{
Copyright (c) 1998-2002 by Florian Klaempfl
This unit implements some support functions
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published
by the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
****************************************************************************
}
{# This unit contains some generic support functions which are used
in the different parts of the compiler.
}
unit cutils;
{$i fpcdefs.inc}
interface
type
pshortstring = ^string;
Tcharset=set of char;
var
internalerrorproc : procedure(i:longint);
{# Returns the minimal value between @var(a) and @var(b) }
function min(a,b : longint) : longint;{$ifdef USEINLINE}inline;{$endif}
function min(a,b : int64) : int64;{$ifdef USEINLINE}inline;{$endif}
{# Returns the maximum value between @var(a) and @var(b) }
function max(a,b : longint) : longint;{$ifdef USEINLINE}inline;{$endif}
function max(a,b : int64) : int64;{$ifdef USEINLINE}inline;{$endif}
{# Returns the value in @var(x) swapped to different endian }
Function SwapInt64(x : int64): int64;{$ifdef USEINLINE}inline;{$endif}
{# Returns the value in @var(x) swapped to different endian }
function SwapLong(x : longint): longint;{$ifdef USEINLINE}inline;{$endif}
{# Returns the value in @va(x) swapped to different endian }
function SwapWord(x : word): word;{$ifdef USEINLINE}inline;{$endif}
{# Returns the value in @va(x) swapped to different endian }
Function SwapQWord(x : qword) : qword;{$ifdef USEINLINE}inline;{$endif}
{# Return value @var(i) aligned on @var(a) boundary }
function align(i,a:longint):longint;{$ifdef USEINLINE}inline;{$endif}
function used_align(varalign,minalign,maxalign:shortint):shortint;
function isbetteralignedthan(new, org, limit: cardinal): boolean;
function size_2_align(len : longint) : shortint;
function packedbitsloadsize(bitlen: int64) : int64;
procedure Replace(var s:string;s1:string;const s2:string);
procedure Replace(var s:AnsiString;s1:string;const s2:AnsiString);
procedure ReplaceCase(var s:string;const s1,s2:string);
Function MatchPattern(const pattern,what:string):boolean;
function upper(const c : char) : char;
function upper(const s : string) : string;
function upper(const s : ansistring) : ansistring;
function lower(const c : char) : char;
function lower(const s : string) : string;
function lower(const s : ansistring) : ansistring;
function trimbspace(const s:string):string;
function trimspace(const s:string):string;
function space (b : longint): string;
function PadSpace(const s:string;len:longint):string;
function GetToken(var s:string;endchar:char):string;
procedure uppervar(var s : string);
function realtostr(e:extended):string;{$ifdef USEINLINE}inline;{$endif}
function tostr(i : qword) : string;{$ifdef USEINLINE}inline;{$endif}overload;
function tostr(i : int64) : string;{$ifdef USEINLINE}inline;{$endif}overload;
function tostr(i : longint) : string;{$ifdef USEINLINE}inline;{$endif}overload;
function tostr_with_plus(i : int64) : string;{$ifdef USEINLINE}inline;{$endif}
function DStr(l:longint):string;
{# Returns true if the string s is a number }
function is_number(const s : string) : boolean;{$ifdef USEINLINE}inline;{$endif}
{# Returns true if value is a power of 2, the actual
exponent value is returned in power.
}
function ispowerof2(value : int64;out power : longint) : boolean;
function nextpowerof2(value : int64; out power: longint) : int64;
function backspace_quote(const s:string;const qchars:Tcharset):string;
function octal_quote(const s:string;const qchars:Tcharset):string;
function maybequoted(const s:string):string;
function maybequoted(const s:ansistring):ansistring;
{# If the string is quoted, in accordance with pascal, it is
dequoted and returned in s, and the function returns true.
If it is not quoted, or if the quoting is bad, s is not touched,
and false is returned.
}
function DePascalQuote(var s: ansistring): Boolean;
function CompareStr(const S1, S2: string): Integer;
function CompareText(S1, S2: string): integer;
{ releases the string p and assignes nil to p }
{ if p=nil then freemem isn't called }
procedure stringdispose(var p : pshortstring);{$ifdef USEINLINE}inline;{$endif}
{ allocates mem for a copy of s, copies s to this mem and returns }
{ a pointer to this mem }
function stringdup(const s : string) : pshortstring;{$ifdef USEINLINE}inline;{$endif}
{# Allocates memory for the string @var(s) and copies s as zero
terminated string to that allocated memory and returns a pointer
to that mem
}
function strpnew(const s : string) : pchar;
{# makes the character @var(c) lowercase, with spanish, french and german
character set
}
function lowercase(c : char) : char;
{ makes zero terminated string to a pascal string }
{ the data in p is modified and p is returned }
function pchar2pshortstring(p : pchar) : pshortstring;
{ ambivalent to pchar2pshortstring }
function pshortstring2pchar(p : pshortstring) : pchar;
{ Ansistring (pchar+length) support }
procedure ansistringdispose(var p : pchar;length : longint);
function compareansistrings(p1,p2 : pchar;length1,length2 : longint) : longint;
function concatansistrings(p1,p2 : pchar;length1,length2 : longint) : pchar;
{Lzw encode/decode to compress strings -> save memory.}
function minilzw_encode(const s:string):string;
function minilzw_decode(const s:string):string;
implementation
uses
SysUtils;
var
uppertbl,
lowertbl : array[char] of char;
function min(a,b : longint) : longint;{$ifdef USEINLINE}inline;{$endif}
{
return the minimal of a and b
}
begin
if a<=b then
min:=a
else
min:=b;
end;
function min(a,b : int64) : int64;{$ifdef USEINLINE}inline;{$endif}
{
return the minimal of a and b
}
begin
if a<=b then
min:=a
else
min:=b;
end;
function max(a,b : longint) : longint;{$ifdef USEINLINE}inline;{$endif}
{
return the maximum of a and b
}
begin
if a>=b then
max:=a
else
max:=b;
end;
function max(a,b : int64) : int64;{$ifdef USEINLINE}inline;{$endif}
{
return the maximum of a and b
}
begin
if a>=b then
max:=a
else
max:=b;
end;
Function SwapLong(x : longint): longint;{$ifdef USEINLINE}inline;{$endif}
var
y : word;
z : word;
Begin
y := x shr 16;
y := word(longint(y) shl 8) or (y shr 8);
z := x and $FFFF;
z := word(longint(z) shl 8) or (z shr 8);
SwapLong := (longint(z) shl 16) or longint(y);
End;
Function SwapInt64(x : int64): int64;{$ifdef USEINLINE}inline;{$endif}
Begin
result:=swaplong(longint(hi(x)));
result:=result or (swaplong(longint(lo(x))) shl 32);
End;
Function SwapQWord(x : qword) : qword;{$ifdef USEINLINE}inline;{$endif}
Begin
result:=swaplong(longint(hi(x)));
result:=result or (swaplong(longint(lo(x))) shl 32);
End;
Function SwapWord(x : word): word;{$ifdef USEINLINE}inline;{$endif}
var
z : byte;
Begin
z := x shr 8;
x := x and $ff;
x := (x shl 8);
SwapWord := x or z;
End;
function align(i,a:longint):longint;{$ifdef USEINLINE}inline;{$endif}
{
return value <i> aligned <a> boundary
}
begin
{ for 0 and 1 no aligning is needed }
if a<=1 then
result:=i
else
begin
if i<0 then
result:=((i-a+1) div a) * a
else
result:=((i+a-1) div a) * a;
end;
end;
function size_2_align(len : longint) : shortint;
begin
if len>16 then
size_2_align:=32
else if len>8 then
size_2_align:=16
else if len>4 then
size_2_align:=8
else if len>2 then
size_2_align:=4
else if len>1 then
size_2_align:=2
else
size_2_align:=1;
end;
function packedbitsloadsize(bitlen: int64) : int64;
begin
case bitlen of
1,2,4,8:
result := 1;
{ 10 bits can never be split over 3 bytes via 1-8-1, because it }
{ always starts at a multiple of 10 bits. Same for the others. }
3,5,7,9,10,12,16:
result := 2;
{$ifdef cpu64bit}
{ performance penalty for unaligned 8 byte access is much }
{ higher than for unaligned 4 byte access, at least on ppc, }
{ so use 4 bytes even in some cases where a value could }
{ always loaded using a single 8 byte load (e.g. in case of }
{ 28 bit values) }
11,13,14,15,17..32:
result := 4;
else
result := 8;
{$else cpu64bit}
else
result := 4;
{$endif cpu64bit}
end;
end;
function isbetteralignedthan(new, org, limit: cardinal): boolean;
var
cnt: cardinal;
begin
cnt:=2;
while (cnt <= limit) do
begin
if (org and (cnt-1)) > (new and (cnt-1)) then
begin
result:=true;
exit;
end
else if (org and (cnt-1)) < (new and (cnt-1)) then
begin
result:=false;
exit;
end;
cnt:=cnt*2;
end;
result:=false;
end;
function used_align(varalign,minalign,maxalign:shortint):shortint;
begin
{ varalign : minimum alignment required for the variable
minalign : Minimum alignment of this structure, 0 = undefined
maxalign : Maximum alignment of this structure, 0 = undefined }
if (minalign>0) and
(varalign<minalign) then
used_align:=minalign
else
begin
if (maxalign>0) and
(varalign>maxalign) then
used_align:=maxalign
else
used_align:=varalign;
end;
end;
procedure Replace(var s:string;s1:string;const s2:string);
var
last,
i : longint;
begin
s1:=upper(s1);
last:=0;
repeat
i:=pos(s1,upper(s));
if i=last then
i:=0;
if (i>0) then
begin
Delete(s,i,length(s1));
Insert(s2,s,i);
last:=i;
end;
until (i=0);
end;
procedure Replace(var s:AnsiString;s1:string;const s2:AnsiString);
var
last,
i : longint;
begin
s1:=upper(s1);
last:=0;
repeat
i:=pos(s1,upper(s));
if i=last then
i:=0;
if (i>0) then
begin
Delete(s,i,length(s1));
Insert(s2,s,i);
last:=i;
end;
until (i=0);
end;
procedure ReplaceCase(var s:string;const s1,s2:string);
var
last,
i : longint;
begin
last:=0;
repeat
i:=pos(s1,s);
if i=last then
i:=0;
if (i>0) then
begin
Delete(s,i,length(s1));
Insert(s2,s,i);
last:=i;
end;
until (i=0);
end;
Function MatchPattern(const pattern,what:string):boolean;
var
found : boolean;
i1,i2 : longint;
begin
i1:=0;
i2:=0;
if pattern='' then
begin
result:=(what='');
exit;
end;
found:=true;
repeat
inc(i1);
if (i1>length(pattern)) then
break;
inc(i2);
if (i2>length(what)) then
break;
case pattern[i1] of
'?' :
found:=true;
'*' :
begin
found:=true;
if (i1=length(pattern)) then
i2:=length(what)
else
if (i1<length(pattern)) and (pattern[i1+1]<>what[i2]) then
begin
if i2<length(what) then
dec(i1)
end
else
if i2>1 then
dec(i2);
end;
else
found:=(pattern[i1]=what[i2]) or (what[i2]='?');
end;
until not found;
if found then
begin
found:=(i2>=length(what)) and
(
(i1>length(pattern)) or
((i1=length(pattern)) and
(pattern[i1]='*'))
);
end;
result:=found;
end;
function upper(const c : char) : char;
{
return uppercase of c
}
begin
upper:=uppertbl[c];
end;
function upper(const s : string) : string;
{
return uppercased string of s
}
var
i : longint;
begin
for i:=1 to length(s) do
upper[i]:=uppertbl[s[i]];
upper[0]:=s[0];
end;
function upper(const s : ansistring) : ansistring;
{
return uppercased string of s
}
var
i : longint;
begin
setlength(upper,length(s));
for i:=1 to length(s) do
upper[i]:=uppertbl[s[i]];
end;
function lower(const c : char) : char;
{
return lowercase of c
}
begin
lower:=lowertbl[c];
end;
function lower(const s : string) : string;
{
return lowercased string of s
}
var
i : longint;
begin
for i:=1 to length(s) do
lower[i]:=lowertbl[s[i]];
lower[0]:=s[0];
end;
function lower(const s : ansistring) : ansistring;
{
return lowercased string of s
}
var
i : longint;
begin
setlength(lower,length(s));
for i:=1 to length(s) do
lower[i]:=lowertbl[s[i]];
end;
procedure uppervar(var s : string);
{
uppercase string s
}
var
i : longint;
begin
for i:=1 to length(s) do
s[i]:=uppertbl[s[i]];
end;
procedure initupperlower;
var
c : char;
begin
for c:=#0 to #255 do
begin
lowertbl[c]:=c;
uppertbl[c]:=c;
case c of
'A'..'Z' :
lowertbl[c]:=char(byte(c)+32);
'a'..'z' :
uppertbl[c]:=char(byte(c)-32);
end;
end;
end;
function DStr(l:longint):string;
var
TmpStr : string[32];
i : longint;
begin
Str(l,TmpStr);
i:=Length(TmpStr);
while (i>3) do
begin
dec(i,3);
if TmpStr[i]<>'-' then
insert('.',TmpStr,i+1);
end;
DStr:=TmpStr;
end;
function trimbspace(const s:string):string;
{
return s with all leading spaces and tabs removed
}
var
i,j : longint;
begin
j:=1;
i:=length(s);
while (j<i) and (s[j] in [#9,' ']) do
inc(j);
trimbspace:=Copy(s,j,i-j+1);
end;
function trimspace(const s:string):string;
{
return s with all leading and ending spaces and tabs removed
}
var
i,j : longint;
begin
i:=length(s);
while (i>0) and (s[i] in [#9,' ']) do
dec(i);
j:=1;
while (j<i) and (s[j] in [#9,' ']) do
inc(j);
trimspace:=Copy(s,j,i-j+1);
end;
function space (b : longint): string;
var
s: string;
begin
space[0] := chr(b);
s[0] := chr(b);
FillChar (S[1],b,' ');
space:=s;
end;
function PadSpace(const s:string;len:longint):string;
{
return s with spaces add to the end
}
begin
if length(s)<len then
PadSpace:=s+Space(len-length(s))
else
PadSpace:=s;
end;
function GetToken(var s:string;endchar:char):string;
var
i : longint;
quote : char;
begin
GetToken:='';
s:=TrimSpace(s);
if (length(s)>0) and
(s[1] in ['''','"']) then
begin
quote:=s[1];
i:=1;
while (i<length(s)) do
begin
inc(i);
if s[i]=quote then
begin
{ Remove double quote }
if (i<length(s)) and
(s[i+1]=quote) then
begin
Delete(s,i,1);
inc(i);
end
else
begin
GetToken:=Copy(s,2,i-2);
Delete(s,1,i);
exit;
end;
end;
end;
GetToken:=s;
s:='';
end
else
begin
i:=pos(EndChar,s);
if i=0 then
begin
GetToken:=s;
s:='';
exit;
end
else
begin
GetToken:=Copy(s,1,i-1);
Delete(s,1,i);
exit;
end;
end;
end;
function realtostr(e:extended):string;{$ifdef USEINLINE}inline;{$endif}
begin
str(e,result);
end;
function tostr(i : qword) : string;{$ifdef USEINLINE}inline;{$endif}overload;
{
return string of value i
}
begin
str(i,result);
end;
function tostr(i : int64) : string;{$ifdef USEINLINE}inline;{$endif}overload;
{
return string of value i
}
begin
str(i,result);
end;
function tostr(i : longint) : string;{$ifdef USEINLINE}inline;{$endif}overload;
{
return string of value i
}
begin
str(i,result);
end;
function tostr_with_plus(i : int64) : string;{$ifdef USEINLINE}inline;{$endif}
{
return string of value i, but always include a + when i>=0
}
begin
str(i,result);
if i>=0 then
result:='+'+result;
end;
function is_number(const s : string) : boolean;{$ifdef USEINLINE}inline;{$endif}
{
is string a correct number ?
}
var
w : integer;
l : longint;
begin
val(s,l,w);
// remove warning
l:=l;
is_number:=(w=0);
end;
function ispowerof2(value : int64;out power : longint) : boolean;
{
return if value is a power of 2. And if correct return the power
}
var
hl : int64;
i : longint;
begin
if value and (value - 1) <> 0 then
begin
ispowerof2 := false;
exit
end;
hl:=1;
ispowerof2:=true;
for i:=0 to 63 do
begin
if hl=value then
begin
power:=i;
exit;
end;
hl:=hl shl 1;
end;
ispowerof2:=false;
end;
function nextpowerof2(value : int64; out power: longint) : int64;
{
returns the power of 2 >= value
}
var
i : longint;
begin
result := 0;
power := -1;
if ((value <= 0) or
(value >= $4000000000000000)) then
exit;
result := 1;
for i:=0 to 63 do
begin
if result>=value then
begin
power := i;
exit;
end;
result:=result shl 1;
end;
end;
function backspace_quote(const s:string;const qchars:Tcharset):string;
var i:byte;
begin
backspace_quote:='';
for i:=1 to length(s) do
begin
if (s[i]=#10) and (#10 in qchars) then
backspace_quote:=backspace_quote+'\n'
else if (s[i]=#13) and (#13 in qchars) then
backspace_quote:=backspace_quote+'\r'
else
begin
if s[i] in qchars then
backspace_quote:=backspace_quote+'\';
backspace_quote:=backspace_quote+s[i];
end;
end;
end;
function octal_quote(const s:string;const qchars:Tcharset):string;
var i:byte;
begin
octal_quote:='';
for i:=1 to length(s) do
begin
if s[i] in qchars then
begin
if ord(s[i])<64 then
octal_quote:=octal_quote+'\'+octstr(ord(s[i]),3)
else
octal_quote:=octal_quote+'\'+octstr(ord(s[i]),4);
end
else
octal_quote:=octal_quote+s[i];
end;
end;
function maybequoted(const s:ansistring):ansistring;
const
{$IFDEF MSWINDOWS}
FORBIDDEN_CHARS = ['!', '@', '#', '$', '%', '^', '&', '*', '(', ')',
'{', '}', '''', '`', '~'];
{$ELSE}
FORBIDDEN_CHARS = ['!', '@', '#', '$', '%', '^', '&', '*', '(', ')',
'{', '}', '''', ':', '\', '`', '~'];
{$ENDIF}
var
s1 : ansistring;
i : integer;
quoted : boolean;
begin
quoted:=false;
s1:='"';
for i:=1 to length(s) do
begin
case s[i] of
'"' :
begin
quoted:=true;
s1:=s1+'\"';
end;
' ',
#128..#255 :
begin
quoted:=true;
s1:=s1+s[i];
end;
else begin
if s[i] in FORBIDDEN_CHARS then
quoted:=True;
s1:=s1+s[i];
end;
end;
end;
if quoted then
maybequoted:=s1+'"'
else
maybequoted:=s;
end;
function maybequoted(const s:string):string;
const
{$IFDEF MSWINDOWS}
FORBIDDEN_CHARS = ['!', '@', '#', '$', '%', '^', '&', '*', '(', ')',
'{', '}', '''', '`', '~'];
{$ELSE}
FORBIDDEN_CHARS = ['!', '@', '#', '$', '%', '^', '&', '*', '(', ')',
'{', '}', '''', ':', '\', '`', '~'];
{$ENDIF}
var
s1 : string;
i : integer;
quoted : boolean;
begin
quoted:=false;
s1:='"';
for i:=1 to length(s) do
begin
case s[i] of
'"' :
begin
quoted:=true;
s1:=s1+'\"';
end;
' ',
#128..#255 :
begin
quoted:=true;
s1:=s1+s[i];
end;
else begin
if s[i] in FORBIDDEN_CHARS then
quoted:=True;
s1:=s1+s[i];
end;
end;
end;
if quoted then
maybequoted:=s1+'"'
else
maybequoted:=s;
end;
function DePascalQuote(var s: ansistring): Boolean;
var
destPos, sourcePos, len: Integer;
t: string;
ch: Char;
begin
DePascalQuote:= false;
len:= length(s);
if (len >= 1) and (s[1] = '''') then
begin
{Remove quotes, exchange '' against ' }
destPos := 0;
sourcepos:=1;
while (sourcepos<len) do
begin
inc(sourcePos);
ch := s[sourcePos];
if ch = '''' then
begin
inc(sourcePos);
if (sourcePos <= len) and (s[sourcePos] = '''') then
{Add the quote as part of string}
else
begin
SetLength(t, destPos);
s:= t;
Exit(true);
end;
end;
inc(destPos);
t[destPos] := ch;
end;
end;
end;
function pchar2pshortstring(p : pchar) : pshortstring;
var
w,i : longint;
begin
w:=strlen(p);
for i:=w-1 downto 0 do
p[i+1]:=p[i];
p[0]:=chr(w);
pchar2pshortstring:=pshortstring(p);
end;
function pshortstring2pchar(p : pshortstring) : pchar;
var
w,i : longint;
begin
w:=length(p^);
for i:=1 to w do
p^[i-1]:=p^[i];
p^[w]:=#0;
pshortstring2pchar:=pchar(p);
end;
function lowercase(c : char) : char;
begin
case c of
#65..#90 : c := chr(ord (c) + 32);
#154 : c:=#129; { german }
#142 : c:=#132; { german }
#153 : c:=#148; { german }
#144 : c:=#130; { french }
#128 : c:=#135; { french }
#143 : c:=#134; { swedish/norge (?) }
#165 : c:=#164; { spanish }
#228 : c:=#229; { greek }
#226 : c:=#231; { greek }
#232 : c:=#227; { greek }
end;
lowercase := c;
end;
function strpnew(const s : string) : pchar;
var
p : pchar;
begin
getmem(p,length(s)+1);
move(s[1],p^,length(s));
p[length(s)]:=#0;
result:=p;
end;
procedure stringdispose(var p : pshortstring);{$ifdef USEINLINE}inline;{$endif}
begin
if assigned(p) then
begin
freemem(p);
p:=nil;
end;
end;
function stringdup(const s : string) : pshortstring;{$ifdef USEINLINE}inline;{$endif}
begin
getmem(result,length(s)+1);
result^:=s;
end;
function CompareStr(const S1, S2: string): Integer;
var
count, count1, count2: integer;
begin
result := 0;
Count1 := Length(S1);
Count2 := Length(S2);
if Count1>Count2 then
Count:=Count2
else
Count:=Count1;
result := CompareChar(S1[1],S2[1], Count);
if result=0 then
result:=Count1-Count2;
end;
function CompareText(S1, S2: string): integer;
begin
UpperVar(S1);
UpperVar(S2);
Result:=CompareStr(S1,S2);
end;
{*****************************************************************************
Ansistring (PChar+Length)
*****************************************************************************}
procedure ansistringdispose(var p : pchar;length : longint);
begin
if assigned(p) then
begin
freemem(p);
p:=nil;
end;
end;
{ enable ansistring comparison }
{ 0 means equal }
{ 1 means p1 > p2 }
{ -1 means p1 < p2 }
function compareansistrings(p1,p2 : pchar;length1,length2 : longint) : longint;
var
i,j : longint;
begin
compareansistrings:=0;
j:=min(length1,length2);
i:=0;
while (i<j) do
begin
if p1[i]>p2[i] then
begin
compareansistrings:=1;
exit;
end
else
if p1[i]<p2[i] then
begin
compareansistrings:=-1;
exit;
end;
inc(i);
end;
if length1>length2 then
compareansistrings:=1
else
if length1<length2 then
compareansistrings:=-1;
end;
function concatansistrings(p1,p2 : pchar;length1,length2 : longint) : pchar;
var
p : pchar;
begin
getmem(p,length1+length2+1);
move(p1[0],p[0],length1);
move(p2[0],p[length1],length2+1);
concatansistrings:=p;
end;
{*****************************************************************************
Ultra basic KISS Lzw (de)compressor
*****************************************************************************}
{This is an extremely basic implementation of the Lzw algorithm. It
compresses 7-bit ASCII strings into 8-bit compressed strings.
The Lzw dictionary is preinitialized with 0..127, therefore this
part of the dictionary does not need to be stored in the arrays.
The Lzw code size is allways 8 bit, so we do not need complex code
that can write partial bytes.}
function minilzw_encode(const s:string):string;
var t,u,i:byte;
c:char;
data:array[128..255] of char;
previous:array[128..255] of byte;
lzwptr:byte;
next_avail:set of 0..255;
label l1;
begin
minilzw_encode:='';
fillchar(data,sizeof(data),#0);
fillchar(previous,sizeof(previous),#0);
if s<>'' then
begin
lzwptr:=127;
t:=byte(s[1]);
i:=2;
u:=128;
next_avail:=[];
while i<=length(s) do
begin
c:=s[i];
if not(t in next_avail) or (u>lzwptr) then goto l1;
while (previous[u]<>t) or (data[u]<>c) do
begin
inc(u);
if u>lzwptr then goto l1;
end;
t:=u;
inc(i);
continue;
l1:
{It's a pity that we still need those awfull tricks
with this modern compiler. Without this performance
of the entire procedure drops about 3 times.}
inc(minilzw_encode[0]);
minilzw_encode[length(minilzw_encode)]:=char(t);
if lzwptr=255 then
begin
lzwptr:=127;
next_avail:=[];
end
else
begin
inc(lzwptr);
data[lzwptr]:=c;
previous[lzwptr]:=t;
include(next_avail,t);
end;
t:=byte(c);
u:=128;
inc(i);
end;
inc(minilzw_encode[0]);
minilzw_encode[length(minilzw_encode)]:=char(t);
end;
end;
function minilzw_decode(const s:string):string;
var oldc,newc,c:char;
i,j:byte;
data:array[128..255] of char;
previous:array[128..255] of byte;
lzwptr:byte;
t:string;
begin
minilzw_decode:='';
fillchar(data,sizeof(data),#0);
fillchar(previous,sizeof(previous),#0);
if s<>'' then
begin
lzwptr:=127;
oldc:=s[1];
c:=oldc;
i:=2;
minilzw_decode:=oldc;
while i<=length(s) do
begin
newc:=s[i];
if byte(newc)>lzwptr then
begin
t:=c;
c:=oldc;
end
else
begin
c:=newc;
t:='';
end;
while c>=#128 do
begin
inc(t[0]);
t[length(t)]:=data[byte(c)];
byte(c):=previous[byte(c)];
end;
inc(minilzw_decode[0]);
minilzw_decode[length(minilzw_decode)]:=c;
for j:=length(t) downto 1 do
begin
inc(minilzw_decode[0]);
minilzw_decode[length(minilzw_decode)]:=t[j];
end;
if lzwptr=255 then
lzwptr:=127
else
begin
inc(lzwptr);
previous[lzwptr]:=byte(oldc);
data[lzwptr]:=c;
end;
oldc:=newc;
inc(i);
end;
end;
end;
procedure defaulterror(i:longint);
begin
writeln('Internal error ',i);
runerror(255);
end;
initialization
internalerrorproc:=@defaulterror;
initupperlower;
end.
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