56 lines
1 KiB
NASM
56 lines
1 KiB
NASM
[org 0x7c00]
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section BOOTSECTOR start=7C00h
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OS_SEGMENT equ 0x100
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; https://github.com/cfenollosa/os-tutorial
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boot:
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; Load from disk
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mov ah, 0x02 ; read
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mov al, 0x02 ; No of sectors (1)
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mov cl, 0x02 ; Sector start (1 = boot sector, 2 = OS)
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mov ch, 0x00 ; Cylinder 0
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mov dh, 0x00 ; Head 0
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mov bx, OS_SEGMENT ; Set target segment
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mov es, bx
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mov bx, 0x0 ; Target offset in segment
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int 0x13 ; Send read interrupt
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jc disk_error
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; Now that the OS is loaded in 0x1000, let's call main!
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jmp 0x100:0x0
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disk_error:
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mov si, DISK_ERR_MSG
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call bs_print
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jmp $
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; https://stackoverflow.com/a/53403853
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bs_print:
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mov ah, 0x0e ; BIOS TTY function
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.L0:
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lodsb
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or al, al
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jnz .J0
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ret
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.J0:
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int 0x10
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jmp .L0
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jmp $ ; Halt
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; Boot sector libs
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; Boot sector data
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DISK_ERR_MSG:
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db 'DISK ERROR: Failed to load kernel!', 0
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; Boot sector padding and magic number
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times 510-($-$$) db 0
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dw 0xaa55
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