Changes between Version 19 and Version 20 of WikiStart

Timestamp:

Jul 24, 2023, 8:01:08 PM (11 months ago)

Author:

pulkomandy

Comment:

--

WikiStart

@@ -113 +113 @@
 == "COND" files
 
-These probably implement the game logic.
-
-CONDSAL is the scripts for each room. I guess this because it has the same number of toplevel chunks as MSG.DAT, and also because "SAL" can be for "salles" (French for "rooms").
-
-CONDGALE may be "conditions générales" and associated with MSGGEN.DAT?
+These implement the game logic.
+
+CONDSAL is the scripts for each room. I found this because it has the same number of toplevel chunks as MSG.DAT, and also because "SAL" can be for "salles" (French for "rooms").
+
+CONDGALE may be "conditions générales" and associated with MSGGEN.DAT? It contains the initialization script that is run at the start of the game and a few other global things.
 
 I don't know what CONDULTI is for yet, but maybe it is for global things and associated with the INIT file?
 
-Each of the COND script contains chunks that contain sub-chunks, in a similar format to the messages files. But the content of the chunks is not decoded yet.
+Each of the COND script contains chunks that contain sub-chunks, in a similar format to the messages files. The content of each script is a sequence of opcodes. Most but not all of them start with the 0D opcode that checks if a specific button was clicked. If this is not the case, the script is not run and the next one is tried. There can be multiple scripts matching a specific button event, usually with extra conditions.
 
 The rehex script, for now:
@@ -154 +154 @@
 === Opcodes
 
-==== 09: ??
+==== 00: Return
+
+"Return" or "End of line". If this is not present at the end of a line, the execution may continue with the next one?
+
+==== 01 xx: CheckFlag
+
+Check if flag number xx is set. This is used for internal flags tracking the game state.
+
+==== 03 xx: HasItem
+
+Check if the player is carrying item xx.
+
+==== 09 xx yyyy: IfEqual
+
+Compare counter xx with value yyyy and continue executing the line if they are equal
+
+==== 0A xx yyyy: IfLess
+
+Compare counter with value and continue if it is less than the value
 
 ==== 0D xx yy: Check event
@@ -166 +184 @@
 Actions involving objects use the second parameter, for example {{{0D 68 05}}} corresponds to action 68 done on object 05.
 
-==== 0E: ??
+==== 0E xx: Check global event
+
+Check global events, for example event 00 is the start of the game.
+
+==== 7E: Or
+
+Used to combine multiple conditions (0D, 09, 0A, ...)
+
+==== 7F: And?
+
+Probably And, also used to combine several conditions.
+
+==== 80 xx: ?
+
+Currently unknown
+
+==== 81 xx: Set flag
+
+Set flag xx
+
+==== 82 xx: Clear flag
+
+Clear flag xx
+
+==== 83 xx: Get item
+
+Add item number x to the player's inventory
+
+==== 85 xx: Remove item
+
+Remove item from the inventory.
+
+==== 87 xx yyyy: Set counter
+
+Set counter xx to value yyyy
+
+==== 89 xx yyyy: Add to counter
+
+Add value yyyy to counter xx
+
+==== 8A xx yyyy: Subtract from counter
+
+Subtract value yyyy from counter xx
 
 ==== 8F xx: Go to room
@@ -172 +232 @@
 Go to room passed as a parameter (single byte)
 
-==== 90 xx xx: Go to screen
+==== 90 xx: Go to screen
 
 Go to a screen (in the same room) passed as a parameter.
 
-TODO parameter on 1 or 2 bytes? Probably 2.
-
-==== 91 xx xx: ??
-
-Followed by a 16 bit value
-
-==== 93 xx xx: ??
-
-{{{93 01 00}}}
+==== 91 xx: Show global screen
+
+Show one of the global screens (from the unique room in MSGGEN).
+
+==== 93 xx: WithScreen
+
+Combined with a "Go to room", allows to set the target screen in the new room
+
+==== 95 xx yy: Initialize flag
+
+==== A0 xx yyyy
+
+Compare counter xx with value yyyy. This triggers an evaluation of the scripts with matching of the corresponding IfLess/IfEqual operations
+
+==== FA: stop interpreter
+
+Do not test the remaining script lines
+
+==== FC: Game over
+
+Trigger the "game over" and stop interpreting. This will ask the user if they want to restart from the last saving point or from the start of the adventure.
+
+==== FD: Continue
+
+Continue execution with the next script line.
+
+==== FE xx: Goto
+
+Call script number xx in the current room
+
+==== FF: Winning the game
+
+The game is won if you manage to execute this opcode!
 
 == INIT file