adventure

The original Fortran version of Adventure by Will Crowther, restored to functionality when compiled with a modern Fortran compiler. For a history of this program, see the Wikipedia article on it.

Downloaded from Wayback Machine archive of

http://www.icynic.com/~don/jerz/advf4.77-03-31

and

http://www.icynic.com/~don/jerz/advdat.77-03-31

Code changes:

• Eliminated tabs from Fortran code; aligned statements to follow legacy fixed format layout.

• Moved DATA statements out of executable code section into declaration section.

• Apparently, the DEC system this program was developed on initialized all program storage to zero when loaded; contemporary systems do not, generally, do this. Consequently, explicitly zeroed variables and arrays that assume a zero initial value: SETUP, KEY, DSEEN, DLOC, ODLOC. Also set uninitialized values of DTRAV array to zero.

• Changed all TYPE commands to PRINT and ACCEPT commands to READ.

• Changed A5 formats to A4 to reflect 32 bit char capacity of an integer word. Defined an integer constant BLNK for checking if at end of text by equivalencing it to a CHARACTER*4 string of that value.

• Changed G formats to In, added OPEN statement to read data file, and forced BLANK='NULL' so that left-justified integer fields could be read.

• Removed most of the functionality of the GETIN subroutine associated with packing of 5 7-bit ASCII chars into a 36 bit word (DEC PDP-10 architecture), changing relevant variables to CHARACTER*5 for string comparisons. This also makes the SHIFT subroutine superfluous, though the functionality was maintained by using more modern ANSI built-in functions IAND, IOR, ISHIFT.

• Changed the program to not PAUSE when the game is over. The code assumes that resumption after PAUSE will restart the game (reset it to its initial conditions), but whether one can resume after a pause is system dependent. Instead, changed the code to ask whether you want to play again, and, if not, stop.

• Fixed a bug in the code which did not recognize the special destination code 314, which was used in the database. It appears that the computed GOTO to reach code labeled 39 left out that jump condition; the fix restores it. The code at 39 appears to choose destinations compatible with the location that uses destination code 314.

• Fixed a bug in the code that controls dwarf attacks. A mis-coded check led to access of element 0 of the DTRAV array.

• Added command line option -loc which prints out location in maze (to help mapping/route finding for the frustrated).

Database changes:

• Eliminated a blank line among the location descriptions, which triggered a bug in the main line code (zero array index).

• Replaced tabs with blanks to reformat numeric fields to fixed-length.

• Deleted motion codes 305 in two places, which was a mistake; there is no motion word with that key, nor do motion codes have any special encoding schemes like destination codes have. Seems to have been a problem setting up the motion database originally by Will Crowther.

• Fixed typos in some messages.

• Changed action word EXCIV to EXCAV (Crowther probably meant "excavate" because it is a synonym of "dig").

• The CHEST/TREAS/BOX object, probably meant to be a treasure chest, is not put anywhere in the maze, nor does any denizen or action cause it to be dropped or created. This probably represents a new feature that Crowther didn't fully implement. (No changes made.)

Assumptions:

• Database must be in the same directory as executable and named adventure.dat.

• Built-in function RAN(I) returns a pseudo-random REAL variable 0 <= X <= 1. (This is a built-in library function in GNU Fortran.)

• Addition of -loc command line option uses GNU Fortran built-in function IARGC() and procedure GETARG(N,VAR) to respectively get number of command line arguments, and command argument N's text as character string VAR.