xref: /src/sys/arch/mvme68k/stand/libsa/SRT0.S

|	$NetBSD: SRT0.S,v 1.1 1995/07/25 23:12:21 chuck Exp $

| Copyright (c) 1995 Gordon W. Ross
| All rights reserved.
|
| Redistribution and use in source and binary forms, with or without
| modification, are permitted provided that the following conditions
| are met:
| 1. Redistributions of source code must retain the above copyright
|    notice, this list of conditions and the following disclaimer.
| 2. Redistributions in binary form must reproduce the above copyright
|    notice, this list of conditions and the following disclaimer in the
|    documentation and/or other materials provided with the distribution.
| 3. The name of the author may not be used to endorse or promote products
|    derived from this software without specific prior written permission.
| 4. All advertising materials mentioning features or use of this software
|    must display the following acknowledgement:
|      This product includes software developed by Gordon Ross
|
| THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
| IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
| OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
| IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
| INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
| NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
| DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
| THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
| (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
| THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

|	SRT0.S - Stand-alone Run-Time startup code, part 0
	.file	"SRT0.S"
	.text
	.globl	__estack
__estack:
	.globl	start
start:
| Check to see if the code is located correctly.
| This SHOULD do a PC-relative load into a0, but...
|	lea	start, a0	| current location (0x4000)
| XXX - GAS version 1.93 gets the above lea wrong!
	.word	0x41fa
	.word	0xfffe
| Now force a long (not PC-relative) load to a1 and compare.
	lea	start:l, a1	| desired location (LINKADDR)
	cmpl	a0, a1
	beqs	restart

| Relocate the code and data to where they belong.
	movl	#_edata,d0	| Desired end of program
	subl	a1,d0		| Calculate length, round up.
	lsrl	#2,d0
Lcp:
	movl	a0@+, a1@+
	dbra	d0, Lcp

| Force a long jump to the relocated code (not pc-relative)
	lea	restart:l, a0
	jmp	a0@

restart:
| now in the relocated code

	movl	a6@(8), __cmd_buf	| get cmd_line from sboot

| Set up stack (just before relocated text)
	lea	__estack:l, a0
	movl	a0, sp
	subl	a6, a6

| Call the run-time startup C code, which will:
|   initialize, call main, call exit
	jsr	__start:l

| If _start returns, fall into abort.
	.globl	_abort
_abort:
	jsr	0x4000

| If abort returns, fall into reset.
	.globl	_reset
_reset:
	reset
	jmp	_reset

| The end.