2022-02-20, 10:42 PM
I use this white noise one all the time...
Code:
SUB noise ()
asm
noise: ld e,250 ; repeat 250 times.
ld hl,0 ; start pointer in ROM.
noise2: push de
ld b,32 ; length of step.
noise0: push bc
ld a,(hl) ; next "random" number.
inc hl ; pointer.
and 248 ; we want a black border.
out (254),a ; write to speaker.
ld a,e ; as e gets smaller...
cpl ; ...we increase the delay.
noise1: dec a ; decrement loop counter.
jr nz,noise1 ; delay loop.
pop bc
djnz noise0 ; next step.
pop de
ld a,e
sub 24 ; size of step.
cp 30 ; end of range.
ret z
ret c
ld e,a
cpl
noise3: ld b,40 ; silent period.
noise4: djnz noise4
dec a
jr nz,noise3
jr noise2
ret
end asm
END SUB