/*      $NetBSD: startprog.S,v 1.4 2016/12/04 08:21:08 maxv Exp $       */

/*
* Ported to boot 386BSD by Julian Elischer ([email protected]) Sept 1992
*
* Mach Operating System
* Copyright (c) 1992, 1991 Carnegie Mellon University
* All Rights Reserved.
*
* Permission to use, copy, modify and distribute this software and its
* documentation is hereby granted, provided that both the copyright
* notice and this permission notice appear in all copies of the
* software, derivative works or modified versions, and any portions
* thereof, and that both notices appear in supporting documentation.
*
* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
* CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
* ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
*
* Carnegie Mellon requests users of this software to return to
*
*  Software Distribution Coordinator  or  [email protected]
*  School of Computer Science
*  Carnegie Mellon University
*  Pittsburgh PA 15213-3890
*
* any improvements or extensions that they make and grant Carnegie Mellon
* the rights to redistribute these changes.
*/

/*
*   Copyright 1988, 1989, 1990, 1991, 1992
*    by Intel Corporation, Santa Clara, California.
*
*                 All Rights Reserved
*
* Permission to use, copy, modify, and distribute this software and
* its documentation for any purpose and without fee is hereby
* granted, provided that the above copyright notice appears in all
* copies and that both the copyright notice and this permission notice
* appear in supporting documentation, and that the name of Intel
* not be used in advertising or publicity pertaining to distribution
* of the software without specific, written prior permission.
*
* INTEL DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE
* INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS,
* IN NO EVENT SHALL INTEL BE LIABLE FOR ANY SPECIAL, INDIRECT, OR
* CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
* LOSS OF USE, DATA OR PROFITS, WHETHER IN ACTION OF CONTRACT,
* NEGLIGENCE, OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
* WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/

#include <machine/asm.h>

/*
* Starts program in protected mode / flat space with given stackframe.
* Needs global variables flatcodeseg and flatdataseg (gdt offsets).
*/

/*
* startprog(phyaddr, argc, argv, stack)
*      start the program on protected mode where phyaddr is the entry point
*/
ENTRY(startprog)
       pushl   %ebp
       movl    %esp,%ebp

       /* Prepare a new stack */
       movl    $flatdataseg,%ebx
       movw    %bx,%es         /* for arg copy */
       movl    20(%ebp),%eax   /* stack */
       subl    $4,%eax
       movl    %eax,%edi

       /* Push some number of args onto the stack */
       movl    12(%ebp),%ecx   /* argc */
       movl    %ecx,%eax
       decl    %eax
       shl     $2,%eax
       addl    16(%ebp),%eax   /* ptr to last arg */
       movl    %eax,%esi

       std                     /* backwards */
       rep
       movsl                   /* copy %ds:(%esi) -> %es:(%edi) */

       cld

       movl    8(%ebp),%ecx    /* entry */

       /* Set new stack pointer (movsl decd sp 1 more -> dummy return address) */
       movw    %bx,%ss
       movl    %edi,%esp

       /* Push on our entry address */
       movl    $flatcodeseg,%ebx
       pushl   %ebx                    /* code segment */
       pushl   %ecx                    /* phyaddr */

       /* Convert over the other data segs */
       movl    $flatdataseg,%ebx
       mov     %bx,%ds
       mov     %bx,%es

       /* Jump to phyaddr, with the new code segment */
       lret