Routines
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60014: 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 (2). 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 60014 LD A,(HL) Jump to Process_Final_Phase_Enemy_Entity if the entity countdown has already expired.
60015 AND A
60016 JP Z,Process_Final_Phase_Enemy_Entity
60019 LD B,H Save the entity pointer in BC and load the associated entity record pointer from offset 5.
60020 LD C,L
60021 LD DE,5
60024 ADD HL,DE
60025 LD E,(HL)
60026 INC HL
60027 LD D,(HL)
60028 LD A,(DE) Read the associated entity state, restore HL, and jump to Process_Replacement_Enemy_Entity_Retire if settled (2).
60029 CP 2
60031 LD H,B
60032 LD L,C
60033 JR Z,Process_Replacement_Enemy_Entity_Retire
60035 DEC (HL) Decrement the entity countdown.
Erase the entity with colour INK: RED, PAPER: BLACK (BRIGHT) .
60036 PUSH HL Stash the entity pointer on the stack.
60037 INC HL Advance to the entity position.
60038 EXX Load INK: RED, PAPER: BLACK (BRIGHT) into B'.
60039 LD B,66
60041 EXX
60042 CALL Draw_Wide_Entity_Sprite Call Draw_Wide_Entity_Sprite to erase the entity.
60045 POP HL Restore the entity pointer from the stack.
Test the countdown and branch.
60046 LD A,(HL) Jump to Process_Replacement_Enemy_Entity_Settle if the countdown has reached zero.
60047 AND A
60048 JR Z,Process_Replacement_Enemy_Entity_Settle
60050 INC HL Advance two bytes into the entity record.
60051 INC HL
Apply a random X nudge to the entity position.
60052 INC HL Advance two more bytes to the X position field.
60053 INC HL
60054 CALL Generate_Random_Byte Call Generate_Random_Byte to generate a random byte.
60057 AND %00001111 Mask to the lower four bits.
60059 SUB 7 Subtract 7 to produce a nudge in the range 249–7.
60061 ADD A,(HL) Apply the nudge to the entity X position and step back two bytes.
60062 DEC HL
60063 DEC HL
60064 LD (HL),A
60065 DEC HL Step back one more byte to the entity record position field.
60066 PUSH HL Stash the entity record pointer on the stack.
Generate a random spawn colour and spawn the entity.
Process_Replacement_Enemy_Entity_Spawn 60067 EXX Switch to alternate registers.
60068 CALL Generate_Random_Byte Call Generate_Random_Byte to generate a random colour byte.
60071 AND %00111000 Mask to bits 3–5 to select the spawn colour.
60073 LD B,A Load the colour into B and switch to main registers.
60074 EXX
60075 CALL Draw_Wide_Entity_Sprite Call Draw_Wide_Entity_Sprite to spawn the entity.
60078 POP HL Restore the entity record pointer from the stack.
60079 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 60082 INC HL Step two bytes ahead, copy HL to DE, step two more, and copy one byte to the destination.
60083 INC HL
60084 LD D,H
60085 LD E,L
60086 INC HL
60087 INC HL
60088 LDI
60090 LD C,(HL) Read the countdown into C, reset it to 10 advance, and read the type byte into B.
60091 LD (HL),10
60093 INC HL
60094 LD B,(HL)
60095 LD (HL),255 Reset the type field to 255 write state value 15 to *DE and 12 to *BC.
60097 INC DE
60098 LD A,15
60100 LD (DE),A
60101 LD A,12
60103 LD (BC),A
60104 DEC DE Step DE back three bytes, stash DE, exchange DE and HL, and jump to Process_Replacement_Enemy_Entity_Spawn.
60105 DEC DE
60106 DEC DE
60107 PUSH DE
60108 EX DE,HL
60109 JP Process_Replacement_Enemy_Entity_Spawn
Write the retire handler, erase the sprite, draw, and return.
Process_Replacement_Enemy_Entity_Retire 60112 LD DE,57347 Write the retire handler Process_Entity_Record_Fast and state byte 50 into the entity record.
60115 DEC HL
60116 LD (HL),D
60117 DEC HL
60118 LD (HL),E
60119 INC HL
60120 INC HL
60121 LD (HL),50
60123 INC HL
60124 PUSH HL Stash the entity pointer on the stack.
60125 CALL Erase_Wide_Entity_Sprite Call Erase_Wide_Entity_Sprite to erase the entity sprite.
60128 POP HL Restore the entity pointer from the stack.
60129 LD (HL),15 Write the state timer 15.
60131 PUSH HL Stash the entity pointer on the stack.
60132 EXX Load INK: WHITE, PAPER: BLACK (BRIGHT) into B'.
60133 LD B,71
60135 EXX
60136 CALL Draw_Entity_Sprite Call Draw_Entity_Sprite to draw the entity.
60139 POP HL Restore the entity pointer from the stack.
60140 INC HL Advance one byte and copy HL to DE.
60141 LD D,H
60142 LD E,L
60143 INC HL Step four bytes to the end-marker field.
60144 INC HL
60145 INC HL
60146 INC HL
60147 LD (HL),255 Write the end marker 255.
60149 INC HL Advance to the next entity slot.
60150 RET Return.
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