X-Git-Url: https://jxself.org/git/?p=open-adventure.git;a=blobdiff_plain;f=notes.adoc;h=6ee80a5a463cc51799207b2295d0f92c671f98f4;hp=f1716baf8b4c0a5d924b7c44c4d9fc6de94d7b28;hb=HEAD;hpb=300d2461799808a5acb8f6f4a866325c0e50d996 diff --git a/notes.adoc b/notes.adoc index f1716ba..b970e7c 100644 --- a/notes.adoc +++ b/notes.adoc @@ -1,5 +1,7 @@ = Open Adventure Maintainer's Notes = by Eric S. Raymond +// SPDX-FileCopyrightText: (C) Eric S. Raymond +// SPDX-License-Identifier: CC-BY-4.0 In which we explain what has been done to this code since Don Woods authorized us to ship it under an open-source license. There's a @@ -11,7 +13,11 @@ The principal maintainers of this code are Eric S. Raymond and Jason Ninneman. Eric received Don Woods's encouragement to update and ship the game; Jason signed on early in the process to help. The assistance of Peje Nilsson in restructuring some particularly grotty gotos is -gratefully acknowledged. Petr Voropaev contributed fuzz testing. +gratefully acknowledged. Petr Voropaev contributed fuzz testing and +code cleanups. Aaron Traas did a lot of painstaking work to improve +test coverage, and factored out the last handful of gotos. Ryan +Sarson nudged us into fixing a longstannding minor bug in the +handling of incorrect magic-word sequebcesm, == Nomenclature == @@ -28,28 +34,78 @@ with the BSD Games version. == Philosophy == Extreme care has been taken not to make changes that would alter the -logic of the game as we received it from Don Woods. By policy, all -user-visible changes must be revertible with the -o (oldstyle) option. - -It is a goal of this project to exactly preserve the *behavior* of -430-point Adventure, but the implementation of it is fair game for -improvement. In particular, we are concerned to move it to a form that -is (a) readable, and (b) friendly to forward translation to future -languages. It has already survived a move from FORTRAN to C; a future -as a Python or Go translation seems possible, even probable. +logic of the game as we received it from Don Woods, except to fix +glitches that were clearly bugs. By policy, all user-visible +changes to gameplay must be revertible with the -o (oldstyle) option. + +It is a goal of this project to exactly preserve the *intended +behavior* of 430-point Adventure, but the implementation of it is fair +game for improvement. In particular, we are concerned to move it to a +form that is (a) readable, and (b) friendly to forward translation to +future languages. It has already survived a move from FORTRAN to C; a +future as a Python or Go translation seems possible, even probable. + +Compatibility with the 2.5 source we found has been checked by +building a version patched minimally to support the seed command and +running it against the entire test suite, which has 100% code +coverage. == Functional changes == +Bug fixes: + +* The caged bird used to be counted as two items in your inventory. + +* Reading the relocated Witt's End sign in the endgame didn't work right. + +* Oyster was readable after first gotten even when not carried. + +* Response to an attempt to unlock the oyster while carrying it was incorrect. + +* Behavior when saying the giant's magic words before having seen them + wasn't quite correct - the game responded as though the player had + already read them ("...can't you read?"). The new message is "Well, + that was remarkably pointless!" The -o option reverts this change. + +* Attempting to extinguish an unlit urn caused it to lose its oil. + +* "A crystal bridge now spans the fissure." (progressive present) was + incorrect most places it appeared and has been replaced by "A crystal + bridge spans the fissure." (timeless present). + +* A few minor typos have been corrected: absence of capitalization on + "Swiss" and "Persian", inconsistent spelling of "imbedded" vs. "embedded", + "eying" for "eyeing", "thresholds" for "threshholds". + +* Under odd circumstances (dropping rug or vase outdoors) the game could + formerly say "floor" when it should say "ground" (or "dirt", or something). + +Enhancements: + By default, advent issues "> " as a command prompt. This feature became common in many variants after the original 350-point version, but was never backported into Crowther & Woods's main line before now. -The "-o" (oldstyle) version reverts the behavior. +The "-o" (oldstyle) option reverts the behavior. + +There is a set of standard one-letter command aliases conventional in modern +text adventure games; 'l' and 'x'; for 'look' (or 'examine'), 'z' to do nothing +for a turn, 'i' for 'inventory', 'g' for 'get', and 'd' for 'drop'. The 'd' +alias collides with 'd' for 'down', but the others have been implemented. +The "-o" (oldstyle) option disables them. + +Unrecognized words are no longer truncated to 5 characters and +uppercased when they are echoed. The "-o" (oldstyle) option restores +this behavior. A "seed" command has been added. This is not intended for human use but as a way for game logs to set the PRNG (pseudorandom-number generator) so that random events (dwarf & pirate appearances, the bird's magic word) will be reproducible. +A "version" command has been added. This has no effect on gameplay. + +The text displayed by the "news" command has been updated. + A -l command-line option has been added. When this is given (with a file path argument) each command entered will be logged to the specified file. Additionally, a generated "seed" command will be put @@ -60,21 +116,38 @@ Using "seed" and -l, the distribution now includes a regression-test suite for the game. Any log captured with -l (and thus containing a "seed" command) will replay reliably, including random events. -The adventure.text file is no longer required at runtime. Instead, it -is compiled at build time to a source module containing C structures, -which is then linked to the advent binary. There is an adventure.yaml file -as well; this is also compiled to C code, and will eventually replace -adventure.text altogether. +The adventure.text file is no longer required at runtime. Instead, an +adventure.yaml file is compiled at build time to a source module +containing C structures, which is then linked to the advent +binary. The YAML is drastically easier to read and edit than +the old ad-hoc format of adventure.txt. The game-save format has changed. This was done to simplify the FORTRAN-derived code that formerly implemented the save/restore functions; without C's fread(3)/fwrite() and structs it was necessarily pretty ugly by modern standards. Encryption and checksumming have been discarded - it's pointless to try -tamper-proofing saves when everyone has the source code. +tamper-proofing saves when everyone has the source code. However +the game still integrity-checks savefiles on resume, including an +abort if the endianness of the restoring machine does not match that of +the saving machine. There is a magic-cookie header on the saves so +in theory they could be identified by programs like file(1). + +Save and resume filenames are stripped of leading and trailing +whitespace before processing. -A -r command-line option has been added. It is functionally equivalent -to RESTORE command, but faster. +A -r command-line option has been added. When it is given (with a file +path argument) it is functionally equivalent to a RESTORE command. + +An -a command-line option has been added (conditionally on +ADVENT_AUTOSAVE) for use in BBS door systems. When this option is +given, the game roads from the specified filename argument on startup +and saves to it on quit or a received signal. There is a new nmessage +to inform the user about this. + +The game can be built in a mode that entirely disables save/resume +(-DADVENT_NOSAVE). If the game had been built this way, a diagnostic is +emitted if you try to save or resume. == Translation == @@ -85,28 +158,35 @@ ugly and quite unreadable. Jason Ninneman and I have moved it to what is almost, but not quite, idiomatic modern C. We refactored the right way, checking correctness against a comprehensive test suite that we built first and verified -with coverage tools (we have 88% coverage, with the remaining 12% -confined to exception cases that are difficult to reach). This is +with coverage tools (there is effectively 100% code coverage). This is what you are running when you do "make check". -This move entailed some structural changes. The most important was -the refactoring of over 350 gotos into if/loop/break structures. We -also abolished almost all shared globals; the main one left is a -struct holding the game's saveable/restorable state. +The move to modern C entailed some structural changes. The most +important was the refactoring of over 350 gotos into if/loop/break +structures. We also abolished almost all shared globals; the main one +left is a struct holding the game's saveable/restorable state. The original code was greatly complicated by a kind of bit-packing that was performed because the FORTRAN it was written in had no string type. Text from the adventure.text file was compiled into sequences of sixbit code points in a restricted character set, packed 5 to a -32-bit word (it seems clear from the code that words were originally +32-bit word (and it seems clear from the code that words were originally *6* chars each packed into a PDP-10 36-bit word). A command noun or verb was one of these words, and what would be string operations in a more recent language were all done on sequences of these words. -We are still in the process of removing all this bit-packing cruft -in favor of proper C strings. C strings may be a weak and leaky -abstraction, but this is one of the rare cases in which they are -an obvious improvement over what they're displacing... +We have removed all this bit-packing cruft in favor of proper C +strings. C strings may be a weak and leaky abstraction, but this is +one of the rare cases in which they are an obvious improvement over +what they're displacing... + +We have also conducted extensive fuzz testing on the game using +afl (American Fuzzy Lop). We've found and fixed some crashers in +our new code (which occasionally uses malloc(3)), but none as yet +in Don's old code (which didn't). + +After version 1.11, correctness was carefully checked against the +behavior of a binary from before the big refactoring. The code falls short of being fully modern C in the following ways: @@ -117,26 +197,28 @@ ways: and the choice to refrain will make forward translation into future languages easier. -* There are a few gotos left that resist restructuring; all of these - are in the principal command interpreter function implementing its - state machine. - * Linked lists (for objects at a location) are implemented using an array of link indices. This is a surviving FORTRANism that is quite unlike normal practice in C or any more modern language. We have not tried to fix it because doing so would (a) be quite difficult, and (b) compromise forward-portability to other languages. -* The code still has an unfortunately high density of magic numbers - in - particular, numeric object IDs. There are plans to fix this. +* Much of the code still assumes one-origin array indexing. Thus, + arrays are a cell larger than they strictly need to be and cell 0 is + unused. -* Much of the code still uses FORTRAN-style uppercase names. +We have made exactly one minor architectural change. In addition to the +old code's per-object state-description messages, we now have a per-object +message series for state *changes*. This makes it possible to pull a fair +amount of text out of the arbitrary-messages list and associate those +messages with the objects that conceptually own them. -* The code still assumes one-origin array indexing. Thus, arrays are - a cell larger than they strictly need to be and cell 0 is unused. +== Development status == -* The code is still mostly typeless, slinging around machine longs - like a FORTRAN or BCPL program. Some (incomplete) effort has been made - to introduce semantic types. +We consider this project finished. All issues and TODOs have been +cleared, behavior has been carefully checked against original ADVENT, +no future demand for new features is expected, and the test suite has +100% code coverage. If new bugs appear as the toolchain bit-rots out +from under underneath, we will fix those problems. // end