Contributor: DOUGLAS WEBB
Unit LZH;
{$A+,B-,D-,E-,F-,I+,L-,N-,O-,R-,S-,V-}
(*
* LZHUF.C English version 1.0
* Based on Japanese version 29-NOV-1988
* LZSS coded by Haruhiko OKUMURA
* Adaptive Huffman Coding coded by Haruyasu YOSHIZAKI
* Edited and translated to English by Kenji RIKITAKE
* Translated from C to Turbo Pascal by Douglas Webb 2/18/91
* Update and bug correction of TP version 4/29/91 (Sorry!!)
*)
{
This Unit allows the user to commpress data using a combination of
LZSS Compression and adaptive Huffman coding, or conversely to deCompress
data that was previously Compressed by this Unit.
There are a number of options as to where the data being Compressed/
deCompressed is coming from/going to.
In fact it requires that you pass the "LZHPack" Procedure 2 procedural
parameter of Type 'GetProcType' and 'PutProcType' (declared below) which
will accept 3 parameters and act in every way like a 'BlockRead'/'BlockWrite'
Procedure call. Your 'GetProcType' Procedure should return the data
to be Compressed, and Your 'PutProcType' Procedure should do something with
the Compressed data (ie., put it in a File). In Case you need to know (and
you do if you want to deCompress this data again) the number of Bytes in the
Compressed data (original, not Compressed size) is returned in 'Bytes_Written'.
GetBytesProc = Procedure(Var DTA; NBytes:Word; Var Bytes_Got : Word);
DTA is the start of a memory location where the inFormation returned should
be. NBytes is the number of Bytes requested. The actual number of Bytes
returned must be passed in Bytes_Got (if there is no more data then 0
should be returned).
PutBytesProc = Procedure(Var DTA; NBytes:Word; Var Bytes_Got : Word);
As above except instead of asking For data the Procedure is dumping out
Compressed data, do somthing With it.
"LZHUnPack" is basically the same thing in reverse. It requires
procedural parameters of Type 'PutProcType'/'GetProcType' which
will act as above. 'GetProcType' must retrieve data Compressed using
"LZHPack" (above) and feed it to the unpacking routine as requested.
'PutProcType' must accept the deCompressed data and do something
withit. You must also pass in the original size of the deCompressed data,
failure to do so will have adverse results.
Don't Forget that as procedural parameters the 'GetProcType'/'PutProcType'
Procedures must be Compiled in the 'F+' state to avoid a catastrophe.
}
{ note: All the large data structures For these routines are allocated when
needed from the heap, and deallocated when finished. So when not in use
memory requirements are minimal. However, this Unit Uses about 34K of
heap space, and 400 Bytes of stack when in use. }
Interface
Type
PutBytesProc = Procedure(Var DTA; NBytes : Word; Var Bytes_Put : Word);
GetBytesProc = Procedure(Var DTA; NBytes : Word; Var Bytes_Got : Word);
Procedure LZHPack(Var Bytes_Written : LongInt;
GetBytes : GetBytesProc;
PutBytes : PutBytesProc);
Procedure LZHUnpack(TextSize : LongInt;
GetBytes : GetBytesProc;
PutBytes : PutBytesProc);
Implementation
Const
Exit_OK = 0;
Exit_FAILED = 1;
{ LZSS Parameters }
N = 4096; { Size of String buffer }
F = 60; { Size of look-ahead buffer }
THRESHOLD = 2;
NUL = N; { end of tree's node }
{ Huffman coding parameters }
N_Char = (256 - THRESHOLD + F);
{ Character code (:= 0..N_Char-1) }
T = (N_Char * 2 - 1); { Size of table }
R = (T - 1); { root position }
{ update when cumulative frequency }
{ reaches to this value }
MAX_FREQ = $8000;
{
* Tables For encoding/decoding upper 6 bits of
* sliding dictionary Pointer
}
{ encoder table }
p_len : Array[0..63] of Byte =
($03, $04, $04, $04, $05, $05, $05, $05,
$05, $05, $05, $05, $06, $06, $06, $06,
$06, $06, $06, $06, $06, $06, $06, $06,
$07, $07, $07, $07, $07, $07, $07, $07,
$07, $07, $07, $07, $07, $07, $07, $07,
$07, $07, $07, $07, $07, $07, $07, $07,
$08, $08, $08, $08, $08, $08, $08, $08,
$08, $08, $08, $08, $08, $08, $08, $08);
p_code : Array[0..63] of Byte =
($00, $20, $30, $40, $50, $58, $60, $68,
$70, $78, $80, $88, $90, $94, $98, $9C,
$A0, $A4, $A8, $AC, $B0, $B4, $B8, $BC,
$C0, $C2, $C4, $C6, $C8, $CA, $CC, $CE,
$D0, $D2, $D4, $D6, $D8, $DA, $DC, $DE,
$E0, $E2, $E4, $E6, $E8, $EA, $EC, $EE,
$F0, $F1, $F2, $F3, $F4, $F5, $F6, $F7,
$F8, $F9, $FA, $FB, $FC, $FD, $FE, $FF);
{ decoder table }
d_code : Array[0..255] of Byte =
($00, $00, $00, $00, $00, $00, $00, $00,
$00, $00, $00, $00, $00, $00, $00, $00,
$00, $00, $00, $00, $00, $00, $00, $00,
$00, $00, $00, $00, $00, $00, $00, $00,
$01, $01, $01, $01, $01, $01, $01, $01,
$01, $01, $01, $01, $01, $01, $01, $01,
$02, $02, $02, $02, $02, $02, $02, $02,
$02, $02, $02, $02, $02, $02, $02, $02,
$03, $03, $03, $03, $03, $03, $03, $03,
$03, $03, $03, $03, $03, $03, $03, $03,
$04, $04, $04, $04, $04, $04, $04, $04,
$05, $05, $05, $05, $05, $05, $05, $05,
$06, $06, $06, $06, $06, $06, $06, $06,
$07, $07, $07, $07, $07, $07, $07, $07,
$08, $08, $08, $08, $08, $08, $08, $08,
$09, $09, $09, $09, $09, $09, $09, $09,
$0A, $0A, $0A, $0A, $0A, $0A, $0A, $0A,
$0B, $0B, $0B, $0B, $0B, $0B, $0B, $0B,
$0C, $0C, $0C, $0C, $0D, $0D, $0D, $0D,
$0E, $0E, $0E, $0E, $0F, $0F, $0F, $0F,
$10, $10, $10, $10, $11, $11, $11, $11,
$12, $12, $12, $12, $13, $13, $13, $13,
$14, $14, $14, $14, $15, $15, $15, $15,
$16, $16, $16, $16, $17, $17, $17, $17,
$18, $18, $19, $19, $1A, $1A, $1B, $1B,
$1C, $1C, $1D, $1D, $1E, $1E, $1F, $1F,
$20, $20, $21, $21, $22, $22, $23, $23,
$24, $24, $25, $25, $26, $26, $27, $27,
$28, $28, $29, $29, $2A, $2A, $2B, $2B,
$2C, $2C, $2D, $2D, $2E, $2E, $2F, $2F,
$30, $31, $32, $33, $34, $35, $36, $37,
$38, $39, $3A, $3B, $3C, $3D, $3E, $3F);
d_len : Array[0..255] of Byte =
($03, $03, $03, $03, $03, $03, $03, $03,
$03, $03, $03, $03, $03, $03, $03, $03,
$03, $03, $03, $03, $03, $03, $03, $03,
$03, $03, $03, $03, $03, $03, $03, $03,
$04, $04, $04, $04, $04, $04, $04, $04,
$04, $04, $04, $04, $04, $04, $04, $04,
$04, $04, $04, $04, $04, $04, $04, $04,
$04, $04, $04, $04, $04, $04, $04, $04,
$04, $04, $04, $04, $04, $04, $04, $04,
$04, $04, $04, $04, $04, $04, $04, $04,
$05, $05, $05, $05, $05, $05, $05, $05,
$05, $05, $05, $05, $05, $05, $05, $05,
$05, $05, $05, $05, $05, $05, $05, $05,
$05, $05, $05, $05, $05, $05, $05, $05,
$05, $05, $05, $05, $05, $05, $05, $05,
$05, $05, $05, $05, $05, $05, $05, $05,
$05, $05, $05, $05, $05, $05, $05, $05,
$05, $05, $05, $05, $05, $05, $05, $05,
$06, $06, $06, $06, $06, $06, $06, $06,
$06, $06, $06, $06, $06, $06, $06, $06,
$06, $06, $06, $06, $06, $06, $06, $06,
$06, $06, $06, $06, $06, $06, $06, $06,
$06, $06, $06, $06, $06, $06, $06, $06,
$06, $06, $06, $06, $06, $06, $06, $06,
$07, $07, $07, $07, $07, $07, $07, $07,
$07, $07, $07, $07, $07, $07, $07, $07,
$07, $07, $07, $07, $07, $07, $07, $07,
$07, $07, $07, $07, $07, $07, $07, $07,
$07, $07, $07, $07, $07, $07, $07, $07,
$07, $07, $07, $07, $07, $07, $07, $07,
$08, $08, $08, $08, $08, $08, $08, $08,
$08, $08, $08, $08, $08, $08, $08, $08);
getbuf : Word = 0;
getlen : Byte = 0;
putlen : Byte = 0;
putbuf : Word = 0;
TextSize : LongInt = 0;
codesize : LongInt = 0;
printcount : LongInt = 0;
match_position : Integer = 0;
match_length : Integer = 0;
Type
FreqType = Array[0..T] of Word;
FreqPtr = ^FreqType;
PntrType = Array[0..pred(T + N_Char)] of Integer;
pntrPtr = ^PntrType;
SonType = Array[0..pred(T)] of Integer;
SonPtr = ^SonType;
TextBufType = Array[0..N + F - 2] of Byte;
TBufPtr = ^TextBufType;
WordRay = Array[0..N] of Integer;
WordRayPtr = ^WordRay;
BWordRay = Array[0..N + 256] of Integer;
BWordRayPtr = ^BWordRay;
Var
Text_buf : TBufPtr;
lson, dad : WordRayPtr;
rson : BWordRayPtr;
freq : FreqPtr; { cumulative freq table }
{
* pointing parent nodes.
* area [T..(T + N_Char - 1)] are Pointers For leaves
}
prnt : pntrPtr;
{ pointing children nodes (son[], son[] + 1)}
son : SonPtr;
Procedure InitTree; { Initializing tree }
Var
i : Integer;
begin
For i := N + 1 to N + 256 do
rson^[i] := NUL; { root }
For i := 0 to N do
dad^[i] := NUL; { node }
end;
Procedure InsertNode(R : Integer); { Inserting node to the tree }
Var
tmp, i, p, cmp : Integer;
key : TBufPtr;
c : Word;
begin
cmp := 1;
key := @Text_buf^[R];
p := succ(N) + key^[0];
rson^[R] := NUL;
lson^[R] := NUL;
match_length := 0;
While match_length < F do
begin
if (cmp >= 0) then
begin
if (rson^[p] <> NUL) then
p := rson^[p]
else
begin
rson^[p] := R;
dad^[R] := p;
Exit;
end;
end
else
begin
if (lson^[p] <> NUL) then
p := lson^[p]
else
begin
lson^[p] := R;
dad^[R] := p;
Exit;
end;
end;
i := 0;
cmp := 0;
While (i < F) and (cmp = 0) do
begin
inc(i);
cmp := key^[i] - Text_buf^[p + i];
end;
if (i > THRESHOLD) then
begin
tmp := pred((R - p) and pred(N));
if (i > match_length) then
begin
match_position := tmp;
match_length := i;
end;
if (match_length < F) and (i = match_length) then
begin
c := tmp;
if (c < match_position) then
match_position := c;
end;
end;
end; { While True do }
dad^[R] := dad^[p];
lson^[R] := lson^[p];
rson^[R] := rson^[p];
dad^[lson^[p]] := R;
dad^[rson^[p]] := R;
if (rson^[dad^[p]] = p) then
rson^[dad^[p]] := R
else
lson^[dad^[p]] := R;
dad^[p] := NUL; { remove p }
end;
Procedure DeleteNode(p : Integer); { Deleting node from the tree }
Var
q : Integer;
begin
if (dad^[p] = NUL) then
Exit; { unregistered }
if (rson^[p] = NUL) then
q := lson^[p]
else if (lson^[p] = NUL) then
q := rson^[p]
else
begin
q := lson^[p];
if (rson^[q] <> NUL) then
begin
Repeat
q := rson^[q];
Until (rson^[q] = NUL);
rson^[dad^[q]] := lson^[q];
dad^[lson^[q]] := dad^[q];
lson^[q] := lson^[p];
dad^[lson^[p]] := q;
end;
rson^[q] := rson^[p];
dad^[rson^[p]] := q;
end;
dad^[q] := dad^[p];
if (rson^[dad^[p]] = p) then
rson^[dad^[p]] := q
else
lson^[dad^[p]] := q;
dad^[p] := NUL;
end;
{ Huffman coding parameters }
Function GetBit(GetBytes : GetBytesProc) : Integer; { get one bit }
Var
i : Byte;
i2 : Integer;
result : Word;
begin
While (getlen <= 8) do
begin
GetBytes(i, 1, result);
if result = 1 then
i2 := i
else i2 := 0;
getbuf := getbuf or (i2 shl (8 - getlen));
inc(getlen, 8);
end;
i2 := getbuf;
getbuf := getbuf shl 1;
dec(getlen);
GetBit := Integer((i2 < 0));
end;
Function GetByte(GetBytes : GetBytesProc) : Integer; { get a Byte }
Var
j : Byte;
i, result : Word;
begin
While (getlen <= 8) do
begin
GetBytes(j, 1, result);
if result = 1 then
i := j
else
i := 0;
getbuf := getbuf or (i shl (8 - getlen));
inc(getlen, 8);
end;
i := getbuf;
getbuf := getbuf shl 8;
dec(getlen, 8);
GetByte := Integer(i shr 8);
end;
Procedure Putcode(l : Integer; c : Word;
PutBytes : PutBytesProc); { output c bits }
Var
Temp : Byte;
Got : Word;
begin
putbuf := putbuf or (c shr putlen);
inc(putlen, l);
if (putlen >= 8) then
begin
Temp := putbuf shr 8;
PutBytes(Temp, 1, Got);
dec(putlen, 8);
if (putlen >= 8) then
begin
Temp := lo(putbuf);
PutBytes(Temp, 1, Got);
inc(codesize, 2);
dec(putlen, 8);
putbuf := c shl (l - putlen);
end
else
begin
putbuf := putbuf shl 8;
inc(codesize);
end;
end;
end;
{ initialize freq tree }
Procedure StartHuff;
Var
i, j : Integer;
begin
For i := 0 to pred(N_Char) do
begin
freq^[i] := 1;
son^[i] := i + T;
prnt^[i + T] := i;
end;
i := 0;
j := N_Char;
While (j <= R) do
begin
freq^[j] := freq^[i] + freq^[i + 1];
son^[j] := i;
prnt^[i] := j;
prnt^[i + 1] := j;
inc(i, 2);
inc(j);
end;
freq^[T] := $ffff;
prnt^[R] := 0;
end;
{ reConstruct freq tree }
Procedure reConst;
Var
i, j, k, tmp : Integer;
F, l : Word;
begin
{ halven cumulative freq For leaf nodes }
j := 0;
For i := 0 to pred(T) do
begin
if (son^[i] >= T) then
begin
freq^[j] := succ(freq^[i]) div 2; {@@ Bug Fix MOD -> div @@}
son^[j] := son^[i];
inc(j);
end;
end;
{ make a tree : first, connect children nodes }
i := 0;
j := N_Char;
While (j < T) do
begin
k := succ(i);
F := freq^[i] + freq^[k];
freq^[j] := F;
k := pred(j);
While F < freq^[k] do
dec(k);
inc(k);
l := (j - k) shl 1;
tmp := succ(k);
move(freq^[k], freq^[tmp], l);
freq^[k] := F;
move(son^[k], son^[tmp], l);
son^[k] := i;
inc(i, 2);
inc(j);
end;
{ connect parent nodes }
For i := 0 to pred(T) do
begin
k := son^[i];
if (k >= T) then
begin
prnt^[k] := i;
end
else
begin
prnt^[k] := i;
prnt^[succ(k)] := i;
end;
end;
end;
{ update freq tree }
Procedure update(c : Integer);
Var
i, j, k, l : Integer;
begin
if (freq^[R] = MAX_FREQ) then
begin
reConst;
end;
c := prnt^[c + T];
Repeat
inc(freq^[c]);
k := freq^[c];
{ swap nodes to keep the tree freq-ordered }
l := succ(c);
if (k > freq^[l]) then
begin
While (k > freq^[l]) do
inc(l);
dec(l);
freq^[c] := freq^[l];
freq^[l] := k;
i := son^[c];
prnt^[i] := l;
if (i < T) then prnt^[succ(i)] := l;
j := son^[l];
son^[l] := i;
prnt^[j] := c;
if (j < T) then prnt^[succ(j)] := c;
son^[c] := j;
c := l;
end;
c := prnt^[c];
Until (c = 0); { Repeat it Until reaching the root }
end;
Var
code, len : Word;
Procedure EncodeChar(c : Word; PutBytes : PutBytesProc);
Var
i : Word;
j, k : Integer;
begin
i := 0;
j := 0;
k := prnt^[c + T];
{ search connections from leaf node to the root }
Repeat
i := i shr 1;
{
if node's address is odd, output 1
else output 0
}
if Boolean(k and 1) then inc(i, $8000);
inc(j);
k := prnt^[k];
Until (k = R);
Putcode(j, i, PutBytes);
code := i;
len := j;
update(c);
end;
Procedure EncodePosition(c : Word; PutBytes : PutBytesProc);
Var
i, j : Word;
begin
{ output upper 6 bits With encoding }
i := c shr 6;
j := p_code[i];
Putcode(p_len[i], j shl 8, PutBytes);
{ output lower 6 bits directly }
Putcode(6, (c and $3f) shl 10, PutBytes);
end;
Procedure Encodeend(PutBytes : PutBytesProc);
Var
Temp : Byte;
Got : Word;
begin
if Boolean(putlen) then
begin
Temp := lo(putbuf shr 8);
PutBytes(Temp, 1, Got);
inc(codesize);
end;
end;
Function DecodeChar(GetBytes : GetBytesProc) : Integer;
Var
c : Word;
begin
c := son^[R];
{
* start searching tree from the root to leaves.
* choose node #(son[]) if input bit = 0
* else choose #(son[]+1) (input bit = 1)
}
While (c < T) do
begin
c := c + GetBit(GetBytes);
c := son^[c];
end;
c := c - T;
update(c);
DecodeChar := Integer(c);
end;
Function DecodePosition(GetBytes : GetBytesProc) : Word;
Var
i, j, c : Word;
begin
{ decode upper 6 bits from given table }
i := GetByte(GetBytes);
c := Word(d_code[i] shl 6);
j := d_len[i];
{ input lower 6 bits directly }
dec(j, 2);
While j <> 0 do
begin
i := (i shl 1) + GetBit(GetBytes);
dec(j);
end;
DecodePosition := c or i and $3f;
end;
{ Compression }
Procedure InitLZH;
begin
getbuf := 0;
getlen := 0;
putlen := 0;
putbuf := 0;
TextSize := 0;
codesize := 0;
printcount := 0;
match_position := 0;
match_length := 0;
new(lson);
new(dad);
new(rson);
new(Text_buf);
new(freq);
new(prnt);
new(son);
end;
Procedure endLZH;
begin
dispose(son);
dispose(prnt);
dispose(freq);
dispose(Text_buf);
dispose(rson);
dispose(dad);
dispose(lson);
end;
Procedure LZHPack(Var Bytes_Written : LongInt;
GetBytes : GetBytesProc;
PutBytes : PutBytesProc);
Var
ct : Byte;
i, len, R, s, last_match_length : Integer;
Got : Word;
begin
InitLZH;
TextSize := 0; { rewind and rescan }
StartHuff;
InitTree;
s := 0;
R := N - F;
fillChar(Text_buf^[0], R, ' ');
len := 0;
Got := 1;
While (len < F) and (Got <> 0) do
begin
GetBytes(ct, 1, Got);
if Got <> 0 then
begin
Text_buf^[R + len] := ct;
inc(len);
end;
end;
TextSize := len;
For i := 1 to F do
InsertNode(R - i);
InsertNode(R);
Repeat
if (match_length > len) then
match_length := len;
if (match_length <= THRESHOLD) then
begin
match_length := 1;
EncodeChar(Text_buf^[R], PutBytes);
end
else
begin
EncodeChar(255 - THRESHOLD + match_length, PutBytes);
EncodePosition(match_position, PutBytes);
end;
last_match_length := match_length;
i := 0;
Got := 1;
While (i < last_match_length) and (Got <> 0) do
begin
GetBytes(ct, 1, Got);
if Got <> 0 then
begin
DeleteNode(s);
Text_buf^[s] := ct;
if (s < pred(F)) then
Text_buf^[s + N] := ct;
s := succ(s) and pred(N);
R := succ(R) and pred(N);
InsertNode(R);
inc(i);
end;
end;
inc(TextSize, i);
While (i < last_match_length) do
begin
inc(i);
DeleteNode(s);
s := succ(s) and pred(N);
R := succ(R) and pred(N);
dec(len);
if Boolean(len) then InsertNode(R);
end;
Until (len <= 0);
Encodeend(PutBytes);
endLZH;
Bytes_Written := TextSize;
end;
Procedure LZHUnpack(TextSize : LongInt;
GetBytes : GetBytesProc;
PutBytes : PutBytesProc);
Var
c, i, j, k, R : Integer;
c2, a : Byte;
count : LongInt;
Put : Word;
begin
InitLZH;
StartHuff;
R := N - F;
fillChar(Text_buf^[0], R, ' ');
count := 0;
While count < TextSize do
begin
c := DecodeChar(GetBytes);
if (c < 256) then
begin
c2 := lo(c);
PutBytes(c2, 1, Put);
Text_buf^[R] := c;
inc(R);
R := R and pred(N);
inc(count);
end
else
begin
i := (R - succ(DecodePosition(GetBytes))) and pred(N);
j := c - 255 + THRESHOLD;
For k := 0 to pred(j) do
begin
c := Text_buf^[(i + k) and pred(N)];
c2 := lo(c);
PutBytes(c2, 1, Put);
Text_buf^[R] := c;
inc(R);
R := R and pred(N);
inc(count);
end;
end;
end;
endLZH;
end;
end.