;=================================================;
;   ____                    _____   ____     2012 ;
;  /\  _`\                 /\  __`\/\  _`\        ;
;  \ \ \/\ \     __   __  _\ \ \/\ \ \,\L\_\      ;
;   \ \ \ \ \  /'__`\/\ \/'\\ \ \ \ \/_\__ \      ;
;    \ \ \_\ \/\  __/\/>  </ \ \ \_\ \/\ \L\ \    ;
;     \ \____/\ \____\/\_/\_\ \ \_____\ `\____\   ;
;      \/___/  \/____/\//\/_/  \/_____/\/_____/   ;
;                                                 ;
;            DexOS Fat Driver Interface           ;
;              By Craig Bamford (Dex)             ;
;=================================================;

1.  Select default drive
2.  Get current default drive
3.  Set Disk Transfer Area Address
4.  Get free disk space
5.  Create subdirectory
6.  Remove subdirectory
7.  Set working directory
8.  CreateWrite file
9.  Open file
10. Close file
11. Read file
12. Delete file
13. Seek file
14. Get/Set file attributes
15. Get current directory
16. Find First
17. Find_Next
18. Rename file
19. Get/Set file date

FunctionNunber 1
;=======================================================  ;
;  SELECT DEFAULT DRIVE                                   ;
;=======================================================  ;
;                                                         ;
; IN:  DL = new default drive (0=A:, 1=B:, 2=C: etc)      ;
;                                                         ;
; OUT  AL = number of potentially valid drive letters     ;
;                                                         ;
; Notes: the return value is the highest drive present    ;
;                                                         ;
;=======================================================  ;
FunctionNunber 2
;=======================================================  ;
;  GET CURRENT DEFAULT DRIVE                              ;
;=======================================================  ;
;                                                         ;
; IN:                                                     ;
;                                                         ;
; OUT  AL =  drive (0=A:, 1=B:, 2=C:, etc)                ;
;                                                         ;
;=======================================================  ;
FunctionNunber 3
;=======================================================  ;
; SetDTA_Address.                                         ;
;                                                         ;
; Set DTA table adress buffer                             ;
; Needs to be 48 bytes at least                           ;
;                                                         ;
; LayOut:                                                 ;
; DTA = 21 bytes ; ignore useless DOS data                ;
; fattr = 1 byte   ; file attribute                       ;
; ftime = 2 bytes  ; file creation/modification time      ;
; fdate = 2 bytes  ; file creation/modification date      ;
; fsize = 2 bytes  ; file size                            ;
; fsmth = 2 bytes  ;                                      ;
; fname = 14 bytes ; file name+etc terminated with zero   ;
; fexten = 3 bytes ; file Exten                           ;
; zero = 1 byte    ; zero end byte                        ;
;                                                         ;
;=======================================================  ;
; IN:   EDX = DTA table adress buffer                     ;
;                                                         ;
; OUT:                                                    ;
;                                                         ;
;=======================================================  ;
FunctionNunber 4
;=======================================================  ;
;  Get disk free space                                    ;
;=======================================================  ;
;                                                         ;
; IN:   DL = 0 for current drive                          ;
;                (NOTE: more will be add latter)          ;
;                                                         ;
; OUT:  If carry is set,                                  ;
;       AX = 0FFFFh if disk error.                        ;
;                                                         ;
;       If carry NOT set                                  ;
;       AX = sectors per cluster                          ;
;       BX = number of free clusters                      ;
;       CX = bytes per sector                             ;
;       DX = total clusters on drive                      ;
;                                                         ;
;       free space on drive in bytes is AX * BX * CX      ;
;        total space on drive in bytes is AX * CX * DX    ;
;                                                         ;
;=======================================================  ;
FunctionNunber 5
;=======================================================  ;
; MkDir.                                                  ;
;                                                         ;
; Creates a Subdirectory                                  ;
;=======================================================  ;
; IN:   EDX = Pointer to Dir/Path name                    ;
;                                                         ;
; OUT:  CF clear if successful AX destroyed               ;
;       CF set on error AX = error code (03h,05h)         ;
;=======================================================  ;
FunctionNunber 6
;=======================================================  ;
; RmDir.                                                  ;
;                                                         ;
; Remove a Subdirectory                                   ;
;=======================================================  ;
; IN:   EDX = Pointer to Dir/Path name                    ;
;                                                         ;
; OUT:  CF clear if successful AX destroyed               ;
;       CF set on error                                   ;
;              AX = error code (03h,05h,06h,10h)          ;
;                                                         ;
; NOTE: Directory must be empty                           ;
;          (contain only '.' and '..' entries) ITS UP TO  ;
;           THE CALLER to check  for this.                ;
;=======================================================  ;
FunctionNunber 7
;=======================================================  ;
;  SET CURRENT DIRECTORY                                  ;
;=======================================================  ;
;                                                         ;
; IN:  DS:EDX -> ASCIZ pathname to become current         ;
;               directory (max 64 bytes)                  ;
;                                                         ;
; OUT  CF clear if successful, AX destroyed               ;
;      CF CF set on error AX = error code (03h)           ;
;                              03h = path not found       ;
;                                                         ;
; NOTES:                                                  ;
;      If new directory name includes a drive letter,     ;
;      the default drive is not changed, only the         ;
;      current directory on that drive.                   ;
;                                                         ;
;=======================================================  ;
FunctionNunber 8
;=======================================================  ;
; CreateWriteFile                                         ;
;=======================================================  ;
;                                                         ;
; IN:   EDX = Address of buffer containing data           ;
;       ECX = file size in bytes                          ;
;       EBX = Pointer to file name/path                   ;
;                                                         ;
; OUT:  EAX  = Number of bytes written                    ;
;       Carry set if not found.                           ;
;       If carry is set AX = error code                   ;
;                                                         ;
;=======================================================  ;
FunctionNunber 9
;=======================================================  ;
; OpenFile.                                               ;
;                                                         ;
; Open a existing file                                    ;
;=======================================================  ;
; IN:   EDX = Pointer to file name                        ;
;                                                         ;
; OUT:  AX  = File handler                                ;
;       ECX = File Size in bytes                          ;
;       Carry set if not found.                           ;
;       If carry is set AX = error code                   ;
;=======================================================  ;
FunctionNunber 10
;=======================================================  ;
; CloseFile.                                              ;
;                                                         ;
; Close file                                              ;
;=======================================================  ;
; IN:   EBX = File handler                                ;
;                                                         ;
; OUT:  Carry clear if successful.                        ;
;       Carry set on error, AX = error code               ;
;=======================================================  ;
FunctionNunber 11
;=======================================================  ;
; ReadFile.                                               ;
;                                                         ;
; Open a existing file                                    ;
;=======================================================  ;
; IN:   EDX = Place to load file too                      ;
;       EBX = File handler                                ;
;       ECX = Number of bytes to read                     ;
;                                                         ;
; OUT:  EAX  = Number of bytes read                       ;
;       Carry clear if OK                                 ;
;       If carry is set AX = error code                   ;
;=======================================================  ;
FunctionNunber 12
;=======================================================  ;
; DelFile                                                 ;
;=======================================================  ;
;                                                         ;
; IN:   EDX = Pointer to file name to del                 ;
;                                                         ;
; OUT:  CF clear if successful.                           ;
;       CF set error.                                     ;
;       If carry is set AX = error code                   ;
;       error code (02h,03h,05h)                          ;
;                                                         ;
;=======================================================  ;
FunctionNunber 13
;=======================================================  ;
; Seek file                                         ***   ;
;=======================================================  ;
;                                                         ;
; IN:  CL = origin of move 00h start of file 01h current  ;
;           file position 02h end of file                 ;
;      BX = file handle                                   ;
;     EDX = offset from origin of new file position       ;
;                                                         ;
; OUT  CF clear if successful,                            ;
;     EDX = new file position in bytes from start of file ;
;      CF set on error, AX = error code (01h,06h)         ;
;                                                         ;
;=======================================================  ;
FunctionNunber 14
;=======================================================  ;
; Get/Set file attributes                                 ;
;=======================================================  ;
;  GET                                              ***   ;
;=======================================================  ;
;                                                         ;
; IN:  EDX -> ASCIZ filename                              ;
;      BL =   00h                                         ;
;                                                         ;
; OUT  CF clear if successful CX = file attributes        ;
;      CF set on error, AX = error code (01h,02h,03h,05h) ;
;                                                         ;
;=======================================================  ;
;  SET                                              ***   ;
;=======================================================  ;
;                                                         ;
; IN:  EDX -> ASCIZ filename                              ;
;      BL =   01h                                         ;
;      CX = new file attributes                           ;
;                                                         ;
; OUT  CF clear if successful CX = file attributes        ;
;      CF set on error, AX = error code (01h,02h,03h,05h) ;
;                                                         ;
;=======================================================  ;
FunctionNunber 15
;=======================================================  ;
;  GET CURRENT DIRECTORY                                  ;
;=======================================================  ;
;                                                         ;
; IN:  DL =  drive (00h = default, 1=A:, 2=B:, 3=C:, etc) ;
;      DS:ESI -> 64-byte buffer for ASCIZ pathname        ;
;                                                         ;
; OUT  CF clear if successful                             ;
;      CF set on error, AX = error code (0Fh)             ;
;                                                         ;
; NOTES:                                                  ;
;      The returned path does not include a drive         ;
;      or the initial backslash.                          ;
;                                                         ;
;=======================================================  ;
FunctionNunber 16
;=======================================================  ;
; Find_First                                              ;
;                                                         ;
; Are used to search for files specified using ambiguous  ;
; file references. An ambiguous file reference is any     ;
; filename containing the "*" and "?" wildcard            ;
; characters. The Find First File function is used to     ;
; locate the first such filename within a specified       ;
; directory, the Find Next File function is used to find  ;
; successive entries in the directory.                    ;
;=======================================================  ;
; IN:    CX = Attributes                                  ;
;       EDX = Pointer to Zero ending filename             ;
;                                                         ;                                                         ;
; OUT:  If carry is set,                                  ;
;       AX contains one of the following error codes      ;
;        2  = File not found                              ;
;       18  = No more files                               ;
;                                                         ;
;       If carry NOT set                                  ;
;       DTA table adress buffer filled in                 ;
;                                                         ;
;=======================================================  ;
FunctionNunber 17
;=======================================================  ;
; Find_First                                              ;
;                                                         ;
; Are used to search for files specified using ambiguous  ;
; file references. An ambiguous file reference is any     ;
; filename containing the "*" and "?" wildcard            ;
; characters. The Find First File function is used to     ;
; locate the first such filename within a specified       ;
; directory, the Find Next File function is used to find  ;
; successive entries in the directory.                    ;
;=======================================================  ;
; IN:    CX = Attributes                                  ;
;       EDX = Pointer to Zero ending filename             ;
;                                                         ;                                                         ;
; OUT:  If carry is set,                                  ;
;       AX contains one of the following error codes      ;
;        2  = File not found                              ;
;       18  = No more files                               ;
;                                                         ;
;       If carry NOT set                                  ;
;       DTA table adress buffer filled in                 ;
;                                                         ;
;=======================================================  ;
FunctionNunber 18
;=======================================================  ;
; ReName                                                  ;
;=======================================================  ;
;                                                         ;
; IN:   EDX = ASCIZ filename of existing file             ;
;       EDI = ASCIZ new filename (No Path)                ;
;                                                         ;
; OUT:  CF clear if successful.                           ;
;       CF set error.                                     ;
;       If carry is set AX = error code                   ;
;       error code (02h,03h,05h,11h)                      ;
;                                                         ;
;=======================================================  ;
*** = NOT IMPLEMENTED YET	

Example Code One
================:
;==================== [Code Start] =====================  ;
;              Test and get driver address:               ;
;=======================================================  ;
mov	esi,ID						  ; module id
call	[ModuleFunction]				  ; call function
jc	ErrorFatModNotLoaded				  ; jump is not loaded
mov	[Fatmod],eax					  ; save the module address
							  ;
;CODE GOES HERE                                           ;
							  ;
ErrorFatModNotLoaded:					  ; get here if not loaded
;CODE GOES HERE                                           ;
ID    db 'DEXOSFAT',0					  ; The FAT module ID
;===================== [Code End] ======================  ;

Example Code Two
================:
;==================== [Code Start] =====================  ;
;        Simple Get_Current_Directory example:            ;
;=======================================================  ;
	mov	esi,CreateFileTempDirBuff+1		  ; the buffer for current dir 64 bytes
	mov	eax,15					  ;
	call	[Fatmod]				  ; Get_Current_Directory
							  ; no error for get current dir
;===================== [Code End] ======================  ;
NOTE:
      When you get current dir your buffer needs to start with \
      that why its +1
      When you set it, its NOT + 1
      Its the same in Dos etc.