Hugi Size Coding Competition

Volume 13: The Soko Ban Compo

Welcome to the Hugi Size Coding Compo #13! Overcome your triskaidekaphobia and accept this challenge to code a Soko-Ban game in as few bytes as possible. "Soko ban" is Japanese for "warehouse man". The game is played using the arrow keys to move a little blue man and coax him into pushing boxes onto loading docks. (Although the man only pushes one box at a time, he still gets blue in the face from the effort.) To avoid needing code that makes the man's face turn red, the Backspace key is used to back out of embarrassing situations, such as pushing a box into a corner where it can no longer be moved. To cover any possible embarrassment (such as when your boss is about to catch you playing this at work) the Esc key can be used to instantly terminate the program. The puzzle is solved by pushing all the boxes onto the loading docks, or, if there are more boxes than docks, by loading all the docks. There are many levels to the game. Each presents a floor plan to be solved. The program defaults by loading level A, but any level (A-Z or 0-9) can be specified by entering it on the command line. When a level is solved, the next level is automatically loaded. Command Line Your program must load any file entered on the command line. The file name is a single character A through Z or 0 through 9. You may assume that the command line will either be empty or contain a valid file name. You also may assume that there is no path or any extra space characters in the name. If no name is entered then level A must be loaded. In other words, the two formats your program must handle are: ENTRY <CR> ENTRY <SPACE> <LEVEL> <CR> File Format The level files consist of 17, 20-character lines each terminated with CR+LF. Besides CR and LF only the following characters are used: Char Hex Represents Space 20 Floor ! 21 Loading dock " 22 Background # 23 Wall $ 24 Box on floor % 25 Box on dock & 26 Man on floor You may assume that: The floor is completely enclosed by walls. In other words, as long as your program doesn't allow moves through walls, you don't need to worry about moving outside the playing area. There is only one man (&). The number of boxes is greater than or equal to the number of loading docks ($+% >= !+%). The level is solvable. The Display To make the display a little more interesting, your program must convert the characters in a level file to the colorful characters shown here: Char Hex Represents Convert to Hex Space 20 Floor White background 20 70 ! 21 Loading dock Cyan background 20 30 " 22 Background Black background 20 07 # 23 Wall White screen on red B0 47 $ 24 Box on floor Yellow box on white FE 7E % 25 Box on dock Yellow box on cyan FE 3E & 26 Man on floor L.Blue face on white 02 79 There are several ways that the solid color character cells used for the background, floor, and loading docks may be displayed. For instance, besides a space character (20h) with a cyan background (30h), a loading dock also may be displayed using 00h or FFh. Since in these cases the foreground color isn't displayed, it may be anything. You may display the floor using the letter 'A' as long as the foreground and background colors are both white. You also may use the solid block character (DBh) as long as the foreground color is correct (and it doesn't flash). Set the video mode to 1 (or 0) for a 40x25 text screen, which gives a somewhat square aspect ratio. Display the converted file characters centered on the screen, beginning on the 5th line in the 11th column. Display the level name in the upper-left corner in light red on the black background (color attribute = 0Ch). The level name may be displayed either in upper or lower case. Display a move counter in the upper-right corner in yellow (attribute = 0Eh). This must be right justified so that the last digit appears in the 40th column. There are no leading zeros. Your starting screen for level A should look something like this: The dots shown above merely indicate the position of the input file. They are not used on your display. Key Commands Your program must handle the following key commands: Arrow keys Move man (possibly pushing a box) Backspace Undo move Esc Terminate program Other keys should be ignored, but for the purposes of the compo they are undefined. They may do anything including crash the machine. Keystrokes must be read using interrupt 16h, function 0. This is necessary so that the test program (which hooks INT 16h) can verify proper operation. Since the up, down, left, and right arrow keys don't return an ASCII value, their scan codes must be used. Scan codes are returned in register ah. (For the other keys, the ASCII value is returned in register al.) The Backspace key is used to undo moves. Pressing it multiple times must undo multiple moves, a step at a time, back to the beginning of the level. Don't forget to undo the move counter. You may assume a maximum of 4000 moves. Beyond this the program's behavior is undefined: it may display an incorrect move count, corrupt the screen, or do anything including crash the machine. Your program must, however, limit the number of undone moves to the beginning of the level. In other words, the Backspace key cannot decrement the move counter below 0. When the Esc key terminates the program, the normal 80x25 text screen (mode 3) must be restored. Next Level When the puzzle is solved, your program must beep, wait for a key to be pressed, and then load the next level. The next level is contained in another file whose name is also a single ASCII character, the ASCII successor of the current level's name (i.e. B follows A, etc.). If the file does not exist (e.g. '[' follows 'Z' but does not exist), your program must restore the 80x25 text screen (mode 3) and exit cleanly to DOS. Moving The up, down, left, and right arrow keys are used to move the man and possibly a box. This pseudo code shows the logic: LET Mx,My = Current man location (screen column and row) LET Nx,Ny = Possible new man location LET Bx,By = Possible new box location IF key = up THEN Ny:= My-1; By:= Ny-1 IF key = down THEN Ny:= My+1; By:= Ny+1 IF key = left THEN Nx:= Mx-1; Bx:= Nx-1 IF key = right THEN Nx:= Mx+1; Bx:= Nx+1 Increment move counter (even if move is illegal) IF contents of Nx,Ny = floor or dock THEN GOTO (1) IF contents of Nx,Ny doesn't = box THEN GOTO (2) IF contents of Bx,By doesn't = floor or dock THEN GOTO (2) Display box at Bx,By (1) Display man at Nx,Ny and blank out man at Mx,My (2) (done) When moving the man or box, be sure to preserve the background color of the floor or dock. Steps Here are the steps your program must do: Read command line for initial input file name (level) Default to level A if no level is specified (1) Open file, or if file does not exist (>Z) go to (3) Switch to 40-column text mode (also clears screen) Turn off flashing cursor Read file, convert to colorful symbols and display them Close file handle (if used) Display file name in upper-left corner Zero move counter Display move counter in upper-right corner Find location of man symbol (2) Read keyboard using AH=00 INT 16h - If arrow key then: Save state so move can be undone Increment move counter and display it Move man, and possibly box, and display them - If Backspace key then undo previous move - If Esc key then go to (3) If level is not solved then go to (2) Beep speaker Wait for keystroke, read and discard character Form next input file name Go to (1) (3) Restore 80-column text display (mode 3) Exit cleanly to DOS To make this all as clear as possible, an example program has been written for you. Look at EXAMPLE.ASM (hcompo13.zip). Test Program A test suite is also included in this pack (hcompo13.zip). Adok will use it to verify that your entry executes properly. Your program must be named "ENTRY.COM". Please note that passing the test suite does not guarantee that your entry has followed all the rules. It's quite possible that a loop hole exists. Check the Hugi website (http://home.pages.de/~hugi-compo/) and the eGroups Hugi-compo mailing list for updated test suites. Besides the rules described in this document, you must comply with the general rules that apply to all Hugi size coding competitions. These are described in the file GENERAL.TXT (hcompo13.zip). If you are unsure about some detail then please post a question to the Hugi compo mailing list (hugi-compo@egroups.com). After the compo deadline, a period of public judgment occurs during which you and others determine penalties for rule violations. Schedule Nov 01, 2000 Compo starts. Dec 15, 2000 11:59 pm CET Deadline for entry submission. Dec 16, 2000 Entries and beta results will be released. Start of Public Judgement. Dec 22, 2000 11:59 pm CET End of Public Judgement. Dec 23, 2000 Final results will be released. History Sokoban (as it is usually spelled) was created in 1982 by Hiroyuki Imabayashi, president of Thinking Rabbit, a company in Japan. It won first prize in a computer game contest because of the simplicity of the rules and the challenge of the problems. It soon became very popular. Many people have created many levels to the game. There are at least 1400 of them available at: http://mujweb.cz/Zabava/sokoban/downloada.htm The 0-9 set included in this pack are the original levels by Thinking Rabbit. The A-Y set are from a Java version written by Riza Purwo Nugroho of Jakarta, Indonesia, although he is not the original author. Credits A big THANX goes to Bonz who wrote the first draft of these rules and who pointed out bugs and made other suggestions for improving the code. (Too bad the graphic version was voted out.) Thank Metalbrain for puzzle "Z", which has more boxes than docks. Credit also goes to TAD and Ruud whose previous compo rules and test code I've ripped off to various degrees. Of course special credit goes to Adok, without whose tireless efforts there would be no compo. And thanks to all you competitors who make these compos fun. Good luck! (even though luck has nothing to do with it) Boreal Back to the main page