Routines
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48465: Play Music Until Key Pressed
Used by the routine at HandlerGameMenu.
Plays a tune in the same way as PlayMusic, but stops as soon as any key is pressed. The key press is then handled by the game selection menu (see HandlerGameMenu), as if it had been read there.
Input
DE Music data terminated by 255
PlayMusic_WaitKey 48465 DI Disable interrupts.
Check for any key being pressed.
PlayMusic_WaitKey_Loop 48466 XOR A Select every row of the keyboard.
48467 OUT (253),A Write A to port 253 (this has no effect).
48469 IN A,(254) Read every half-row of the keyboard at once (the high byte of the port number is zero).
48471 CPL Flip the bits.
48472 AND %00011111 Keep only bits 0-4.
48474 JR Z,PlayMusic_WaitKey_Process Jump to PlayMusic_WaitKey_Process if no keys were pressed.
A key was pressed, so stop playing and hand over to the game menu.
48476 LD A,(38546) Fetch the game options from GameOptions.
48479 INC SP Discard the return address.
48480 INC SP
48481 JP GameSelect_ReadSecondKeyRow Jump to GameSelect_ReadSecondKeyRow to handle the key press in the game selection menu.
This is identical to PlayMusic except it also handles exiting on a keypress.
PlayMusic_WaitKey_Process 48484 LD A,(DE) Fetch the next note.
48485 CP 255 Jump to PlayMusic_Return if the end of the tune has been reached (255).
48487 JR Z,PlayMusic_Return
48489 CALL PlayNote Play the note.
48492 JR PlayMusic_WaitKey_Loop Jump to PlayMusic_WaitKey_Loop to check for a key press.
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