{
    This file is part of the Free Pascal run time library.
    Copyright (c) 2020 by Free Pascal development team

    Low level file functions for the Sinclair QL

    See the file COPYING.FPC, included in this distribution,
    for details about the copyright.

    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.

 **********************************************************************}


{****************************************************************************
                        Low level File Routines
               All these functions can set InOutRes on errors
****************************************************************************}

{ close a file from the handle value }
procedure do_close(handle : longint);
begin
  Error2InOutRes(io_close(handle));
end;


procedure do_erase(p : pchar; pchangeable: boolean);
begin
end;


procedure do_rename(p1,p2 : pchar; p1changeable, p2changeable: boolean);
begin
end;


function do_write(h: longint; addr: pointer; len: longint) : longint;
var
  res: longint;
begin
  do_write:=0;
  res:=io_sstrg(h, -1, addr, len);
  if res < 0 then
    Error2InOutRes(res)
  else
    do_write:=res;
end;


function do_read(h: longint; addr: pointer; len: longint) : longint;
var
  res: longint;
begin
  do_read := 0;
  res := io_fline(h, -1, addr, len);
  if res < 0 then
    Error2InOutRes(res)
  else
    do_read := res;
end;


function do_filepos(handle: longint): longint;
var
  res: longint;
begin
  do_filepos := 0;
  res := fs_posre(handle, 0);
  if res < 0 then
    Error2InOutRes(res)
  else
    do_filepos := res;
end;


procedure do_seek(handle, pos: longint);
var
  res: longint;
begin
  res := fs_posab(handle, pos);
  if res < 0 then
    Error2InOutRes(res);
end;


function do_seekend(handle: longint): longint;
begin
  do_seek(handle, -1);
  do_seekend := do_filepos(handle);
end;


function do_filesize(handle: longint): longint;
var
  res: longint;
  header: array [0..$39] of byte;
begin
  do_filesize := 0;
  res := fs_headr(handle, @header, $40);
  if res < 0 then
    Error2InOutRes(res)
  else
    do_filesize := plongint(@header[0])^;
end;


{ truncate at a given position }
procedure do_truncate(handle, pos: longint);
begin
  do_seek(handle, pos);
  fs_truncate(handle);
end;


procedure do_open(var f;p:pchar;flags:longint; pchangeable: boolean);
{
  filerec and textrec have both handle and mode as the first items so
  they could use the same routine for opening/creating.
  when (flags and $100)   the file will be append
  when (flags and $1000)  the file will be truncate/rewritten
  when (flags and $10000) there is no check for close (needed for textfiles)
}
var
  res: longint;
  openMode: longint;
begin
  openMode:=Q_OPEN;

  { close first if opened }
  if ((flags and $10000)=0) then
   begin
     case filerec(f).mode of
       fmInput, fmOutput, fmInout:
         do_close(filerec(f).handle);
       fmClosed: ;
     else
       begin
         InOutRes:=102; {not assigned}
         exit;
       end;
     end;
   end;

  { reset file handle }
  filerec(f).handle:=UnusedHandle;

  { convert filemode to filerec modes }
  case (flags and 3) of
    0 : filerec(f).mode:=fmInput;
    1 : filerec(f).mode:=fmOutput;
    2 : filerec(f).mode:=fmInout;
  end;

  { empty name is special }
  if p[0]=#0 then begin
    case filerec(f).mode of
      fminput :
        filerec(f).handle:=StdInputHandle;
      fmappend,
      fmoutput : begin
        filerec(f).handle:=StdOutputHandle;
        filerec(f).mode:=fmOutput; {fool fmappend}
      end;
    end;
    exit;
  end;

  { rewrite (create a new file) }
  { FIX ME: this will just create a new file, actual overwriting
    seems to be a more complex endeavor... }
  if (flags and $1000)<>0 then openMode:=Q_OPEN_NEW;

  res:=io_open(p,openMode);

  if res < 0 then
    begin
      Error2InOutRes(res);
      filerec(f).mode:=fmClosed;
      exit;
    end
  else
    filerec(f).handle:=res;

  { append mode }
  if ((Flags and $100)<>0) and
      (FileRec(F).Handle<>UnusedHandle) then begin
    do_seekend(filerec(f).handle);
    filerec(f).mode:=fmOutput; {fool fmappend}
  end;
end;


function do_isdevice(handle: thandle): boolean;
begin
  do_isdevice:=false;
end;