Arithmetic coding algorithm
The arithmetic code is to represent a source representing a range between the real shafts 0 and 1, and each element in the source set is used to shorten the interval.
The process of arithmetic encoding is as follows:
(1) Set the high segment of the encoding section to h, the length of the encoding section is g, and ENDC is a high section of the encoded character allocation, startc
Low ends between the character allocation interval.
(2) Estimating the probability of each element based on a limited source of sources.
(3) Du Yu encoded element A1, according to (2) estimated probability and interval, new L, and H after encoding the element is calculated. The formula is as follows:
H = STARTC G *K;
L = ENDC G * K1;
The specific procedures are as follows:
Const Ca = 0.2; CE = 0.3;
Ci = 0.2; CO = 0.2;
Cu = 0.1;
VAR
FORM1: TFORM1;
String;
STARTC, ENDC: Extended;
IMPLEMENTATION
{$ R * .dfm}
Procedure ConvertTo (S: String; Var Startc, Endc: Extended); {Turn the string to values}
Var n, i: integer;
C: char;
g: extended;
Begin
STARTC: = 0;
Endc: = 1;
N: = Strlen (PCHAR (S));
For i: = 1 to n DO
Begin
C: = s [i];
g: = endc - startc;
Case C of
'a':
Begin
ENDC: = STARTC G * CA;
STARTC: = STARTC G * 0;
END;
'e':
Begin
ENDC: = STARTC G * (CA CE);
STARTC: = STARTC G * CA;
END;
'i':
Begin
Endc: = STARTC G * (CA CE CI);
STARTC: = STARTC G * (CA CE);
END;
'o':
Begin
ENDC: = STARTC G * (CA CE CI CO);
STARTC: = STARTC G * (CA CE CI);
END;
'u':
Begin
ENDC: = STARTC G * (CA CE CI CO CU);
STARTC: = STARTC G * (CA CE CI CO);
END;
Else
Begin
ShowMessage ('Enter string is wrong);
EXIT;
END;
END;
END;
END;
Procedure nemuricaltostr (var s: string; var startc, endc: extend);
{Convert value to string}
Const EPS = -1e-5;
Begin
IF Startc-0.2 <-eps Then
IF (Endc- 0.2 <= -EPS) and (endc> startc) thenbegin
STARTC: = startC / 0.2;
ENDC: = ENDC / 0.2;
S: = S 'A';
IF (STARTC <> 0) or (Endc <> 1) THEN
NemuricalTOSTR (S, STARTC, ENDC);
END;
IF (startc- 0.2> = EPS) and (startc-0.5 <-epses) THEN
IF (Endc-0.5 <= -EPS) and (endc> startc) THEN
Begin
STARTC: = STARTC - 0.2;
Endc: = ENDC - 0.2;
STARTC: = startc / 0.3;
ENDC: = ENDC / 0.3;
S: = S 'E';
IF (STARTC <> 0) or (Endc <> 1) THEN
NemuricalTOSTR (S, STARTC, ENDC);
END;
IF (StartC- 0.5> = EPS) and (startc- 0.7 <-eps) THEN
IF (Endc-0.7 <= -EPS) and (endc> startc) THEN
Begin
STARTC: = STARTC - 0.5;
ENDC: = ENDC - 0.5;
STARTC: = startC / 0.2;
ENDC: = ENDC / 0.2;
S: = S 'I';
IF (STARTC <> 0) or (Endc <> 1) THEN
NemuricalTOSTR (S, STARTC, ENDC);
END;
IF (STARTC-0.7> = EPS) and (startc-0.9 <-eps).
IF (endc-0.9 <= - EPS) and (endc> startc) THEN
Begin
STARTC: = STARTC - 0.7;
Endc: = endc - 0.7;
STARTC: = startC / 0.2;
ENDC: = ENDC / 0.2;
s: = s 'o';
IF (STARTC <> 0) or (Endc <> 1) THEN
NemuricalTOSTR (S, STARTC, ENDC);
END;
IF (startc -0.9> = EPS) and (startc-1 <-eps) THEN
IF (Endc-1 <= -EPS) and (endc> startc) THEN
Begin
STARTC: = STARTC - 0.9;
ENDC: = ENDC - 0.9;
STARTC: = startc / 0.1;
Endc: = endc / 0.1;
S: = s 'u';
IF (STARTC <> 0) or (Endc <> 1) THEN
NemuricalTOSTR (S, STARTC, ENDC);
END;
END;
Procedure TFORM1.BUTTON1CLICK (Sender: TOBJECT);
Begin
s: = edit1.text;
ConvertTo (S, STARTC, ENDC);
Edit2.text: = floattostr (startc); edit3.text: = floattostr (endc);
END;
Procedure TFORM1.BUTTON2CLICK (Sender: TOBJECT);
Begin
s: = '';
STARTC: = strtofloat (edit2.text);
Endc: = strtofloat (edit3.text);
NemuricalTOSTR (S, STARTC, ENDC);
Edit1.text: = s;
END;
End.
Secondary program
Delphi6 windows2000
Under the pass.
