Routines
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91C0: Run Game
Used by the routine at Select_Game_Options.
Starts a new game and then runs the main loop forever.
The loop at Main_Loop goes through the object records one at a time. Byte 00 of a record is the type of the object, which is used as an index into the Object_Handler_Table handler table. The handler is run with IX pointing at the record and with Finish_Object_Pass stacked as its return address, so every handler ends by returning to Finish_Object_Pass which moves on to the next record.
Start a new game: empty the room table, clear the workspace and the objects, and clear the screen.
Run_Game 91C0 CALL Reset_Room_Table Empty the room visit table.
91C3 CALL Clear_Workspace Clear the sprite workspace, the score and the other variables.
91C6 CALL Clear_Object_Records Clear all of the object records except the first two.
91C9 CALL Clear_Attributes Set every attribute to white ink on black paper.
91CC CALL Clear_Screen Clear the screen.
91CF CALL Clear_Collected_Flags Set up the fifth small object record.
Set up Sabreman and draw the status panel and the room.
91D2 CALL Reset_Sabreman Copy the template of Sabreman into his object record.
91D5 LD IX,$8F1A Point at the object record of Sabreman (Sabreman_Record).
91D9 CALL Draw_Lives Draw the lives icon and the number of lives.
91DC CALL Print_Status_Panel Print the status panel.
91DF CALL Print_Score_Label Print the word SCORE and the score.
91E2 CALL Draw_Room Draw the room. This does not return: it resets the stack and jumps to Main_Loop.
This entry point is used by the routine at Finish_Object_Pass.
This is the main loop. The normal pass starts with Sabreman's record, unless his type is from 09 to 1B. Those types are handled with the priority records (see Finish_Object_Pass_Priority_Records), so then the pass starts with the record after his. The first two records are only ever handled as priority records.
Main_Loop 91E5 EI Enable interrupts.
91E6 LD IX,$8F1A Point at the object record of Sabreman (Sabreman_Record).
91EA LD A,($8F1A) Fetch the type of Sabreman.
91ED CP $1C Jump to Run_Game_Spawn_Creatures if the type is greater than or equal to 1C.
91EF JR NC,Run_Game_Spawn_Creatures
91F1 CP $09 Jump to Run_Game_Spawn_Creatures if the type is less than 09.
91F3 JR C,Run_Game_Spawn_Creatures
91F5 LD IX,$8F2A Point at the record after Sabreman's (Rope_Record).
Give the creature spawners a chance to run, then run the handler of the object that IX points at.
Run_Game_Spawn_Creatures 91F9 CALL Spawn_Falling_Stalactite Maybe spawn a stalactite.
91FC CALL Spawn_Flying_Creature Maybe spawn a flying creature.
91FF LD A,($AAAC) Fetch the room flags from Room_Flags.
9202 AND %00010000 Keep only bit 4.
9204 CALL Z,Spawn_Bubble Maybe spawn a bubble if bit 4 is not set.
This entry point is used by the routines at Finish_Object_Pass and Draw_Room.
Run the handler of the object that IX points at.
Run_Object_Handler 9207 LD HL,$9459 Point at the return address of the handler (Finish_Object_Pass).
This entry point is used by the routine at Finish_Object_Pass.
Run_Object_Handler_Stash_Return 920A PUSH HL Stash it on the stack.
920B LD BC,$921A Point at the handler table (Object_Handler_Table).
920E LD L,(IX+$00) Fetch the type of the object.
This entry point is used by the routine at Finish_Object_Pass.
Run_Object_Handler_Look_Up 9211 LD H,$00 Clear H so that HL holds the type.
9213 ADD HL,HL Double the type to get the offset of its handler in the table.
9214 ADD HL,BC Add the address of the table.
9215 LD A,(HL) Fetch the low byte of the handler address.
9216 INC HL Move on to the high byte.
9217 LD H,(HL) Fetch the high byte of the handler address.
9218 LD L,A Copy the low byte of the handler address to L.
9219 JP (HL) Jump to the handler.
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