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|
| $OpenBSD: SRT0.S,v 1.7 2001/07/04 08:06:56 niklas Exp $
| $NetBSD: SRT0.S,v 1.2 1995/08/12 18:38:55 gwr 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.
| this is a pre-startup wrapper for bugcrt which relocates the
| code to the correct place before exec()ing.
| SRT0.S - Stand-alone Run-Time startup code, part 0
.file "SRT0.S"
.text
.globl __estack
__estack:
.globl xstart
xstart:
| first, relocate code to correct place without touching critical regs
| (args are in: d0, d1, d4, a0, a1, a2, a3, a4, a5, a6)
| [a3 and a4 only when netbooting]
movl a3, d3 | SAVE a3 in d3
movl a4, d5 | SAVE a4 in d5
lea pc@(xstart:w), a3 | a3 = current addr (could be anywhere)
lea xstart:l, a4 | a4 = desired location (LINKADDR)
cmpl a3, a4 | already there?
beqs restart | short-circuit out
| Relocate the code and data
movl #_edata,d2 | Desired end of program
subl a4,d2 | Calculate length, round up.
lsrl #2,d2
Lcp:
movl a3@+, a4@+
dbra d2, Lcp
| Force a long jump to the relocated code (not pc-relative)
lea restart:l, a3
jmp a3@
restart:
| now in the relocated code
| Set up stack (just before relocated text)
lea __estack:l, a3
movl a3, sp
| now that we have relocated, call the bugcrt (note we skip over the special
| bug header which has a PC and SP in it)
movl d3, a3 | RESTORE a3
movl d5, a4 | RESTORE a4
jmp _start
| The end.
|
