]> Joshua Wise's Git repositories - netwatch.git/blame - aseg/aseg.asm
make static things static
[netwatch.git] / aseg / aseg.asm
CommitLineData
eee8da2e 1 org 0xA8000
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2[bits 16]
3entry:
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4 mov ax, 0xA800 ; Take us out of flat unreal mode,
5 mov ds, ax ; and put us in true real mode.
6 mov es, ax
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7 mov fs, ax
8 mov gs, ax
9 mov ss, ax
eee8da2e 10 jmp 0xA800:(entry2-0xA8000) ; Long jump to a correct cs.
f23390bf 11entry2:
eee8da2e 12 lgdt [(gdtr-0xA8000)] ; Set up a new GDT.
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13 mov eax, 0x1
14 mov cr0, eax ; ... and enter pmode!
eee8da2e 15 jmp long 0x10:continue ; Now longjmp into the new code.
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16[bits 32]
17continue:
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18 mov ax, 0x08 ; Set up segment selectors.
19 mov ds, ax
20 mov es, ax
21 mov fs, ax
22 mov gs, ax
23 mov ss, ax
1458b275 24 mov esp, [dataptr] ; Load stack pointer.
f23390bf 25
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26 mov al, [needclear] ; Has the aseg been run before?
27 cmp al, 0 ; If so,
28 jz noclear ; don't clear BSS.
29 mov al, 0 ; Otherwise, clear BSS.
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30 mov edi, [dataptr+4]
31 mov ecx, [dataptr+8]
32 rep stosb
33 mov [needclear], al
34
35noclear:
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36 mov eax, [dataptr+12] ; Load target jump address
37 call eax ; then jump into C.
015cd976 38
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39 rsm ; and leave SMM
40
41 align 0x4
42gdtr:
9b8c947b 43 db 0x17, 0x00
eee8da2e 44 dd gdt
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45 align 0x4
46gdt:
1458b275 47 db 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 ; initial null entry
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48 db 0xFF, 0xFF, 0x00, 0x00, 0x00, 0x93, 0xCF, 0x00 ; data segment
49 db 0xFF, 0xFF, 0x00, 0x00, 0x00, 0x9B, 0xCF, 0x00 ; code segment
f23390bf 50
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51needclear:
52 db 0x01
4bea7daf 53
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54dataptr:
55 ; 4 bytes of stack top
56 ; 4 bytes of BSS start
57 ; 4 bytes of BSS length
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58 ; 4 bytes of C entry point
59 ; These show up
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