amiga_boottest
annotate src/startup.s @ 0:51422ea54b9d
initial commit
| author | John Tsiombikas <nuclear@member.fsf.org> |
|---|---|
| date | Wed, 21 Feb 2018 12:00:13 +0200 |
| parents | |
| children | 48093e4bd99a |
| rev | line source |
|---|---|
| nuclear@0 | 1 | vi:filetype=gas68k: |
| nuclear@0 | 2 .text |
| nuclear@0 | 3 |
| nuclear@0 | 4 .equ REG_COL0, 0xdff180 |
| nuclear@0 | 5 |
| nuclear@0 | 6 .global start |
| nuclear@0 | 7 .global halt_cpu |
| nuclear@0 | 8 |
| nuclear@0 | 9 start: |
| nuclear@0 | 10 | zero the .bss section |
| nuclear@0 | 11 move.l #_bss_start, %a0 |
| nuclear@0 | 12 move.l #_bss_end, %a1 |
| nuclear@0 | 13 cmp.l %a0, %a1 |
| nuclear@0 | 14 beq.s 1f | skip zeroing if the section is empty |
| nuclear@0 | 15 0: clr.l (%a0)+ |
| nuclear@0 | 16 cmp.l %a0, %a1 |
| nuclear@0 | 17 bne.s 0b |
| nuclear@0 | 18 1: |
| nuclear@0 | 19 | setup the stack |
| nuclear@0 | 20 move.l #_stacktop, %sp |
| nuclear@0 | 21 |
| nuclear@0 | 22 | test output |
| nuclear@0 | 23 move.w #0xf0f, REG_COL0 |
| nuclear@0 | 24 0: bra.b 0b | infloop |
| nuclear@0 | 25 |
| nuclear@0 | 26 halt_cpu: |
| nuclear@0 | 27 stop #0x2700 |