mirror of
https://github.com/gbowne1/ClassicOS.git
synced 2024-11-22 06:06:52 -08:00
86 lines
1.2 KiB
NASM
86 lines
1.2 KiB
NASM
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section .boot
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bits 16
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global boot
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boot:
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mov ax, 0x2401
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int 0x15
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mov ax, 0x3
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int 0x10
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mov [disk],dl
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mov ah, 0x2 ;read sectors
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mov al, 6 ;sectors to read
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mov ch, 0 ;cylinder idx
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mov dh, 0 ;head idx
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mov cl, 2 ;sector idx
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mov dl, [disk] ;disk idx
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mov bx, copy_target;target pointer
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int 0x13
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cli
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lgdt [gdt_pointer]
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mov eax, cr0
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or eax,0x1
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mov cr0, eax
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mov ax, DATA_SEG
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mov ds, ax
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mov es, ax
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mov fs, ax
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mov gs, ax
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mov ss, ax
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jmp CODE_SEG:boot2
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gdt_start:
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dq 0x0
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gdt_code:
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dw 0xFFFF
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dw 0x0
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db 0x0
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db 10011010b
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db 11001111b
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db 0x0
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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_pointer:
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dw gdt_end - gdt_start
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dd gdt_start
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disk:
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db 0x0
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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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times 510 - ($-$$) db 0
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dw 0xaa55
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copy_target:
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bits 32
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hello: db "Hello more than 512 bytes world!!",0
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boot2:
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mov esi,hello
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mov ebx,0xb8000
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.loop:
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lodsb
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or al,al
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jz halt
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or eax,0x0F00
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mov word [ebx], ax
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add ebx,2
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jmp .loop
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halt:
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mov esp,kernel_stack_top
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extern kmain
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call kmain
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cli
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hlt
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section .bss
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align 4
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kernel_stack_bottom: equ $
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resb 16384 ; 16 KB
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kernel_stack_top:
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