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Routines |
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Used by the routine at MoveRobotHorizontally.
Works out how far the robot moves in this frame. When the robot is told to speed up it uses some energy and accelerates, up to a limit of 40. When it is not it slows down: the speed is the distance to the next cell, in the direction that it is heading, so the robot always stops at the start of a cell.
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| GetRobotSpeed | A8E4 | LD A,($9625) | Fetch the controls. | |||||||||
| A8E7 | BIT 2,A | Jump if the key to speed up is being pressed. | ||||||||||
| A8E9 | JR NZ,GetRobotSpeed_Accelerate | |||||||||||
| A8EB | LD A,(IX+$00) | Fetch the type of the robot... | ||||||||||
| A8EE | RRCA | ...and turn it into the direction that it is heading in. | ||||||||||
| A8EF | RRCA | |||||||||||
| A8F0 | AND $03 | Jump if the robot is heading in direction zero (X decreasing). | ||||||||||
| A8F2 | JR Z,GetRobotSpeed_XDecreasing | |||||||||||
| A8F4 | DEC A | Count down the direction. | ||||||||||
| A8F5 | JR Z,GetRobotSpeed_YIncreasing | Jump if the robot is heading in direction one (Y increasing). | ||||||||||
| A8F7 | DEC A | Count down the direction. | ||||||||||
| A8F8 | JR Z,GetRobotSpeed_XIncreasing | Jump if the robot is heading in direction two (X increasing). | ||||||||||
| A8FA | LD A,(IX+$03) | The robot is heading in direction three (Y decreasing), so fetch the fraction of the Y position... | ||||||||||
| A8FD | JR GetRobotSpeed_Limit | ...and jump to limit the distance. | ||||||||||
| GetRobotSpeed_XIncreasing | A8FF | LD A,(IX+$01) | Fetch the fraction of the X position of the robot... | |||||||||
| A902 | JR GetRobotSpeed_Negate | ...and jump to turn it round. | ||||||||||
| GetRobotSpeed_YIncreasing | A904 | LD A,(IX+$03) | Fetch the fraction of the Y position of the robot. | |||||||||
| GetRobotSpeed_Negate | A907 | NEG | Subtract it from zero, to get the distance to the next cell. | |||||||||
| A909 | JR GetRobotSpeed_Limit | Jump to limit the distance. | ||||||||||
| GetRobotSpeed_XDecreasing | A90B | LD A,(IX+$01) | Fetch the fraction of the X position of the robot. | |||||||||
| GetRobotSpeed_Limit | A90E | CP $40 | Jump if the distance is below 40... | |||||||||
| A910 | JR C,GetRobotSpeed_Store | |||||||||||
| GetRobotSpeed_UseDefault | A912 | LD A,$40 | ...otherwise use 40. | |||||||||
| GetRobotSpeed_Store | A914 | LD (IX+$06),A | Store the speed of the robot... | |||||||||
| A917 | LD A,(IX+$06) | ...and fetch it... | ||||||||||
| A91A | LD B,A | ...into B. | ||||||||||
| A91B | RET | Return. | ||||||||||
| GetRobotSpeed_Accelerate | A91C | RES 2,A | Clear the bit for speeding up... | |||||||||
| A91E | LD ($9625),A | ...and store the controls. | ||||||||||
| A921 | LD DE,$0008 | Using this costs eight units of energy. | ||||||||||
| A924 | CALL UseEnergy | Take them out of the battery using UseEnergy. | ||||||||||
| A927 | LD A,(IX+$06) | Fetch the speed of the robot... | ||||||||||
| A92A | ADD A,$10 | ...and add 10. | ||||||||||
| A92C | CP $40 | Jump to store it if the new speed is below 40. | ||||||||||
| A92E | JR C,GetRobotSpeed_Store | |||||||||||
| A930 | JR GetRobotSpeed_UseDefault | Otherwise jump to use 40. | ||||||||||
| Prev: A8A4 | Up: Map | Next: A932 |