pascal lzh

, en meget hurtigt lzh kompressor, bidragyder: kurt haenen, {$r -} {ikke vifte kontrol.!} {, ---------------------------------------------------------------, denne udstationering omfatter kilder til turbo pascal, version af lzrw1 /kh motorer algoritm., ---------------------------------------------------------------, fil: lzrw1kh enhed, --------------------------,} {###################################################################} {#&## #} {#&##&###### #####&##&##&##&##&##&##&##&##&##} {#&##&##&##&##&##&##&##&##&##&##&##&##&##&##&##} {#&##&##&## ##### #######&##&##&##&## ######&##} {#&##&##&##&##&##&##&##&##&##&###&##&##&##&## #} {#&###### #####&##&##&##&##&##&##&##&##&##&##&##&##} {#&## #} {#&#meget hurtigt og let at forstå motorer algoritm&##} (#&## #} {###################################################################} {#&## #} {#&#denne enhed gennemfører den ajourførte lzrw1 /kh algoritm, som&##} {#&#også gennemfører nogle rle kodning, der er nyttig, når&##} {#&#komprimere filer, der indeholder mange på hinanden følgende bytes&##} {#&#under.den samme værdi.den algoritm ikke er så god, som&##} {#&#lzh, men kan konkurrere med lempel. ziff.det ' er fastende&##} {#&#jeg ' har oplevet indtil nu.# #} {#&## #} {#&## #} {#&## #} {#&#kurt haenen&##} {#&## #} {###################################################################}, enhed lzrw1kh; interface, bruger sysutils; ($ifdef win32}, type int16 = smallint; ($andet}, type int16 = heltal ($endif}, konstant, buffermaxsize = 32768;, buffermax = buffermaxsize-1;, flag_copied = 80 dollars. flag_compress = 40 dollars.type, bufferindex = 0. buffermax + 15, buffersize = 0. buffermaxsize;, (ekstra byte nødvendig her, hvis motorer ikke *) *), bufferarray = system [bufferindex] byte;, bufferptr = ^ bufferarray;, elzrw1khcompressor = klasse (undtagelse), funktion motorer (kilde: bufferptr;, - sourcesize: buffersize): buffersize;, funktion dekompression (kilde: bufferptr;, - sourcesize: buffersize): buffersize;, gennemførelse, type, hashtable = system [0 - 4095] af int16;, hashtabptr = ^hashtable;, var, hash: hashtabptr;, {se, om den her allerede har set}, {i det nuværende 4 kb vindue}, funktion getmatch (kilde: bufferptr;, x: bufferindex;, sourcesize: buffersize;, hash: hashtabptr, var størrelse: ord; og, var bufferi producentorganisationer:ndex ) : BOOLEAN;, VAR, HashValue : WORD;, TmpHash : Int16;, BEGIN, HashValue := (40543*((((Source^[X] SHL 4) XOR Source^[X+1]) SHL 4) XOR, Source^[X+2]) SHR 4) AND $0FFF;, Result := FALSE;, TmpHash := Hash^[HashValue];, IF (TmpHash <> -1) and (X - TmpHash < 4096) THEN BEGIN, Pos := TmpHash;, Size := 0;, WHILE ((Size < 18) AND (Source^[X+Size] = Source^[Pos+Size]), AND (X+Size < SourceSize)) DO begin, INC(Size);, end;, Result := (Size >= 3), END;, Hash^[HashValue] := X, END; ,, {kompres en buffer på højst 32 b}, funktion motorer (kilde: bufferptr;, - sourcesize: buffersize): buffersize;, var, lidt, kommando, størrelse: ord;, nøgle: ord;, x, y og z, producentorganisationer: bufferindex;, begynder, fillchar ('), 7 (hashtable), $ff), - ([0]: = flag_compress;, x: = 0, y: = 3, z: = 1, del: = 0, kommando: = 0, , mens (x < sourcesize) og y < = sourcesize) begynder, hvis (bed > 15) så begynde, best ^ [z]: = hej (kommando), best ^ [z + 1] = lo (kommando), z: = y;, lidt:= 0;, INC(Y,2), END;, Size := 1;, WHILE ((Source^[X] = Source^[X+Size]) AND (Size < $FFF), AND (X+Size < SourceSize)) DO begin, INC(Size);, end;, IF (Size >= 16) THEN BEGIN, Dest^[Y] := 0;, Dest^[Y+1] := HI(Size-16);, Dest^[Y+2] := LO(Size-16);, Dest^[Y+3] := Source^[X];, INC(Y,4);, INC(X,Size);, Command := (Command SHL 1) + 1;, END, ELSE begin { not size >= 16 }, IF (GetMatch(Source,X,SourceSize,Hash,Size,Pos)) THEN BEGIN, Key := ((X-Pos) SHL 4) + (Size-3);, best ^ [x]: = hej (centrale), best ^ [x + 1] = lo (centrale), inc (y, 2), inc (x, størrelse), kommando: = (kommando sømhaj shb. 1 + 1, , ellers begynder, best ^ [x]: = kilde ^ [x];, inc (y), inc. (x), kommando: = kommando sømhaj shb 1, ;, størrelse; (< = 16), inc (bit), ; (mens x < sourcesize...}, kommando: = kommando sømhaj shb (16 - bit), best ^ [z]: = hej (kommando), best ^ [z + 1] = lo (kommando), hvis (y > sourcesize) så begynde, træk (kilde ([0], dest) [1], sourcesize), - ([0]: = flag_copied;, y: = succ (sourcesize), ;, resultat: = y,;, {dekompresse en buffer på max 32 b}, funktion dekompression (kilde: bufferptr -;, sourcesize: buffersize): buffersize;, var, x, y, producentorganisationer: bufferindex;, kommando, størrelse, k: ord;, del: byte;, savey: bufferindex. {*) * usikker for loop variable y}, BEGIN, IF (Source^[0] = FLAG_Copied) THEN begin, FOR Y := 1 TO PRED(SourceSize) DO begin, Dest^[PRED(Y)] := Source^[Y];, SaveY := Y;, end;, Y := SaveY;, end, ELSE BEGIN, Y := 0;, X := 3;, Command := (Source^[1] SHL 8) + Source^[2];, Bit := 16;, WHILE (X < SourceSize) DO BEGIN, IF (Bit = 0) THEN BEGIN, Command := (Source^[X] SHL 8) + Source^[X+1];, Bit := 16;, INC(X,2), END;, IF ((Command AND $8000) = 0) THEN BEGIN, Dest^[Y] := Source^[X];, INC(X);, INC(Y), END, ELSE BEGIN { command and $8000 }, Pos := ((Source^[X] SHL 4), +(Source^[X+1] SHR 4));, IF (Pos = 0) THEN BEGIN, Size := (Source^[X+1] SHL 8) + Source^[X+2] + 15;, FOR K := 0 TO Size DO begin, Dest^[Y+K] := Source^[X+3];, end;, INC(X,4);, INC(Y,Size+1), END, ELSE BEGIN { pos = 0 }, Size := (Source^[X+1] AND $0F)+2;, FOR K := 0 TO Size DO, Dest^[Y+K] := Dest^[Y-Pos+K];, INC(X,2);, INC(Y,Size+1), END; { pos = 0 }, END; { command and $8000 }, Command := Command SHL 1;, DEC(Bit), END { while x < sourcesize }, END;, Result := Y, END; { decompression }, {, Unit "Finalization" as Delphi 2.0 would have it, }, var, ExitSave : Pointer;, Procedure Cleanup; far;, begin, ExitProc := ExitSave;, if (Hash <> Nil) then, Freemem(Hash, Sizeof(HashTable));, end;, Initialization, Hash := Nil;, try, Getmem(Hash,Sizeof(Hashtable));, except, Raise ELzrw1KHCompressor.Create('LZRW1KH : no memory for HASH table');, end;, ExitSave := ExitProc;, ExitProc := @Cleanup;, END.,

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