{
    $Id$
    This file is part of the Free Pascal run time library.
    Copyright (c) 1993,97 by Pierre Muller,
    member of the Free Pascal development team.

    Loads the emu387 Fpu emulator

    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.

 **********************************************************************}
unit emu387;
interface

procedure npxsetup(prog_name : string);

implementation

uses
  dxeload,dpmiexcp;

{$ASMMODE ATT}

const
  defaultdxe = 'wmemu387.dxe';

type
  emu_entry_type = function(exc : pexception_state) : longint;

var
  _emu_entry : emu_entry_type;


function getenv(const envvar:string):string;
{ Copied here, preserves uses Dos (PFV) }
var
  hp      : ppchar;
  hs,
  _envvar : string;
  eqpos   : longint;
begin
  _envvar:=upcase(envvar);
  hp:=envp;
  getenv:='';
  while assigned(hp^) do
   begin
     hs:=strpas(hp^);
     eqpos:=pos('=',hs);
     if copy(hs,1,eqpos-1)=_envvar then
      begin
        getenv:=copy(hs,eqpos+1,255);
        exit;
      end;
     hp:=hp+4;
   end;
end;


procedure _control87(mask1,mask2 : word);
{ Copyright (C) 1995 DJ Delorie, see COPYING.DJ for details }
{ from file cntrl87.s in src/libc/pc_hw/fpu }
begin
  asm
      { make room on stack }
        pushl   %eax
        fstcw   (%esp)
        fwait
        popl    %eax
        andl    $0xffff, %eax
      { OK;  we have the old value ready }
        movl    mask2, %ecx
        notl    %ecx
        andl    %eax, %ecx       { the bits we want to keep }
        movl    mask2, %edx
        andl    mask1, %edx      { the bits we want to change }
        orl     %ecx, %edx       { the new value }
        pushl   %edx
        fldcw   (%esp)
        popl    %edx
  end;
end;


function emu_entry(exc : pexception_state) : longint;
{
  the problem with the stack that is not cleared
}
begin
  emu_entry:=_emu_entry(exc);
end;


function nofpsig( sig : longint) : longint;
var
  res : longint;
const
 last_eip : longint = 0;
begin
  {if last_eip=djgpp_exception_state^.__eip then
    begin
       writeln('emu call two times at same address');
       dpmi_set_coprocessor_emulation(1);
       _raise(SIGFPE);
       exit(0);
    end; }

  last_eip:=djgpp_exception_state^.__eip;
  res:=emu_entry(djgpp_exception_state);
  if res<>0 then
    begin
       writeln('emu call failed. res = ',res);
       dpmi_set_coprocessor_emulation(1);
       _raise(SIGFPE);
       exit(0);
    end;
  longjmp(pjmprec(djgpp_exception_state)^, djgpp_exception_state^.__eax);
  nofpsig:=0;
end;


var
  prev_exit : pointer;
procedure restore_DPMI_fpu_state;
begin
  exitproc:=prev_exit;
  dpmi_set_coprocessor_emulation(1);
{ writeln('Coprocessor restored '); }
{ Enable Coprocessor, no exceptions }
end;


{$L fpu.o }

procedure npxsetup(prog_name : string);
const
   veryfirst : boolean = True;
var
   cp         : string;
   i          : byte;
   have_80387 : boolean;
   emu_p      : pointer;
begin
  cp:=getenv('387');
  if (cp<>'') and (upcase(cp[1])='N') then
    have_80387:=False
  else
    begin
       dpmi_set_coprocessor_emulation(1);
{$ASMMODE DIRECT}
       asm
          call __detect_80387
          movb %al,have_80387
       end;
{$ASMMODE ATT}
    end;
  if (cp<>'') and (upcase(cp[1])='Q') then
    begin
       if not have_80387 then
         write(stderr,'No ');
       writeln(stderr,'80387 detected.');
    end;

  if have_80387 then
    begin
    { mask all exceptions, except invalid operation }
       _control87($033e, $ffff);
    end
  else
    begin
    { Flags value 3 means coprocessor emulation, exceptions to us */}
       if (dpmi_set_coprocessor_emulation(3)<>0) then
        begin
          writeln(stderr,'Warning: Coprocessor not present and DPMI setup failed!');
          writeln(stderr,'         If application attempts floating operations system may hang!');
        end
       else
        begin
          cp:=getenv('EMU387');
          if cp='' then
            begin
               for i:=length(prog_name) downto 1 do
                 if (prog_name[i]='\') or (prog_name[i]='/') then
                   break;
               if i>1 then
                 cp:=copy(prog_name,1,i);
               cp:=cp+defaultdxe
            end;
          emu_p:=dxe_load(cp);
          _emu_entry:=emu_entry_type(emu_p);
          if (emu_p=nil) then
            begin
               writeln(cp+' load failed !');
               halt;
            end;
          if veryfirst then
            begin
               veryfirst:=false;
               prev_exit:=exitproc;
               exitproc:=@restore_DPMI_fpu_state;
            end;
          signal(SIGNOFP,@nofpsig);
        end;
    end;
end;


begin
   npxsetup(paramstr(0));
end.

{
  $Log$
  Revision 1.5  1998-05-31 14:18:25  peter
    * force att or direct assembling
    * cleanup of some files

}