Routines
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61E0: Input: Accelerate
Used by the routine at UpdatePlayerCar.
Reads the accelerator control. From the keyboard any key in the rows Q to T, or P to Y, accelerates the car.
Output
A F7 if accelerate is pressed, else FF
Check if this should be read from the Kempston joystick instead?
ReadInputAccelerate 61E0 LD A,($5E3E) If GameOptions indicates the control method is via the Kempston joystick then jump to ReadKempstonJoystick.
61E3 BIT 1,A
61E5 JR NZ,ReadKempstonJoystick
Check for "Accelerator" button input.
61E7 LD B,$02 Set the keyboard row counter to 02.
61E9 LD A,$FB A=FB (the first keyboard row).
ReadInputAccelerate_Loop 61EB OUT ($FD),A Read from the keyboard;
Port Number Bit
0 1 2 3 4
FB Q W E R T
DF P O I U Y
61ED IN A,($FE)
61EF AND %00011111 Keep only bits 0-4.
61F1 CP $1F If any buttons were pressed jump to Input_Accelerate.
61F3 JR NZ,Input_Accelerate
61F5 LD A,$DF A=DF (the second keyboard row).
61F7 DJNZ ReadInputAccelerate_Loop Decrease the keyboard row counter by one and loop back to ReadInputAccelerate_Loop until both rows have been checked.
61F9 JR Input_None Jump to Input_None.
Return "Accelerator" button pressed.
Input_Accelerate 61FB LD A,$F7 A=11110111.
61FD RET Return.
View the equivalent code in;
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