Routines
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43791: Control Player
Used by the routine at RunFrame.
Reads the controls and makes the player entity turn, jump and move forward. The controls are a byte with one bit for each direction, as read by ReadControls: bit 0 and bit 1 turn the player, bit 2 makes the player jump if it is on the ground, and bit 3 makes the player move forward. While the player is held (fields 36 and 37 are not both zero) bits 2-4 are ignored. The rate of turning builds up while a turn control is held, and is kept in TurningRate.
Input
IX The player entity
ControlPlayer 43791 CALL ReadControls Read the controls.
43794 LD A,(IX+36) Read field 36 of the entity.
43797 OR (IX+37) Combine it with field 37.
43800 JR Z,ControlPlayer_Store Jump to ControlPlayer_Store if both are zero.
43802 RES 2,C Ignore bit 2 of the controls.
43804 RES 3,C Ignore bit 3 of the controls.
43806 RES 4,C Ignore bit 4 of the controls.
ControlPlayer_Store 43808 LD A,C Fetch the controls.
43809 LD (23774),A Store them in GameVariable.
43812 LD HL,(23798) Fetch the rate of turning from TurningRate.
43815 LD DE,128 Set the amount by which the rate builds up.
43818 RR C Move bit 0 into the carry flag.
43820 JR NC,ControlPlayer_TestLeft Jump to ControlPlayer_TestLeft if it is reset.
43822 RR C Move bit 1 into the carry flag.
43824 JR C,ControlPlayer_NoTurn Jump to ControlPlayer_NoTurn if both are set.
43826 LD B,255 Set the direction of the turn to 255.
43828 JR ControlPlayer_Turn Jump to ControlPlayer_Turn.
ControlPlayer_TestLeft 43830 RR C Move bit 1 into the carry flag.
43832 JR NC,ControlPlayer_NoTurn Jump to ControlPlayer_NoTurn if neither bit is set.
43834 LD B,0 Set the direction of the turn to 0.
ControlPlayer_Turn 43836 ADD HL,DE Increase the rate of turning.
43837 LD A,H Fetch the whole part of the rate.
43838 CP 3 Jump to ControlPlayer_StoreRate if it is less.
43840 JR C,ControlPlayer_StoreRate
43842 DEC H Limit the rate to below 3.
ControlPlayer_StoreRate 43843 LD (23798),HL Store the rate of turning.
43846 LD A,H Fetch the whole part of the rate.
43847 BIT 7,B Jump to ControlPlayer_Heading if the turn is in the positive direction.
43849 JR Z,ControlPlayer_Heading
43851 NEG Make the turn negative.
ControlPlayer_Heading 43853 LD B,A Keep the turn in B.
43854 LD A,(IX+17) Fetch the heading of the player.
43857 ADD A,B Add the turn.
43858 AND %00111111 Use bits 0-5.
43860 LD (IX+17),A Store the new heading.
43863 JR ControlPlayer_Jump Jump to ControlPlayer_Jump.
ControlPlayer_NoTurn 43865 RES 7,(IX+17) Reset bit 7 of the heading of the player, so that it is not moving forward.
43869 LD E,64 Set the amount by which the rate of turning falls.
43871 AND A Clear the carry flag.
43872 SBC HL,DE Reduce the rate of turning.
43874 JR NC,ControlPlayer_StoreRate2 Jump to ControlPlayer_StoreRate2 if it is still positive.
43876 LD HL,0 Set the rate of turning to zero.
ControlPlayer_StoreRate2 43879 LD (23798),HL Store the rate of turning.
ControlPlayer_Jump 43882 RR C Move bit 2 into the carry flag.
43884 JR NC,ControlPlayer_Forward Jump to ControlPlayer_Forward if it is reset.
43886 BIT 7,(IX+30) Jump to ControlPlayer_Forward if bit 7 of field 30 of the player is reset.
43890 JR Z,ControlPlayer_Forward
43892 LD A,(23808) Fetch the jump flag from JumpCounter.
43895 AND A Test it.
43896 JR NZ,ControlPlayer_Forward Jump to ControlPlayer_Forward if the player is already jumping.
43898 LD (IX+18),4 Set the vertical speed of the player (field 18) to 4...
43902 LD (IX+19),0 ...and field 19 to 0.
43906 LD A,1 Set the jump flag to 1...
43908 LD (23808),A ...and store it.
ControlPlayer_Forward 43911 RR C Move bit 3 into the carry flag.
43913 RET NC Return if it is reset.
43914 SET 7,(IX+17) Set bit 7 of the heading of the player, so that it moves forward.
43918 RET Return.
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