|
Routines |
| Prev: E5A5 | Up: Map | Next: E5FE |
|
||||||||
|
There are two tunes/melodies.
(1) The first tune is played at the end of the intro sequence when a new game is started, and also when the game is completed. Uses music data stored at EBF0.
(2) The second tune is played then the game is paused. Uses music data at EC72.
|
||||||||
| E5B6 | CP $01 | Check which tune needs to be played | ||||||
| E5B8 | JR NZ,$E5BF | |||||||
| E5BA | LD HL,$EBF0 | Point HL at first note(s) of the intro/end tune data | ||||||
| E5BD | JR $E5C2 | |||||||
| E5BF | LD HL,$EC72 | Point HL at first note(s) of the paused game tune data. | ||||||
|
Play notes
|
||||||||
| E5C2 | LD A,(HL) | Get note value | ||||||
| E5C3 | CP $FF | 255 is an end-of-music marker | ||||||
| E5C5 | JR Z,$E5FD | If so, RETurn to previous routine | ||||||
| E5C7 | LD B,A | Get first note of pair | ||||||
| E5C8 | INC HL | Get second note of pair | ||||||
| E5C9 | LD A,(HL) | |||||||
| E5CA | LD C,A | ...and store in C register | ||||||
| E5CB | INC HL | Move note data pointer on ready for next note | ||||||
| E5CC | LD ($EB54),HL | ...and store | ||||||
| E5CF | LD H,B | H = first note of pair, e.g. 190 | ||||||
| E5D0 | LD A,C | |||||||
| E5D1 | ADD A,$20 | +32 to create a phase-type effect | ||||||
| E5D3 | LD L,A | L = second note of pair, plus 32, e.g. 222 | ||||||
| E5D4 | LD DE,$1C00 | 7168 = Note duration | ||||||
| E5D7 | LD A,$00 | Reset A to 0 | ||||||
| E5D9 | DEC H | Decrement first note byte (for sound note loop) | ||||||
| E5DA | JR NZ,$E5DF | Reached zero? | ||||||
| E5DC | OR $10 | If zero, ensure speaker bit (4) is set to play sound | ||||||
| E5DE | LD H,B | ...and restore first note of pair again | ||||||
| E5DF | DEC L | Decrement second note byte (for sound note loop) | ||||||
| E5E0 | JR NZ,$E5E5 | Reached zero? | ||||||
| E5E2 | OR $10 | If zero, ensure speaker bit (4) is set | ||||||
| E5E4 | LD L,C | ...and restore second note of pair again | ||||||
| E5E5 | ADD A,$08 | 'Thickens out' the sound by ensuring speaker is toggled on a bit more | ||||||
| E5E7 | AND $10 | Filter out other bits, only keeping bit (4) speaker toggle bit | ||||||
| E5E9 | OUT ($FE),A | ...and play sound by toggling speaker on or off accordingly | ||||||
| E5EB | SRA A | Shift bits right | ||||||
| E5ED | LD ($EB53),A | ..and store, as A register needed for next bit | ||||||
| E5F0 | DEC DE | Decrement note counter | ||||||
| E5F1 | LD A,D | And check if at zero | ||||||
| E5F2 | OR E | |||||||
| E5F3 | LD A,($EB53) | Restore A register which holds the speaker bits | ||||||
| E5F6 | JR NZ,$E5D9 | If not at zero yet, continue to play note | ||||||
| E5F8 | LD HL,($EB54) | Note played. Get data pointer | ||||||
| E5FB | JR $E5C2 | ...and go and play next note | ||||||
| E5FD | RET | Return to routine at C0C1 or C763. | ||||||
| Prev: E5A5 | Up: Map | Next: E5FE |