22 #include <stdlib.h>
  23 #include <string.h>
  24 #include <sys/ioctl.h>
  25 #include <sys/time.h>
  26 #include <termios.h>
  27 #include <time.h>
  28 #include <unistd.h>
  29
  30 #include "viiper.h"
  31 #include "schemes.h"
  32
  33 #define MIN(a,b) (a>b?b:a)
  34 #define MAX(a,b) (a>b?a:b)
  35 #define CLAMP(a,m,M) (a<m?m:(a>M?M:a))
  36 #define printm(n, s) for (int _loop = 0; _loop < n; _loop++) fputs (s, stdout)
  37 #define print(str) fputs (str?str:"", stdout)
  38 #define CTRL_ 0x1F &
  39
  40 #define OPPOSITE(dir) ( \
  41         dir == EAST  ? WEST  :   \
  42         dir == WEST  ? EAST  :   \
  43         dir == NORTH ? SOUTH :   \
  44         dir == SOUTH ? NORTH : -1)
  45
  46 #define COL_OFFSET 1
  47 #define LINE_OFFSET 1
  48 #define LINES_AFTER 1
  49 #define CW op.sch->cell_width
  50
  51 #define SPEEDUP_AFTER 100 /* increment speed every n points */
  52 #define BONUS_INTERVAL 90 /* how often a bonus item is spawned */
  53 #define BONUS_DURATION 15 /* how long one can catch the bonus */
  54 #define BONUS_WARN      5 /* how long before the removal to warn */
  55
  56 struct game {
  57         int w; /* field width */
  58         int h; /* field height */
  59         int d; /* direction the snake is looking */
  60         int p; /* score */
  61         float v; /* velocity in moves per second */
  62         time_t t; /* time of game start */
  63         struct snake* s; /* snek */
  64         struct item* i; /* items (food, boni) */
  65         struct bonus {
  66                 int t; /* bonus type (bitmask based on enum bonus_value) */
  67                 time_t n; /* time of next bonus item spawn */
  68                 time_t w; /* time of wall-wrap end */
  69         } b; /* bonus-related values */
  70         struct directions {
  71                 int h; /* write head */
  72                 int n; /* number of elements */
  73                 int c[16];
  74         } k; /* ring buffer for direction events */
  75 } g;
  76
  77 struct opt {
  78         int l; /* initial snake length */
  79         int s; /* initial snake speed */
  80         struct scheme* sch;
  81 } op;
  82
  83 jmp_buf game_over;
  84
  85 int main (int argc, char** argv) {
  86         /* defaults: */
  87         g.w = 30;
  88         g.h = 20;
  89         op.l = 10;
  90         op.s = 8;
  91         op.sch = &unic0de;
  92
  93         int optget;
  94         opterr = 0; /* don't print message on unrecognized option */
  95         while ((optget = getopt (argc, argv, "+s:l:dh")) != -1) {
  96                 switch (optget) {
  97                 case 's':
  98                         op.s = atof(optarg);
  99                         if (op.s < 1) {
 100                                 fprintf (stderr, "speed must be >= 1\n");
 101                                 return 1;
 102                         }
 103                         break;
 104                 case 'l':
 105                         op.l = atoi(optarg);
 106                         if (op.s < 2 || op.s > g.w*g.h-1) {
 107                                 fprintf (stderr, "length must be >= 2 and < W*H\n");
 108                                 return 1;
 109                         }
 110                         break;
 111                 case 'h':
 112                 default:
 113                         fprintf (stderr, SHORTHELP LONGHELP, argv[0]);
 114                         return !(optget=='h');
 115                 }
 116         } if (optind < argc) { /* parse Fieldspec */
 117                 int n = sscanf (argv[optind], "%dx%d", &g.w, &g.h);
 118
 119                 if (n < 2) {
 120                         fprintf(stderr,"FIELDSIZE is WxH (width 'x' height)\n");
 121                         return 1;
 122                 }
 123         }
 124
 125         clamp_fieldsize();
 126
 127         srand(time(0));
 128         signal_setup();
 129         screen_setup(1);
 130         atexit (*quit);
 131
 132         char* end_screen_msg = "";
 133 restart:
 134         switch (sigsetjmp(game_over, 1)) {
 135         case GAME_INIT:
 136         case GAME_START:
 137                 viiper();
 138                 break; /* function doesn't return, but `-Wextra' complains */
 139         case GAME_OVER:
 140                 end_screen_msg = " GAME  OVER ";
 141                 goto end_screen;
 142         case GAME_WON:
 143                 end_screen_msg = "CONGRATULATIONS!";
 144                 goto end_screen;
 145 end_screen:
 146                 timer_setup(0);
 147                 show_playfield();
 148                 for (;;) switch (end_screen(end_screen_msg)) {
 149                 case 'r': goto restart;
 150                 case 'q': goto quit;
 151                 case CTRL_'L':
 152                         screen_setup(1);
 153                         show_playfield();
 154                         break;
 155                 default: continue;
 156                 }
 157         case GAME_EXIT:
 158                 goto quit;
 159         }
 160
 161 quit:
 162         return 0;
 163 }
 164
 165 int viiper(void) {
 166         init_snake();
 167         show_playfield ();
 168         g.d = EAST;
 169         g.v = op.s;
 170
 171         timer_setup(1);
 172         g.t = time(NULL);
 173         g.p = 0;
 174         g.k.n = 0;
 175         g.b.n = time(NULL) + BONUS_INTERVAL;
 176         g.b.t = 0;
 177
 178         spawn_item(FOOD, rand() % NUM_FOODS, NULL);
 179
 180         for(;;) {
 181                 switch (getctrlseq()) {
 182                 case 'h': case CTRSEQ_CURSOR_LEFT: append_movement(WEST); break;
 183                 case 'j': case CTRSEQ_CURSOR_DOWN: append_movement(SOUTH);break;
 184                 case 'k': case CTRSEQ_CURSOR_UP:   append_movement(NORTH);break;
 185                 case 'l': case CTRSEQ_CURSOR_RIGHT:append_movement(EAST); break;
 186                 case 'p': pause_game(); break;
 187                 case 'r': siglongjmp(game_over, GAME_START);
 188                 case 'q': siglongjmp(game_over, GAME_EXIT);
 189                 case CTRL_'L':
 190                         screen_setup(1);
 191                         show_playfield();
 192                         break;
 193                 case 0x02: /* STX; gets sent when returning from SIGALRM */
 194                         continue;
 195                 }
 196         }
 197
 198 }
 199
 200 #define pop_dir() (g.k.n? g.k.c[(16+g.k.h-g.k.n--)%16] : NONE)
 201 void snake_advance (void) {
 202         int respawn = 0;
 203         struct item* i; /*temporary item (defined here to respawn at the end) */
 204         int new_dir = pop_dir();
 205         /* switch direction if new one is in the buffer and it won't kill us: */
 206         if (new_dir && g.d != OPPOSITE(new_dir)) g.d = new_dir;
 207
 208         int new_row = g.s->r +(g.d==SOUTH) -(g.d==NORTH);
 209         int new_col = g.s->c +(g.d==EAST)  -(g.d==WEST);
 210
 211         /* detect food hit and spawn a new food */
 212         for (i = g.i; i; i = i->next) {
 213                 if (i->r == new_row && i->c == new_col) {
 214                         consume_item (i);
 215
 216                         switch (i->t) {
 217                         case FOOD: respawn = 1; break;
 218                         case BONUS: remove_bonus(i); break;
 219                         }
 220                         break;
 221                 }
 222         }
 223
 224         if (g.b.t & 1<<BONUS_WRAP) {
 225           if (new_row >= g.h) new_row = 0;
 226           if (new_col >= g.w) new_col = 0;
 227           if (new_row < 0) new_row = g.h-1;
 228           if (new_col < 0) new_col = g.w-1;
 229         } else {
 230           if (new_row >= g.h || new_col >= g.w || new_row < 0 || new_col < 0)
 231                 siglongjmp(game_over, GAME_OVER);
 232         }
 233
 234         struct snake* new_head;
 235         struct snake* new_tail; /* former second-to-last element */
 236         for (new_tail = g.s; new_tail->next->next; new_tail = new_tail->next)
 237                 /*use the opportunity of looping to check if we eat ourselves:*/
 238                 if(new_tail->next->r == new_row && new_tail->next->c == new_col)
 239                         siglongjmp(game_over, GAME_OVER);
 240         int old_tail[2] = {new_tail->next->r, new_tail->next->c};/*gets erased*/
 241         new_head = new_tail->next; /* reuse element instead of malloc() */
 242         new_tail->next = NULL;
 243
 244         new_head->r = new_row;
 245         new_head->c = new_col;
 246         new_head->next = g.s;
 247
 248         g.s = new_head;
 249
 250         /* bonus mode(s) still active? */
 251         if (g.b.t&1<<BONUS_WRAP && g.b.w < time(NULL)) {
 252                 g.b.t &= ~(1<<BONUS_WRAP);
 253                 show_playfield();
 254         }
 255
 256         if (respawn) spawn_item(FOOD, rand() % NUM_FOODS, i);
 257         draw_sprites (old_tail[0], old_tail[1]);
 258 }
 259
 260 void spawn_item (int type, int value, struct item* p_item) {
 261         int row, col;
 262         char occupied[g.w][g.h]; int snake_len = 0;
 263         memset(*occupied, 0, g.w*g.h);
 264 try_again:
 265         row = rand() % g.h;
 266         col = rand() % g.w;
 267         if (snake_len >= g.w*g.h-1) siglongjmp(game_over, GAME_WON);
 268         /* loop through snake to check if we aren't on it */
 269         if (occupied[row][col]) goto try_again; /* shortcut */
 270         for (struct snake* s = g.s; s; s = s->next)
 271                 if (s->r == row && s->c == col) {
 272                         occupied[s->r][s->c] = 1; snake_len++;
 273                         goto try_again;
 274                 }
 275
 276         /* if we got a item buffer reuse it, otherwise create a new one: */
 277         struct item* new_item;
 278         if (p_item) new_item = p_item;
 279         else new_item = malloc (sizeof(struct item));
 280
 281         new_item->r = row;
 282         new_item->c = col;
 283         new_item->t = type;
 284         new_item->v = value;
 285         new_item->s = time(0);
 286         if (g.i) g.i->prev = new_item;
 287         new_item->next = g.i;
 288         new_item->prev = NULL;
 289
 290         g.i = new_item;
 291 }
 292
 293 void consume_item (struct item* i) {
 294         int old_score = g.p;
 295
 296         switch (i->t) {
 297         case FOOD:
 298                 switch (i->v) {
 299                 case FOOD_5:  g.p +=  5; break;
 300                 case FOOD_10: g.p += 10; break;
 301                 case FOOD_20: g.p += 20; break;
 302                 }
 303                 snake_append(&g.s, -1, -1);
 304                 break;       /* will be reused as the head before it is drawn */
 305         case BONUS:
 306                 switch (i->v) {
 307                 case BONUS_SNIP:
 308                         for (int i = 5; i && g.s->next->next; i--) {
 309                                 struct snake* p = g.s;
 310                                 while (p->next->next) p = p->next;
 311                                 free (p->next);
 312                                 p->next = NULL;
 313                         }
 314                         show_playfield();
 315                         break;
 316                 case BONUS_GROW:
 317                         for (int i = 5; i; i--) snake_append(&g.s, -1, -1);
 318                         break;
 319                 case BONUS_SLOW:
 320                         if (g.v > 1) g.v--;
 321                         timer_setup(1);
 322                         break;
 323                 case BONUS_FAST:
 324                         g.v++;
 325                         timer_setup(1);
 326                         break;
 327                 case BONUS_WRAP:
 328                         g.b.w = time(NULL)+30;
 329                         g.b.t |= 1<<BONUS_WRAP;
 330                         show_playfield();
 331                         break;
 332                 }
 333                 g.b.n = time(NULL) + BONUS_INTERVAL; /*next bonus in x seconds*/
 334                 break;
 335         }
 336
 337         if (i->next) i->next->prev = i->prev;
 338         if (i->prev) i->prev->next = i->next;
 339         else g.i = i->next;
 340
 341         /* snake speedup every 100 points: */
 342         if (g.p/SPEEDUP_AFTER - old_score/SPEEDUP_AFTER) g.v++, timer_setup(1);
 343 }
 344
 345 void spawn_bonus(void) {
 346         for (struct item* i = g.i; i; i = i->next)
 347                 if (i->t == BONUS) { /* bonus already there */
 348                         if (((i->s+BONUS_DURATION)-time(NULL)) < 0) {
 349                                 remove_bonus(i); /* remove if over lifetime */
 350                         }
 351                         return;
 352                 }
 353         if (g.b.n < time(NULL)) { /* time to spawn item: */
 354                 spawn_item(BONUS, rand() % NUM_BONI, NULL);
 355                 g.b.n = time(NULL) + BONUS_INTERVAL + BONUS_DURATION;
 356         }
 357 }
 358
 359 void show_playfield (void) {
 360         move_ph (0,0);
 361
 362         /* top border */
 363         print(BORDER(T,L));
 364         printm (g.w, BORDER(T,C));
 365         printf ("%s\n", BORDER(T,R));
 366
 367         /* main area */
 368         for (int row = 0; row < g.h; row++)
 369                 printf ("%s%*s%s\n", BORDER(C,L), CW*g.w, "", BORDER(C,R));
 370
 371         /* bottom border */
 372         print(BORDER(B,L));
 373         printm (g.w, BORDER(B,C));
 374         print (BORDER(B,R));
 375
 376         draw_sprites (-1,-1);
 377 }
 378
 379 void draw_sprites (int erase_r, int erase_c) {
 380         /* erase old tail, if any */
 381         if (erase_r >= 0 && erase_c >= 0) {
 382                 move_ph (erase_r+LINE_OFFSET, erase_c*CW+COL_OFFSET);
 383                 printm (CW, " ");
 384         }
 385
 386         /* print snake */
 387         struct snake* last = NULL;
 388         int color = 2;
 389         for (struct snake* s = g.s; s; s = s->next) {
 390                 if (s->r < 0 || s->c < 0) continue; /*can't draw outside term.*/
 391                 move_ph (s->r+LINE_OFFSET, s->c*CW+COL_OFFSET);
 392
 393                 int predecessor = (last==NULL)?NONE:
 394                         (last->r < s->r) ? NORTH:
 395                         (last->r > s->r) ? SOUTH:
 396                         (last->c > s->c) ? EAST:
 397                         (last->c < s->c) ? WEST:NONE;
 398                 int successor = (s->next == NULL)?NONE:
 399                         (s->next->r < s->r) ? NORTH:
 400                         (s->next->r > s->r) ? SOUTH:
 401                         (s->next->c > s->c) ? EAST:
 402                         (s->next->c < s->c) ? WEST:NONE;
 403
 404                 printf ("\033[%sm", op.sch->color[color]);
 405                 print (op.sch->snake[predecessor][successor]);
 406                 printf ("\033[0m");
 407                 last = s;
 408                 color = !color;
 409         }
 410
 411         /* print item queue */
 412         for (struct item* i = g.i; i; i = i->next) {
 413                 move_ph (i->r+LINE_OFFSET, i->c*CW+COL_OFFSET);
 414                 if      (i->t == FOOD)  print(op.sch->food[i->v]);
 415                 else if (i->t == BONUS) {
 416                         if (i->s + BONUS_DURATION-BONUS_WARN < time(NULL))
 417                                 printf("\033[5m%s\033[25m", op.sch->boni[i->v]);
 418                         else print(op.sch->boni[i->v]);
 419                 }
 420         }
 421
 422         /* print score */
 423         int score_width = g.p > 9999?6:4;
 424         move_ph (0, (g.w*CW-score_width)/2-COL_OFFSET);
 425         printf ("%s %0*d %s", BORDER(S,L), score_width, g.p, BORDER(S,R));
 426 }
 427
 428 void pause_game (void) {
 429         time_t pause_start = time(NULL);
 430         time_t pause_diff;
 431         timer_setup(0);
 432
 433         move_ph (g.h/2+LINE_OFFSET, g.w*CW/2);
 434         printf ("\033[5;7m PAUSE \033[0m"); /* blinking reverse text */
 435         if (getchar() == 'q')
 436                 siglongjmp(game_over, GAME_EXIT);
 437
 438         /* update all timers, so bonus items don't get out of sync: */
 439         pause_diff = time(NULL) - pause_start;
 440         g.b.n += pause_diff;
 441         for (struct item* i = g.i; i; i = i->next)
 442                 i->s += pause_diff;
 443
 444         show_playfield();
 445         timer_setup(1);
 446 }
 447
 448 #define MOVE_POPUP(WIDTH, LINE) \
 449         move_ph(g.h/2+LINE_OFFSET-1+LINE,(g.w*op.sch->display_width-WIDTH)/2)
 450         //TODO: macro does not correctly centre in DEC mode
 451 int end_screen(char* message) {
 452         int msg_w = strlen(message);
 453         MOVE_POPUP(msg_w, -1);
 454         print(BORDER(T,L));
 455         printm ((msg_w+2)/op.sch->display_width, BORDER(T,C));
 456         print (BORDER(T,R));
 457
 458         MOVE_POPUP(msg_w, 0);
 459         printf("%s %s %s", BORDER(C,L), message, BORDER(C,R));
 460         MOVE_POPUP(msg_w, 1);
 461         //TODO: requires shifting into ASCII/multilingual charset in DEC mode -- put graphics into upper/right charset?
 462         printf("%s `r' restart%*s%s", BORDER(C,L), msg_w-10, "", BORDER(C,R));
 463         MOVE_POPUP(msg_w, 2);
 464         printf("%s `q' quit%*s%s", BORDER(C,L), msg_w-7, "", BORDER(C,R));
 465
 466         MOVE_POPUP(msg_w, 3);
 467         print(BORDER(B,L));
 468         printm ((msg_w+2)/op.sch->display_width, BORDER(B,C));
 469         print (BORDER(B,R));
 470         fflush(stdout);
 471
 472         return getctrlseq();
 473 }
 474
 475 void snake_append (struct snake** s, int row, int col) {
 476         struct snake* new = malloc (sizeof(struct snake));
 477         new->r = row;
 478         new->c = col;
 479         new->next = NULL;
 480
 481         if (*s) {
 482                 struct snake* p = *s;
 483                 while (p->next) p = p->next;
 484                 p->next = new;
 485         } else {
 486                 *s = new;
 487         }
 488 }
 489
 490 void remove_bonus (struct item*  i) {
 491         if (i->next) i->next->prev = i->prev;
 492         if (i->prev) i->prev->next = i->next;
 493         else g.i = i->next;
 494
 495         draw_sprites (i->r, i->c); /* overwrite sprite */
 496
 497         free(i);
 498 }
 499
 500 #define free_ll(head) do{ \
 501         while (head) { \
 502                 void* tmp = head; \
 503                 head = head->next; \
 504                 free(tmp); \
 505         } \
 506         head = NULL; \
 507 }while(0)
 508
 509 void init_snake() {
 510         free_ll(g.s);
 511         free_ll(g.i);
 512
 513         int direction = WEST;
 514         int r = g.h/2;
 515         int c = g.w/2;
 516         int min_r = 0;
 517         int max_r = g.h-1;
 518         int min_c = 0;
 519         int max_c = g.w-1;
 520         for (int i = 0; i < op.l; i++) {
 521                 switch (direction) {
 522                 case NORTH: r--; if(r <= min_r){direction=EAST; min_r++;}break;
 523                 case EAST:  c++; if(c >= max_c){direction=SOUTH;max_c--;}break;
 524                 case SOUTH: r++; if(r >= max_r){direction=WEST; max_r--;}break;
 525                 case WEST:  c--; if(c <= min_c){direction=NORTH;min_c++;}break;
 526                 }
 527
 528                 snake_append(&g.s, r, c);
 529         }
 530 }
 531
 532 void quit (void) {
 533         screen_setup(0);
 534         free_ll(g.s);
 535         free_ll(g.i);
 536 }
 537
 538 enum esc_states {
 539         START,
 540         ESC_SENT,
 541         CSI_SENT,
 542         MOUSE_EVENT,
 543 };
 544 int getctrlseq (void) {
 545         int c;
 546         int state = START;
 547         while ((c = getchar()) != EOF) {
 548                 switch (state) {
 549                 case START:
 550                         switch (c) {
 551                         case '\033': state=ESC_SENT; break;
 552                         default: return c;
 553                         }
 554                         break;
 555                 case ESC_SENT:
 556                         switch (c) {
 557                         case '[': state=CSI_SENT; break;
 558                         default: return CTRSEQ_INVALID;
 559                         }
 560                         break;
 561                 case CSI_SENT:
 562                         switch (c) {
 563                         case 'A': return CTRSEQ_CURSOR_UP;
 564                         case 'B': return CTRSEQ_CURSOR_DOWN;
 565                         case 'C': return CTRSEQ_CURSOR_RIGHT;
 566                         case 'D': return CTRSEQ_CURSOR_LEFT;
 567                         default: return CTRSEQ_INVALID;
 568                         }
 569                         break;
 570                 default:
 571                         return CTRSEQ_INVALID;
 572                 }
 573         }
 574         return 2;
 575 }
 576
 577 void append_movement (int dir) {
 578         if (g.k.n > 15) return; /* no space in buffer */
 579         if (g.k.n && g.k.c[(16+g.k.h-1)%16] == dir)
 580                 return; /* don't add the same direction twice */
 581
 582         g.k.c[g.k.h] = dir;
 583         g.k.n++;
 584         g.k.h = (g.k.h+1) % 16;
 585 }
 586
 587 void move_ph (int line, int col) {
 588         /* move printhead to zero-indexed position */
 589         printf ("\033[%d;%dH", line+1, col+1);
 590 }
 591
 592 void clamp_fieldsize (void) {
 593         /* clamp field size to terminal size and mouse maximum: */
 594         struct winsize w;
 595         ioctl(STDOUT_FILENO, TIOCGWINSZ, &w);
 596
 597         if (g.w < 10) g.w = 10;
 598         if (g.h < 10) g.h = 10;
 599
 600         if (COL_OFFSET + g.w*CW + COL_OFFSET > w.ws_col)
 601                 g.w = (w.ws_col - 2*COL_OFFSET) / op.sch->display_width;
 602         if (LINE_OFFSET + g.h + LINES_AFTER > w.ws_row)
 603                 g.h = w.ws_row - (LINE_OFFSET+LINES_AFTER);
 604 }
 605
 606 void timer_setup (int enable) {
 607         static struct itimerval tbuf;
 608         tbuf.it_interval.tv_sec  = 0;
 609         tbuf.it_interval.tv_usec = (1000000/g.v)-1; /*WARN: 1 <= g.v <= 999999*/
 610
 611         if (enable) {
 612                 tbuf.it_value.tv_sec  = tbuf.it_interval.tv_sec;
 613                 tbuf.it_value.tv_usec = tbuf.it_interval.tv_usec;
 614         } else {
 615                 tbuf.it_value.tv_sec  = 0;
 616                 tbuf.it_value.tv_usec = 0;
 617         }
 618
 619         if ( setitimer(ITIMER_REAL, &tbuf, NULL) == -1 ) {
 620                 perror("setitimer");
 621                 exit(1);
 622         }
 623
 624 }
 625
 626 void signal_setup (void) {
 627         struct sigaction saction;
 628
 629         saction.sa_handler = signal_handler;
 630         sigemptyset(&saction.sa_mask);
 631         saction.sa_flags = 0;
 632         if (sigaction(SIGALRM, &saction, NULL) < 0 ) {
 633                 perror("SIGALRM");
 634                 exit(1);
 635         }
 636
 637         if (sigaction(SIGINT, &saction, NULL) < 0 ) {
 638                 perror ("SIGINT");
 639                 exit (1);
 640         }
 641
 642         if (sigaction(SIGCONT, &saction, NULL) < 0 ) {
 643                 perror ("SIGCONT");
 644                 exit (1);
 645         }
 646 }
 647
 648 void signal_handler (int signum) {
 649         switch (signum) {
 650         case SIGALRM:
 651                 snake_advance();
 652                 spawn_bonus();
 653                 break;
 654         case SIGINT:
 655                 exit(128+SIGINT);
 656         case SIGCONT:
 657                 screen_setup(1);
 658                 show_playfield();
 659         }
 660 }
 661
 662 void screen_setup (int enable) {
 663         if (enable) {
 664                 raw_mode(1);
 665                 printf ("\033[s\033[?47h"); /* save cursor, alternate screen */
 666                 printf ("\033[H\033[J"); /* reset cursor, clear screen */
 667                 printf ("\033[?25l"); /* hide cursor */
 668         } else {
 669                 printf ("\033[?25h"); /* show cursor */
 670                 printf ("\033[?47l\033[u"); /* primary screen, restore cursor */
 671                 raw_mode(0);
 672         }
 673 }
 674
 675 /* http://users.csc.calpoly.edu/~phatalsk/357/lectures/code/sigalrm.c */
 676 void raw_mode(int enable) {
 677         static struct termios saved_term_mode;
 678         struct termios raw_term_mode;
 679
 680         if (enable) {
 681                 tcgetattr(STDIN_FILENO, &saved_term_mode);
 682                 raw_term_mode = saved_term_mode;
 683                 raw_term_mode.c_lflag &= ~(ICANON | ECHO);
 684                 raw_term_mode.c_cc[VMIN] = 1 ;
 685                 raw_term_mode.c_cc[VTIME] = 0;
 686                 tcsetattr(STDIN_FILENO, TCSAFLUSH, &raw_term_mode);
 687         } else {
 688                 tcsetattr(STDIN_FILENO, TCSAFLUSH, &saved_term_mode);
 689         }
 690 }