musicdsp.org source code archive - WSInf

FTable[256] := 1;
end;
exponent:
begin
// symetric exponent similar to triangle
for i:=0 to 127 do
begin
FTable[i] := 2 * ((exp(i/128) - 1) / (exp(1) - 1)) - 1 ;
FTable[i+128] := 2 * ((exp((128-i)/128) - 1) / (exp(1) - 1)) - 1 ;
end;
FTable[256] := -1;
end;
end;
end;
function TPaLfo.WaveformName:String;
begin
result:=WFStrings[Ord(Fwaveform)];
end;
function TPaLfo.Tick: Single;
var
i:integer;
frac:Single;
begin
// the 8 MSB are the index in the table in the range 0-255
i := Pinteger(Fphase)^ shr 24;
// and the 24 LSB are the fractionnal part
frac := (PInteger(Fphase)^ and $00FFFFFF) * k1Div24lowerBits;
// increment the phase for the next tick
Fphase :=FPhase + Finc; // the phase overflows itself
Result:= Ftable[i]*(1-frac) + Ftable[i+1]* frac; // linear interpolation
end;
end.
from : thaddy@thaddy.com
comment : Oops,
This one is correct:
code:
unit PALFO;
//
// purpose: LUT based LFO
// author: © 2004, Thaddy de Koning
// Remarks: Translated from c++ sources by Remy Mueller, www.musicdsp.org
interface
uses
{$IFDEF KOL}
Windows, Kol,KolMath;
{$ELSE}
Windows, math;
{$ENDIF}
const
k1Div24lowerBits = 1/(1 shl 24);
WFStrings:array[0..4] of string =
('triangle','sinus', 'sawtooth', 'square', 'exponent');
type
Twaveform = (triangle, sinus, sawtooth, square, exponent);
{$IFDEF KOL}
PPaLfo = ^TPALfo;
TPaLfo = object(TObj)
{$ELSE}
TPaLfo = class
{$ENDIF}
private
FTable:array[0..256] of Single;// 1 more for linear interpolation
FPhase,
FInc:dword;
FRate: Single;
FSampleRate: Single;
FWaveForm: TWaveForm;
procedure SetRate(const Value: Single);