annotate src/startup.s @ 1:2560a8be8cb8
hblank interrupt test
| author |
John Tsiombikas <nuclear@member.fsf.org> |
| date |
Tue, 14 Mar 2017 09:02:43 +0200 |
| parents |
ce1b05082ac4 |
| children |
b22bc95f0cc0 |
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line source |
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1 .text
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2 .extern main
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3
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4 .global start
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5 .global halt_cpu
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6 start:
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7 jsr disable_intr
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8
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9 | copy .data section from ROM to RAM
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10 move.l #_data_lma, %a0
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11 move.l #_data_start, %a1
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12 move.l #_data_end, %a2
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13 cmp.l %a1, %a2
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14 beq.s 1f | skip data copy if the section is empty
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15 0: move.l (%a0)+, (%a1)+
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16 cmp.l %a1, %a2
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17 bne.s 0b
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18 1:
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19
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20 | zero the .bss section
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21 move.l #_bss_start, %a0
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22 move.l #_bss_end, %a1
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23 cmp.l %a0, %a1
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24 beq.s 1f | skip bss zeroing if the section is empty
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25 0: clr.l (%a0)+
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26 cmp.l %a0, %a1
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27 bne.s 0b
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28 1:
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29
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30 | setup the stack pointer stack
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31 move.l #_stacktop, %sp
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32 | now that we have a stack, we can enable interrupts
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33 jsr enable_intr
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34
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35 jsr main
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36 halt_cpu:
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37 stop #0x2700
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