{
    This file is part of the Free Pascal run time library.
    Copyright (c) 2005 by Michael Van Canneyt, Peter Vreman,
    & Daniel Mantione, members of the Free Pascal development team.

    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.

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

{
 Linux ELF startup code for Free Pascal


 Stack layout at program start:

         nil
         envn
         ....
         ....           ENVIRONMENT VARIABLES
         env1
         env0
         nil
         argn
         ....
         ....           COMMAND LINE OPTIONS
         arg1
         arg0
         argc <--- esp
}

var
  gmon_etext: longint; external name '_etext';
  gmon_start: longint; external name '_start';
  gmon_mcleanup: procedure; external name '_mcleanup';
  libc21_fpc_ret, libc21_fpc_ret_ebx: ptrint; { return address to libc }
  libc21_fpc_ret_esi, libc21_fpc_ret_edi: ptrint;
  gmon_monstarted: longint = 0;

procedure gmon_monstartup; external name 'monstartup';

procedure libc_atexit; external name 'atexit';
procedure libc_exit; external name '__libc_exit';
procedure libc_init; external name '__libc_init';
procedure libc_setfpucw; external name '__setfpucw';
procedure libc_start_main; external name '__libc_start_main';

procedure PASCALMAIN; external name 'PASCALMAIN';

{******************************************************************************
                       glibc 2.1 lib + profiling start/halt
 ******************************************************************************}
{$asmmode ATT}

procedure _FPC_libc21_gprof_gmon_start; assembler; nostackframe;
asm
  pushl   %ebp
  movl    gmon_monstarted,%eax
  leal    0x1(%eax),%edx
  movl    %esp,%ebp
  movl    %edx,gmon_monstarted
  testl   %eax,%eax
  jnz     .Lnomonstart
  pushl   $gmon_etext                  { Initialize gmon }
  pushl   $gmon_start
  call    gmon_monstartup
  addl    $8,%esp
  pushl   $gmon_mcleanup
  call    libc_atexit
  addl    $4,%esp
.Lnomonstart:
  movl   %ebp,%esp
  popl   %ebp
  ret
end;

procedure _FPC_libc21_gprof_start; assembler; nostackframe; public name '_start';
asm
  { First locate the start of the environment variables }
  popl    %esi
  movl    %eax,%edi

  movl    %esp,%ebx               { Points to the arguments }
  movl    %esi,%eax
  incl    %eax
  shll    $2,%eax
  addl    %esp,%eax
  andl    $0xfffffff8,%esp        { Align stack }

  movl    %eax,operatingsystem_parameter_envp    { Move the environment pointer }
  movl    %esi,operatingsystem_parameter_argc    { Move the argument counter    }
  movl    %ebx,operatingsystem_parameter_argv    { Move the argument pointer    }

  movl    %edi,%eax
  xorl    %ebp,%ebp
  pushl   %eax
  pushl   %esp
  pushl   %edx
  pushl   $.Lfini_dummy
  pushl   $.Linit_dummy
  pushl   %ebx
  pushl   %esi
  pushl   $.Lcmain
  call    libc_start_main
.Linit_dummy:
.Lfini_dummy:
  ret

{ fake main routine which will be run from libc }
.Lcmain:
  { save return address }
  popl    %eax
  movl    %eax,libc21_fpc_ret
  movl    %ebx,libc21_fpc_ret_ebx
  movl    %esi,libc21_fpc_ret_esi
  movl    %edi,libc21_fpc_ret_edi
  pushl   %eax

  call    _FPC_libc21_gprof_gmon_start

  { Save initial stackpointer }
  movl    %esp,initialstkptr

  { start the program }
  call    PASCALMAIN
  hlt
end;

procedure _FPC_libc21_gprof_haltproc; assembler; nostackframe; public name '_haltproc';
asm
{$if sizeof(ExitCode)=2}
  movzwl  ExitCode,%eax
{$else}
  mov     ExitCode,%eax
{$endif}

  movl    libc21_fpc_ret,%edx         { return to libc }
  movl    libc21_fpc_ret_ebx,%ebx
  movl    libc21_fpc_ret_esi,%esi
  movl    libc21_fpc_ret_edi,%edi
  push    %edx
  ret
end;