forked from PoliEcho-holding-org/kern
Began moving to C. (No C yet)
If you want to build the assembly version, run the buildAsm.sh script Currently just setting up the bootloader.
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@@ -0,0 +1,331 @@
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;
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; Loads a file from the filetable into a memory location
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; Params:
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; dl - Disk number
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; Filename (Null terminated)
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; Destination location segment
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; Destination location offset
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;
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; Returns:
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; al - Exit code : 0 - Success; 1 - File not found; 2 - Disk error
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;
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loadFile:
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; Func prologue
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push bp
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mov bp, sp
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push bx
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push fs
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push cx
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push dx
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push si
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push es
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mov byte [diskNum], dl
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mov bx, [bp+4] ; src Offset
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mov fs, [bp+6] ; src Segment
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mov si, [bp+8] ; Filename
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push bx
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mov cx, 10
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mov di, fileName
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.getFilename:
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lodsb ; mov byte al, [si]; inc si
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cmp al, 0 ; End of fileName
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je .filenamePad
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stosb
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loop .getFilename
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jmp .filenameDone
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.filenamePad:
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dec si ; Fill the rest with Null
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.filenamePadLoop:
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stosb
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loop .filenamePadLoop
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.filenameDone:
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mov ax, FILETAB_LOC
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mov es, ax
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xor di, di ; es:di - Filetable location
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mov si, fileName
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.fileNameCheck:
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mov al, [es:di]
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cmp al, 0 ; End of filetable
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je .notFound
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cmp al, [si]
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je .beginCmp
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add di, 16
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jmp .fileNameCheck
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.beginCmp:
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push di
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mov cl, 10
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.cmpLoop:
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mov al, [es:di]
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inc di
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cmp al, [si]
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jne .redoCheck
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dec cl
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jz .found
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inc si
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jmp .cmpLoop
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.redoCheck:
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mov si, fileName
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pop di
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add di, 16
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jmp .fileNameCheck
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.notFound:
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mov byte [exitCode], NOT_FOUND
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jmp .done
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.found:
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add di, 3 ; Skip extension
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inc di ; Skip Number of entries
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xor ax, ax ; Reset disk
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mov dl, [diskNum]
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int 0x13
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mov ch, 0 ; Cylinder
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mov dh, 0 ; Head
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mov cl, [es:di] ; Sector
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inc di
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mov al, [es:di] ; Length in sectors
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mov bx, fs
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mov es, bx
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pop bx
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mov dx, bx
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call printHexByte
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mov ah, 2 ; Read from disk
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int 0x13
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jnc .done
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mov byte [exitCode], DISK_ERROR
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.done:
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; Func epilogue
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pop es
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pop si
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pop dx
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pop cx
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pop fs
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pop bx
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mov sp, bp
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pop bp
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mov byte al, [exitCode]
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ret
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;
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; Saves a file to the disk and updates filetable
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; dl - Disk number
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; Params:
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; Filename (Null terminated)
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; Filetype (Null terminated)
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; Filesize (Byte)
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; Source location segment
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; Source location offset
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;
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; Returns:
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; al - Exit code : 0 - Success; 1 - File not found; 2 - Disk error
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;
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saveFile:
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; Func prologue
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push bp
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mov bp, sp
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push bx
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push fs
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push cx
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push dx
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push si
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push es
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mov byte [diskNum], dl
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mov bx, [bp+4] ; src Offset
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mov fs, [bp+6] ; src Segment
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mov cx, [bp+8] ; Filesize
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mov ax, [bp+10] ; Filetype
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push bx
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mov byte [filesize], cl
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mov si, ax
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mov di, filetype
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mov cx, 3
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rep movsb
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mov si, [bp+12] ; Filename
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mov cx, 10
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mov di, fileName
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.getFilename:
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lodsb ; mov byte al, [si]; inc si
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cmp al, 0 ; End of fileName
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je .filenamePad
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stosb
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loop .getFilename
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jmp .filenameDone
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.filenamePad:
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dec si ; Fill the rest with Null
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.filenamePadLoop:
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stosb
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loop .filenamePadLoop
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.filenameDone:
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mov ax, FILETAB_LOC
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mov es, ax
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xor di, di ; es:di - Filetable location
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mov si, fileName
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.fileNameCheck:
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mov byte al, [es:di+14] ; Starting sector
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cmp al, 0 ; No file, create one
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je createFile
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add byte al, [es:di+15] ; Filesize
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mov byte [availableSector], al
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mov al, [es:di]
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cmp al, 0 ; End of filetable
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je createFile ; File doesn't exist, create new one
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cmp al, [si]
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je .beginCmp
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add di, 16
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jmp .fileNameCheck
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.beginCmp:
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push di
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mov cl, 10
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.cmpLoop:
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mov al, [es:di]
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inc di
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cmp al, [si]
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jne .redoCheck
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dec cl
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jz .found
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inc si
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jmp .cmpLoop
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.redoCheck:
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mov si, fileName
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pop di
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add di, 16
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jmp .fileNameCheck
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.found: ; File already exists (override)
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; TODO: Ask user if they want to override file
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add di, 3 ; Skip extension
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inc di ; Skip Number of entries
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xor ax, ax ; Reset disk
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mov dl, [diskNum]
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int 0x13
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; TODO: Override current file
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; push fs
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; mov ch, 0 ; Cylinder
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; mov dh, 0 ; Head
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; mov cl, [es:di] ; Sector
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; inc di
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; mov al, [es:di] ; Length in sectors
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; mov ah, 3 ; Write to disk
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; pop es ; es:bx - Destination
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; int 0x13
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; jnc returnToCaller
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mov byte [exitCode], DISK_ERROR
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jmp returnToCaller ; TODO: Fix this
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createFile: ; Appends a file to the filetable.
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mov di, FILETAB_LOC
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mov es, di
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xor di, di
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.filetabEnd: ; Move to the end of filetable
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cmp byte [es:di], 0
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je .filetabEndDone
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add di, 16
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jmp .filetabEnd
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.filetabEndDone:
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mov cx, 10
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mov si, fileName
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rep movsb ; Append the fileName
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mov cx, 3
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mov si, filetype
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rep movsb ; Append the extension
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mov byte [es:di], 0 ; Number of entries
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inc di
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mov byte al, [availableSector]
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stosb ; Starting sector
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mov byte al, [filesize]
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stosb ; File length in sectors
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; Write changed filetable to disk
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;! If filetable size changes, this will have to change (probably)
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mov bx, FILETAB_LOC
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mov es, bx
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xor bx, bx ; es:bx - Filetable location
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mov dl, [diskNum]
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mov ah, 3 ; Write to disk
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mov al, 1 ; Write 1 sector
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mov ch, 0 ; Cylinder
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mov dh, 0 ; Head
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mov cl, 2 ; Sector
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int 0x13
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jnc writeFileData
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mov byte [exitCode], DISK_ERROR
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jmp returnToCaller
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writeFileData: ; Writes file data to the disk
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mov ax, 0x8000 ; Source segment
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mov es, ax
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pop bx ; es:bx - Source
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mov ah, 3 ; Write to disk
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mov byte al, [filesize]
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mov dl, [diskNum]
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mov ch, 0 ; Cylinder
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mov dh, 0 ; Head
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mov byte cl, [availableSector]
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int 0x13
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jnc returnToCaller
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mov byte [exitCode], DISK_ERROR ; Exit code - Disk Error
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returnToCaller:
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; Func epilogue
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pop es
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pop si
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pop dx
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pop cx
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pop fs
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pop bx
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mov sp, bp
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pop bp
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mov byte al, [exitCode]
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ret
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;
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; Removes a file from the disk/filetable
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;
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; Params:
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; Filename
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;
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removeFile:
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;; Variables
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availableSector: db 0
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exitCode: db 0
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diskNum: db 0
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filesize: db 0
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filetype: times 3 db 0
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fileName: times 10 db 0
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;; Constants
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FILETAB_LOC equ 0x1000
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; Exit codes
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SUCCESS equ 0
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NOT_FOUND equ 1
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DISK_ERROR equ 2
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