270 lines
6.3 KiB
NASM
270 lines
6.3 KiB
NASM
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[BITS 16]
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[ORG 0x7C00]
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section .text
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start:
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jmp near Boot
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Disk_ID db "COS2000A" ;Fabricant + n<> de s<>rie Formatage
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Sectors_Size dw 512 ;Nombre d'octets/secteur
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Sectors_Per_Cluster db 4 ;Nombre de secteurs/cluster
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Reserved_Sectors dw 1 ;Nombre de secteurs r<>serv<72>
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Fats_Number db 2 ;Nombre de copies de la FAT
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Fits_Number dw 512 ;Taille du r<>pertoire racine
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Sectors_Per_Disk dw 2880 ;Nombre secteurs du volume si < 32 Mo
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Media_Descriptor db 0xF8 ;Descripteur de m<>dia
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Sectors_Per_Fat dw 207 ;Nombre secteurs/FAT
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Sectors_Per_Track dw 18 ;Nombre secteurs/piste
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Heads_Number dw 38 ;Nombre de tete de lecture/<2F>criture
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Sectors_Hidden dd 16 ;Nombre de secteurs cach<63>s
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Sectors_Per_Disk2 dd 39 ;Nombre secteurs du volume si > 32 Mo
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Boot_Drive db 0x80 ;Lecteur de d<>marrage
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Reserved db 0 ;NA (pour NT seulement)
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Extended_Boot_ID db 0x29 ;Signature Boot <20>tendu 29h
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Serial_Number dd 0x01020304 ;N<> de s<>rie
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Disk_Name db "COS2000 " ;Nom de volume
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Fat_Type db "FAT16 " ;Type de syst<73>me de fichiers
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;Cpu_Message db "CPU test",0
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;Boot_Message db "Booting ",0
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;Finding_Message db "System ",0
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;Loading_Message db "Loading ",0
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System_File db "SYSTEM SYS"
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Is_Ok db "[ OK ]",0x0A,0x0D,0
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Is_Failed db "[Failed]",0x0A,0x0D,"Press a key",0x0A,0x0D,0
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The_Dot db '.',0
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Boot_Error:
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mov si,Is_Failed
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call ShowString
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mov ah,0
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int 0x16
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int 0x19
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Boot_Ok:
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; mov al,[Stage]
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; cmp al,0
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; jz No_Ok
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mov si,Is_Ok
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call ShowString
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;No_Ok:
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; xor ah,ah
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; mov si,ax
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; add si,Boot_Message ;Cpu_Message
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; call ShowString
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; add byte [Stage],0x09
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ret
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;
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;Stage db 0
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Boot:
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push cs
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push cs
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pop es
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pop ds
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mov [Boot_Drive],dl
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cli
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mov ax,0x9000
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mov ss,ax
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mov sp,0xFFFF
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sti
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; call Detect_Cpu
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; jc Boot_Error
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; call Boot_Ok
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xor ax,ax
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int 0x13
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; jc Boot_Error
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xor eax,eax
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add ax,[Reserved_Sectors]
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add ecx,eax
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mov di,Fat_Buffer
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call ReadSector
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jc Boot_Error
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xor eax,eax
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mov al,[Fats_Number]
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mov bx,[Sectors_Per_Fat]
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mul bx
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add ecx,eax
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mov ax,32
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mul word [Fits_Number]
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div word [Sectors_Size]
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add eax,ecx
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mov dword [Serial_Number],eax
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xor dx,dx
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; call Boot_Ok
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Find_System:
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mov di,Buffer
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call ReadSector
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jc near Boot_Error
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xor bx,bx
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Next_Root_Entrie:
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cmp byte [di],0
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je near Boot_Error
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push di
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push cx
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mov si,System_File
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mov cx,11
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rep cmpsb
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pop cx
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pop di
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je System_Found
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add di,32
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add bx,32
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inc dx
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cmp dx,[Fits_Number]
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ja near Boot_Error
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cmp bx,[Sectors_Size]
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jb Next_Root_Entrie
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inc ecx
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jmp Find_System
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System_Found:
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xor ecx,ecx
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mov cx,[di+26]
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mov ax,0x0071
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mov es,ax
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push es
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mov di,0x100
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push di
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; call Boot_Ok
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mov si,The_Dot
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Resume_Loading:
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cmp cx,0x0FFF0
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jae Finish_Loading
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call ReadGroup
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jc near Boot_Error
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call ShowString
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mov bx,cx
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shl bx,1
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mov cx,[bx+Fat_Buffer]
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jmp Resume_Loading
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Finish_Loading:
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call Boot_Ok
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retf
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;====================READSECTOR=======================
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;Lit le secteur logique LBA ECX et le met en es:di
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;-> ECX (limit<69> <20> 2^32 secteurs, soit 2 To avec secteur 512 octets)
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;<- Flag Carry si erreur
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;=====================================================
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ReadSector:
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pushad
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mov ax, cx
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ror ecx,16
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mov dx,cx
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rol ecx,16
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cmp ecx,4128705
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ja Extended_CHS
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div word [Sectors_Per_Track]
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inc dl
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mov bl, dl
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xor dx,dx
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div word [Heads_Number]
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mov dh, [Boot_Drive]
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xchg dl, dh
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mov cx, ax
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xchg cl, ch
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shl cl, 6
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or cl, bl
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mov bx, di
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mov si, 4
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mov al, 1
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Read_Again:
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mov ah, 2
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int 0x13
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jnc Read_Done
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dec si
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jnz Read_Again
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Read_Done:
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popad
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ret
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Extended_CHS:
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mov si,ECHS_Block
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mov byte [si+Sizes],0x10
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mov byte [si+Reserve],0x01
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mov byte [si+NumSectors],0x01
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mov [si+Adressseg],es
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mov [si+Adressoff],di
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mov [si+SectorLow],ax
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mov [si+SectorHigh],dx
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mov di,4
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mov dl,[Boot_Drive]
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Read_AgainX:
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mov ah, 42h
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int 13h
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jnc Read_Done
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dec di
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jnz Read_AgainX
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;======================READGROUP======================
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;lit le groupe cx en es:di et incr<63>mente DI
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;-> cx, es:di
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;<- di, Flag Carry si erreur
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;=====================================================
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ReadGroup:
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push ax
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push cx
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push dx
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mov al,[Sectors_Per_Cluster]
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sub cx,2
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xor ah,ah
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mul cx
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mov cx,dx
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shl ecx,16
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mov cx,ax
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add ecx,dword [Serial_Number]
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mov al,[Sectors_Per_Cluster]
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read:
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call ReadSector
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jc errors
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inc ecx
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add di,[Sectors_Size]
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dec al
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jnz read
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clc
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errors:
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pop dx
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pop cx
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pop ax
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ret
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;======================SHOWSTR========================
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;Affiche la chaine de caract<63>re point<6E> par ds:si <20> l'<27>cran
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;-> DS, SI
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;<- Flag Carry si erreur
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;=====================================================
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ShowString:
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;push ax
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;push bx
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;push si
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pusha
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Next_Char:
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lodsb
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or al,al
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jz End_Show
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mov ah,0x0E
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mov bx,0x07
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int 0x10
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jmp Next_Char
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End_Show:
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;pop si
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;pop bx
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;pop ax
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popa
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ret
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times 510-($-$$) db ' '
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dw 0xAA55
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ECHS_Block equ $
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Buffer equ $+26
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Fat_Buffer equ $+26+512
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section .bss
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%include "echs.h"
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;ECHS_Block resb 24
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;Buffer resb 512
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;Fat_Buffer resb 10000
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