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Listing 1: Description
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| nstate |
ds |
1 |
;state of noise generator (shift reg) |
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org |
p:$100 |
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| init |
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move |
#$ff,x0 |
;initial state of noise generator |
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move |
x0,x:nstate |
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| get |
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do |
#200,_eget |
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jsr |
noise |
;generate noise sample |
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move |
x:nstate,a |
;get noise |
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movep |
a1,y:$ffff |
;output noise sample |
| _eget |
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| ; |
assumes scaling mode is off |
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| ; |
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| noise |
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;do noise generation loop |
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clr |
b x:nstate,a |
;get a zero in b |
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tst |
a #>$000100,x0 |
;check a, get a 1 in lsb position |
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tnr |
x0,b |
;if normalized, then xor=1 |
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add |
b,a |
;set lsb |
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asl |
a |
;shift bits |
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move |
a1,x:nstate |
;save state |
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rts |
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;return with state |
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