217 lines
4.4 KiB
NASM
217 lines
4.4 KiB
NASM
model tiny,stdcall
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p486
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locals
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jumps
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codeseg
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option procalign:byte
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include "..\include\mem.h"
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include "..\include\fat.h"
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include "..\include\divers.h"
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org 7C00h
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jmp boot
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bootsec bootinfo <"COS2000A",512,1,1,2,224,2880,0F0h,9,18,2,0,0,0,0,0,29h,01020304h,"COS2000 ","FAT12 ">
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errorloading db " [Erreur]",0dh,0ah,0
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okloading db "Recherche noyau ",0Dh,0ah," -"
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sys db "SYSTEME SYS",0
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syst db " [ Ok ]",0dh,0ah,"Chargement ",0
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dot db ".",0
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errorboot:
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mov si,offset errorloading
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call showstr
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mov ah,0
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int 16h
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int 19h
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boot:
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mov [bootsec.bootdrive],dl
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cli
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mov ax,09000h
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mov ss,ax
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mov sp,0FFFFh
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sti
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boot2:
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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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xor ax,ax
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mov dl,[bootsec.bootdrive]
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int 13h
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jc errorboot
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mov si,offset okloading
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call showstr
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mov cx,[bootsec.reservedsectors]
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add cx,[bootsec.hiddensectorsh]
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adc cx,[bootsec.hiddensectorsl]
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push cx
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mov bx,[bootsec.sectorsperfat]
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mov di,offset bufferfat
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readfat:
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call readsector
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jc errorboot
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inc cx
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add di,[bootsec.sectorsize]
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dec bx
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jnz readfat
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pop cx
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xor ax,ax
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mov al,[bootsec.fatsperdrive]
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mov bx,[bootsec.sectorsperfat]
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mul bx
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add cx,ax
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mov ax,32
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mul [bootsec.directorysize]
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div [bootsec.sectorsize]
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add ax,cx
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sub ax,2
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mov [word ptr bootsec.reservedfornt],ax
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xor dx,dx
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checkroot:
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mov di,offset buffer
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call readsector
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jc errorboot
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xor bx,bx
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findnext:
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cmp [byte ptr di],0
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je errorboot
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cmp [byte ptr di],0E5h
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je no
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cmp [byte ptr di],041h
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je no
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mov si,offset dot
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call showstr
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push di cx
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mov si,offset sys
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mov cx,11
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rep cmpsb
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pop cx di
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je oksystem
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no:
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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,[bootsec.directorysize]
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ja errorboot
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cmp bx,[bootsec.sectorsize]
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jb findnext
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inc cx
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jmp checkroot
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oksystem:
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mov si,offset syst
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call showstr
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mov cx,[di+26]
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mov ax,8000h
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mov es,ax
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push es
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mov di,0000h
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push 0010h
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mov si,offset dot
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xor ax,ax
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fatagain:
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cmp cx,0FF0h
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jae finishload
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push cx
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add cx,[word ptr bootsec.reservedfornt]
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call readsector
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pop cx
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jc errorboot
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inc ax
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call showstr
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add di,[bootsec.sectorsize]
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call getfat
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jnc fatagain
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finishload:
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retf
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;=============READSECTOR (Fonction 01H)===============
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;Lit le secteur CX et le met en es:di
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;-> AH=1
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;<- Flag Carry si erreur
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;=====================================================
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readsector:
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push ax bx cx dx si
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mov ax,cx
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xor dx,dx
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div [bootsec.sectorspertrack]
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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 [bootsec.headsperdrive]
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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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tryagain:
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mov ah, 2
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mov dl,[bootsec.bootdrive]
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int 13h
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jnc done
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dec si
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jnz tryagain
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done:
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pop si dx cx bx ax
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ret
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getfat:
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push ax bx dx di
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mov di,offset bufferfat
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mov ax,cx
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mov bx,ax
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and bx,0000000000000001b
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shr ax,1
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mov cx,3
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mul cx
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add di,ax
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cmp bx,0h
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jnz evenfat
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oddfat:
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mov dx,[di]
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and dx,0FFFh
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mov cx,dx
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jmp endfat
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evenfat:
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mov dx,[di+1]
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and dx,0FFF0h
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shr dx,4
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mov cx,dx
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endfat:
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pop di dx bx ax
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ret
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showstr:
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push ax bx si
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again:
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lodsb
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or al,al
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jz fin
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mov ah,0Eh
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mov bx,07h
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int 10h
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jmp again
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fin:
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pop si bx ax
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ret
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db 055h,0AAh
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endof:
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buffer equ offset endof+2048
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bufferfat equ offset endof+4096
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