Contributor: MARK LEWIS
{
MARK LEWIS> The problem is that Without allocating a new FCB For Dos, you> can't have more than 15 or so Files open at a time in TP, no> matter WHAT the CONFIG.SYS FileS= statement says. (By default,
i cannot remember exactly what INT 21ドル Function 6700ドル is but here's a PD Unit
i got from borland's bbs the other day... i've trimmed the Text down for
posting... if anyone Really needs everything that comes With it, they should
look For EXTend6.*
}
Unit Extend;
{ This extends the number of File handles from 20 to 255 }
{ Dos requires 5 For itself. Applications can use up to 250 }
Interface
Implementation
Uses
Dos;
Const
Handles = 255;
{ You can reduce the value passed to Handles if fewer Files are required. }
Var
Reg : Registers;
begin
{ Check the Dos Version - This technique only works For Dos 3.0 or later }
Reg.ah := 30ドル;
MsDos(Reg);
if Reg.al<3 then begin Writeln('Extend Unit Require Dos 3.0 or greater'); halt(1); end; {Reset the FreePtr - This reduces the heap space used by Turbo Pascal} if HeapOrg HeapPtr then
{Checks to see if the Heap is empty}
begin
Write('Heap must be empty before Extend Unit initializes');
Writeln;
halt(1);
end;
Heapend := ptr(Seg(Heapend^) - (Handles div 8 + 1), Ofs(Heapend^));
{Determine how much memory is allocated to Program}
{Reg.Bx will return how many paraGraphs used by Program}
Reg.ah := 4ドルA;
Reg.es := PrefixSeg;
Reg.bx := $FFFF;
msDos(Reg);
{Set the Program size to the allow For new handles}
Reg.ah := 4ドルA;
Reg.es := PrefixSeg;
Reg.bx := reg.bx - (Handles div 8 + 1);
msDos(Reg);
{Error when a Block Size is not appropriate}
if (Reg.flags and 1) = 1 then
begin
Writeln('Runtime Error ', Reg.ax, ' in Extend.');
halt(1);
end;
{Allocate Space For Additional Handles}
reg.ah := 67ドル;
reg.bx := Handles;
MsDos(reg);
end.
{
Write the following Program to a separate File. This Program tests the EXTend
Unit. This test should be done on systems equipped With a hard disk.
}
Program TestEx;
Uses
EXTend;
Type
FileArray = Array [1..250] of Text;
Var
f : ^FileArray;
i : Integer;
s : String;
begin
{Allocate Space For fILE Variable Table}
new(f);
{oPEN 250 Files simultaneously}
For i:=1 to 250 do
begin
str(i,s);
Assign(f^[i],'Dum'+s+'.txt');
reWrite(f^[i]);
Writeln('Open #',s);
end;
{Write some Text to the Files}
For i:=1 to 250 do
Write(f^[i],'This is a test File');
{Close the Files}
For i:=1 to 250 do
begin
close(f^[i]);
Writeln('Closing #',i);
end;
{Erase the Files}
For i:=1 to 250 do
begin
erase(f^[i]);
Writeln('Erasing #',i);
end;
end.