The Hobbit (v1.0): Routine at 87AD

Called when 8405 did not settle on exactly one workable target, to explain why - or to make the best of it. Inside a quotation (an order to a character) it says nothing at all and returns, so characters are not given the player's excuses.

If exactly one candidate target would work, the instrument is dealt with instead (8789). Otherwise the target's flags at 832E decide:

No noun was given (8821): the words of the action are pushed and, if nothing suitable could be found at all, 'i see nothing to open' is printed; if there was something, the command is left unfinished (8765) and the game asks 'open what?', so that the next thing typed completes it.
A noun was given but nothing matching it was found (87EF): the search is widened - first to the rooms leading off this one (9DE9, for commands such as GO INTO), then to every object anywhere (9D2E with the filter set to 2) - so that something the player has named but cannot use is still recognised. If it is found, it is made the target and the action is reported as a failure (7111, 'you cannot open the door'); if not, 'i do not see the door here'.
Several candidates fit the words: 'which key?' (8774), again leaving the command unfinished.
Exactly one candidate, or none, but the action would not work with it: the action is carried out for real anyway (87E6), so that its own handler prints the proper reason.

Called when 8405 did not settle on exactly one workable target, to explain why - or to make the best of it. Inside a quotation (an order to a character) it says nothing at all and returns, so characters are not given the player's excuses. If exactly one candidate target would work, the instrument is dealt with instead (8789). Otherwise the target's flags at 832E decide: No noun was given (8821): the words of the action are pushed and, if nothing suitable could be found at all, 'i see nothing to open' is printed; if there was something, the command is left unfinished (8765) and the game asks 'open what?', so that the next thing typed completes it. A noun was given but nothing matching it was found (87EF): the search is widened - first to the rooms leading off this one (9DE9, for commands such as GO INTO), then to every object anywhere (9D2E with the filter set to 2) - so that something the player has named but cannot use is still recognised. If it is found, it is made the target and the action is reported as a failure (7111, 'you cannot open the door'); if not, 'i do not see the door here'. Several candidates fit the words: 'which key?' (8774), again leaving the command unfinished. Exactly one candidate, or none, but the action would not work with it: the action is carried out for real anyway (87E6), so that its own handler prints the proper reason.
87AD	LD A,($B60B)	Are we inside a quotation (an order to a character)?
87B0	DEC A	Are we inside a quotation (an order to a character)?
87B1	RET Z	Yes: say nothing - characters are not given the player's own excuses
87B2	LD A,($B60C)	Is an ALL command still working through a list of objects?
87B5	AND A	Is an ALL command still working through a list of objects?
87B6	JR Z,$87BC	No: work out what really went wrong, below
87B8	POP HL	Yes: this particular object just did not work out, but others might - abandon it quietly...
87B9	JP $8385	...and go straight on to whatever ALL should try next
87BC	LD A,($8331)	Did EXACTLY ONE target candidate work, with the problem lying only with the instrument?
87BF	CP $01
87C1	JR Z,$8789	Yes: go and sort out the instrument specifically
87C3	LD HL,$832E	No: was any noun at all given for the target?
87C6	BIT 0,(HL)	No: was any noun at all given for the target?
87C8	JP Z,$8821	No: go and ask "open what?" or say there was nothing to open
87CB	BIT 1,(HL)	Are we still in the middle of searching?
87CD	LD HL,$8333
87D0	LD DE,$B5D9
87D3	LD BC,$B5EF
87D6	JR Z,$87EF	Not searching yet: go and search properly, below
87D8	LD A,($8330)	Already searched: how many candidates fitted the words at all?
87DB	AND A
87DC	JR Z,$87E6	None at all: let the action's own handler explain why
87DE	DEC A	None at all: let the action's own handler explain why
87DF	JR NZ,$8774	More than one: ask "which one?"
87E1	CALL $84C9	Exactly one candidate, but the action still failed - does it even need an instrument?
87E4	JR NZ,$8789	It does: go and sort that out instead
This entry point is used by the routines at 8351 and 8789.
87E6	CALL $875C	It does not, or nothing else fits: carry the action out anyway...
87E9	CALL $946F	...so its own handler can explain the real reason ("you cannot open the door")
87EC	JP $837F	Then carry on with the rest of the turn as usual
This entry point is used by the routine at 8789.
87EF	PUSH HL	SEARCH PROPERLY: save the noun that was given
87F0	CALL $9DDE	IX = the actor's own room's exits
87F3	LD A,$01	Assume, for now, that the noun names a nearby room
87F5	LD (BC),A	Assume, for now, that the noun names a nearby room
87F6	CALL $9DE9	Does any exit lead to a room with that name?
87F9	CP $FF	Does any exit lead to a room with that name?
87FB	JR NZ,$8811	Yes: that settles it - use that room
87FD	POP HL	No: restore the noun
87FE	LD A,$02	Widen the search to EVERY object in the game, not just nearby ones...
8800	LD ($B600),A
8803	LD IX,$BF50
8807	XOR A	...and note that reach no longer matters
8808	LD (BC),A	...and note that reach no longer matters
8809	PUSH HL	Save the noun again
880A	CALL $9D2E	Search absolutely everywhere for something matching it
880D	CP $FF	Search absolutely everywhere for something matching it
880F	JR Z,$8816	Nothing anywhere fits those words
8811	POP HL	Something was found (a room, or a distant object): use it as the target/instrument...
8812	LD (DE),A
8813	JP $7111	...and report the action as a failure ("you cannot open the door"), since it is out of reach
8816	CALL $875C	Truly nothing fits those words anywhere
8819	LD HL,$ACC7	"I do not see the X here."
881C	CALL $72CA	"I do not see the X here."
881F	XOR A	The command could not be completed
8820	RET	The command could not be completed
8821	CALL $8869	NO NOUN GIVEN FOR THE TARGET: push the action's own words as message parameters
8824	LD HL,($8349)
8827	PUSH HL
8828	LD HL,$ACD5	"I see nothing to <verb> <particle> <preposition>."
882B	LD A,($8331)	Was there in fact exactly one possible object, even with no noun named?
882E	AND A
882F	JP Z,$8781	No, none at all: print that message and give up
8832	LD A,($8345)	Yes, exactly one: use it anyway, and say which one was chosen
8835	CALL $8765
8838	LD HL,$ACB8	"<verb> <particle> <preposition> what?" (one more chance to name it precisely)
883B	JP $8781