85 lines
2.2 KiB
ArmAsm
85 lines
2.2 KiB
ArmAsm
; This file is part of stage0.
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;
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; stage0 is free software: you can redistribute it and/or modify
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; it under the terms of the GNU General Public License as published by
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; the Free Software Foundation, either version 3 of the License, or
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; (at your option) any later version.
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;
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; stage0 is distributed in the hope that it will be useful,
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; but WITHOUT ANY WARRANTY; without even the implied warranty of
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; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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; GNU General Public License for more details.
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;
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; You should have received a copy of the GNU General Public License
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; along with stage0. If not, see <http://www.gnu.org/licenses/>.
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BITS 16
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;; Steps for building
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;; nasm -o stage1_loader stage1_loader.s
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;;
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;; Steps for testing
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;; qemu -fda stage1_loader
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;; Then insert another program to load and run
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start:
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;; Wait for user input before running
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mov ah, 00h
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int 16h
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;; Clear the screen to be nice
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;; Routine: clears the display
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mov al, 0 ; Clear screen
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mov ah, 06h ; Scroll up
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mov bh, 07h ; Move Color
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mov cl, 0 ; UL x coordinate
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mov ch, 0 ; UL y coordinate
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mov dl, 80 ; LR x coordinate
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mov dh, 24 ; LR y coordinate
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int 10h
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;; Routine: reset the cursor
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mov ah, 02h ; Set cursor position
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mov bh, 0 ; Set Page number to 0
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mov dh, 0 ; Set Row Number
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mov dl, 0 ; Set Column Number
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int 10h
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read_floppy:
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;; Read bytes from floppy
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mov al, 128 ; Number of sectors to read
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mov ah, 02h ; Read sectors to memory
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mov ch, 0 ; Cylinder Number
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mov cl, 1 ; Starting sector number
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mov dh, 0 ; Drive head number
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mov dl, 00h ; Drive number [floppy A:]
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mov bx, 01000h ; Starting segment
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mov es, bx ; Loaded into the required segment register
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mov bx, 0 ; At the exact start of the segment
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int 13h ; Make the function call
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jc read_floppy
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;; Zero all registers and segments before jump
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mov ax, 0
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mov bx, 0
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mov cx, 0
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mov dx, 0
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mov si, 0
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mov di, 0
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mov bp, 0
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mov ds, ax
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mov ss, 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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;; Prepare to Jump to the code we loaded
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push 01000h
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push 0h
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;; Using intersegment return
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iret
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done:
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hlt
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times 510-($-$$) db 90h ; Pad remainder of boot sector with NOPs
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dw 0xAA55 ; The standard PC boot signature
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