Routines
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EA6E: Process Replacement Enemy Entity
Per-frame handler for the replacement entity spawned by Handle_Enemy_Collision_Chain. Jumps to Process_Final_Phase_Enemy_Entity if the countdown has already expired. Otherwise locates the associated entity record pointer and jumps to Process_Replacement_Enemy_Entity_Retire to retire if the associated record is in settled state (02). Decrements the countdown and calls Draw_Wide_Entity_Sprite to erase. If the countdown is still non-zero, applies a random X nudge (±7) and spawns via Draw_Wide_Entity_Sprite. If the countdown reaches zero, copies entity data, resets state, and spawns via Process_Replacement_Enemy_Entity_Spawn. When settled, installs the retire handler Process_Entity_Record_Fast.
Input
HL Entity record pointer
Test the countdown and locate the associated entity record.
Process_Replacement_Enemy_Entity EA6E LD A,(HL) Jump to Process_Final_Phase_Enemy_Entity if the entity countdown has already expired.
EA6F AND A
EA70 JP Z,Process_Final_Phase_Enemy_Entity
EA73 LD B,H Save the entity pointer in BC and load the associated entity record pointer from offset 05.
EA74 LD C,L
EA75 LD DE,$0005
EA78 ADD HL,DE
EA79 LD E,(HL)
EA7A INC HL
EA7B LD D,(HL)
EA7C LD A,(DE) Read the associated entity state, restore HL, and jump to Process_Replacement_Enemy_Entity_Retire if settled (02).
EA7D CP $02
EA7F LD H,B
EA80 LD L,C
EA81 JR Z,Process_Replacement_Enemy_Entity_Retire
EA83 DEC (HL) Decrement the entity countdown.
Erase the entity with colour INK: RED, PAPER: BLACK (BRIGHT) .
EA84 PUSH HL Stash the entity pointer on the stack.
EA85 INC HL Advance to the entity position.
EA86 EXX Load INK: RED, PAPER: BLACK (BRIGHT) into B'.
EA87 LD B,$42
EA89 EXX
EA8A CALL Draw_Wide_Entity_Sprite Call Draw_Wide_Entity_Sprite to erase the entity.
EA8D POP HL Restore the entity pointer from the stack.
Test the countdown and branch.
EA8E LD A,(HL) Jump to Process_Replacement_Enemy_Entity_Settle if the countdown has reached zero.
EA8F AND A
EA90 JR Z,Process_Replacement_Enemy_Entity_Settle
EA92 INC HL Advance two bytes into the entity record.
EA93 INC HL
Apply a random X nudge to the entity position.
EA94 INC HL Advance two more bytes to the X position field.
EA95 INC HL
EA96 CALL Generate_Random_Byte Call Generate_Random_Byte to generate a random byte.
EA99 AND %00001111 Mask to the lower four bits.
EA9B SUB $07 Subtract 07 to produce a nudge in the range F9–07.
EA9D ADD A,(HL) Apply the nudge to the entity X position and step back two bytes.
EA9E DEC HL
EA9F DEC HL
EAA0 LD (HL),A
EAA1 DEC HL Step back one more byte to the entity record position field.
EAA2 PUSH HL Stash the entity record pointer on the stack.
Generate a random spawn colour and spawn the entity.
Process_Replacement_Enemy_Entity_Spawn EAA3 EXX Switch to alternate registers.
EAA4 CALL Generate_Random_Byte Call Generate_Random_Byte to generate a random colour byte.
EAA7 AND %00111000 Mask to bits 3–5 to select the spawn colour.
EAA9 LD B,A Load the colour into B and switch to main registers.
EAAA EXX
EAAB CALL Draw_Wide_Entity_Sprite Call Draw_Wide_Entity_Sprite to spawn the entity.
EAAE POP HL Restore the entity record pointer from the stack.
EAAF JP Process_Entity_Record_Next6 Jump to Process_Entity_Record_Next6 to advance the entity pointer.
Copy entity data and reset the settle state.
Process_Replacement_Enemy_Entity_Settle EAB2 INC HL Step two bytes ahead, copy HL to DE, step two more, and copy one byte to the destination.
EAB3 INC HL
EAB4 LD D,H
EAB5 LD E,L
EAB6 INC HL
EAB7 INC HL
EAB8 LDI
EABA LD C,(HL) Read the countdown into C, reset it to 0A advance, and read the type byte into B.
EABB LD (HL),$0A
EABD INC HL
EABE LD B,(HL)
EABF LD (HL),$FF Reset the type field to FF write state value 0F to *DE and 0C to *BC.
EAC1 INC DE
EAC2 LD A,$0F
EAC4 LD (DE),A
EAC5 LD A,$0C
EAC7 LD (BC),A
EAC8 DEC DE Step DE back three bytes, stash DE, exchange DE and HL, and jump to Process_Replacement_Enemy_Entity_Spawn.
EAC9 DEC DE
EACA DEC DE
EACB PUSH DE
EACC EX DE,HL
EACD JP Process_Replacement_Enemy_Entity_Spawn
Write the retire handler, erase the sprite, draw, and return.
Process_Replacement_Enemy_Entity_Retire EAD0 LD DE,$E003 Write the retire handler Process_Entity_Record_Fast and state byte 32 into the entity record.
EAD3 DEC HL
EAD4 LD (HL),D
EAD5 DEC HL
EAD6 LD (HL),E
EAD7 INC HL
EAD8 INC HL
EAD9 LD (HL),$32
EADB INC HL
EADC PUSH HL Stash the entity pointer on the stack.
EADD CALL Erase_Wide_Entity_Sprite Call Erase_Wide_Entity_Sprite to erase the entity sprite.
EAE0 POP HL Restore the entity pointer from the stack.
EAE1 LD (HL),$0F Write the state timer 0F.
EAE3 PUSH HL Stash the entity pointer on the stack.
EAE4 EXX Load INK: WHITE, PAPER: BLACK (BRIGHT) into B'.
EAE5 LD B,$47
EAE7 EXX
EAE8 CALL Draw_Entity_Sprite Call Draw_Entity_Sprite to draw the entity.
EAEB POP HL Restore the entity pointer from the stack.
EAEC INC HL Advance one byte and copy HL to DE.
EAED LD D,H
EAEE LD E,L
EAEF INC HL Step four bytes to the end-marker field.
EAF0 INC HL
EAF1 INC HL
EAF2 INC HL
EAF3 LD (HL),$FF Write the end marker FF.
EAF5 INC HL Advance to the next entity slot.
EAF6 RET Return.
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