Routines
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43301: Handle Sabreman Tumbling
Handler for the object types 24 to 27 which are the tumbling sprites of Sabreman. The sprite id is 24 plus bits 1 and 2 of the tick counter at GameTimer, so the frames follow each other as time passes.
He tumbles after the stalactite or a creature has hit him and when he bumps into a side wall while he is falling. The routine decreases the countdown, checks for contact with the bubbles and the creatures (which push him sideways with an x velocity of 2 or 254), moves him sideways and applies gravity in the same way as Handle_Sabreman_Falling, and goes on at Handle_Sabreman_Falling_Above_Floor once the y position is less than 159.
Unlike the falling handler the y velocity here has a limit of 118.
Input
IX Object record of Sabreman
Handle_Sabreman_Tumbling 43301 CALL StoreEntity Remember the position and sprite id of Sabreman.
This entry point is used by the routines at Handle_Sabreman_Jumping, Handle_Sabreman_Falling and Tumble_Sabreman.
Deal with the special states in the same way as Handle_Sabreman_Walking.
Continue_Sabreman_Tumbling 43304 BIT 6,(IX+15) Jump to Start_Being_Carried if Sabreman is being carried (bit 6 of the redraw flags).
43308 JP NZ,Start_Being_Carried
43311 BIT 7,(IX+15) Jump to Start_Tumbling if Sabreman is tumbling (bit 7 of the redraw flags).
43315 JP NZ,Start_Tumbling
Read the world map entry and decrease the countdown unless it is zero.
43318 CALL Read_World_Map Read the world map entry of the room.
43321 LD A,(IX+10) Fetch the countdown of Sabreman.
43324 AND A Jump to Handle_Sabreman_Tumbling_Save_Room_Flags if the countdown is zero.
43325 JR Z,Handle_Sabreman_Tumbling_Save_Room_Flags
43327 DEC (IX+10) Decrease the countdown of Sabreman.
Handle_Sabreman_Tumbling_Save_Room_Flags 43330 LD A,E Store the room flags in Room_Flags.
43331 LD (43692),A
Check for contact with the bubbles and the creatures.
43334 CALL Check_Bubble_Contact Check for contact with the bubbles.
43337 BIT 2,C Jump to Handle_Sabreman_Tumbling_Bubble_Contact if Sabreman touches a bubble (bit 2 of C is set).
43339 JR NZ,Handle_Sabreman_Tumbling_Bubble_Contact
43341 PUSH DE Stash the world map entry on the stack.
43342 CALL Check_Decoration_Contact Check for contact with the creatures.
43345 POP DE Restore the world map entry from the stack.
43346 BIT 2,C Jump to Handle_Sabreman_Tumbling_Combine_Flags if Sabreman touches no creature (bit 2 of C is not set).
43348 JR Z,Handle_Sabreman_Tumbling_Combine_Flags
Handle_Sabreman_Tumbling_Creature_Check_Side 43350 BIT 0,C Jump to Handle_Sabreman_Tumbling_Creature_Check_Top if he is touching the middle of it (bit 0 of C is clear).
43352 JR Z,Handle_Sabreman_Tumbling_Creature_Check_Top
43354 BIT 1,C Jump to Handle_Sabreman_Tumbling_Combine_Flags if he is on top of the edge of it (bit 1 of C is set).
43356 JR NZ,Handle_Sabreman_Tumbling_Combine_Flags
Handle_Sabreman_Tumbling_Creature_Bounce 43358 BIT 7,C Jump to Handle_Sabreman_Tumbling_Creature_Bounce_Left if he is on the left of it (bit 7 of C is clear).
43360 JR Z,Handle_Sabreman_Tumbling_Creature_Bounce_Left
43362 LD B,2 Set the new x velocity to 2 (pushed to the right).
43364 JR Handle_Sabreman_Tumbling_Set_Velocity Jump to Handle_Sabreman_Tumbling_Set_Velocity.
Handle_Sabreman_Tumbling_Creature_Bounce_Left 43366 LD B,254 Set the new x velocity to 254 (pushed to the left).
43368 JR Handle_Sabreman_Tumbling_Set_Velocity Jump to Handle_Sabreman_Tumbling_Set_Velocity.
Handle_Sabreman_Tumbling_Creature_Check_Top 43370 BIT 1,C Jump to Handle_Sabreman_Tumbling_Creature_Bounce and push him away sideways if he is not on top of it (bit 1 of C is clear).
43372 JR Z,Handle_Sabreman_Tumbling_Creature_Bounce
43374 LD A,B Set the y position so that Sabreman stands on top of the creature.
43375 DEC A
43376 NEG
43378 ADD A,160
43380 LD (IX+3),A
43383 JP Land_Sabreman Jump to Land_Sabreman.
Handle_Sabreman_Tumbling_Bubble_Contact 43386 LD A,C Copy the bubble contact result to A.
43387 AND %00000011 Keep only bits 0 and 1.
43389 CP 2 Jump to Handle_Sabreman_Tumbling_Creature_Check_Side unless he is on top of the middle of the bubble (the result is 2).
43391 JR NZ,Handle_Sabreman_Tumbling_Creature_Check_Side
43393 LD (IX+9),0 Stop him falling by setting the y velocity to 0.
43397 JR Handle_Sabreman_Tumbling_Creature_Check_Top Jump to Handle_Sabreman_Tumbling_Creature_Check_Top.
Handle_Sabreman_Tumbling_Set_Velocity 43399 LD A,B Copy the new x velocity to A.
43400 XOR (IX+6) Combine it with the old x velocity using XOR to find out if the direction has changed.
43403 LD (IX+6),B Set the new x velocity of Sabreman.
43406 AND %10000000 Keep only bit 7 (set when the direction has changed).
43408 EXX Switch to the shadow registers to keep BC, DE and HL.
43409 CALL NZ,Play_Low_Tone Play a low tone if the direction has changed.
43412 EXX Switch back to the main registers.
Combine the room flags with the contact flags and clear the contact flags. The sprite id is set to 24 plus bits 1 and 2 of the tick counter.
Handle_Sabreman_Tumbling_Combine_Flags 43413 LD A,E Combine the contact flags of Sabreman with the contact flags of the room.
43414 OR (IX+11)
43417 LD E,A
43418 XOR A Clear the contact flags of Sabreman.
43419 LD (IX+11),A
43422 LD A,(36566) Fetch the tick counter from GameTimer.
43425 RRA Rotate the tick counter right, so that the frame changes every other tick.
43426 AND %00000011 Keep only bits 0-1.
43428 ADD A,24 Add 24 to make the sprite id of a tumbling frame.
43430 LD (IX+0),A Set the sprite id of Sabreman.
43433 LD A,(IX+6) Fetch the x velocity of Sabreman.
43436 AND A Test the x velocity.
Move Sabreman sideways. This is done when the x velocity is not zero or the x position is less than 128.
43437 LD A,(IX+1) Fetch the x position of Sabreman.
43440 JR NZ,Handle_Sabreman_Tumbling_Move_Sideways Jump to Handle_Sabreman_Tumbling_Move_Sideways if he is moving sideways (the x velocity is not zero).
43442 BIT 7,A Jump to Handle_Sabreman_Tumbling_Check_Left_Edge if he is in the left half of the room (bit 7 of the x position is clear).
43444 JR Z,Handle_Sabreman_Tumbling_Check_Left_Edge
Handle_Sabreman_Tumbling_Move_Sideways 43446 ADD A,(IX+6) Add the x velocity of Sabreman.
43449 LD (IX+1),A Store the new x position of Sabreman.
43452 BIT 7,A Jump to Handle_Tumbling_At_Right_Edge if he is in the right half of the room (bit 7 of the x position is set).
43454 JP NZ,Handle_Tumbling_At_Right_Edge
Handle_Sabreman_Tumbling_Check_Left_Edge 43457 CP 24 Jump to Apply_Tumbling_Gravity if he is clear of the left wall (x position 24 or more).
43459 JP NC,Apply_Tumbling_Gravity
43462 BIT 6,E Jump to Handle_Sabreman_Tumbling_No_Left_Wall if the left wall is not solid (bit 6 of E is clear).
43464 JR Z,Handle_Sabreman_Tumbling_No_Left_Wall
43466 LD A,(IX+6) Fetch the x velocity of Sabreman.
43469 NEG Negate the x velocity, so that he bounces off the wall.
43471 LD (IX+6),A Store the new x velocity of Sabreman.
43474 LD (IX+1),24 Stop him at the left wall by setting the x position to 24.
43478 JR Apply_Tumbling_Gravity Jump to Apply_Tumbling_Gravity.
Handle_Sabreman_Tumbling_No_Left_Wall 43480 EX AF,AF' Mark the ceiling and the floor as solid (bits 0 and 4 of the contact flags of Sabreman), as he is in the gap in the wall, keeping the new x position in AF'.
43481 LD A,17
43483 OR (IX+11)
43486 LD (IX+11),A
43489 EX AF,AF'
43490 SET 4,E Mark the room as having a floor (bit 4 of E).
43492 CP 8 Jump to Apply_Tumbling_Gravity if he has not left the room (x position 8 or more).
43494 JR NC,Apply_Tumbling_Gravity
43496 DEC (IX+2) Decrease the room x, to go to the room on the left.
43499 LD (IX+1),231 Put him at the right edge of the next room (x position 231).
43503 CALL Draw_Room Draw the new room.
43506 JP Update_Object_Sprite Jump to Update_Object_Sprite.
This entry point is used by the routine at Handle_Tumbling_At_Right_Edge.
Apply gravity. The y velocity is increased by 2 each time up to a limit of 118 and the y position is changed by the y velocity divided by 16. A y position of 159 or more sends him to Handle_Sabreman_Falling_Reach_Floor when the room has a floor.
Apply_Tumbling_Gravity 43509 LD A,(IX+9) Fetch the y velocity of Sabreman.
43512 BIT 7,A Jump to Apply_Tumbling_Gravity_Increase_Velocity if he is moving up (bit 7 of the y velocity is set).
43514 JR NZ,Apply_Tumbling_Gravity_Increase_Velocity
43516 CP 118 Jump to Apply_Tumbling_Gravity_Move_Vertically if he is falling at full speed (the y velocity is 118 or more).
43518 JR NC,Apply_Tumbling_Gravity_Move_Vertically
Apply_Tumbling_Gravity_Increase_Velocity 43520 INC (IX+9) Increase the y velocity (gravity pulls him down).
43523 INC (IX+9) Increase the y velocity again.
Apply_Tumbling_Gravity_Move_Vertically 43526 SRA A Divide the y velocity by sixteen, keeping the sign.
43528 SRA A
43530 SRA A
43532 SRA A
43534 ADD A,(IX+3) Add the y position of Sabreman to get the new y position.
43537 LD (IX+3),A Store the new y position of Sabreman.
43540 CP 159 Jump to Handle_Sabreman_Falling_Above_Floor if he has not reached the bottom of the room (the y position is less than 159).
43542 JP C,Handle_Sabreman_Falling_Above_Floor
43545 EX AF,AF' Mark both side walls as solid (bits 2 and 6 of the contact flags of Sabreman), keeping the new y position in AF'.
43546 LD A,68
43548 OR (IX+11)
43551 LD (IX+11),A
43554 EX AF,AF'
43555 BIT 4,E Jump to Apply_Tumbling_Gravity_Check_Bottom_Edge if the room has no floor (bit 4 of E is clear).
43557 JR Z,Apply_Tumbling_Gravity_Check_Bottom_Edge
43559 JP Handle_Sabreman_Falling_Reach_Floor Jump to Handle_Sabreman_Falling_Reach_Floor to land on the floor.
Apply_Tumbling_Gravity_Check_Bottom_Edge 43562 CP 188 Jump to Update_Object_Sprite if he has not reached the bottom of the room (the y position is less than 188).
43564 JP C,Update_Object_Sprite
43567 INC (IX+4) Increase the room y, to go to the room below.
43570 LD (IX+3),44 Put him at the top of the room below (y position 44).
43574 CALL Draw_Room Draw the new room.
43577 JP Update_Object_Sprite Jump to Update_Object_Sprite.
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