Routines
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57634: Spawn Wave Enemies
Used by the routine at Stage_Next_Wave.
Reads three spawn-count bytes from HL (slots 16 32 48) and populates the entity list at *Entity_List_Working_Pointer with entities via Spawn_Wave_Enemies_Populate_Slot. Each record has a random screen position and a slot-typed variant; Draw_Wide_Entity_Sprite spawns each entity. Terminates the list with 53668 and updates *Entity_List_Write_Pointer.
Spawn_Wave_Enemies 57634 LD DE,(50441) DE=*Entity_List_Write_Pointer (current entity list write pointer).
57638 LD (50445),DE Copy DE to *Entity_List_Working_Pointer and *Entity_List_Snapshot.
57642 LD (50443),DE
57646 LD C,16 Call Spawn_Wave_Enemies_Populate_Slot with enemy slot 16.
57648 CALL Spawn_Wave_Enemies_Populate_Slot
57651 LD C,32 Call Spawn_Wave_Enemies_Populate_Slot with enemy slot 32.
57653 CALL Spawn_Wave_Enemies_Populate_Slot
57656 LD C,48 Call Spawn_Wave_Enemies_Populate_Slot with enemy slot 48.
57658 CALL Spawn_Wave_Enemies_Populate_Slot
57661 EX DE,HL Save the final entity list write pointer to *Entity_List_Write_Pointer.
57662 LD (50441),HL
57665 LD BC,53668 Write the entity list terminator 53668 to *HL.
57668 LD (HL),C
57669 INC HL
57670 LD (HL),B
57671 EX DE,HL Restore HL and DE.
57672 RET Return.
Reads the count byte from *HL. Caches it in the entity count table at 50215+index. If zero, jumps to Spawn_Wave_Enemies_Update_Pointer; otherwise loops B times, writing a nine-byte entity record and calling Draw_Wide_Entity_Sprite.
Spawn_Wave_Enemies_Populate_Slot 57673 PUSH HL Stash the source pointer on the stack.
57674 LD D,(HL) D=*HL (entity count for this slot).
57675 LD A,C Save the slot ID in A.
57676 SRL C Shift C right four times to derive the slot count table index.
57678 SRL C
57680 SRL C
57682 SRL C
57684 LD B,0 Write entity count (D) to *50215+index.
57686 LD HL,50215
57689 ADD HL,BC
57690 LD (HL),D
57691 POP HL Restore the source pointer.
57692 LD C,A C=A (restore the slot ID).
57693 LD A,D A=B=entity count (B drives the entity spawn loop).
57694 LD B,A
57695 AND A Test if the entity count is zero.
57696 PUSH HL Stash the source pointer on the stack.
57697 LD HL,(50445) HL=*Entity_List_Working_Pointer (entity list write pointer).
57700 JP Z,Spawn_Wave_Enemies_Update_Pointer Jump to Spawn_Wave_Enemies_Update_Pointer if the entity count is zero.
Build one entity record at *HL: entity handler 57351 zero byte, type nibble, random Y (16-170), random X (8-240), then 13 7 255; call Draw_Wide_Entity_Sprite to spawn. Loop B times.
Spawn_Wave_Enemies_Write_Record 57703 LD DE,57351 DE=57351 (entity update handler address).
57706 LD (HL),E Write DE to *HL as a little-endian word.
57707 INC HL
57708 LD (HL),D
57709 INC HL
57710 LD (HL),0 Write 0 to *HL; advance HL.
57712 INC HL
57713 CALL Generate_Random_Byte Call Generate_Random_Byte to generate a random byte.
57716 AND %00000011 Mask to the low two bits.
57718 OR C Write entity type (slot ORed with random bits) to *HL.
57719 LD (HL),A
57720 INC HL
Spawn_Wave_Enemies_Get_Y 57721 CALL Generate_Random_Byte Call Generate_Random_Byte to generate a random byte.
57724 CP 16 Retry if below 16 (outside valid Y range).
57726 JP C,Spawn_Wave_Enemies_Get_Y
57729 CP 171 Retry if 171 or greater (outside valid Y range).
57731 JP NC,Spawn_Wave_Enemies_Get_Y
57734 LD (HL),A Write random Y coordinate to *HL; advance HL.
57735 INC HL
Spawn_Wave_Enemies_Get_X 57736 CALL Generate_Random_Byte Call Generate_Random_Byte to generate a random byte.
57739 CP 8 Retry if below 8 (outside valid X range).
57741 JP C,Spawn_Wave_Enemies_Get_X
57744 CP 241 Retry if 241 or greater (outside valid X range).
57746 JP NC,Spawn_Wave_Enemies_Get_X
57749 LD (HL),A Write random X coordinate to *HL.
57750 PUSH HL Stash HL on the stack; step HL back to the type byte.
57751 DEC HL
57752 DEC HL
57753 EXX Set B'=INK: WHITE, PAPER: BLACK (BRIGHT) via shadow registers.
57754 LD B,71
57756 EXX
57757 PUSH BC Spawn the entity via Draw_Wide_Entity_Sprite, preserving BC.
57758 CALL Draw_Wide_Entity_Sprite
57761 POP BC
57762 POP HL Restore HL (X coordinate position).
57763 INC HL Write trailing record bytes 13 7 and 255.
57764 LD (HL),13
57766 INC HL
57767 LD (HL),7
57769 INC HL
57770 LD (HL),255
57772 INC HL Advance HL; loop back to Spawn_Wave_Enemies_Write_Record for the next entity.
57773 DJNZ Spawn_Wave_Enemies_Write_Record
Spawn_Wave_Enemies_Update_Pointer 57775 LD (50445),HL Save the entity list write pointer to *Entity_List_Working_Pointer.
57778 EX DE,HL Restore DE.
57779 POP HL Restore the source pointer; advance past the count byte.
57780 INC HL
57781 RET Return.
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