annotate src/startup.s @ 10:ca7108a82867
fixed gamepad input on real megadrive
| author |
John Tsiombikas <nuclear@member.fsf.org> |
| date |
Sat, 24 Jun 2017 02:33:52 +0300 |
| parents |
b22bc95f0cc0 |
| children |
54caa2b214ca |
| rev |
line source |
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1 | vi:filetype=gas68k:
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2 .text
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3 .extern main
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4
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5 .global start
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6 .global halt_cpu
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7 start:
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8 jsr disable_intr
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9
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10 | copy .data section from ROM to RAM
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11 move.l #_data_lma, %a0
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12 move.l #_data_start, %a1
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13 move.l #_data_end, %a2
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14 cmp.l %a1, %a2
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15 beq.s 1f | skip data copy if the section is empty
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16 0: move.l (%a0)+, (%a1)+
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17 cmp.l %a1, %a2
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18 bne.s 0b
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19 1:
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20
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21 | zero the .bss section
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22 move.l #_bss_start, %a0
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23 move.l #_bss_end, %a1
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24 cmp.l %a0, %a1
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25 beq.s 1f | skip bss zeroing if the section is empty
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26 0: clr.l (%a0)+
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27 cmp.l %a0, %a1
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28 bne.s 0b
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29 1:
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30
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31 | setup the stack pointer stack
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32 move.l #_stacktop, %sp
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33 | now that we have a stack, we can enable interrupts
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34 jsr enable_intr
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35
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36 jsr main
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37 halt_cpu:
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38 stop #0x2700
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