annotate src/startup.s @ 3:54739a11be66
- .data copy and .bss clearing
- also made sure .data and .bss start and end markers are dword-aligned to make
sure I can copy 4bytes at a time
| author |
John Tsiombikas <nuclear@member.fsf.org> |
| date |
Tue, 31 Jan 2017 07:11:17 +0200 |
| parents |
909c22dc18d2 |
| children |
862f8a034cae |
| rev |
line source |
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nuclear@0
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1 .text
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nuclear@0
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2 .extern main
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3
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4 .global start
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5 start:
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6 | copy .data section from ROM to RAM
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7 move.l #_data_lma, %a0
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8 move.l #_data_start, %a1
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9 move.l #_data_end, %a2
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10 cmp.l %a1, %a2
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11 beq.s 1f | skip data copy if the section is empty
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12 0: move.l (%a0)+, (%a1)+
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13 cmp.l %a1, %a2
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14 bne.s 0b
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15 1:
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16
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17 | zero the .bss section
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18 move.l #_bss_start, %a0
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19 move.l #_bss_end, %a1
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20 cmp.l %a0, %a1
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21 beq.s 1f | skip bss zeroing if the section is empty
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22 0: clr.l (%a0)+
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23 cmp.l %a0, %a1
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24 bne.s 0b
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25 1:
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26 jsr main
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27 stop #0x2700
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