forked from KolibriOS/kolibrios
297 lines
7.6 KiB
NASM
297 lines
7.6 KiB
NASM
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;; ;;
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;; Copyright (C) KolibriOS team 2014-2015. All rights reserved. ;;
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;; Distributed under terms of the GNU General Public License ;;
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;; ;;
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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; Kolibri OS support loader for GRUB
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;
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; Copyright (C) Alex Nogueira Teixeira
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; Copyright (C) Diamond
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; Copyright (C) Dmitry Kartashov aka shurf
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; Copyright (C) Serge
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;
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; Distributed under GPL, see file COPYING for details
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;
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; Version 1.0
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lf = 0x0A
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cr = 0x0D
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use32
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org 0x100000
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mboot:
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dd 0x1BADB002
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dd 0x00010003
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dd -(0x1BADB002 + 0x00010003)
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dd mboot
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dd 0x100000
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dd __edata
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dd __end
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dd __start
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align 16
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__start:
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virtual at ebp+3
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.BS_OEMName rb 8
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.BPB_BytsPerSec rw 1 ; bytes per sector
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.BPB_SecPerClus rb 1 ; sectors per cluster
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.BPB_RsvdSecCnt rw 1 ; number of reserver sectors
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.BPB_NumFATs rb 1 ; count of FAT data structures
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.BPB_RootEntCnt rw 1 ; count of 32-byte dir. entries (224*32 = 14 sectors)
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.BPB_TotSec16 rw 1 ; count of sectors on the volume (2880 for 1.44 mbytes disk)
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.BPB_Media rb 1 ; f0 - used for removable media
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.BPB_FATSz16 rw 1 ; count of sectors by one copy of FAT
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.BPB_SecPerTrk rw 1 ; sectors per track
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.BPB_NumHeads rw 1 ; number of heads
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.BPB_HiddSec rd 1 ; count of hidden sectors
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.BPB_TotSec32 rd 1 ; count of sectors on the volume (if > 65535)
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end virtual
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cld
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mov esi, mboot
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mov edi, 0x80000
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mov ecx, 624/4 ;magic value
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rep movsd
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jmp .check_mbi
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org $-0x80000
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align 4
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.check_mbi:
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cmp eax, 0x2BADB002
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mov esi, sz_invboot
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jne .panic
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bt dword [ebx], 3
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mov esi, sz_nomods
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jnc .panic
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mov edx, [ebx+20] ;mods_count
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mov edi, [ebx+24] ;mods_addr
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cmp edx, 1
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mov esi, sz_nomods
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jne .panic
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.scan_mod:
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mov ebp, [edi] ;image start
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mov ecx, [edi+4] ;image end
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sub ecx, ebp ;image size
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cmp ecx, 512*18*80*2 ;1.44 floppy
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mov esi, sz_image
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jne .panic
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mov [_image_start], ebp
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mov [_image_size], ecx
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; calculate some disk parameters
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; - beginning sector of RootDir
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movzx eax, word [.BPB_FATSz16]
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movzx ecx, byte [.BPB_NumFATs]
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mul ecx
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add ax, [.BPB_RsvdSecCnt]
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mov [FirstRootDirSecNum], eax
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mov esi, eax
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; - count of sectors in RootDir
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movzx ebx, word [.BPB_BytsPerSec]
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mov cl, 5 ; divide ax by 32
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shr ebx, cl ; bx = directory entries per sector
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movzx eax, word [.BPB_RootEntCnt]
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xor edx, edx
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div ebx
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mov [RootDirSecs], eax
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; - data start
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add esi, eax ; add beginning sector of RootDir and count sectors in RootDir
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mov [data_start], esi
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; reading root directory
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; al=count root dir sectrors !!!! TODO: al, max 255 sectors !!!!
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mov eax, [FirstRootDirSecNum]
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mul word [.BPB_BytsPerSec]
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lea esi, [ebp+eax]
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mov eax, [RootDirSecs]
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mul word [.BPB_BytsPerSec]
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add eax, esi ; EAX = end of root dir. in buffer pos_read_tmp
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; find kernel file in root directory
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.loop_find_dir_entry:
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push esi
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mov ecx, 11
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mov edi, kernel_name
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rep cmpsb ; compare es:si and es:di, cx bytes long
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pop esi
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je .found_kernel_file
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add esi, 32 ; next dir. entry
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cmp esi, eax ; end of directory
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jb .loop_find_dir_entry
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mov esi, sz_kernel
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jmp .panic
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; === KERNEL FOUND. LOADING... ===
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.found_kernel_file:
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movzx ecx, word [esi+01ah] ; first cluster of kernel file
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; reading first FAT table
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movzx eax, word [.BPB_RsvdSecCnt] ; begin first FAT abs sector number
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mul word [.BPB_BytsPerSec]
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lea ebx, [ebp+eax] ; FAT address
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;ebx = FAT
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;ecx = cluster
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;esi = src
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;edi = dst
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;ebp = image
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; copy kernel file
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movzx eax, word [.BPB_BytsPerSec]
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movsx edx, byte [.BPB_SecPerClus]
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mul edx
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shr eax, 2
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mov [cluster_size], eax
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mov edi, 0x10000 ;kernel base address
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.copy_kernel:
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; convert cluster number to sector number
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mov eax, ecx ; data cluster to read
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sub eax, 2
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movzx edx, byte [.BPB_SecPerClus]
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mul edx
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add eax, [data_start]
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movzx edx, word [.BPB_BytsPerSec]
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mul edx
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lea esi, [ebp+eax]
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mov edx, ecx
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mov ecx, [cluster_size]
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rep movsd
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mov ecx, edx
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shr edx, 1
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pushf
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add edx, ecx ; di = bp * 1.5
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mov ax, word [ebx+edx] ; read next entry from FAT-chain
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popf
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jc .move_4_right
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and ax, 0fffh
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jmp .verify_end_sector
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.move_4_right:
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shr ax, 4
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.verify_end_sector:
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cmp ax, 0ff8h ; last cluster
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jae .execute_kernel
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movzx ecx, ax
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jmp .copy_kernel
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.execute_kernel:
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mov edi, 0x100000
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mov esi, [_image_start]
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mov ecx, [_image_size]
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shr ecx, 2
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rep movsd
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xor eax, eax
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mov ecx, 1024
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rep stosd
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xor ebx, ebx
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xor ecx, ecx
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xor edx, edx
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xor esi, esi
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xor edi, edi
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xor ebp, ebp
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xor esp, esp
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lgdt [.tmp_gdt]
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jmp far 0x08:.mode_16 and 0xFFFF
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.panic:
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mov ebx, sz_halt
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mov edx, 0xb8000+160*10+2
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mov ah, 0x07
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.line:
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mov edi, edx
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.print:
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lodsb
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test al, al
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jz .print_next
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stosw
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jmp .print
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.print_next:
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test ebx, ebx
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jz ._hlt
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mov esi, ebx
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xor ebx, ebx
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add edx, 160
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jmp .line
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._hlt:
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hlt
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jmp ._hlt
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align 8
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.tmp_gdt: dw 15
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dd .tmp_gdt
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dw 0
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.code16: dw 0xFFFF
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dw 0
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db 8
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db 10011010b
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dw 0
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use16
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.mode_16:
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mov eax, cr0
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and eax, not 0x80000001
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mov cr0, eax
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jmp far 0x8000:.real_mode and 0xFFFF
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.real_mode:
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xor eax, eax
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mov ds, ax
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mov es, ax
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mov ss, ax
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mov gs, ax
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mov fs, ax
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jmp far 0x1000:0000
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sz_invboot db 'Invalid multiboot loader magic value',0
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sz_nomods db 'No image loaded',0
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sz_image db 'Image size invalid',0
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sz_halt db 'Halted',0
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sz_kernel db cr
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kernel_name db 'KERNEL MNT ?',0
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org $+0x80000
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__edata:
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align 4
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_image_start rd 1
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_image_size rd 1
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FirstRootDirSecNum rd 1
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RootDirSecs rd 1
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data_start rd 1
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cluster_size rd 1
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__end:
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