Routines
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F2C7: Test Entity Overlap At Depth
Used by the routines at Update_Berk_ReadControls, ScriptRoutine_TaskThreeSeekBerk, ScriptRoutine_VatRoomTransition and ScriptRoutine_CollectibleLeaveRoomUp.
As Test_EntityOverlap, but match entities whose room is one deeper than IX (room−01). Used when Berk moves forward into the next depth band.
Input
IX Address of complex state data for the subject entity
Test_EntityOverlap_AtDepth F2C7 LD BC,$0001 Load BC with 0001 (reject bit 05, then room−01).
This entry point is used by the routines at Test_EntityOverlap_AllowSpecial and Test_EntityOverlap.
Walk the simple-entity table for a collidable overlap with IX.
Test_EntityOverlap_Scan F2CA PUSH HL Stash HL and DE on the stack.
F2CB PUSH DE
F2CC LD DE,$000E Each entity record is 000E bytes, then load that into DE.
F2CF LD HL,$8B69 Point HL at the simple entity table (StateData_SimpleEntities).
Next simple-entity slot for the overlap test (or miss on FF).
Test_EntityOverlap_ScanSlot F2D2 LD A,(HL) Fetch this entity's type. Is it the table terminator (FF)? If not, test the slot at Test_EntityOverlap_CheckSlot.
F2D3 CP $FF
F2D5 JR NZ,Test_EntityOverlap_CheckSlot
Simple-entity scan miss: restore registers and return carry set.
F2D7 POP DE Restore DE and HL from the stack.
F2D8 POP HL
F2D9 SCF Signal a miss.
F2DA RET Return.
Reject empty/inactive/same-type slots; require collidable bit 00 (and optional bit 05).
Test_EntityOverlap_CheckSlot F2DB LD A,(HL) Re-fetch the type. Is the slot empty (type 00)? If so, skip to Test_EntityOverlap_AdvanceSlot.
F2DC OR A
F2DD JR Z,Test_EntityOverlap_AdvanceSlot
F2DF BIT 7,A Is the high bit set (inactive)? If so, skip to Test_EntityOverlap_AdvanceSlot.
F2E1 JR NZ,Test_EntityOverlap_AdvanceSlot
F2E3 CP (IX+$00) Is it the same type as the subject? If so, skip to Test_EntityOverlap_AdvanceSlot.
F2E6 JR Z,Test_EntityOverlap_AdvanceSlot
F2E8 PUSH HL Stash HL on the stack.
F2E9 INC HL Advance onto flags byte 1.
F2EA LD A,(HL) Fetch flags byte 1.
F2EB AND %00000001 Keep only the collidable bit (bit 00).
F2ED JR Z,Test_EntityOverlap_Reject If it was clear, reject at Test_EntityOverlap_Reject.
F2EF BIT 0,B Has the caller allowed bit-05 entities (B bit 00)? If so, skip the bit-05 reject at Test_EntityOverlap_CheckBounds.
F2F1 JR NZ,Test_EntityOverlap_CheckBounds
F2F3 BIT 5,(HL) Is bit 05 set on this entity? If so, reject at Test_EntityOverlap_Reject.
F2F5 JR NZ,Test_EntityOverlap_Reject
Require matching room (minus C) and overlapping y/x extents with IX.
Test_EntityOverlap_CheckBounds F2F7 INC HL Advance HL past the unused entity fields onto the room byte.
F2F8 INC HL
F2F9 INC HL
F2FA LD A,(HL) Fetch the entity's room.
F2FB SUB C Subtract the caller's room bias in C.
F2FC CP (IX+$04) Does it match the subject's room (IX+04)? If not, jump to Test_EntityOverlap_Reject.
F2FF JR NZ,Test_EntityOverlap_Reject
F301 INC HL Advance onto the entity's y-coordinate.
F302 LD A,(IX+$06) Does the subject's y-extent (IX+06) reach this candidate y? If not, reject at Test_EntityOverlap_Reject.
F305 CP (HL)
F306 JR C,Test_EntityOverlap_Reject
F308 INC HL Advance onto the entity's y-extent.
F309 LD A,(HL) Does this candidate y-extent reach the subject's y (IX+05)? If not, reject at Test_EntityOverlap_Reject.
F30A CP (IX+$05)
F30D JR C,Test_EntityOverlap_Reject
F30F INC HL Advance onto the entity's x-coordinate.
F310 LD A,(IX+$08) Does the subject's x-extent (IX+08) reach this candidate x? If not, reject at Test_EntityOverlap_Reject.
F313 CP (HL)
F314 JR C,Test_EntityOverlap_Reject
F316 INC HL Advance onto the entity's x-extent.
F317 LD A,(HL) Does this candidate x-extent reach the subject's x (IX+07)? If not, reject at Test_EntityOverlap_Reject.
F318 CP (IX+$07)
F31B JR C,Test_EntityOverlap_Reject
Hit: remember the entity and return its type with carry clear.
F31D POP HL Restore HL from the stack.
F31E XOR A Clear A / carry.
F31F LD ($72AA),HL Store the entity pointer at Pointer_LastCollidedEntity.
F322 LD A,(HL) Fetch the entity's type into A.
F323 POP DE Restore DE and HL from the stack.
F324 POP HL
F325 RET Return.
Reject this overlap candidate and continue the simple-entity walk.
Test_EntityOverlap_Reject F326 POP HL Restore HL from the stack.
Advance to the next simple-entity record in the overlap scan.
Test_EntityOverlap_AdvanceSlot F327 ADD HL,DE Advance HL by one entity record.
F328 JR Test_EntityOverlap_ScanSlot Jump to Test_EntityOverlap_ScanSlot to test the next simple entity.
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