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|
| $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.
| 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.
| Get current location via PC-relative load, then...
lea pc@(start:w), a0 | current location (0x4000)
| ...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
| 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:
trap #0
| If abort returns, fall into reset.
.globl _reset
_reset:
reset
jmp _reset
| function to get the vector base register
.globl _getvbr
_getvbr:
movc vbr, d0
rts
| The end.
|
