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! gcrt1.s for Solaris 2, x86

!   Copyright (C) 1993 Free Software Foundation, Inc.

!   Written By Fred Fish, Nov 1992

!

! This file 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, or (at your option) any

! later version.

!

! In addition to the permissions in the GNU General Public License, the

! Free Software Foundation gives you unlimited permission to link the

! compiled version of this file with other programs, and to distribute

! those programs without any restriction coming from the use of this

! file.  (The General Public License restrictions do apply in other

! respects; for example, they cover modification of the file, and

! distribution when not linked into another program.)

!

! This file 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; see the file COPYING.  If not, write to

! the Free Software Foundation, 51 Franklin Street, Fifth Floor,

! Boston, MA 02110-1301, USA.

!

!    As a special exception, if you link this library with files

!    compiled with GCC to produce an executable, this does not cause

!    the resulting executable to be covered by the GNU General Public License.

!    This exception does not however invalidate any other reasons why

!    the executable file might be covered by the GNU General Public License.

!

! This file takes control of the process from the kernel, as specified

! in section 3 of the System V Application Binary Interface, Intel386

! Processor Supplement.  It has been constructed from information obtained

! from the ABI, information obtained from single stepping existing

! Solaris executables through their startup code with gdb, and from

! information obtained by single stepping executables on other i386 SVR4

! implementations.  This file is the first thing linked into any executable.

! This is a modified crt1.s by J.W.Hawtin  15/8/96,

! to allow program profiling, by calling monstartup on entry and _mcleanup

! on exit

        .file   "gcrt1.s"

        .ident  "GNU C gcrt1.s"

        .weak   _DYNAMIC

        .text

! Start creating the initial frame by pushing a NULL value for the return

! address of the initial frame, and mark the end of the stack frame chain

! (the innermost stack frame) with a NULL value, per page 3-32 of the ABI.

! Initialize the first stack frame pointer in %ebp (the contents of which

! are unspecified at process initialization).

        .globl  _start

_start:

        pushl   $0x0

        pushl   $0x0

        movl    %esp,%ebp

! As specified per page 3-32 of the ABI, %edx contains a function

! pointer that should be registered with atexit(), for proper

! shared object termination.  Just push it onto the stack for now

! to preserve it.  We want to register _cleanup() first.

        pushl   %edx

! Check to see if there is an _cleanup() function linked in, and if

! so, register it with atexit() as the last thing to be run by

! atexit().

        movl    $_mcleanup,%eax

        testl   %eax,%eax

        je      .L1

        pushl   $_mcleanup

        call    atexit

        addl    $0x4,%esp

.L1:

! Now check to see if we have an _DYNAMIC table, and if so then

! we need to register the function pointer previously in %edx, but

! now conveniently saved on the stack as the argument to pass to

! atexit().

        movl    $_DYNAMIC,%eax

        testl   %eax,%eax

        je      .L2

        call    atexit

.L2:

! Register _fini() with atexit().  We will take care of calling _init()

! directly.

        pushl   $_fini

        call    atexit

! Start profiling

        pushl %ebp

        movl %esp,%ebp

        pushl $_etext

        pushl $_start

        call monstartup

        addl $8,%esp

        popl %ebp

! Compute the address of the environment vector on the stack and load

! it into the global variable _environ.  Currently argc is at 8 off

! the frame pointer.  Fetch the argument count into %eax, scale by the

! size of each arg (4 bytes) and compute the address of the environment

! vector which is 16 bytes (the two zero words we pushed, plus argc,

! plus the null word terminating the arg vector) further up the stack,

! off the frame pointer (whew!).

        movl    8(%ebp),%eax

        leal    16(%ebp,%eax,4),%edx

        movl    %edx,_environ

! Push the environment vector pointer, the argument vector pointer,

! and the argument count on to the stack to set up the arguments

! for _init(), _fpstart(), and main().  Note that the environment

! vector pointer and the arg count were previously loaded into

! %edx and %eax respectively.  The only new value we need to compute

! is the argument vector pointer, which is at a fixed address off

! the initial frame pointer.

!

! Make sure the stack is properly aligned.

!

        andl $0xfffffff0,%esp

        subl $4,%esp

        pushl   %edx

        leal    12(%ebp),%edx

        pushl   %edx

        pushl   %eax

! Call _init(argc, argv, environ), _fpstart(argc, argv, environ), and

! main(argc, argv, environ).

        call    _init

        call    __fpstart

        call    main

! Pop the argc, argv, and environ arguments off the stack, push the

! value returned from main(), and call exit().

        addl    $12,%esp

        pushl   %eax

        call    exit

! An inline equivalent of _exit, as specified in Figure 3-26 of the ABI.

        pushl   $0x0

        movl    $0x1,%eax

        lcall   $7,$0

! If all else fails, just try a halt!

        hlt

        .type   _start,@function

        .size   _start,.-_start