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 #define DW op.sch->display_width
  51
  52 #define SPEEDUP_AFTER 100 /* increment speed every n points */
  53 #define BONUS_INTERVAL 90 /* how often a bonus item is spawned */
  54 #define BONUS_DURATION 15 /* how long one can catch the bonus */
  55 #define BONUS_WARN      5 /* how long before the removal to warn */
  56 #define BONUS_STOP_NUM 10 /* how many steps the time freezes */
  57
  58 struct game {
  59         int w; /* field width */
  60         int h; /* field height */
  61         int d; /* direction the snake is looking */
  62         int p; /* score */
  63         float v; /* velocity in moves per second */
  64         time_t t; /* time of game start */
  65         struct snake* s; /* snek */
  66         struct item* i; /* items (food, boni) */
  67         struct bonus {
  68                 int t; /* bonus type (bitmask based on enum bonus_value) */
  69                 int s; /* steps left of time freeze bonus */
  70                 time_t n; /* time of next bonus item spawn */
  71                 time_t w; /* time of wall-wrap end */
  72         } b; /* bonus-related values */
  73         struct directions {
  74                 int h; /* write head */
  75                 int n; /* number of elements */
  76                 int c[16];
  77         } k; /* ring buffer for direction events */
  78 } g;
  79
  80 struct opt {
  81         int l; /* initial snake length */
  82         int s; /* initial snake speed */
  83         struct scheme* sch;
  84 } op;
  85
  86 jmp_buf game_over;
  87
  88 int main (int argc, char** argv) {
  89         /* defaults: */
  90         g.w = 30;
  91         g.h = 20;
  92         op.l = 10;
  93         op.s = 8;
  94         op.sch = &unic0de;
  95
  96         int optget;
  97         opterr = 0; /* don't print message on unrecognized option */
  98         while ((optget = getopt (argc, argv, "+s:l:dh")) != -1) {
  99                 switch (optget) {
 100                 case 's':
 101                         op.s = atof(optarg);
 102                         if (op.s < 1) {
 103                                 fprintf (stderr, "speed must be >= 1\n");
 104                                 return 1;
 105                         }
 106                         break;
 107                 case 'l':
 108                         op.l = atoi(optarg);
 109                         if (op.s < 2 || op.s > g.w*g.h-1) {
 110                                 fprintf (stderr, "length must be >= 2 and < W*H\n");
 111                                 return 1;
 112                         }
 113                         break;
 114                 case 'h':
 115                 default:
 116                         fprintf (stderr, SHORTHELP LONGHELP, argv[0]);
 117                         return !(optget=='h');
 118                 }
 119         } if (optind < argc) { /* parse Fieldspec */
 120                 int n = sscanf (argv[optind], "%dx%d", &g.w, &g.h);
 121
 122                 if (n < 2) {
 123                         fprintf(stderr,"FIELDSIZE is WxH (width 'x' height)\n");
 124                         return 1;
 125                 }
 126         }
 127
 128         clamp_fieldsize();
 129
 130         srand(time(0));
 131         signal_setup();
 132         screen_setup(1);
 133         atexit (*quit);
 134
 135         char* end_screen_msg = "";
 136 restart:
 137         switch (sigsetjmp(game_over, 1)) {
 138         case GAME_INIT:
 139         case GAME_START:
 140                 viiper();
 141                 break; /* function doesn't return, but `-Wextra' complains */
 142         case GAME_OVER:
 143                 end_screen_msg = " GAME  OVER ";
 144                 goto end_screen;
 145         case GAME_WON:
 146                 end_screen_msg = "CONGRATULATIONS!";
 147                 goto end_screen;
 148 end_screen:
 149                 timer_setup(0);
 150                 show_playfield();
 151                 for (;;) switch (end_screen(end_screen_msg)) {
 152                 case 'r': goto restart;
 153                 case 'q': goto quit;
 154                 case CTRL_'L':
 155                         screen_setup(1);
 156                         show_playfield();
 157                         break;
 158                 default: continue;
 159                 }
 160         case GAME_EXIT:
 161                 goto quit;
 162         }
 163
 164 quit:
 165         return 0;
 166 }
 167
 168 int viiper(void) {
 169         init_snake();
 170         show_playfield ();
 171         g.d = EAST;
 172         g.v = op.s;
 173
 174         timer_setup(1);
 175         g.t = time(NULL);
 176         g.p = 0;
 177         g.k.n = 0;
 178         g.b.n = time(NULL) + BONUS_INTERVAL;
 179         g.b.s = 0;
 180         g.b.t = 0;
 181
 182         spawn_item(FOOD, rand() % NUM_FOODS, NULL);
 183
 184         for(;;) {
 185                 switch (getctrlseq()) {
 186                 case 'h': case CTRSEQ_CURSOR_LEFT: append_movement(WEST); break;
 187                 case 'j': case CTRSEQ_CURSOR_DOWN: append_movement(SOUTH);break;
 188                 case 'k': case CTRSEQ_CURSOR_UP:   append_movement(NORTH);break;
 189                 case 'l': case CTRSEQ_CURSOR_RIGHT:append_movement(EAST); break;
 190                 case 'p': pause_game(); break;
 191                 case 'r': siglongjmp(game_over, GAME_START);
 192                 case 'q': siglongjmp(game_over, GAME_EXIT);
 193                 case CTRL_'L':
 194                         screen_setup(1);
 195                         show_playfield();
 196                         break;
 197                 case 0x02: /* STX; gets sent when returning from SIGALRM */
 198                         continue;
 199                 }
 200
 201                 if (g.b.s) { /* highjack keyboard function for time freeze */
 202                         snake_advance();
 203                         if (!--g.b.s) timer_setup(1);/*turn back on afterwards*/
 204                 }
 205         }
 206
 207 }
 208
 209 #define pop_dir() (g.k.n? g.k.c[(16+g.k.h-g.k.n--)%16] : NONE)
 210 void snake_advance (void) {
 211         int respawn = 0;
 212         struct item* i; /*temporary item (defined here to respawn at the end) */
 213         int new_dir = pop_dir();
 214         /* switch direction if new one is in the buffer and it won't kill us: */
 215         if (new_dir && g.d != OPPOSITE(new_dir)) g.d = new_dir;
 216
 217         int new_row = g.s->r +(g.d==SOUTH) -(g.d==NORTH);
 218         int new_col = g.s->c +(g.d==EAST)  -(g.d==WEST);
 219
 220         /* detect food hit and spawn a new food */
 221         for (i = g.i; i; i = i->next) {
 222                 if (i->r == new_row && i->c == new_col) {
 223                         consume_item (i);
 224
 225                         switch (i->t) {
 226                         case FOOD: respawn = 1; break;
 227                         case BONUS: remove_bonus(i); break;
 228                         }
 229                         break;
 230                 }
 231         }
 232
 233         if (g.b.t & 1<<BONUS_WRAP) {
 234           if (new_row >= g.h) new_row = 0;
 235           if (new_col >= g.w) new_col = 0;
 236           if (new_row < 0) new_row = g.h-1;
 237           if (new_col < 0) new_col = g.w-1;
 238         } else {
 239           if (new_row >= g.h || new_col >= g.w || new_row < 0 || new_col < 0)
 240                 siglongjmp(game_over, GAME_OVER);
 241         }
 242
 243         struct snake* new_head;
 244         struct snake* new_tail; /* former second-to-last element */
 245         for (new_tail = g.s; new_tail->next->next; new_tail = new_tail->next)
 246                 /*use the opportunity of looping to check if we eat ourselves:*/
 247                 if(new_tail->next->r == new_row && new_tail->next->c == new_col)
 248                         siglongjmp(game_over, GAME_OVER);
 249         int old_tail[2] = {new_tail->next->r, new_tail->next->c};/*gets erased*/
 250         new_head = new_tail->next; /* reuse element instead of malloc() */
 251         new_tail->next = NULL;
 252
 253         new_head->r = new_row;
 254         new_head->c = new_col;
 255         new_head->next = g.s;
 256
 257         g.s = new_head;
 258
 259         /* bonus mode(s) still active? */
 260         if (g.b.t&1<<BONUS_WRAP && g.b.w < time(NULL)) {
 261                 g.b.t &= ~(1<<BONUS_WRAP);
 262                 show_playfield();
 263         }
 264
 265         if (respawn) spawn_item(FOOD, rand() % NUM_FOODS, i);
 266         draw_sprites (old_tail[0], old_tail[1]);
 267 }
 268
 269 void spawn_item (int type, int value, struct item* p_item) {
 270         int row, col;
 271         char occupied[g.w][g.h]; int snake_len = 0;
 272         memset(*occupied, 0, g.w*g.h);
 273 try_again:
 274         row = rand() % g.h;
 275         col = rand() % g.w;
 276         if (snake_len >= g.w*g.h-1) siglongjmp(game_over, GAME_WON);
 277         /* loop through snake to check if we aren't on it */
 278         if (occupied[row][col]) goto try_again; /* shortcut */
 279         for (struct snake* s = g.s; s; s = s->next)
 280                 if (s->r == row && s->c == col) {
 281                         occupied[s->r][s->c] = 1; snake_len++;
 282                         goto try_again;
 283                 }
 284
 285         /* if we got a item buffer reuse it, otherwise create a new one: */
 286         struct item* new_item;
 287         if (p_item) new_item = p_item;
 288         else new_item = malloc (sizeof(struct item));
 289
 290         new_item->r = row;
 291         new_item->c = col;
 292         new_item->t = type;
 293         new_item->v = value;
 294         new_item->s = time(0);
 295         if (g.i) g.i->prev = new_item;
 296         new_item->next = g.i;
 297         new_item->prev = NULL;
 298
 299         g.i = new_item;
 300 }
 301
 302 void consume_item (struct item* i) {
 303         int old_score = g.p;
 304
 305         switch (i->t) {
 306         case FOOD:
 307                 switch (i->v) {
 308                 case FOOD_PEAR:
 309                 case FOOD_WMELON:
 310                 case FOOD_BANANA:
 311                 case FOOD_KIWI:
 312                         g.p +=  5;
 313                         break;
 314                 case FOOD_APPLER:
 315                 case FOOD_CHERRY:
 316                         g.p += 10;
 317                         break;
 318                 case FOOD_AVOCADO:
 319                         g.p += 20;
 320                         break;
 321                 }
 322                 snake_append(&g.s, -1, -1);
 323                 break; /* will be reused as the head before it is drawn */
 324         case BONUS:
 325                 switch (i->v) {
 326                 case BONUS_SNIP:
 327                         for (int i = 5; i && g.s->next->next; i--) {
 328                                 struct snake* p = g.s;
 329                                 while (p->next->next) p = p->next;
 330                                 free (p->next);
 331                                 p->next = NULL;
 332                         }
 333                         show_playfield();
 334                         break;
 335                 case BONUS_GROW:
 336                         for (int i = 5; i; i--) snake_append(&g.s, -1, -1);
 337                         break;
 338                 case BONUS_SLOW:
 339                         if (g.v > 1) g.v--;
 340                         timer_setup(1);
 341                         break;
 342                 case BONUS_FAST:
 343                         g.v++;
 344                         timer_setup(1);
 345                         break;
 346                 case BONUS_WRAP:
 347                         g.b.w = time(NULL)+30;
 348                         g.b.t |= 1<<BONUS_WRAP;
 349                         show_playfield();
 350                         break;
 351                 case BONUS_STOP:
 352                         g.b.s = BONUS_STOP_NUM; /* stop the time for 5 steps */
 353                         timer_setup(0);
 354                         break;
 355                 }
 356                 g.b.n = time(NULL) + BONUS_INTERVAL; /*next bonus in x seconds*/
 357                 break;
 358         }
 359
 360         if (i->next) i->next->prev = i->prev;
 361         if (i->prev) i->prev->next = i->next;
 362         else g.i = i->next;
 363
 364         /* snake speedup every 100 points: */
 365         if (g.p/SPEEDUP_AFTER - old_score/SPEEDUP_AFTER) g.v++, timer_setup(1);
 366 }
 367
 368 void spawn_bonus(void) {
 369         for (struct item* i = g.i; i; i = i->next)
 370                 if (i->t == BONUS) { /* bonus already there */
 371                         if (((i->s+BONUS_DURATION)-time(NULL)) < 0) {
 372                                 remove_bonus(i); /* remove if over lifetime */
 373                         }
 374                         return;
 375                 }
 376         if (g.b.n < time(NULL)) { /* time to spawn item: */
 377                 spawn_item(BONUS, rand() % NUM_BONI, NULL);
 378                 g.b.n = time(NULL) + BONUS_INTERVAL + BONUS_DURATION;
 379         }
 380 }
 381
 382 void show_playfield (void) {
 383         move_ph (0,0);
 384
 385         /* top border */
 386         print(BORDER(T,L));
 387         printm (g.w, BORDER(T,C));
 388         printf ("%s\n", BORDER(T,R));
 389
 390         /* main area */
 391         for (int row = 0; row < g.h; row++)
 392                 printf ("%s%*s%s\n", BORDER(C,L), CW*g.w, "", BORDER(C,R));
 393
 394         /* bottom border */
 395         print(BORDER(B,L));
 396         printm (g.w, BORDER(B,C));
 397         print (BORDER(B,R));
 398
 399         draw_sprites (-1,-1);
 400 }
 401
 402 void draw_sprites (int erase_r, int erase_c) {
 403         /* erase old tail, if any */
 404         if (erase_r >= 0 && erase_c >= 0) {
 405                 move_ph (erase_r+LINE_OFFSET, erase_c*CW+COL_OFFSET);
 406                 printm (CW, " ");
 407         }
 408
 409         /* print snake */
 410         struct snake* last = NULL;
 411         int color = 2;
 412         for (struct snake* s = g.s; s; s = s->next) {
 413                 if (s->r < 0 || s->c < 0) continue; /*can't draw outside term.*/
 414                 move_ph (s->r+LINE_OFFSET, s->c*CW+COL_OFFSET);
 415
 416                 int predecessor = (last==NULL)?NONE:
 417                         (last->r < s->r) ? NORTH:
 418                         (last->r > s->r) ? SOUTH:
 419                         (last->c > s->c) ? EAST:
 420                         (last->c < s->c) ? WEST:NONE;
 421                 int successor = (s->next == NULL)?NONE:
 422                         (s->next->r < s->r) ? NORTH:
 423                         (s->next->r > s->r) ? SOUTH:
 424                         (s->next->c > s->c) ? EAST:
 425                         (s->next->c < s->c) ? WEST:NONE;
 426
 427                 printf ("\033[%sm", op.sch->color[color]);
 428                 print (op.sch->snake[predecessor][successor]);
 429                 printf ("\033[0m");
 430                 last = s;
 431                 color = !color;
 432         }
 433
 434         /* print item queue */
 435         for (struct item* i = g.i; i; i = i->next) {
 436                 move_ph (i->r+LINE_OFFSET, i->c*CW+COL_OFFSET);
 437                 if      (i->t == FOOD)  print(op.sch->food[i->v]);
 438                 else if (i->t == BONUS) {
 439                         if (i->s + BONUS_DURATION-BONUS_WARN < time(NULL))
 440                                 printf("\033[5m%s\033[25m", op.sch->boni[i->v]);
 441                         else print(op.sch->boni[i->v]);
 442                 }
 443         }
 444
 445         /* print score */
 446         int score_width = g.p > 9999?6:4;
 447         move_ph (0, (g.w*CW-score_width)/2-COL_OFFSET);
 448         printf ("%s %0*d %s", BORDER(S,L), score_width, g.p, BORDER(S,R));
 449 }
 450
 451 void pause_game (void) {
 452         time_t pause_start = time(NULL);
 453         time_t pause_diff;
 454         timer_setup(0);
 455
 456         move_ph (g.h/2+LINE_OFFSET, g.w*CW/2);
 457         printf ("\033[5;7m PAUSE \033[0m"); /* blinking reverse text */
 458         if (getchar() == 'q')
 459                 siglongjmp(game_over, GAME_EXIT);
 460
 461         /* update all timers, so bonus items don't get out of sync: */
 462         pause_diff = time(NULL) - pause_start;
 463         g.b.n += pause_diff;
 464         for (struct item* i = g.i; i; i = i->next)
 465                 i->s += pause_diff;
 466
 467         show_playfield();
 468         timer_setup(1);
 469 }
 470
 471 #define MOVE_POPUP(WIDTH, LINE) \
 472         move_ph(g.h/2+LINE_OFFSET-1+LINE,(g.w*DW-WIDTH)/2)
 473         //TODO: macro does not correctly centre in DEC mode
 474 int end_screen(char* message) {
 475         int msg_w = strlen(message);
 476         MOVE_POPUP(msg_w, -1);
 477         print(BORDER(T,L));
 478         printm ((msg_w+2)/DW, BORDER(T,C));
 479         print (BORDER(T,R));
 480
 481         MOVE_POPUP(msg_w, 0);
 482         printf("%s %s %s", BORDER(C,L), message, BORDER(C,R));
 483         MOVE_POPUP(msg_w, 1);
 484         //TODO: requires shifting into ASCII/multilingual charset in DEC mode -- put graphics into upper/right charset?
 485         printf("%s `r' restart%*s%s", BORDER(C,L), msg_w-10, "", BORDER(C,R));
 486         MOVE_POPUP(msg_w, 2);
 487         printf("%s `q' quit%*s%s", BORDER(C,L), msg_w-7, "", BORDER(C,R));
 488
 489         MOVE_POPUP(msg_w, 3);
 490         print(BORDER(B,L));
 491         printm ((msg_w+2)/DW, BORDER(B,C));
 492         print (BORDER(B,R));
 493         fflush(stdout);
 494
 495         return getctrlseq();
 496 }
 497
 498 void snake_append (struct snake** s, int row, int col) {
 499         struct snake* new = malloc (sizeof(struct snake));
 500         new->r = row;
 501         new->c = col;
 502         new->next = NULL;
 503
 504         if (*s) {
 505                 struct snake* p = *s;
 506                 while (p->next) p = p->next;
 507                 p->next = new;
 508         } else {
 509                 *s = new;
 510         }
 511 }
 512
 513 void remove_bonus (struct item*  i) {
 514         if (i->next) i->next->prev = i->prev;
 515         if (i->prev) i->prev->next = i->next;
 516         else g.i = i->next;
 517
 518         draw_sprites (i->r, i->c); /* overwrite sprite */
 519
 520         free(i);
 521 }
 522
 523 #define free_ll(head) do{ \
 524         while (head) { \
 525                 void* tmp = head; \
 526                 head = head->next; \
 527                 free(tmp); \
 528         } \
 529         head = NULL; \
 530 }while(0)
 531
 532 void init_snake() {
 533         free_ll(g.s);
 534         free_ll(g.i);
 535
 536         int direction = WEST;
 537         int r = g.h/2;
 538         int c = g.w/2;
 539         int min_r = 0;
 540         int max_r = g.h-1;
 541         int min_c = 0;
 542         int max_c = g.w-1;
 543         for (int i = 0; i < op.l; i++) {
 544                 switch (direction) {
 545                 case NORTH: r--; if(r <= min_r){direction=EAST; min_r++;}break;
 546                 case EAST:  c++; if(c >= max_c){direction=SOUTH;max_c--;}break;
 547                 case SOUTH: r++; if(r >= max_r){direction=WEST; max_r--;}break;
 548                 case WEST:  c--; if(c <= min_c){direction=NORTH;min_c++;}break;
 549                 }
 550
 551                 snake_append(&g.s, r, c);
 552         }
 553 }
 554
 555 void quit (void) {
 556         screen_setup(0);
 557         free_ll(g.s);
 558         free_ll(g.i);
 559 }
 560
 561 enum esc_states {
 562         START,
 563         ESC_SENT,
 564         CSI_SENT,
 565         MOUSE_EVENT,
 566 };
 567 int getctrlseq (void) {
 568         int c;
 569         int state = START;
 570         while ((c = getchar()) != EOF) {
 571                 switch (state) {
 572                 case START:
 573                         switch (c) {
 574                         case '\033': state=ESC_SENT; break;
 575                         default: return c;
 576                         }
 577                         break;
 578                 case ESC_SENT:
 579                         switch (c) {
 580                         case '[': state=CSI_SENT; break;
 581                         default: return CTRSEQ_INVALID;
 582                         }
 583                         break;
 584                 case CSI_SENT:
 585                         switch (c) {
 586                         case 'A': return CTRSEQ_CURSOR_UP;
 587                         case 'B': return CTRSEQ_CURSOR_DOWN;
 588                         case 'C': return CTRSEQ_CURSOR_RIGHT;
 589                         case 'D': return CTRSEQ_CURSOR_LEFT;
 590                         default: return CTRSEQ_INVALID;
 591                         }
 592                         break;
 593                 default:
 594                         return CTRSEQ_INVALID;
 595                 }
 596         }
 597         return 2;
 598 }
 599
 600 void append_movement (int dir) {
 601         if (g.k.n > 15) return; /* no space in buffer */
 602         if (g.k.n && g.k.c[(16+g.k.h-1)%16] == dir)
 603                 return; /* don't add the same direction twice */
 604
 605         g.k.c[g.k.h] = dir;
 606         g.k.n++;
 607         g.k.h = (g.k.h+1) % 16;
 608 }
 609
 610 void move_ph (int line, int col) {
 611         /* move printhead to zero-indexed position */
 612         printf ("\033[%d;%dH", line+1, col+1);
 613 }
 614
 615 void clamp_fieldsize (void) {
 616         /* clamp field size to terminal size and mouse maximum: */
 617         struct winsize w;
 618         ioctl(STDOUT_FILENO, TIOCGWINSZ, &w);
 619
 620         if (g.w < 10) g.w = 10;
 621         if (g.h < 10) g.h = 10;
 622
 623         if (COL_OFFSET + g.w*CW + COL_OFFSET > w.ws_col)
 624                 g.w = (w.ws_col - 2*COL_OFFSET) / DW;
 625         if (LINE_OFFSET + g.h + LINES_AFTER > w.ws_row)
 626                 g.h = w.ws_row - (LINE_OFFSET+LINES_AFTER);
 627 }
 628
 629 void timer_setup (int enable) {
 630         static struct itimerval tbuf;
 631         tbuf.it_interval.tv_sec  = 0;
 632         tbuf.it_interval.tv_usec = (1000000/g.v)-1; /*WARN: 1 <= g.v <= 999999*/
 633
 634         if (enable) {
 635                 tbuf.it_value.tv_sec  = tbuf.it_interval.tv_sec;
 636                 tbuf.it_value.tv_usec = tbuf.it_interval.tv_usec;
 637         } else {
 638                 tbuf.it_value.tv_sec  = 0;
 639                 tbuf.it_value.tv_usec = 0;
 640         }
 641
 642         if ( setitimer(ITIMER_REAL, &tbuf, NULL) == -1 ) {
 643                 perror("setitimer");
 644                 exit(1);
 645         }
 646
 647 }
 648
 649 void signal_setup (void) {
 650         struct sigaction saction;
 651
 652         saction.sa_handler = signal_handler;
 653         sigemptyset(&saction.sa_mask);
 654         saction.sa_flags = 0;
 655         if (sigaction(SIGALRM, &saction, NULL) < 0 ) {
 656                 perror("SIGALRM");
 657                 exit(1);
 658         }
 659
 660         if (sigaction(SIGINT, &saction, NULL) < 0 ) {
 661                 perror ("SIGINT");
 662                 exit (1);
 663         }
 664
 665         if (sigaction(SIGCONT, &saction, NULL) < 0 ) {
 666                 perror ("SIGCONT");
 667                 exit (1);
 668         }
 669 }
 670
 671 void signal_handler (int signum) {
 672         switch (signum) {
 673         case SIGALRM:
 674                 snake_advance();
 675                 spawn_bonus();
 676                 break;
 677         case SIGINT:
 678                 exit(128+SIGINT);
 679         case SIGCONT:
 680                 screen_setup(1);
 681                 show_playfield();
 682         }
 683 }
 684
 685 void screen_setup (int enable) {
 686         if (enable) {
 687                 raw_mode(1);
 688                 printf ("\033[s\033[?47h"); /* save cursor, alternate screen */
 689                 printf ("\033[H\033[J"); /* reset cursor, clear screen */
 690                 printf ("\033[?25l"); /* hide cursor */
 691         } else {
 692                 printf ("\033[?25h"); /* show cursor */
 693                 printf ("\033[?47l\033[u"); /* primary screen, restore cursor */
 694                 raw_mode(0);
 695         }
 696 }
 697
 698 /* http://users.csc.calpoly.edu/~phatalsk/357/lectures/code/sigalrm.c */
 699 void raw_mode(int enable) {
 700         static struct termios saved_term_mode;
 701         struct termios raw_term_mode;
 702
 703         if (enable) {
 704                 tcgetattr(STDIN_FILENO, &saved_term_mode);
 705                 raw_term_mode = saved_term_mode;
 706                 raw_term_mode.c_lflag &= ~(ICANON | ECHO);
 707                 raw_term_mode.c_cc[VMIN] = 1 ;
 708                 raw_term_mode.c_cc[VTIME] = 0;
 709                 tcsetattr(STDIN_FILENO, TCSAFLUSH, &raw_term_mode);
 710         } else {
 711                 tcsetattr(STDIN_FILENO, TCSAFLUSH, &saved_term_mode);
 712         }
 713 }