Routines
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29502: Input: Left/ Right
Used by the routines at JetmanThrust and JetmanWalk.
Check if this should be read from the Kempston joystick instead?
ReadInputLR 29502 LD A,(23795) If GameOptions indicates the control method is via the Kempston joystick then jump to ReadKempstonJoystick.
29505 BIT 1,A
29507 JR NZ,ReadKempstonJoystick
Check for "Left" and "Right" button inputs for port 254.
29509 LD A,254 Read from the keyboard;
Port Number Bit
0 1 2 3 4
254 SHIFT Z X C V
29511 OUT (253),A
29513 IN A,(254)
29515 AND %00011110 Strip out the SHIFT key.
29517 CP 30 If none of these keys have been pressed, jump to ReadInputLR_7F.
29519 JR Z,ReadInputLR_7F
29521 AND %00010100 Keep only bits 2 ("X") and 4 ("V").
29523 CP 20 If neither key is pressed jump to Input_Left.
29525 JR Z,Input_Left
29527 JR Input_Right Jump to Input_Right.
Check for "Left" and "Right" button input for port 127.
ReadInputLR_7F 29529 LD A,127 Read from the keyboard;
Port Number Bit
0 1 2 3 4
127 SPACE FULL-STOP M N B
29531 OUT (253),A
29533 IN A,(254)
29535 AND %00011110 Strip out the SPACE key.
29537 CP 30 If none of these keys have been pressed, jump to Input_None.
29539 JR Z,Input_None
29541 AND %00010100 Keep only bits 2 ("M") and 4 ("B").
29543 CP 20 If neither key is pressed jump to Input_Right.
29545 JR Z,Input_Right
Return "Left" button pressed.
Input_Left 29547 LD A,253 A=11111101.
29549 RET Return.
Return "Right" button pressed.
Input_Right 29550 LD A,254 A=11111110.
29552 RET Return.
Return "no input".
Input_None 29553 LD A,255 A=11111111.
29555 RET Return.
View the equivalent code in;
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