Routines
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33432: Controls: Pause
If "O" is pressed on its own, waits for it to be released, then for a second press and release of "O" before returning.
Hold the game while "O" is pressed.
ControlsPause 33432 DI Disable interrupts.
33433 LD A,223 Read from the keyboard;
Port Number Bit
0 1 2 3 4
223 P O I U Y
33435 OUT (253),A
33437 IN A,(254)
If key "O" is not being pressed, then just return.
33439 BIT 1,A Return if bit 1 is set.
33441 RET NZ
Return if any other key has been pressed with "O".
33442 CPL Flip the bits.
33443 AND %00011101 Keep only bits 0, 2-4.
33445 RET NZ Return if the result is not zero.
Loop until the "O" button is released.
GamePaused_Debounce 33446 LD A,223 Read from the keyboard;
Port Number Bit
0 1 2 3 4
223 P O I U Y
33448 OUT (253),A
33450 IN A,(254)
33452 BIT 1,A Jump to GamePaused_Debounce if "O" is still pressed.
33454 JR Z,GamePaused_Debounce
Creates an infinite loop which only exits when "O" is pressed again.
GamePaused 33456 LD A,223 Read from the keyboard;
Port Number Bit
0 1 2 3 4
223 P O I U Y
33458 OUT (253),A
33460 IN A,(254)
33462 BIT 1,A Jump to GamePaused if "O" is not pressed.
33464 JR NZ,GamePaused
Likewise, to prevent the pause from recurring instantly, loop until the "O" button is released.
GamePaused_Debounce_Exit 33466 LD A,223 Read from the keyboard;
Port Number Bit
0 1 2 3 4
223 P O I U Y
33468 OUT (253),A
33470 IN A,(254)
33472 BIT 1,A Jump to GamePaused_Debounce_Exit if "O" is still pressed.
33474 JR Z,GamePaused_Debounce_Exit
33476 RET Return.
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