31 lines
669 B
NASM
31 lines
669 B
NASM
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gdt_start: ; use labels to compute sizes and jumps
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; gdt starts with 8 byte null
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dd 0x0
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dd 0x0
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; GDT for code segment, base = 0x00000000, length = 0xfffff
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gdt_code:
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dw 0xffff ; segment length
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dw 0x0 ; segment base
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db 0x0 ; segment base
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db 10011010b ; flags
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db 11001111b ; flags + segment length
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db 0x0 ; segment base
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; GDT for data segment
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gdt_data:
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dw 0xffff
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dw 0x0
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db 0x0
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db 10010010b
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db 11001111b
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db 0x0
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gdt_end:
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gdt_descriptor:
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dw gdt_end - gdt_start - 1 ; size, always 1 less than what it actually is
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dd gdt_start ; address
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CODE_SEG equ gdt_code - gdt_start
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DATA_SEG equ gdt_data - gdt_start
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