Hydrofool: Routines

Address	Description
61A7	JP (HL) trampoline
61A8	Initialize the object free list: chain B 24-byte records starting at DE (each record's first word points to the next)
61C1	Routine at 61C1
61E3	Routine at 61E3
6254	Set object position (IX+5/+6) from grid index A (cell centre: row8+4, col8+4)
6269	Set current room to A: locate its description record and build the room
62F9	Test whether the current room is this level's Plug Room (via the per-level table at $7287); returns Z if so, with HL pointing at the entry's state byte
630D	Routine at 630D
6329	Build the door/exit bitfield at $612B from the room description's byte1
6344	Draw single-piece doors, for $612B bits 0 and 3
6377	Draw three-piece doors, for $612B bits 1 and 2
63D0	Clear shadow screen
642F	Draw the fixed wall/decoration layout selected by $6129
6470	Routine at 6470
64BB	Routine at 64BB
64F3	Routine at 64F3
6503	Routine ?? Oil
6543	Routine at 6543
655E	Routine at 655E
6580	Routine at 6580
6593	Routine at 6593
65DB	Draw message window: room/creature title line + rotating clue/joke message line
6622	Use an oil can (kind $6E pickup, see 8AFB): resets rust timer, decrements oil-can count, plays sound
663B	Routine at 663B
6653	Prepare room with color 0
6657	Get room color from room description and store to 6175
6663	Spawn the room's creature (dynamic object)
6692	Routine at 6692
66CE	Routine at 66CE
6728	Routine at 6728
6743	Routine at 6743
676D	Draw current room
67F1	Attempt to move to an adjacent room (horizontal, via a door) in the direction given by ($8DC1)
6880	Routine at 6880
6895	HUD: draw the currently-held item's icon, and its ammo count if it's a weapon
68C1	Consume one shot of ammo; auto-drop the weapon when empty
69AC	Prepare the Room ??
6AAA	Routine at 6AAA
6AE7	Routine at 6AE7
6AF1	Routine at 6AF1
6AF8	Routine at 6AF8
6AFB	Routine at 6AFB
6AFC	Routine at 6AFC
6B05	Routine at 6B05
6B71	Routine at 6B71
7CEC	Print engine entry point
7CF9	Print char routine (default mode)
7D32	Print engine mode: set inverse video flag
7D3F	Print engine mode: dispatch control code $16
7D48	Print engine mode: set cursor row
7D57	Print engine mode: set cursor column
7D68	Print string routine
7DC7	Routine at 7DC7
7E4F	Flip sprite horizontally
7EA9	Routine at 7EA9
7EBE	Read input: normalize the active control method into the 5-bit mask at 6186
7F8E	Routine at 7F8E
7F9B	Routine at 7F9B
7FC0	Routine at 7FC0
7FCD	Routine at 7FCD
8011	Routine at 8011
809D	Routine at 809D
8107	Routine at 8107
8128	Draw sprite C with its mask at screen position DE (mask sprite number from the table at 6C06; A bit 7 = mirror flag)
8230	Routine at 8230
82A6	Routine at 82A6
82DB	Routine at 82DB
82F0	Routine at 82F0
8315	Routine at 8315
835E	Routine at 835E
8445	Routine at 8445
848E	Request sound effect A (queued at $61A2, gated by the $61A0/$61A1 flags)
84AE	Dynamic object allocator
84ED	Load a sprite's A5DC record into the "current sprite" scratch variables at 618D, ready for 8128 to draw it
8501	Print string at HL until terminator byte $5E or $2B
850E	Print an inline string embedded right after the caller's CALL instruction
8513	Routine at 8513
8523	Print a BCD number: B bytes from (HL), two digits per byte, leading zeros as spaces; DE = per-digit print routine (self-modifies 854C's JP)
854C	Print one digit (JP target self-modified by 8523)
854F	Print BCD byte A as two digits, high digit blanked to a space if zero
8596	Routine at 8596
85A1	Main menu screen: title, entry list A-D, controls menu; loops until a selection starts the game
86CC	Draw the end-game stats screen
885A	HUD: redraw the score display (last 4 BCD digits of 611B via 8523)
8879	Add a 5-digit BCD value at 8874 to the score (611B)
888E	Add a bonus (HL, 5-digit BCD) to the score, then redraw the score display
8894	Subtract a 5-digit BCD value at 8874 from the score (611B); if the score can't cover it, resets $611B-$611F from a fixed 5-byte block at $5C92 instead
88B9	Routine at 88B9
88D7	Routine at 88D7
88DD	Routine at 88DD
88E3	Search the buffer at $7C83 for byte A (CPIR, length from $7C88)
8968	PLAYER per-frame behaviour handler
8A87	Attempt to move to an adjacent room (vertical, via whirlpool/bubble)
8ABB	Apply the object's facing direction to its position (IX+5/+6), returning the OLD position in BC
8AD9	Take one walk step: apply the facing delta, then check for a room-edge/door transition and a collision, reverting the position if blocked
8AFB	Fire/pick-up button handler: attack with the held weapon, or pick up/drop an item
8C35	Routine at 8C35
8CDF	Routine at 8CDF
8D11	Alternate PLAYER behaviour handler (swapped into $8DB9 by 9564; see 8968 and 8DB6)
8D8D	Attack: fire the held weapon (reached from 8AFB when a weapon is held)
8E3F	Special grid-value spawn routine (value $68) -- rearing snake
8E6E	Routine at 8E6E
8EA7	Special grid-value spawn routine (values $66/$6A) -- bubble source ($6A full-strength, $66 weak; see 9602)
8EF2	Special grid-value spawn routine (value $67) -- plant/coral
8F1E	Special grid-value spawn routine (value $69) -- whirlpool
8F4C	Special grid-value spawn routine (value $6B) -- plug
8F82	Re-initialize the state blocks of the two fixed object records at $8DCF and $8DEF (22 bytes each from $5C92 to $8DD1/$8DF1 -- see 8DB6)
9021	Routine at 9021
9085	Routine at 9085
90A8	Routine at 90A8
91A6	Routine at 91A6
9208	Routine at 9208
9232	Routine at 9232
923E	Save continuation: set the object's handler (+3/+4) to the address just after the caller's CALL, then jump there (the object resumes at that point next frame)
925C	Routine at 925C
9341	Room-creature per-frame behaviour handler (installed by the creature spawn at 6663) -- dual purpose: item-delivery detector in Plug Rooms, settle/float physics + hit detection elsewhere
9401	Creature hit/defeat sequence, called from 9341 when the "just hit" flag (bit 2 of +0x0D) is set
9471	Behaviour handler of the fixed object record at $8E0F (object identity not yet known)
949E	Behaviour handler of the fixed object record at $8E27 (object identity not yet known)
94CA	Routine at 94CA
94EE	Per-frame behaviour handler for value-$67 objects -- plant/coral
94F4	Per-frame behaviour handler for value-$6B objects -- plug. WIN-CONDITION TRIGGER: polls every frame for full item delivery, then pops and increments the "Plugs Pulled" counter.
952D	Per-frame behaviour handler for value-$69 objects -- whirlpool
957C	Per-frame behaviour handler for value-$66/$6A objects -- bubble source
9602	Per-frame behaviour handler for the individual rising-bubble particle spawned by 957C
9684	Per-frame behaviour handler for value-$68 objects -- rearing snake
9745	Routine at 9745
97BA	Draw an object's sprite: convert record position (+5/+6) to screen coordinates and draw sprite (+8) with its mask via 8128
97FC	Change current room to A = new room number
9808	Per-frame main loop entry: saves SP to $60E9 (restored by 97FC on room change); restores the message-window title when the $618A timer expires
983C	Per-frame dynamic object dispatcher (walks the active object list from the head at 610E)
9900	Draw all queued objects: walk the record-pointer list at $60EC (count at $60EB), drawing each via 97BA
9923	Spawn the weapon projectile object (thrown from the player's position, facing $8DC1), handler 9963
9963	Weapon projectile per-frame handler: move (double step) and detect a hit on collision
99A1	Direction-indexed sprite-animation stepper: pick one of 4 per-direction tables via (IX+$0B), then run 99D5's stepper on it
99D1	NEG / not NEG
99D5	Sprite-animation stepper: read next entry from a per-object sprite-number table, advancing a phase counter
9A49	Routine at 9A49
9A60	Dynamic object finalizer (called at the end of every spawn routine's object setup)
9AAB	Search the (key,data) pair table at $74CE for key A; returns Z with HL pointing at the matched pair's data byte
9ABC	Terrain collision test for one screen point (B,C): convert to a grid cell and check its content
9AFD	Routine at 9AFD
9B5A	Collision/overlap scan: walk the active object list looking for another same-room object whose bounding box (+$10..+$13) overlaps IX's; DE = the object found
9BD4	Routine at 9BD4
9BF0	Collision test: check the object's 4 bounding-box corners against the room grid, then check for overlap with other objects
9C35	Routine at 9C35
FB90	Menu tune + key-wait driver
FBB4	Melody-index table reader/advancer, used by FBD7
FBC1	Melody-index to period lookup, used by FBD7
FBCF	Continuation of FBB4
FBD7	Play one note / check key selection
FC34	Tone generator loop (continued)
FC46	Plain delay loop (no sound)