prog8/examples/c64/bdmusic-irq.p8

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%import syslib
%import textio
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%zeropage basicsafe
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main {
sub start() {
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txt.print("playing the music from boulderdash,\nmade in 1984 by peter liepa.\n\n")
sys.set_rasterirq(&irq.irqhandler, 60, true) ; enable playback via raster irq
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}
}
irq {
const ubyte waveform = %0001 ; triangle
ubyte note_index = 0
ubyte delay = 0
sub irqhandler() {
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c64.EXTCOL++
delay++
if delay >= 8 {
delay = 0
c64.AD1 = %00011010
c64.SR1 = %00000000
c64.AD2 = %00011010
c64.SR2 = %00000000
c64.MVOL = 15
uword note = notes[note_index]
note_index++
ubyte note1 = lsb(note)
ubyte note2 = msb(note)
c64.FREQ1 = music_freq_table[note1] ; set lo+hi freq of voice 1
c64.FREQ2 = music_freq_table[note2] ; set lo+hi freq of voice 2
; retrigger voice 1 and 2 ADSR
c64.CR1 = waveform <<4 | 0
c64.CR2 = waveform <<4 | 0
c64.CR1 = waveform <<4 | 1
c64.CR2 = waveform <<4 | 1
}
c64.EXTCOL--
}
; details about the boulderdash music can be found here:
; https://www.elmerproductions.com/sp/peterb/sounds.html#Theme%20tune
uword[] notes = [
$1622, $1d26, $2229, $252e, $1424, $1f27, $2029, $2730,
$122a, $122c, $1e2e, $1231, $202c, $3337, $212d, $3135,
$1622, $162e, $161d, $1624, $1420, $1430, $1424, $1420,
$1622, $162e, $161d, $1624, $1e2a, $1e3a, $1e2e, $1e2a,
$142c, $142c, $141b, $1422, $1c28, $1c38, $1c2c, $1c28,
$111d, $292d, $111f, $292e, $0f27, $0f27, $1633, $1627,
$162e, $162e, $162e, $162e, $222e, $222e, $162e, $162e,
$142e, $142e, $142e, $142e, $202e, $202e, $142e, $142e,
$162e, $322e, $162e, $332e, $222e, $322e, $162e, $332e,
$142e, $322e, $142e, $332e, $202c, $302c, $142c, $312c,
$162e, $163a, $162e, $3538, $222e, $2237, $162e, $3135,
$142c, $1438, $142c, $1438, $202c, $2033, $142c, $1438,
$162e, $322e, $162e, $332e, $222e, $322e, $162e, $332e,
$142e, $322e, $142e, $332e, $202c, $302c, $142c, $312c,
$2e32, $292e, $2629, $2226, $2c30, $272c, $2427, $1420,
$3532, $322e, $2e29, $2926, $2730, $242c, $2027, $1420
]
uword[] music_freq_table = [
0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
732, 778, 826, 876, 928, 978, 1042, 1100, 1170, 1238, 1312, 1390, 1464, 1556,
1652, 1752, 1856, 1956, 2084, 2200, 2340, 2476, 2624, 2780, 2928, 3112, 3304,
3504, 3712, 3912, 4168, 4400, 4680, 4952, 5248, 5560, 5856, 6224, 6608, 7008,
7424, 7824, 8336, 8800, 9360, 9904, 10496, 11120, 11712
]
}