Routines
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25569: Play Tune
Used by the routine at LevelComplete.
Plays a tune one note at a time until the terminator is reached. The low five bits of each byte in the tune data are a note number from 1 to 8 which is used to look up the pitch and the duration of the note in the table at NoteTable for the ROM BEEPER routine.
Input
DE Pointer to the tune data
PlayMusic 25569 LD A,(DE) Fetch the next note of the tune.
25570 CP 255 Return if the terminator (255) has been reached.
25572 RET Z
25573 AND %00011111 Keep only bits 0-4 (the note number).
25575 DEC A Decrease the note number by one (the notes are numbered from one).
25576 SLA A Double it, as there are two bytes for each note in the table.
25578 LD C,A Make this the offset into the note table in BC.
25579 LD B,0
25581 LD HL,25613 HL=NoteTable (the note table).
25584 ADD HL,BC Add the offset to find the note.
25585 PUSH DE Stash the tune pointer on the stack.
25586 LD A,(HL) Fetch the pitch of the note.
25587 INC HL Move onto the duration of the note.
25588 LD E,(HL) E=the duration of the note.
25589 LD D,0 Set the high byte of the duration (D) to 0.
25591 LD L,A HL=the pitch of the note.
25592 LD H,0
25594 SLA L Multiply HL by four to make the pitch for the beeper.
25596 RL H
25598 SLA L
25600 RL H
25602 PUSH IX Stash IX on the stack, as the beeper routine overwrites it.
25604 CALL 949 Call BEEPER.
25607 POP IX Restore IX and the tune pointer from the stack.
25609 POP DE
25610 INC DE Move onto the next note of the tune.
25611 JR PlayMusic Loop back round to PlayMusic to play the next note (the tune only ends when the terminator is reached).
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