41 lines
810 B
NASM
41 lines
810 B
NASM
global entry
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entry:
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mov dword [0xb8000], 0x07000700 | 'E' | 'N' << 16
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mov dword [0xb8004], 0x07000700 | 'T' | 'R' << 16
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mov dword [0xb8008], 0x07000700 | 'Y' | ' ' << 16
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lgdt [gdt_desc] ; load gdt register
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jmp 08h:Pmodecode
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extern gdt_desc
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[BITS 32]
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Pmodecode:
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mov ax, 0x10 ; set up segments
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mov ds, ax
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mov es, ax
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mov ss, ax
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mov fs, ax
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mov gs, ax
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mov ebp, 0x800000
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mov esp, ebp
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mov eax, 0x1f001f00
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mov ecx, (80*25)/2
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mov edi, 0xb8000
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rep stosd ; clear screen
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mov eax, dword [kernel_check]
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cmp eax, 0x12345678
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jne err
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call start
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hlt_loop:
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hlt
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jmp hlt_loop
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err:
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mov dword [0xb8000], 0x07000700 | 'L' | 'O' << 16
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mov dword [0xb8004], 0x07000700 | 'A' | 'D' << 16
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mov dword [0xb8008], 0x07000700 | 'F' | 'A' << 16
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mov dword [0xb800C], 0x07000700 | 'I' | 'L' << 16
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jmp hlt_loop
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extern start
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extern kernel_check
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