forked from KolibriOS/kolibrios
454 lines
8.1 KiB
NASM
454 lines
8.1 KiB
NASM
; KolibriOS bootloader
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; this code has been written by diamond in 2005,2006,2007 specially for KolibriOS
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; this code is loaded by our bootsector to 0000:8000
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format binary
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use16
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out_string = 0x7DAB
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read_cluster = 0x7D15
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relative_read = 0x7D22
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next_cluster = 0x7D65
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org 0x8000
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start:
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; cs=ds=0, es undefined, ss=0, sp=7C00
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movzx esp, sp
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push 1000h
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pop es
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; say hi to user
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mov si, start_msg
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call out_string
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; parse image name
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mov eax, [7C2Ch] ; root_cluster
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and eax, 0xFFFFFFF
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mov [cur_obj], root_string
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.parsedir:
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push ax
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mov si, [imgnameofs]
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push si
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@@:
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lodsb
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cmp al, 0
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jz @f
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cmp al, '\'
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jnz @b
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dec si
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mov [missing_slash], si
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inc si
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@@:
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xchg ax, [esp+2]
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mov byte [si-1], 0
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mov [imgnameofs], si
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call fat32_parse_dir
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call restore_slash
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pop cx
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test cl, cl
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jz .end
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test byte [es:di+0Bh], 10h
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mov si, notdir_string
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jz find_error_si
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jmp .parsedir
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.end:
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test byte [es:di+0Bh], 10h
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mov si, directory_string
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jnz find_error_si
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; parse FAT chunk
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; runlist at 5000:0000
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mov di, 4
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push 5000h
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pop es
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mov dword [es:di-4], 1
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stosd
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.parsefat:
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call next_cluster
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jnc .done
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mov ecx, [es:di-8]
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add ecx, [es:di-4]
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cmp eax, ecx
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jz .contc
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mov dword [es:di], 1
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scasd
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stosd
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jmp .parsefat
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.contc:
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inc dword [es:di-8]
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jmp .parsefat
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.done:
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xor eax, eax
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stosd
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read_img_file:
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xor si, si
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push es
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pop fs
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; yes! Now read file to 0x100000
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xor edi, edi
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; read buffer to 1000:0000 and move it to extended memory
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push 1000h
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pop es
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xor bx, bx
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.img_read_block:
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lods dword [fs:si] ; eax=length
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xchg eax, ecx
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jecxz .img_read_done
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lods dword [fs:si] ; eax=disk cluster
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.img_read_cluster:
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pushad
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; read part of file
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movzx esi, byte [7C0Dh]
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mul esi
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add eax, [7A04h]
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push ax
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mov ax, 0x200
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div si
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cmp cx, ax
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jb @f
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mov cx, ax
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@@:
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pop ax
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add [esp+1Ch], ecx
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sub [esp+18h], cx
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imul cx, si
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push cx
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call relative_read
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pop cx
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; move it to extended memory
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mov byte [sou_addr+2], 1
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.move_loop:
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push cx
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cmp cx, 80h
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jbe @f
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mov cx, 80h
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@@:
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mov ah, 87h
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xchg cl, ch
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mov si, movedesc
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push cx es
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push ds
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pop es
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int 15h
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pop es cx
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test ah, ah
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mov si, exmem_string
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jnz find_error_si
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add [dest_addr], ecx
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add [dest_addr], ecx
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inc byte [sou_addr+2]
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mov al, ch
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mov ah, cl
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pop cx
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sub cx, ax
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jnz .move_loop
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popad
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test cx, cx
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jnz .img_read_cluster
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jmp .img_read_block
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.img_read_done:
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; kolibri.img loaded; now load kernel.mnt
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load_kernel:
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push ds
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pop es
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mov [cur_obj], kernel_mnt_name
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; read boot sector
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xor eax, eax
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mov bx, 500h
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mov cx, 1
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call read_img
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; init vars
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mov ax, [50Eh] ; reserved_sect
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add ax, [51Ch] ; hidden
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mov word [fat_start], ax
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xchg ax, bx
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movzx ax, byte [510h] ; num_fats
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mul word [516h] ; fat_length
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add ax, bx
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; read root dir
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mov bx, 700h
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mov cx, [511h] ; dir_entries
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add cx, 0Fh
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shr cx, 4
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call read_img
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add ax, cx
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mov [img_data_start], ax
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shl cx, 9
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mov di, bx
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add bx, cx
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mov byte [bx], 0
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.scan_loop:
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cmp byte [di], 0
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mov si, notfound_string
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jz find_error_si
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mov si, kernel_mnt_name
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call fat_compare_name
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jz .found
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and di, not 1Fh
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add di, 20h
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jmp .scan_loop
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.found:
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and di, not 1Fh
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mov si, directory_string
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test byte [di+0Bh], 10h
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jnz find_error_si
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; found, now load it to 1000h:0000h
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mov ax, [di+1Ah]
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; first cluster of kernel.mnt in ax
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; translate it to sector on disk in kolibri.img
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push ax
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dec ax
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dec ax
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movzx cx, byte [50Dh]
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mul cx
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add ax, [img_data_start]
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; now ax is sector in kolibri.img
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mov [kernel_mnt_in_img], ax
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movzx cx, byte [7C0Dh]
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div cx
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; now ax is cluster in kolibri.img and
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; dx is offset from the beginning of cluster
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movzx eax, ax
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push 5000h
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pop ds
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xor si, si
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mov si, 1
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.scani:
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sub eax, [si]
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jb .scanidone
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; sanity check
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cmp dword [si], 0
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push data_error_msg
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jz find_error_sp
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pop cx
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; next chunk
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add si, 8
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jmp .scani
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.scanidone:
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add eax, [si] ; undo last subtract
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add eax, [si+4] ; get cluster
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push 0
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pop ds
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movzx ecx, byte [7C0Dh]
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push dx
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mul ecx ; get sector
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pop dx
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movzx edx, dx
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add eax, edx
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add eax, [7A04h]
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mov [kernel_mnt_1st], eax
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pop ax
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push 1000h
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pop es
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.read_loop:
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push ax
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xor bx, bx
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call img_read_cluster
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shl cx, 9-4
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mov ax, es
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add ax, cx
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mov es, ax
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pop ax
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call img_next_cluster
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jc .read_loop
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mov ax, 'KL'
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mov si, loader_block
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jmp 1000h:0000h
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img_next_cluster:
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mov bx, 700h
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push ax
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shr ax, 1
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add ax, [esp]
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mov dx, ax
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shr ax, 9
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add ax, word [fat_start]
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mov cx, 2
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push es
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push ds
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pop es
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call read_img
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pop es
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and dx, 1FFh
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add bx, dx
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mov ax, [bx]
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pop cx
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test cx, 1
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jz .1
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shr ax, 4
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.1:
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and ax, 0FFFh
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mov si, bad_cluster_string
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cmp ax, 0FF7h
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jz find_error_si
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ret
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img_read_cluster:
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dec ax
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dec ax
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movzx cx, byte [50Dh] ; sects_per_clust
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mul cx
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add ax, [img_data_start]
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movzx eax, ax
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; call read_img
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; ret
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read_img:
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; in: ax = sector, es:bx->buffer, cx=length in sectors
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pushad
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movzx ebx, bx
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mov si, movedesc
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shl eax, 9
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add eax, 93100000h
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mov dword [si+sou_addr-movedesc], eax
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mov eax, 9300000h
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mov ax, es
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shl eax, 4
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add eax, ebx
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mov [si+dest_addr-movedesc], eax
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mov ah, 87h
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shl cx, 8 ; mul 200h/2
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push es
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push 0
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pop es
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int 15h
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pop es
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cmp ah, 0
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mov si, exmem_string
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jnz find_error_si
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popad
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ret
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movedesc:
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times 16 db 0
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; source
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dw 0xFFFF ; segment length
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sou_addr dw 0000h ; linear address
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db 1 ; linear address
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db 93h ; access rights
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dw 0
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; destination
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dw 0xFFFF ; segment length
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dest_addr dd 93100000h ; high byte contains access rights
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; three low bytes contains linear address (updated when reading)
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dw 0
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times 32 db 0
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find_error_si:
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push si
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find_error_sp:
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mov si, error_msg
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call out_string
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mov si, [cur_obj]
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call out_string
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mov si, colon
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call out_string
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pop si
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call out_string
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mov si, newline
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call out_string
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jmp $
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file_not_found:
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mov si, [esp+2]
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mov [cur_obj], si
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push notfound_string
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jmp find_error_sp
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restore_slash:
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mov si, [missing_slash]
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test si, si
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jz @f
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and [missing_slash], 0
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mov byte [si], '\'
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@@: ret
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include 'fat32.inc'
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if 0
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write1st:
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; callback from kernel.mnt
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; write first sector of kernel.mnt from 1000:0000 back to disk
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push cs
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pop ds
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push cs
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pop es
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; sanity check
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mov bx, 500h
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mov si, bx
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mov cx, 1
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push cx
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mov eax, [kernel_mnt_1st]
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push eax
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call relative_read
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push 1000h
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pop es
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xor di, di
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mov cx, 8
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repz cmpsw
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mov si, data_error_msg
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jnz find_error_si
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; ok, now write back to disk
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or byte [read.patch1+2], 1
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or byte [read.patch2+2], 1
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xor bx, bx
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pop eax
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pop cx
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call relative_read
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and byte [read.patch1+1], not 1
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and byte [read.patch2+2], not 2
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; and to image in memory (probably this may be done by kernel.mnt itself?)
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mov dword [sou_addr], 93010000h
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movzx eax, [kernel_mnt_in_img]
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shl eax, 9
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add eax, 93100000h
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mov dword [dest_addr], eax
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mov si, movedesc
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push ds
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pop es
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mov ah, 87h
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mov cx, 100h
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int 15h
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cmp ah, 0
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mov si, exmem_string
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jnz find_error_si
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retf
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else
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write1st = 0
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end if
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loader_block:
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db 1 ; version
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dw 1 ; flags - image is loaded
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dw write1st ; offset
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dw 0 ; segment
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imgnameofs dw kolibri_img_name
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; -----------------------------------------------
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; ------------------ Settings -------------------
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; -----------------------------------------------
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; must be in lowercase, see ntfs_parse_dir.scan, fat32_parse_dir.scan
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kernel_mnt_name db 'kernel.mnt',0
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kolibri_img_name db 'kolibri.img',0
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missing_slash dw 0
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start_msg db 2,' KolibriOS bootloader, FAT32 flash version'
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newline db 13,10,0
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error_msg db 'Error'
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colon db ': ',0
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root_string db '\',0
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nodata_string db '$DATA '
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notfound_string db 'not found',0
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directory_string db 'is a directory',0
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notdir_string db 'not a directory',0
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exmem_string db 'extended memory error',0
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bad_cluster_string db 'bad cluster',0
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data_error_msg db 'data error',0
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align 2
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; uninitialized data follows
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cur_obj dw ?
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img_data_start dw ?
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kernel_mnt_in_img dw ?
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fat_start dw ?
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kernel_mnt_1st dd ?
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