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Routines |
| Prev: AA89 | Up: Map | Next: AB1F |
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The update routine for the clockwork mouse (objects 74 to 77), which is deadly to touch. It runs along one axis for a random number of passes in IX+10, or until it hits something. Then it chooses a new random speed and turns through a right angle, alternating between the x and y axes. The sprite number says which way it faces, and the flip flag says which axis it uses.
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Move the mouse, or choose a new direction.
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| HandleClockworkMouse | AAA1 | CALL SetPixelAdjustments_Mouse | Call SetPixelAdjustments_Mouse. | |||||
| AAA4 | CALL ApplyGravityAndMove | Call ApplyGravityAndMove. | ||||||
| AAA7 | LD A,(IX+$09) | Jump to HandleClockworkMouse_ChooseDirection if the mouse is not moving. | ||||||
| AAAA | OR (IX+$0A) | |||||||
| AAAD | JR Z,HandleClockworkMouse_ChooseDirection | |||||||
| AAAF | LD A,(IX+$0C) | Fetch the collision flags. | ||||||
| AAB2 | AND %00000011 | Keep bits 0 and 1. | ||||||
| AAB4 | JR NZ,HandleClockworkMouse_ChooseDirection | Jump to HandleClockworkMouse_ChooseDirection if the mouse has hit something. | ||||||
| AAB6 | DEC (IX+$10) | Count down the remaining passes. | ||||||
| AAB9 | JR Z,HandleClockworkMouse_ChooseDirection | Jump to HandleClockworkMouse_ChooseDirection if they have run out. | ||||||
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Animate the mouse and redraw it.
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| HandleClockworkMouse_Animate | AABB | CALL ToggleSpriteNumber | Call ToggleSpriteNumber. | |||||
| AABE | JP SetDeadlyFlagsAndDraw | Jump to SetDeadlyFlagsAndDraw. | ||||||
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Choose a new direction.
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| HandleClockworkMouse_ChooseDirection | AAC1 | CALL PlayHighBeep | Call PlayHighBeep. | |||||
| AAC4 | LD A,($5B03) | Fetch 5B03. | ||||||
| AAC7 | LD C,A | Keep it in C. | ||||||
| AAC8 | LD A,($5B05) | Fetch RandomSeed2. | ||||||
| AACB | XOR C | Combine the two. | ||||||
| AACC | AND %00001111 | Keep bits 0 to 3. | ||||||
| AACE | LD (IX+$10),A | Set the remaining passes. | ||||||
| AAD1 | LD A,(IX+$07) | Fetch the flags of the mouse. | ||||||
| AAD4 | XOR %01000000 | Flip bit 6. | ||||||
| AAD6 | LD (IX+$07),A | Store the flags. | ||||||
| AAD9 | LD A,($5B05) | Fetch RandomSeed2. | ||||||
| AADC | AND %00000001 | Keep bit 0. | ||||||
| AADE | JR Z,HandleClockworkMouse_CheckFlippedForward | Jump to HandleClockworkMouse_CheckFlippedForward if it is zero. | ||||||
| AAE0 | BIT 6,(IX+$07) | Jump to HandleClockworkMouse_ChooseSpeed if the mouse is not flipped. | ||||||
| AAE4 | JR Z,HandleClockworkMouse_ChooseSpeed | |||||||
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Turn the mouse round.
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| HandleClockworkMouse_TurnRound | AAE6 | LD A,(IX+$00) | Fetch the sprite number. | |||||
| AAE9 | XOR %00000010 | Flip bit 1. | ||||||
| AAEB | LD (IX+$00),A | Store the sprite number. | ||||||
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Choose a speed of 02 to 05.
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| HandleClockworkMouse_ChooseSpeed | AAEE | LD A,($5B02) | Fetch FrameCounter. | |||||
| AAF1 | AND %00000011 | Keep bits 0 and 1. | ||||||
| AAF3 | ADD A,$02 | Add 02. | ||||||
| AAF5 | BIT 1,(IX+$00) | Jump to HandleClockworkMouse_CheckFlipped if the mouse is facing forwards. | ||||||
| AAF9 | JR NZ,HandleClockworkMouse_CheckFlipped | |||||||
| AAFB | NEG | Make the speed negative. | ||||||
| HandleClockworkMouse_CheckFlipped | AAFD | BIT 6,(IX+$07) | Jump to HandleClockworkMouse_NegativeSpeed if the mouse is flipped. | |||||
| AB01 | JR NZ,HandleClockworkMouse_NegativeSpeed | |||||||
| AB03 | LD (IX+$09),A | Set the speed along the x axis. | ||||||
| AB06 | LD (IX+$0A),$00 | Write 00 as the speed along the y axis. | ||||||
| AB0A | JR HandleClockworkMouse_Animate | Jump to HandleClockworkMouse_Animate. | ||||||
| HandleClockworkMouse_CheckFlippedForward | AB0C | BIT 6,(IX+$07) | Jump to HandleClockworkMouse_TurnRound if the mouse is not flipped. | |||||
| AB10 | JR Z,HandleClockworkMouse_TurnRound | |||||||
| AB12 | JR HandleClockworkMouse_ChooseSpeed | Jump to HandleClockworkMouse_ChooseSpeed. | ||||||
| HandleClockworkMouse_NegativeSpeed | AB14 | NEG | Make the speed negative. | |||||
| AB16 | LD (IX+$0A),A | Set the speed along the y axis. | ||||||
| AB19 | LD (IX+$09),$00 | Write 00 as the speed along the x axis. | ||||||
| AB1D | JR HandleClockworkMouse_Animate | Jump to HandleClockworkMouse_Animate. | ||||||
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