|
Routines |
| Prev: B4EB | Up: Map | Next: B537 |
|
Used by the routine at B482.
|
||||||||||
| B505 | LD A,($B4EA) | Get the sound type. | ||||||||
| B508 | OR A | Is it 0 (sawtooth)? | ||||||||
| B509 | JR Z,$B50F | Jump forward if it is. | ||||||||
|
Play a square wave.
|
||||||||||
| B50B | LD H,B | Copy the pitch from BC to HL. | ||||||||
| B50C | LD L,C | |||||||||
| B50D | JR $B520 | Jump forward to play the note. | ||||||||
|
Play a sawtooth wave.
|
||||||||||
| B50F | LD H,B | Copy the pitch from BC to HL. | ||||||||
| B510 | LD L,C | |||||||||
| B511 | SRA B | Add three quarters of the pitch (?) | ||||||||
| B513 | RR C | |||||||||
| B515 | ADD HL,BC | |||||||||
| B516 | SRA B | |||||||||
| B518 | RR C | |||||||||
| B51A | ADD HL,BC | |||||||||
| B51B | SRA B | |||||||||
| B51D | RR C | |||||||||
| B51F | ADD HL,BC | |||||||||
|
Now play the note.
|
||||||||||
| B520 | LD A,$10 | Switch the speaker on. | ||||||||
| B522 | OUT ($FE),A | |||||||||
| B524 | CALL $B4EB | Pause and collect a keypress. | ||||||||
| B527 | XOR A | Switch the speaker off. | ||||||||
| B528 | OUT ($FE),A | |||||||||
| B52A | PUSH BC | Store BC. | ||||||||
| B52B | LD B,H | Restore the value that was previously copied to HL. | ||||||||
| B52C | LD C,L | |||||||||
| B52D | CALL $B4EB | Pause and collect a keypress. | ||||||||
| B530 | POP BC | Restore BC. | ||||||||
| B531 | DEC DE | Decrease the length. | ||||||||
| B532 | LD A,D | Loop while there is more to play. | ||||||||
| B533 | OR E | |||||||||
| B534 | JR NZ,$B520 | |||||||||
| B536 | RET | Otherwise return. | ||||||||
| Prev: B4EB | Up: Map | Next: B537 |