The Hobbit (v1.0): Routine at 8ED3

The barrel's FILL handler. The instrument must be something that pours (bit 1 of its flags: water and wine, for example) and the target must not already be full ('the barrel is full'). The work is done by PUT IN (91B9) with target and instrument swapped (9E93), so FILL THE BARREL WITH WATER is really PUT THE WATER IN THE BARREL.

Filling from a river is a special case: if the instrument is object 23 or 24 (the river's water or black water), a fresh object 21 or 22 ('water', 'black water') is used instead, so the river never runs dry.

The barrel's FILL handler. The instrument must be something that pours (bit 1 of its flags: water and wine, for example) and the target must not already be full ('the barrel is full'). The work is done by PUT IN (91B9) with target and instrument swapped (9E93), so FILL THE BARREL WITH WATER is really PUT THE WATER IN THE BARREL. Filling from a river is a special case: if the instrument is object 23 or 24 (the river's water or black water), a fresh object 21 or 22 ('water', 'black water') is used instead, so the river never runs dry.
8ED3	LD IX,($B5F8)	IX = the target's own record (the container being filled)
8ED7	LD A,($B5DA)	Is the instrument the fast river's water, or the enchanted river's black water?
8EDA	CP $17
8EDC	JR Z,$8EFC	Ordinary river water: go and use a fresh copy of it, below
8EDE	CP $18	Ordinary river water: go and use a fresh copy of it, below
8EE0	JR Z,$8F04	Black water: likewise
8EE2	LD IY,($B5FA)	Anything else: IY = the instrument's own record
8EE6	BIT 1,(IY+$07)	Does it actually pour (is it a liquid)?
8EEA	JP Z,$9EBF	No: fail with the usual message
8EED	BIT 2,(IX+$07)	Is the container already full?
8EF1	LD A,$82	A = the state code for FULL
8EF3	JP NZ,$A09C	Yes: say so and stop
8EF6	LD HL,$91B9	No: do the work as an ordinary PUT IN...
8EF9	JP $9E93	...with target and instrument swapped, so "fill X with Y" becomes "put Y in X"
8EFC	LD A,$15	Ordinary river water: A = a FRESH water object
8EFE	LD IY,$C343	IY = its own record
8F02	JR $8F0A	IY = its own record
8F04	LD A,$16	Black water: A = a fresh black-water object instead
8F06	LD IY,$C358	Black water: A = a fresh black-water object instead
8F0A	LD ($B5DA),A	That fresh object becomes the instrument
8F0D	LD ($B5FA),IY	That fresh object becomes the instrument
8F11	LD (IY+$01),$FF	It starts out held by nobody...
8F15	JR $8EE2	...then join the ordinary FILL code above (so the river itself never runs dry)