tetris.bt

// This is based on stapgames' tetris.spt made by Tomoki Sekiyama.
// The license is the same as the original.
//
// Copyright (C) 2019 Masanori Misono <m.misono760@gmail.com>
//
// This file is free software and is distributed under the terms of the GNU
// General Public License (GPL); either version 2, or (at your option) any
// later version.

kprobe:pty_write // (struct tty_struct *tty, const unsigned char *buf, int c)
/ arg2 == 1 /
{
  // this value is ascii code
  @K = *((int8*)arg1);
}

// row = 20
// column = 12
// @B: blocks
// @Z[0:240]: board
//    -1: empty
//     0: O
//     1: L
//     2: J
//     3: S
//     4: Z
//     5: T
//     6: I
//     7: wall
// @Z[240:480]: display buffer
// @h: current position
// @t: current block
// @K: pressed key
// @P: points

BEGIN {
  @K = 0;
  @e = 0;
  @P = 0;
  @t = rand % 7;

  // Create blocks
  // block is represented by the position from the center.
  // Every block has "L" part in the center except for a bar.
  @B[0,0] = -11; // non-"L" part for each block
  @B[1,0] = -24;
  @B[2,0] = 2;
  @B[3,0] = 13;
  @B[4,0] = -13;
  @B[5,0] = -1;
  @B[6,0] = 2;
  $i = 0;
  unroll(7) {
    // common "L" part
    @B[$i,1]=0;
    @B[$i,2]=1;
    @B[$i,3]=-12;
    $i = $i + 1;
  }
  @B[6,3] = -1; // bar is not common
  // Position: 1 row has 12 columns, and (x,y) is represented by h=x+y*12.
  @h=17; // First block position (center)

  // bpftrace supports unrolling at most 20 loops
  $i = 0;
  unroll(20) {
    $j = $i*12;
    unroll(12) {
      if ((($j+1) % 12) < 2 || (($j+1) > 228)) { @Z[$j] = 7; @Z[$j+240] = 7; }
      else { @Z[$j] = -1; @Z[$j+240] = -1; }
      $j += 1;
    }
    $i += 1;
  }
  printf("\033[H\033[2J"); // clear screen
}

interval:ms:99
{
  $f = 0; // move/rotate flag

  if (@K != 0){ // if key is pressed
   if (@K != 0x20){ // move left or right ('h' or 'l')
     $d = @K-0x68 ? @K-0x6C ? 0 : 1 : -1; // d: movement direction
     $i = 0;
     unroll(4){ // check if the block can be moved
       $f += @Z[@h+@B[@t,$i]+$d] >= 0; // destination is free
       $i += 1;
     }
     if ($f == 0) {
       @h = @h + $d; // move if destinations of every block are free
     }
   } else { // rotate (space = 0x20)
     $i = 0;
     unroll(4){ // check if block can be rotated
       $p = @B[@t,$i]; // each block position
       $v = ($p*2+252)/24-10; // destination x pos(p/12 rounded)
       $w = $p-$v*12; // destination y pos
       @C[$i] = $w*12-$v; // destination position

       if (@Z[@h+@C[$i]] >= 0){ // check if destination is free
         $f = 1;
       }
       $i += 1;
     }

     if (@t && ($f == 0)){ // rotate if destinations of every block are free
       $i = 0;
       unroll(4){
         @B[@t,$i] = @C[$i];
         $i += 1;
       }
     }
   } }
  @K = 0; // clear the input key

  $i = 0;
  $f = 0;
  unroll(4){ // drop 1 row
   $p = @h+@B[@t,$i];
   $f += @Z[12+$p] >= 0; // check if destination is free
   if ((240 + $p) >= 240){
     @Z[240+$p] = @t; // copy the moving block to display buffer
   }
   $i += 1;
  }

  @e = 1 - @e;
  if (@e){
    if ($f){ // the block can't drop anymore
      $i = 0;
      unroll(4){
        @Z[@h+@B[@t,$i]] = @t; // fix the block
        $i += 1;
      }
      @t = elapsed % 7; // determin the next block
      @h = 17; // make the block to initial position
    } else {
      @h += 12; // drop the block 1 row
    }
  }

  // check if line is filled
  $k = 1; $l=18; $i = 18;
  unroll(19){
    $j = 10; $f = 0;
    unroll(10){
      $f += @Z[$i*12 + $j] >= 0;
      $j -= 1;
    }
    if ($f == 10){ // filled!
      @P += $k;
      $k += 1;
    } else {
      @C[$l] = $i;
      $l -= 1;
    }
    $i -= 1;
  }

  // drop block
  $i = 18;
  unroll(19){
    $j = 10;
    unroll(10){
      if ($i < $l){
        @Z[$i*12 + $j] = -1;
      } else {
        @Z[$i*12 + $j] = @Z[@C[$i]*12 + $j];
      }
      $j -= 1;
    }
    $i -= 1;
  }

  $i = 0;
  printf("\033[H"); // move cursor to top left
  printf("\n");
  unroll(20){
    $j = $i*12;
    printf("  ");
    unroll(12){
      $v = @Z[240+$j];
      if($v == -1){
        printf("  ");
      }
      if ($v == 0){
        printf("\033[41m  \033[m");
      }
      if ($v == 1){
        printf("\033[42m  \033[m");
      }
      if ($v == 2){
        printf("\033[43m  \033[m");
      }
      if ($v == 3){
        printf("\033[44m  \033[m");
      }
      if ($v == 4){
        printf("\033[45m  \033[m");
      }
      if ($v == 5){
        printf("\033[46m  \033[m");
      }
      if ($v == 6){
        printf("\033[47m  \033[m");
      }
      if ($v == 7){
        printf("\033[47m  \033[m");
      }
      if ((($j % 12) -11) == 0){
        printf("\n");
      }
      @Z[240+$j] = @Z[$j]; // clear the display buffer
      $j += 1;
    }
    $i += 1;
  }
  printf("Move:  h,l  | Rotate: <Space>\n");
  printf("Quit: <C-c> | Score : %d\n", @P);

  if (@Z[5] != -1){
    exit(); // exit if there are block at initial position
  }
}

END
{
  clear(@B); clear(@C); clear(@K); clear(@P);
  clear(@Z); clear(@e); clear(@h); clear(@t);
}