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complete revise of sun3 SRT0 so that it works with bugcrt by me.

This commit is contained in:
chuck 1996-05-17 20:53:49 +00:00
parent 316f45753f
commit 86a71fe9e7
1 changed files with 30 additions and 40 deletions
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70
sys/arch/mvme68k/stand/libsa/SRT0.S
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@ -1,4 +1,4 @@
| $NetBSD: SRT0.S,v 1.1.1.1 1995/07/25 23:12:21 chuck Exp $
| $NetBSD: SRT0.S,v 1.2 1996/05/17 20:53:49 chuck Exp $
| Copyright (c) 1995 Gordon W. Ross
| All rights reserved.
@ -28,59 +28,49 @@
| (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 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
.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 to where they belong.
movl #_edata,d0 | Desired end of program
subl a1,d0 | Calculate length, round up.
lsrl #2,d0
| Relocate the code and data
movl #_edata,d2 | Desired end of program
subl a4,d2 | Calculate length, round up.
lsrl #2,d2
Lcp:
movl a0@+, a1@+
dbra d0, Lcp
movl a3@+, a4@+
dbra d2, Lcp
| Force a long jump to the relocated code (not pc-relative)
lea restart:l, a0
jmp a0@
lea restart:l, a3
jmp a3@
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
lea __estack:l, a3
movl a3, sp
| 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
| 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.