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AsciiCoder.Mod
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AsciiCoder.Mod
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(* OBERON System 3, Release 2.3.
Copyright 1999 ETH Zürich Institute for Computer Systems,
ETH Center, CH-8092 Zürich. e-mail: [email protected].
This module may be used under the conditions of the general Oberon
System 3 license contract. The full text can be downloaded from
"ftp://ftp.inf.ethz.ch/pub/software/Oberon/System3/license.txt;A"
Under the license terms stated it is in particular (a) prohibited to modify
the interface of this module in any way that disagrees with the style
or content of the system and (b) requested to provide all conversions
of the source code to another platform with the name OBERON. *)
MODULE AsciiCoder; (** portable *) (* Wolfgang Weck 14 Dec 93, compression due to Stefan Ludwig/ jm modified for System 3 *)
IMPORT Oberon, Texts, Files, Display;
CONST
Base = 48; StopBase = 35;
N = 16384;
TYPE
NameList = POINTER TO NameDesc;
NameDesc = RECORD
next: NameList;
name: ARRAY 64 OF CHAR
END;
VAR
w: Texts.Writer;
table: ARRAY N OF CHAR; (* hash table for compression *)
PROCEDURE Compress*(src, dest: Files.File); (* due to Stefan Ludwig *)
VAR hash, byte, bit, i: LONGINT; ch: CHAR; from, to: Files.Rider;
BEGIN
i := 0; REPEAT table[i] := 0X; INC(i) UNTIL i = N;
Files.Set(from, src, 0); Files.Set(to, dest, 0);
i := Files.Length(src); Files.WriteNum(to, i);
IF i > 0 THEN
hash := 0; bit := 0; byte := 0;
REPEAT
Files.Read(from, ch);
IF table[hash] = ch THEN (* 0 bit for correct prediction *)
INC(bit); IF bit = 8 THEN Files.Write(to, CHR(byte)); byte := 0; bit := 0 END
ELSE (* Incorrect prediction -> 1'xxxx'xxxx bits where x = ch[0..7] *)
table[hash] := ch; INC(byte, ASH(1, bit)); INC(bit);
IF bit = 8 THEN Files.Write(to, CHR(byte)); Files.Write(to, ch); byte := 0; bit := 0
ELSE Files.Write(to, CHR(byte+ASH(ORD(ch), bit) MOD 256)); byte := ASH(ORD(ch), bit) DIV 256
END
END;
DEC(i); hash := (16*hash+ORD(ch)) MOD N (* hash value *)
UNTIL i = 0;
IF bit # 0 THEN Files.Write(to, CHR(byte)) END (* write last byte *)
END
END Compress;
PROCEDURE Expand*(src, dest: Files.File); (* due to Stefan Ludwig *)
VAR hash, val, byte, bit, i: LONGINT; ch: CHAR; from, to: Files.Rider;
BEGIN
i := 0; REPEAT table[i] := 0X; INC(i) UNTIL i = N;
Files.Set(from, src, 0); Files.Set(to, dest, 0);
Files.ReadNum(from, i);
IF i > 0 THEN
Files.Read(from, ch); val := ORD(ch); bit := 0; hash := 0;
REPEAT
INC(bit);
IF ODD(val) THEN (* Incorrect prediction -> 1'xxxx'xxxx *)
Files.Read(from, ch);
IF bit = 8 THEN byte := ORD(ch)
ELSE byte := val DIV 2 + ASH(ORD(ch), 8-bit) MOD 256; val := ASH(ORD(ch), -bit)
END;
table[hash] := CHR(byte)
ELSE byte := ORD(table[hash]); val := val DIV 2 (* correct prediction *)
END;
hash := (16*hash+byte) MOD N; Files.Write(to, CHR(byte)); DEC(i);
IF bit = 8 THEN Files.Read(from, ch); val := ORD(ch); bit := 0 END
UNTIL i = 0
END
END Expand;
PROCEDURE Code*(from: Files.File; to: Texts.Text);
VAR byte, rest, div, factor, packs: INTEGER; ch: CHAR; r: Files.Rider;
BEGIN Files.Set(r, from, 0); Files.Read(r, ch); byte := ORD(ch); rest := 0; div := 64; factor := 1; packs := 0;
WHILE ~r.eof DO Texts.Write(w, CHR(Base + rest + (byte MOD div) * factor)); rest := byte DIV div;
IF div = 4 THEN Texts.Write(w, CHR(Base + rest));
rest := 0; div := 64; factor := 1; INC(packs);
IF packs = 19 THEN Texts.WriteLn(w); packs := 0 END
ELSE factor := factor * 4; div := div DIV 4
END;
Files.Read(r, ch); byte := ORD(ch)
END;
IF div = 64 THEN Texts.Write(w, CHR(StopBase))
ELSIF div = 16 THEN Texts.Write(w, CHR(Base + rest)); Texts.Write(w, CHR(StopBase + 1))
ELSIF div = 4 THEN Texts.Write(w, CHR(Base + rest)); Texts.Write(w, CHR(StopBase + 2))
END;
Texts.WriteLn(w); Texts.Append(to, w.buf)
END Code;
PROCEDURE Decode*(from: Texts.Text; VAR pos: LONGINT; to: Files.File; VAR ok: BOOLEAN);
VAR rest, div, factor, byte: INTEGER; ch: CHAR; r: Texts.Reader; w: Files.Rider;
BEGIN Texts.OpenReader(r, from, pos); Files.Set(w, to, 0); factor := 1; div := 256; rest := 0;
REPEAT Texts.Read(r, ch) UNTIL (ch > " ") OR r.eot;
WHILE ~r.eot & (ch >= CHR(Base)) & (ch < CHR(Base + 64)) DO byte := ORD(ch) - Base;
IF factor # 1 THEN Files.Write(w, CHR(rest + (byte MOD div) * factor));
rest := byte DIV div; div := div * 4; factor := factor DIV 4
ELSE rest := byte; div := 4; factor := 64
END;
REPEAT Texts.Read(r, ch) UNTIL (ch > " ") OR r.eot
END;
byte := ORD(ch) - StopBase;
ok := (byte = 0) & (div = 256) OR (byte = 1) & (div = 16) OR (byte = 2) & (div = 64) & (rest = 0);
pos := Texts.Pos(r)
END Decode;
PROCEDURE OpenViewer(name: ARRAY OF CHAR; text: Texts.Text);
BEGIN
Oberon.OpenText(name, text, Display.Width DIV 8 * 3 + 20, Display.Height DIV 2)
END OpenViewer;
PROCEDURE ReadFileNames(t: Texts.Text; beg, end: LONGINT; VAR names: NameList; VAR pos: LONGINT);
VAR last, n: NameList; s: Texts.Scanner;
BEGIN NEW(names); last := names; Texts.OpenScanner(s, t, beg); pos := beg; Texts.Scan(s);
WHILE (pos < end) & ((s.class = Texts.String) OR (s.class = Texts.Name)) DO NEW(n); last.next := n; last := n;
n.name := s.s;
pos := Texts.Pos(s); Texts.Scan(s)
END;
last.next := NIL; names := names.next; pos := Texts.Pos(s)
END ReadFileNames;
PROCEDURE CodeFiles*;
VAR pos, beg, end, time: LONGINT; compress: BOOLEAN; names, n: NameList;
f, f1: Files.File; text: Texts.Text; s: Texts.Scanner;
BEGIN pos := Oberon.Par.pos; compress := FALSE;
Texts.OpenScanner(s, Oberon.Par.text, pos); Texts.Scan(s);
IF (s.line = 0) & (s.class = Texts.Char) & (s.c = "%") THEN compress := TRUE; pos := Texts.Pos(s); Texts.Scan(s) END;
IF (s.line = 0) & (s.class = Texts.Char) & (s.c = "^") THEN Oberon.GetSelection(text, beg, end, time);
IF time >= 0 THEN ReadFileNames(text, beg, end, names, time) ELSE names := NIL END
ELSE ReadFileNames(Oberon.Par.text, pos, Oberon.Par.text.len, names, time)
END;
IF names # NIL THEN n := names; NEW(text); Texts.Open(text, "");
Texts.WriteString(w, "AsciiCoder.CodeFiles"); Texts.WriteLn(w);
REPEAT f := Files.Old(n.name); Texts.WriteString(w, n.name);
IF f = NIL THEN Texts.WriteString(w, " not found"); n.name := ""
ELSE Texts.WriteString(w, " coding"); Texts.Append(Oberon.Log, w.buf);
IF compress THEN f1 := Files.New(""); Compress(f, f1); f := f1 END;
Code(f, text)
END;
Texts.WriteLn(w); Texts.Append(Oberon.Log, w.buf); n := n.next
UNTIL n = NIL;
Texts.WriteString(w,"AsciiCoder.DecodeFiles ");
IF compress THEN Texts.WriteString(w, "% ") END;
REPEAT
IF names.name # "" THEN Texts.WriteString(w, names.name); Texts.Write(w, " ") END;
names := names.next
UNTIL names = NIL;
Texts.Write(w, "~"); Texts.WriteLn(w); Texts.WriteLn(w); Texts.Insert(text, 0, w.buf);
Texts.WriteInt(w, text.len, 0); Texts.WriteString(w, " characters"); Texts.WriteLn(w);
Texts.Append(Oberon.Log, w.buf);
OpenViewer("AsciiCoder.CodeFiles", text)
END
END CodeFiles;
PROCEDURE DecodeFiles*;
VAR pos, beg, end, time: LONGINT; i, res: INTEGER; ch: CHAR; ok, compress: BOOLEAN;
f, f1: Files.File; text: Texts.Text; s: Texts.Scanner; names: NameList; bakname: ARRAY 256 OF CHAR;
BEGIN text := Oberon.Par.text; pos := Oberon.Par.pos; compress := FALSE;
Texts.OpenScanner(s, text, pos); Texts.Scan(s);
IF (s.line = 0) & (s.class = Texts.Char) & (s.c = "%") THEN compress := TRUE; pos := Texts.Pos(s); Texts.Scan(s) END;
IF (s.line = 0) & (s.class = Texts.Char) & (s.c = "@") THEN Oberon.GetSelection(text, beg, end, time);
IF time >= 0 THEN ReadFileNames(text, beg, end, names, pos) ELSE names := NIL END
ELSE ReadFileNames(text, pos, text.len, names, pos)
END;
Texts.WriteString(w, "AsciiCoder.DecodeFiles"); Texts.WriteLn(w); ok := TRUE;
WHILE (names # NIL) & ok DO f := Files.New(names.name);
Texts.WriteString(w, names.name); Texts.WriteString(w, " decoding"); Texts.Append(Oberon.Log, w.buf);
i := 0; ch := names.name[0];
WHILE ch # 0X DO bakname[i] := ch; INC(i); ch := names.name[i] END;
bakname[i] := "."; bakname[i + 1] := "B"; bakname[i + 2] := "a"; bakname[i + 3] := "k"; bakname[i + 4] := 0X;
Files.Rename(names.name, bakname, res); Decode(text, pos, f, ok);
IF ok THEN
IF compress THEN f1 := Files.New(names.name); Expand(f, f1); f := f1 END;
Files.Register(f)
ELSE Texts.WriteString(w, " error.")
END;
Texts.WriteLn(w); Texts.Append(Oberon.Log, w.buf); names := names.next
END
END DecodeFiles;
PROCEDURE CodeText*;
VAR beg, end, time: LONGINT; compress: BOOLEAN;
f, f1: Files.File; t, text: Texts.Text; s: Texts.Scanner; len: LONGINT;
BEGIN compress := FALSE;
Texts.OpenScanner(s, Oberon.Par.text, Oberon.Par.pos); Texts.Scan(s);
IF (s.line = 0) & (s.class = Texts.Char) & (s.c = "%") THEN compress := TRUE; Texts.Scan(s) END;
IF (s.line = 0) & (s.class = Texts.Char) THEN t := NIL;
IF s.c = "*" THEN t := Oberon.MarkedText()
ELSIF s.c = "@" THEN Oberon.GetSelection(text, beg, end, time);
IF time >= 0 THEN NEW(t); Texts.Open(t, ""); Texts.Save(text, beg, end, w.buf); Texts.Append(t, w.buf) END
END;
IF t # NIL THEN f := Files.New(""); (*Files.Set(r, f, 0);
Files.Write(r, 0F0X); Files.Write(r, 01X); Texts.Store(r, t); *)
Texts.Store(t, f, 0, len);
NEW(text); Texts.Open(text, "");
Texts.WriteString(w, "AsciiCoder.DecodeText");
IF compress THEN Texts.WriteString(w, " %") END;
Texts.WriteLn(w); Texts.WriteLn(w); Texts.Append(text, w.buf);
IF compress THEN f1 := Files.New(""); Compress(f, f1); f := f1 END;
Code(f, text); OpenViewer("AsciiCoder.CodeText", text);
Texts.WriteString(w, "AsciiCoder.CodeText "); Texts.WriteInt(w, text.len, 0);
Texts.WriteString(w, " characters"); Texts.WriteLn(w); Texts.Append(Oberon.Log, w.buf)
END
END
END CodeText;
PROCEDURE DecodeText*;
VAR pos, beg, end, time: LONGINT; ok, compress: BOOLEAN;
f, f1: Files.File; text: Texts.Text; s: Texts.Scanner; len: LONGINT;
BEGIN compress := FALSE; pos := Oberon.Par.pos; f := Files.New("");
Texts.OpenScanner(s, Oberon.Par.text, Oberon.Par.pos); Texts.Scan(s);
IF (s.line = 0) & (s.class = Texts.Char) & (s.c = "%") THEN compress := TRUE; pos := Texts.Pos(s); Texts.Scan(s) END;
IF (s.line = 0) & (s.class = Texts.Char) & (s.c = "@") THEN Oberon.GetSelection(text, beg, end, time);
IF time >= 0 THEN Decode(text, beg, f, ok) ELSE ok := FALSE END
ELSE Decode(Oberon.Par.text, pos, f, ok)
END;
IF ok THEN
IF compress THEN f1 := Files.New(""); Expand(f, f1); f := f1 END;
NEW(text); Texts.Open(text, ""); (*Files.Set(r, f, 2); Texts.Load(r, text);*) Texts.Load(text, f, 1, len);
OpenViewer("AsciiCoder.DecodeText", text)
ELSE Texts.WriteString(w, "AsciiCoder.DecodeText error."); Texts.WriteLn(w); Texts.Append(Oberon.Log, w.buf)
END
END DecodeText;
BEGIN Texts.OpenWriter(w)
END AsciiCoder.
AsciiCoder.CodeText *
AsciiCoder.DecodeText