kolibrios-gitea/kernel/trunk/blkdev/rd.inc

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;                                                                      ;;
;; RAMDISK functions                                                    ;;
;; (C) 2004 Ville Turjanmaa, License: GPL                               ;;
;; Addings by M.Lisovin                                                 ;;
;; LFN support by diamond                                               ;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

; calculate fat chain

calculatefatchain:

   pushad

   mov  esi,0x100000+512
   mov  edi,0x280000

 fcnew:
   mov  eax,dword [esi]
   mov  ebx,dword [esi+4]
   mov  ecx,dword [esi+8]
   mov  edx,ecx
   shr  edx,4   ;8 ok
   shr  dx,4    ;7 ok
   xor  ch,ch
   shld ecx,ebx,20 ;6 ok
   shr  cx,4     ;5 ok
   shld ebx,eax,12
   and  ebx,0x0fffffff  ;4 ok
   shr  bx,4    ;3 ok
   shl  eax,4
   and  eax,0x0fffffff  ;2 ok
   shr  ax,4  ;1 ok
   mov  dword [edi],eax
   mov  dword [edi+4],ebx
   mov  dword [edi+8],ecx
   mov  dword [edi+12],edx
   add  edi,16
   add  esi,12

   cmp  edi,0x280000+2856*2   ;2849 clusters
   jnz  fcnew

   popad
   ret


restorefatchain:   ; restore fat chain

   pushad

   mov  esi,0x280000
   mov  edi,0x100000+512

  fcnew2:
   mov  eax,dword [esi]
   mov  ebx,dword [esi+4]
   shl  ax,4
   shl  eax,4
   shl  bx,4
   shr  ebx,4
   shrd eax,ebx,8
   shr  ebx,8
   mov  dword [edi],eax
   mov  word [edi+4],bx
   add  edi,6
   add  esi,8

   cmp  edi,0x100000+512+4278     ;4274 bytes - all used FAT
   jb   fcnew2

   mov  esi,0x100000+512           ; duplicate fat chain
   mov  edi,0x100000+512+0x1200
   mov  ecx,1069        ;4274/4
   cld
   rep  movsd

   popad
   ret


ramdisk_free_space:
;---------------------------------------------
;
; returns free space in edi
; rewr.by Mihasik
;---------------------------------------------

        push   eax ebx ecx

        mov  edi,0x280000 ;start of FAT
        xor  ax,ax    ;Free cluster=0x0000 in FAT
        xor  ebx,ebx  ;counter
        mov  ecx,2849 ;2849 clusters
        cld
    rdfs1:
        repne scasw
        jnz  rdfs2    ;if last cluster not 0
        inc  ebx
        test    ecx, ecx
        jnz     rdfs1
    rdfs2:
        shl  ebx,9    ;free clusters*512
        mov  edi,ebx
        
        pop    ecx ebx eax
        ret


expand_filename:
;---------------------------------------------
;
; exapand filename with '.' to 11 character
; eax - pointer to filename
;---------------------------------------------

        push esi edi ebx

        mov  edi,esp                  ; check for '.' in the name
        add  edi,12+8

        mov  esi,eax

        mov  eax,edi
        mov  [eax+0],dword '    '
        mov  [eax+4],dword '    '
        mov  [eax+8],dword '    '

      flr1:

        cmp  [esi],byte '.'
        jne  flr2
        mov  edi,eax
        add  edi,7
        jmp  flr3

      flr2:

        mov  bl,[esi]
        mov  [edi],bl

      flr3:

        inc  esi
        inc  edi

        mov  ebx,eax
        add  ebx,11

        cmp  edi,ebx
        jbe  flr1

        pop  ebx edi esi
        ret

fileread:
;----------------------------------------------------------------
;
;  fileread - sys floppy
;
;  eax  points to filename 11 chars
;  ebx  first wanted block       ; 1+ ; if 0 then set to 1
;  ecx  number of blocks to read ; 1+ ; if 0 then set to 1
;  edx  mem location to return data
;  esi  length of filename 12*X 0=root
;
;  ret ebx = size or 0xffffffff file not found
;      eax = 0 ok read or other = errormsg
;
;--------------------------------------------------------------
        test   ebx,ebx ;if ebx=0 - set to 1
        jnz    frfl5
        inc    ebx
      frfl5:
        test   ecx,ecx ;if ecx=0 - set to 1
        jnz    frfl6
        inc    ecx
      frfl6:
        test   esi,esi          ; return ramdisk root
        jnz    fr_noroot        ;if not root
        cmp    ebx,14           ;14 clusters=root dir
        ja     oorr
        cmp    ecx,14
        ja     oorr
        jmp    fr_do
      oorr:
        mov    eax,5            ;out of root range (fnf)
        xor    ebx,ebx
        dec    ebx              ;0xffffffff
        ret

      fr_do:                    ;reading rootdir
        mov    edi,edx
        dec    ebx
        push   edx
        mov    edx,ecx     
        add    edx,ebx
        cmp    edx,15     ;ebx+ecx=14+1
        pushf
        jbe    fr_do1
        sub    edx,14
        sub    ecx,edx
      fr_do1:
        shl    ebx,9
        mov    esi,0x100000+512*19
        add    esi,ebx
        shl    ecx,7
        cld
        rep    movsd
        popf
        pop    edx
        jae    fr_do2
        xor    eax,eax ; ok read
        xor    ebx,ebx
        ret
      fr_do2:        ;if last cluster
        mov    eax,6  ;end of file
        xor    ebx,ebx
        ret

     fr_noroot:

        sub    esp,32
        call   expand_filename

        dec    ebx

        push   eax

        push   eax ebx ecx edx esi edi
        call   rd_findfile
        je     fifound
        add    esp,32+28   ;if file not found
        ret

     fifound:

        mov    ebx,[edi-11+28]          ;file size
        mov    [esp+20],ebx
        mov    [esp+24],ebx
        add    edi,0xf
        movzx  eax,word [edi]
        mov    edi,eax                  ;edi=cluster

      frnew:

        add    eax,31                   ;bootsector+2*fat+filenames
        shl    eax,9                    ;*512
        add    eax,0x100000             ;image base
        mov    ebx,[esp+8]
        mov    ecx,512                  ;[esp+4]

        cmp    [esp+16],dword 0         ; wanted cluster ?
        jne    frfl7
        call   memmove
        add    [esp+8],dword 512
        dec    dword [esp+12]           ; last wanted cluster ?
        je     frnoread
        jmp    frfl8
      frfl7:
        dec    dword [esp+16]
      frfl8:
        movzx  eax,word [edi*2+0x280000]	; find next cluster from FAT
        mov    edi,eax
        cmp    edi,4095                 ;eof  - cluster
        jz     frnoread2

        cmp    [esp+24],dword 512       ;eof  - size
        jb     frnoread
        sub    [esp+24],dword 512

        jmp    frnew

      frnoread2:

        cmp    [esp+16],dword 0         ; eof without read ?
        je     frnoread

        pop    edi esi edx ecx
        add    esp,4
        pop    ebx     ; ebx <- eax : size of file
        add    esp,36
        mov    eax,6   ; end of file
        ret

      frnoread:

        pop    edi esi edx ecx
        add    esp,4
        pop    ebx     ; ebx <- eax : size of file
        add    esp,36
        xor    eax,eax  ;read ok
        ret

filedelete:
;--------------------------------------------
;
; filedelete - sys floppy
; in:
; eax -  pointer to filename 11 chars
;
; out:
; eax - 0 = successful, 5 = file not found
;
;--------------------------------------------

        sub    esp,32
        call   expand_filename

        push   eax ebx ecx edx esi edi
        
        call   rd_findfile
        je     fifoundd
        pop    edi esi edx ecx ebx eax ;file not found
        add    esp,32
        mov    eax,5
        ret

     fifoundd:

        mov    [edi-11],byte 0xE5       ;mark filename deleted
        add    edi,0xf
        movzx  eax,word [edi]
        mov    edi,eax                  ;edi = cluster

      frnewd:

        shl    edi,1                    ;find next cluster from FAT
        add    edi,0x280000
        movzx  eax,word [edi]
        mov    [edi],word 0x0           ;clear fat chain cluster
        mov    edi,eax
        cmp    edi,dword 0xff8          ;last cluster ?
        jb     frnewd

        pop    edi esi edx ecx ebx eax
        add    esp,32
        xor    eax,eax       ; file found
        ret

      

filesave:
;----------------------------------------------------------
;
; filesave - sys floppy
;
; eax points to filename 11 chars
;
;        eax      ; pointer to file name
;        ebx      ; buffer
;        ecx      ; count to write in bytes
;        edx      ; 0 create new , 1 append
;
;-----------------------------------------------------------

        sub  esp,32
        call expand_filename
        test edx,edx
        jnz  fsdel
        pusha
        call filedelete
        popa

      fsdel:

        call   ramdisk_free_space
        cmp    ecx,edi
        jbe    rd_do_save
        add    esp,32
        mov    eax,8    ;disk full
        ret

      rd_do_save:

        push   eax ebx ecx edx esi edi

        mov    edi,0x100000+512*18+512  ;Point at directory
        mov    edx,224 +1
        ; find an empty spot for filename in the root dir
     l20ds:
        dec    edx
        jz     frnoreadds
     l21ds:
        cmp    [edi],byte 0xE5
        jz     fifoundds
        cmp    [edi],byte 0x0
        jz     fifoundds
        add    edi,32                   ; Advance to next entry
        jmp    l20ds
     fifoundds:

        push   edi                      ; move the filename to root dir
        mov    esi,[esp+4+20]
        mov    ecx,11
        cld
        rep    movsb
        pop    edi
        mov    edx,edi
        add    edx,11+0xf               ; edx <- cluster save position
        mov    ebx,[esp+12]             ; save file size
        mov    [edi+28],ebx
        mov    [edi+11],byte 0x20       ; attribute
; Ivan Poddubny 11/12/2003:
call get_date_for_file   ; from FAT32.INC
mov [edi+24],ax          ; date
call get_time_for_file   ; from FAT32.INC
mov [edi+22],ax          ; time
; End
        mov    edi,0x280000            ;pointer to first cluster
        mov    ecx,2849
        cld
      frnewds:
        xor    ax,ax
        repne  scasw
        mov    ebx,2848
        sub    ebx,ecx
        mov    [edx],bx                 ; save next cluster pos. to prev cl.
        mov    edx,edi                  ; next save pos abs mem add
        dec    edx
        dec    edx
        call   fdc_filesave
        pusha                           ; move save to floppy cluster
        add    ebx,31
        shl    ebx,9
        add    ebx,0x100000
        mov    eax,[esp+32+16]
        mov    ecx,512
        call   memmove
        popa

        mov    eax,[esp+12]
        cmp    eax,512
        jbe    flnsa
        sub    eax,512
        mov    [esp+12],eax
        add     dword [esp+16], 512
        jmp    frnewds

     flnsa:
        mov    [edi-2],word 4095          ; mark end of file - last cluster

      frnoreadds:

        pop    edi esi edx ecx ebx eax
        add    esp,32

;        pusha
;        cli
;        call   fdc_commitfile
;        sti
;        popa

        xor    eax,eax ;ok write
        ret

   rd_findfile:
   ;by Mihasik
   ;IN: eax - pointer to filename OUT: filestring+11 in edi or notZero in flags and fnf in eax,ebx

        mov    edi,0x100000+512*18+512  ;Point at directory
        cld
    rd_newsearch:
        mov    esi,eax
        mov    ecx,11
        rep    cmpsb
        je     rd_ff
        add    cl,21
        add    edi,ecx
        cmp    edi,0x100000+512*33
        jb     rd_newsearch
        mov    eax,5      ;if file not found - eax=5
        xor    ebx,ebx
        dec    ebx    ;ebx=0xffffffff and zf=0    
     rd_ff:
        ret            

  rd_getfileinfo:
     ;get date, time, size or attributes of file
     ;IN: eax - pointer to file, ebx - type of function: 12-get filesize, 13-get fileattr, 14-get filedate
     ;ecx - filelengh 0=root
     ;OUT: eax=0 - Ok or 5 - file not found ebx - date/time, size or attributes 
        test   ecx,ecx
        jnz    no_getfinfo_root
        mov    eax,5      ;if root - fnf
        xor    ebx,ebx
        dec    ebx
        ret
    no_getfinfo_root:     ;if not root
        sub    esp,32
        call   expand_filename
        call   rd_findfile
        je     fifoundi
        add    esp,32      ;if file not found
        ret
    fifoundi:    
        cmp    ebx,13
        jne    no_rd_attr
        movzx ebx,byte [edi]    ;get attributes
        jmp    rd_getfileinfo_end 
     no_rd_attr:
        cmp    ebx,14
        jne    no_rd_date
        mov    ebx,dword [edi+11] ;get date/time
        jmp    rd_getfileinfo_end
     no_rd_date:
        mov    ebx,dword [edi+17] ;get size
     rd_getfileinfo_end:
        xor    eax,eax
        add    esp,32
        ret

; \begin{diamond}

uni2ansi_str:
; convert UNICODE zero-terminated string to ASCII-string (codepage 866)
; in: esi->source, edi->buffer (may be esi=edi)
; destroys: eax,esi,edi
        lodsw
        test    ax, ax
        jz      .done
        cmp     ax, 0x80
        jb      .ascii
        cmp     ax, 0x401
        jz      .yo1
        cmp     ax, 0x451
        jz      .yo2
        cmp     ax, 0x410
        jb      .unk
        cmp     ax, 0x440
        jb      .rus1
        cmp     ax, 0x450
        jb      .rus2
.unk:
        mov     al, '_'
        jmp     .doit
.yo1:
        mov     al, '<27>'
        jmp     .doit
.yo2:
        mov     al, '<27>'
        jmp     .doit
.rus1:
; 0x410-0x43F -> 0x80-0xAF
        add     al, 0x70
        jmp     .doit
.rus2:
; 0x440-0x44F -> 0xE0-0xEF
        add     al, 0xA0
.ascii:
.doit:
        stosb
        jmp     uni2ansi_str
.done:
        mov     byte [edi], 0
        ret

ansi2uni_char:
; convert ANSI character in al to UNICODE character in ax, using cp866 encoding
        mov     ah, 0
; 0x00-0x7F - trivial map
        cmp     al, 0x80
        jb      .ret
; 0x80-0xAF -> 0x410-0x43F
        cmp     al, 0xB0
        jae     @f
        add     ax, 0x410-0x80
.ret:
        ret
@@:
; 0xE0-0xEF -> 0x440-0x44F
        cmp     al, 0xE0
        jb      .unk
        cmp     al, 0xF0
        jae     @f
        add     ax, 0x440-0xE0
        ret
; 0xF0 -> 0x401
; 0xF1 -> 0x451
@@:
        cmp     al, '<27>'
        jz      .yo1
        cmp     al, '<27>'
        jz      .yo2
.unk:
        mov     al, '_'         ; ah=0
        ret
.yo1:
        mov     ax, 0x401
        ret
.yo2:
        mov     ax, 0x451
        ret

char_toupper:
; convert character to uppercase, using cp866 encoding
; in: al=symbol
; out: al=converted symbol
        cmp     al, 'a'
        jb      .ret
        cmp     al, 'z'
        jbe     .az
        cmp     al, '<27>'
        jb      .ret
        cmp     al, '<27>'
        jb      .rus1
        cmp     al, '<27>'
        ja      .ret
; 0xE0-0xEF -> 0x90-0x9F
        sub     al, '<27>'-'<27>'
.ret:
        ret
.rus1:
; 0xA0-0xAF -> 0x80-0x8F
.az:
        and     al, not 0x20
        ret

fat_get_name:
; in: edi->FAT entry
; out: CF=1 - no valid entry
; else CF=0 and ebp->ASCIIZ-name
; (maximum length of filename is 255 (wide) symbols without trailing 0,
;  but implementation requires buffer 261 words)
; destroys eax
        cmp     byte [edi], 0
        jz      .no
        cmp     byte [edi], 0xE5
        jnz     @f
.no:
        stc
        ret
@@:
        cmp     byte [edi+11], 0xF
        jz      .longname
        push    ecx
        mov     ecx, 8
        push    edi ebp ecx
        test    byte [ebp-4], 1
        jnz     .unicode_short
@@:
        mov     al, [edi]
        inc     edi
        mov     [ebp], al
        inc     ebp
        loop    @b
        pop     ecx
@@:
        cmp     byte [ebp-1], ' '
        jnz     @f
        dec     ebp
        loop    @b
@@:
        mov     byte [ebp], '.'
        inc     ebp
        mov     ecx, 3
        push    ecx
@@:
        mov     al, [edi]
        inc     edi
        mov     [ebp], al
        inc     ebp
        loop    @b
        pop     ecx
@@:
        cmp     byte [ebp-1], ' '
        jnz     @f
        dec     ebp
        loop    @b
        dec     ebp
@@:
        and     byte [ebp], 0	; CF=0
        pop     ebp edi ecx
        ret
.unicode_short:
@@:
        mov     al, [edi]
        inc     edi
        call    ansi2uni_char
        mov     [ebp], ax
        inc     ebp
        inc     ebp
        loop    @b
        pop     ecx
@@:
        cmp     word [ebp-2], ' '
        jnz     @f
        dec     ebp
        dec     ebp
        loop    @b
@@:
        mov     word [ebp], '.'
        inc     ebp
        inc     ebp
        mov     ecx, 3
        push    ecx
@@:
        mov     al, [edi]
        inc     edi
        call    ansi2uni_char
        mov     [ebp], ax
        inc     ebp
        inc     ebp
        loop    @b
        pop     ecx
@@:
        cmp     word [ebp-2], ' '
        jnz     @f
        dec     ebp
        dec     ebp
        loop    @b
        dec     ebp
        dec     ebp
@@:
        and     word [ebp], 0	; CF=0
        pop     ebp edi ecx
        ret
.longname:
; LFN
        mov     al, byte [edi]
        and     eax, 0x3F
        dec     eax
        cmp     al, 20
        jae     .no     ; ignore invalid entries
        mov     word [ebp+260*2], 0     ; force null-terminating for orphans
        imul    eax, 13*2
        add     ebp, eax
        test    byte [edi], 0x40
        jz      @f
        mov     word [ebp+13*2], 0
@@:
        push    eax
; now copy name from edi to ebp ...
        mov     eax, [edi+1]
        mov     [ebp], eax      ; symbols 1,2
        mov     eax, [edi+5]
        mov     [ebp+4], eax	; 3,4
        mov     eax, [edi+9]
        mov     [ebp+8], ax	; 5
        mov     eax, [edi+14]
        mov     [ebp+10], eax	; 6,7
        mov     eax, [edi+18]
        mov     [ebp+14], eax	; 8,9
        mov     eax, [edi+22]
        mov     [ebp+18], eax	; 10,11
        mov     eax, [edi+28]
        mov     [ebp+22], eax	; 12,13
; ... done
        pop     eax
        sub     ebp, eax
        test    eax, eax
        jz      @f
; if this is not first entry, more processing required
        stc
        ret
@@:
; if this is first entry:
        test    byte [ebp-4], 1
        jnz     .ret
; buffer at ebp contains UNICODE name, convert it to ANSI
        push    esi edi
        mov     esi, ebp
        mov     edi, ebp
        call    uni2ansi_str
        pop     edi esi
.ret:
        clc
        ret

fat_compare_name:
; compares ASCIIZ-names, case-insensitive (cp866 encoding)
; in: esi->name, ebp->name
; out: if names match: ZF=1 and esi->next component of name
;      else: ZF=0, esi is not changed
; destroys eax
        push    ebp esi
.loop:
        mov     al, [ebp]
        inc     ebp
        call    char_toupper
        push    eax
        lodsb
        call    char_toupper
        cmp     al, [esp]
        jnz     .done
        pop     eax
        test    al, al
        jnz     .loop
        dec     esi
        pop     eax
        pop     ebp
        xor     eax, eax	; set ZF flag
        ret
.done:
        cmp     al, '/'
        jnz     @f
        cmp     byte [esp], 0
        jnz     @f
        mov     [esp+4], esi
@@:
        pop     eax
        pop     esi ebp
        ret

fat_time_to_bdfe:
; in: eax=FAT time
; out: eax=BDFE time
        push    ecx edx
        mov     ecx, eax
        mov     edx, eax
        shr     eax, 11
        shl     eax, 16	; hours
        and     edx, 0x1F
        add     edx, edx
        mov     al, dl	; seconds
        shr     ecx, 5
        and     ecx, 0x3F
        mov     ah, cl	; minutes
        pop     edx ecx
        ret

fat_date_to_bdfe:
        push    ecx edx
        mov     ecx, eax
        mov     edx, eax
        shr     eax, 9
        add     ax, 1980
        shl     eax, 16	; year
        and     edx, 0x1F
        mov     al, dl	; day
        shr     ecx, 5
        and     ecx, 0xF
        mov     ah, cl	; month
        pop     edx ecx
        ret

fat_entry_to_bdfe:
; convert FAT entry at edi to BDFE (block of data of folder entry) at esi, advance esi
; destroys eax
        movzx   eax, byte [edi+11]
        mov     [esi], eax	; attributes
        mov     eax, [ebp-4]
        mov     [esi+4], eax	; ASCII/UNICODE name
        movzx   eax, word [edi+14]
        call    fat_time_to_bdfe
        mov     [esi+8], eax	; creation time
        movzx   eax, word [edi+16]
        call    fat_date_to_bdfe
        mov     [esi+12], eax	; creation date
        and     dword [esi+16], 0	; last access time is not supported on FAT
        movzx   eax, word [edi+18]
        call    fat_date_to_bdfe
        mov     [esi+20], eax	; last access date
        movzx   eax, word [edi+22]
        call    fat_time_to_bdfe
        mov     [esi+24], eax	; last write time
        movzx   eax, word [edi+24]
        call    fat_date_to_bdfe
        mov     [esi+28], eax	; last write date
        mov     eax, [edi+28]
        mov     [esi+32], eax	; file size (low dword)
        xor     eax, eax
        mov     [esi+36], eax	; file size (high dword)
        push    ecx edi
        lea     edi, [esi+40]
        mov     esi, ebp
        test    byte [esi-4], 1
        jz      .ansi
        mov     ecx, 260/2
        rep     movsd
        mov     [edi-2], ax
@@:
        mov     esi, edi
        pop     edi ecx
        ret
.ansi:
        mov     ecx, 264/4
        rep     movsd
        mov     [edi-1], al
        jmp     @b

rd_find_lfn:
; in: esi->name
; out: CF=1 - file not found
;      else CF=0 and edi->direntry
        push    esi ebp edi
        sub     esp, 262*2      ; allocate space for LFN
        mov     ebp, esp        ; ebp points to buffer
        push    0               ; for fat_get_name: read ASCII name
        mov     edi, 0x100000+512*19    ; to root dir
.l1:
        call    fat_get_name
        jc      .l2
        call    fat_compare_name
        jz      .found
.l2:
        add     edi, 0x20
        cmp     edi, 0x100000+512*33
        jb      .l1
.notfound:
        add     esp, 262*2+4
        pop     edi ebp esi
        stc
        ret
.found:
; found
; if this is LFN entry, advance to true entry
        cmp     byte [edi+11], 0xF
        jnz     @f
        add     edi, 0x20
@@:
; folders are not supported
        cmp     byte [esi], 0
        jnz     .notfound
        add     esp, 262*2+4+4  ; CF=0
        pop     ebp esi
        ret

;----------------------------------------------------------------
;
;  fs_RamdiskRead - LFN variant for reading sys floppy
;
;  esi  points to filename
;  ebx  pointer to 64-bit number = first wanted byte, 0+
;       may be ebx=0 - start from first byte
;  ecx  number of bytes to read, 0+
;  edx  mem location to return data
;
;  ret ebx = bytes read or 0xffffffff file not found
;      eax = 0 ok read or other = errormsg
;
;--------------------------------------------------------------
fs_RamdiskRead:
        cmp     byte [esi], 0
        jnz     @f
        or      ebx, -1
        mov     eax, 10         ; access denied
        ret
@@:
        push    edi
        call    rd_find_lfn
        jnc     .found
        pop     edi
        or      ebx, -1
        mov     eax, 5          ; file not found
        ret
.found:
        test    ebx, ebx
        jz      .l1
        cmp     dword [ebx+4], 0
        jz      @f
        xor     ebx, ebx
.reteof:
        mov     eax, 6          ; EOF
        pop     edi
        ret
@@:
        mov     ebx, [ebx]
.l1:
        push    ecx edx
        push    0
        mov     eax, [edi+28]
        sub     eax, ebx
        jb      .eof
        cmp     eax, ecx
        jae     @f
        mov     ecx, eax
        mov     byte [esp], 6           ; EOF
@@:
        movzx   edi, word [edi+26]	; cluster
.new:
        jecxz   .done
        test    edi, edi
        jz      .eof
        cmp     edi, 0xFF8
        jae     .eof
        lea     eax, [edi+31]           ; bootsector+2*fat+filenames
        shl     eax, 9                  ; *512
        add     eax, 0x100000           ; image base
; now eax points to data of cluster
        sub     ebx, 512
        jae     .skip
        lea     eax, [eax+ebx+512]
        neg     ebx
        push    ecx
        cmp     ecx, ebx
        jbe     @f
        mov     ecx, ebx
@@:
        mov     ebx, edx
        call    memmove
        add     edx, ecx
        sub     [esp], ecx
        pop     ecx
        xor     ebx, ebx
.skip:
        movzx   edi, word [edi*2+0x280000]      ; find next cluster from FAT
        jmp     .new
.eof:
        mov     ebx, edx
        pop     eax edx ecx
        sub     ebx, edx
        jmp     .reteof
.done:
        mov     ebx, edx
        pop     eax edx ecx edi
        sub     ebx, edx
        ret

;----------------------------------------------------------------
;
;  fs_RamdiskReadFolder - LFN variant for reading sys floppy folder
;
;  esi  points to filename; only root is folder on ramdisk
;  ebx  pointer to structure 32-bit number = first wanted block
;                          & flags (bitfields)
; flags: bit 0: 0=ANSI names, 1=UNICODE names
;  ecx  number of blocks to read, 0+
;  edx  mem location to return data
;
;  ret ebx = size or 0xffffffff file not found
;      eax = 0 ok read or other = errormsg
;
;--------------------------------------------------------------
fs_RamdiskReadFolder:
        cmp     byte [esi], 0
        jz      @f
; ramdisk doesn't support folders
        mov     eax, ERROR_ACCESS_DENIED
        or      ebx, -1
        ret
@@:
        push    esi edi ecx
; init header
        push    ecx
        mov     edi, edx
        mov     ecx, 32/4
        xor     eax, eax
        rep     stosd
        mov     byte [edx], 1   ; version
        pop     ecx
        push    ebp
        sub     esp, 262*2      ; allocate space for LFN
        mov     ebp, esp
        push    dword [ebx+4]   ; for fat_get_name: read ANSI/UNICODE name
        mov     ebx, [ebx]
; read root
        mov     esi, edi        ; esi points to block of data of folder entry (BDFE)
        mov     edi, 0x100000+512*19
.l1:
        call    fat_get_name
        jc      .l2
        cmp     byte [edi+11], 0xF
        jnz     @f
        add     edi, 0x20
@@:
        inc     dword [edx+8]   ; new file found
        dec     ebx
        jns     .l2
        dec     ecx
        js      .l2
        inc     dword [edx+4]  ; new file block copied
        call    fat_entry_to_bdfe
.l2:
        add     edi, 0x20
        cmp     edi, 0x100000+512*33
        jb      .l1
        add     esp, 262*2+4
        pop     ebp
        mov     ebx, [edx+4]
        xor     eax, eax
        dec     ecx
        js      @f
        mov     al, ERROR_END_OF_FILE
@@:
        pop     ecx edi esi
        ret

iglobal
label fat_legal_chars byte
; 0 = not allowed
; 1 = allowed only in long names
; 3 = allowed
        times 32 db 0
;                 ! " # $ % & ' ( ) * + , - . /
        db      1,3,0,3,3,3,3,3,3,3,0,1,1,3,3,0
;               0 1 2 3 4 5 6 7 8 9 : ; < = > ?
        db      3,3,3,3,3,3,3,3,3,3,0,1,0,1,0,0
;               @ A B C D E F G H I J K L M N O
        db      3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3
;               P Q R S T U V W X Y Z [ \ ] ^ _
        db      3,3,3,3,3,3,3,3,3,3,3,1,0,1,3,3
;               ` a b c d e f g h i j k l m n o
        db      3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3
;               p q r s t u v w x y z { | } ~
        db      3,3,3,3,3,3,3,3,3,3,3,3,0,3,3,0
endg

fat_name_is_legal:
; in: esi->(long) name
; out: CF set <=> legal
; destroys eax
        push    esi
        xor     eax, eax
@@:
        lodsb
        test    al, al
        jz      .done
        cmp     al, 80h
        jae     .big
        test    [fat_legal_chars+eax], 1
        jnz     @b
.err:
        pop     esi
        clc
        ret
.big:
; 0x80-0xAF, 0xE0-0xEF
        cmp     al, 0xB0
        jb      @b
        cmp     al, 0xE0
        jb      .err
        cmp     al, 0xF0
        jb      @b
        jmp     .err
.done:
        sub     esi, [esp]
        cmp     esi, 257
        pop     esi
        ret

fat_next_short_name:
; in: edi->8+3 name
; out: name corrected
;      CF=1 <=> error
        pushad
        mov     ecx, 8
        mov     al, '~'
        std
        push    edi
        add     edi, 7
        repnz   scasb
        pop     edi
        cld
        jz      .tilde
; tilde is not found, insert "~1" at end
        add     edi, 6
        cmp     word [edi], '  '
        jnz     .insert_tilde
@@:     dec     edi
        cmp     byte [edi], ' '
        jz      @b
        inc     edi
.insert_tilde:
        mov     word [edi], '~1'
        popad
;       clc     ; CF already cleared
        ret
.tilde:
        push    edi
        add     edi, 7
        xor     ecx, ecx
@@:
; after tilde may be only digits and trailing spaces
        cmp     byte [edi], '~'
        jz      .break
        cmp     byte [edi], ' '
        jz      .space
        cmp     byte [edi], '9'
        jnz     .found
        dec     edi
        jmp     @b
.space:
        dec     edi
        inc     ecx
        jmp     @b
.found:
        inc     byte [edi]
.succ:
        pop     edi
        popad
        clc
        ret
.break:
        jecxz   .noplace
        inc     edi
        mov     al, '1'
@@:
        xchg    al, [edi]
        inc     edi
        cmp     al, ' '
        mov     al, '0'
        jnz     @b
        jmp     .succ
.noplace:
        dec     edi
        cmp     edi, [esp]
        jz      .err
        add     dword [esp], 8
        mov     word [edi], '~1'
        inc     edi
        inc     edi
@@:
        mov     byte [edi], '0'
        inc     edi
        cmp     edi, [esp]
        jb      @b
        pop     edi
        popad
        ;clc    ; automatically
        ret
.err:
        pop     edi
        popad
        stc
        ret

fat_gen_short_name:
; in: esi->long name
;     edi->buffer (8+3=11 chars)
; out: buffer filled
        pushad
        mov     eax, '    '
        push    edi
        stosd
        stosd
        stosd
        pop     edi
        xor     eax, eax
        push    8
        pop     ebx
        lea     ecx, [edi+8]
.loop:
        lodsb
        test    al, al
        jz      .done
        call    char_toupper
        cmp     al, ' '
        jz      .space
        cmp     al, 80h
        ja      .big
        test    [fat_legal_chars+eax], 2
        jnz     .symbol
.inv_symbol:
        mov     al, '_'
        or      bh, 1
.symbol:
        cmp     al, '.'
        jz      .dot
.normal_symbol:
        dec     bl
        jns     .store
        mov     bl, 0
.space:
        or      bh, 1
        jmp     .loop
.store:
        stosb
        jmp     .loop
.big:
        cmp     al, 0xB0
        jb      .normal_symbol
        cmp     al, 0xE0
        jb      .inv_symbol
        cmp     al, 0xF0
        jb      .normal_symbol
        jmp     .inv_symbol
.dot:
        test    bh, 2
        jz      .firstdot
        pop     ebx
        add     ebx, edi
        sub     ebx, ecx
        push    ebx
        cmp     edi, ecx
        jbe     .skip
@@:
        dec     edi
        mov     al, ' '
        xchg    al, [edi]
        dec     ebx
        mov     [ebx], al
        cmp     edi, ecx
        ja      @b
.skip:
        mov     bh, 3
        jmp     @f
.firstdot:
        cmp     bl, 8
        jz      .space
        push    edi
        or      bh, 2
@@:
        mov     edi, ecx
        mov     bl, 3
        jmp     .loop
.done:
        test    bh, 2
        jz      @f
        pop     edi
@@:
        lea     edi, [ecx-8]
        test    bh, 1
        jz      @f
        call    fat_next_short_name
@@:
        popad
        ret

;----------------------------------------------------------------
;
;  fs_RamdiskRewrite - LFN variant for writing sys floppy
;
;  esi  points to filename
;  ebx  ignored (reserved)
;  ecx  number of bytes to write, 0+
;  edx  mem location to data
;
;  ret ebx = number of written bytes
;      eax = 0 ok read or other = errormsg
;
;--------------------------------------------------------------
@@:
        mov     eax, ERROR_ACCESS_DENIED
        xor     ebx, ebx
        ret

fs_RamdiskRewrite:
        cmp     byte [esi], 0
        jz      @b
; ramdisk doesn't support folders
        push    esi
@@:
        lodsb
        test    al, al
        jz      @f
        cmp     al, '/'
        jnz     @b
        pop     esi
.err5:
        mov     eax, 5  ; file not found
        xor     ebx, ebx
        ret
@@:
        pop     esi
; check existence
        push    edi
        call    rd_find_lfn
        jc      .notfound
; found, delete FAT chain
        push    edi
        xor     eax, eax
        mov     dword [edi+28], eax     ; zero size
        xchg    ax, word [edi+26]       ; start cluster
        test    eax, eax
        jz      .done1
@@:
        cmp     eax, 0xFF8
        jae     .done1
        lea     edi, [0x280000 + eax*2] ; position in FAT
        xor     eax, eax
        xchg    ax, [edi]
        jmp     @b
.done1:
        pop     edi
        call    get_time_for_file
        mov     [edi+22], ax
        call    get_date_for_file
        mov     [edi+24], ax
        mov     [edi+18], ax
        or      byte [edi+11], 20h      ; set 'archive' attribute
        jmp     .doit
.notfound:
; file is not found; generate short name
        call    fat_name_is_legal
        jc      @f
        pop     edi
        jmp     .err5
@@:
        sub     esp, 12
        mov     edi, esp
        call    fat_gen_short_name
.test_short_name_loop:
        push    esi ecx
        mov     esi, 0x100000+512*19
.test_short_name_entry:
        cmp     byte [esi+11], 0xF
        jz      .test_short_name_cont
        mov     ecx, 11
        push    esi edi
        repz    cmpsb
        pop     edi esi
        jz      .short_name_found
.test_short_name_cont:
        add     esi, 20h
        cmp     esi, 0x100000+512*33
        jb      .test_short_name_entry
        pop     ecx esi
        jmp     .found
.short_name_found:
        call    fat_next_short_name
        pop     ecx esi
        jnc     .test_short_name_loop
.disk_full:
        add     esp, 12
        pop     edi
        mov     eax, ERROR_DISK_FULL
        xor     ebx, ebx
        ret
.found:
; now find space in directory
; we need to save LFN <=> LFN is not equal to short name <=> generated name contains '~'
        mov     al, '~'
        push    ecx edi
        mov     ecx, 8
        repnz   scasb
        push    1
        pop     eax     ; 1 entry
        jnz     .notilde
; we need ceil(strlen(esi)/13) additional entries = floor((strlen(esi)+12+13)/13) total
        xor     eax, eax
@@:
        cmp     byte [esi], 0
        jz      @f
        inc     esi
        inc     eax
        jmp     @b
@@:
        sub     esi, eax
        add     eax, 12+13
        mov     ecx, 13
        push    edx
        cdq
        div     ecx
        pop     edx
.notilde:
; find <eax> successive entries in directory
        xor     ecx, ecx
        mov     edi, 0x100000+512*19
.scan_dir:
        cmp     byte [edi], 0
        jz      .free
        cmp     byte [edi], 0xE5
        jz      .free
        xor     ecx, ecx
.scan_cont:
        add     edi, 0x20
        cmp     edi, 0x100000+512*33
        jb      .scan_dir
        pop     edi ecx
        jmp     .disk_full
.free:
        inc     ecx
        cmp     ecx, eax
        jb      .scan_cont
; found!
; calculate name checksum
        push    esi ecx
        mov     esi, [esp+8]
        mov     ecx, 11
        xor     eax, eax
@@:
        ror     al, 1
        add     al, [esi]
        inc     esi
        loop    @b
        pop     ecx esi
; edi points to last entry in free chunk
        dec     ecx
        jz      .nolfn
        push    esi
        push    edi
.writelfn:
        sub     edi, 20h
        push    ecx eax
        mov     eax, [esp+8]
        sub     eax, edi
        shr     eax, 5
        cmp     ecx, 1
        jnz     @f
        or      al, 40h
@@:
        stosb
        mov     cl, 5
        call    .read_symbols
        mov     ax, 0xF
        stosw
        pop     eax
        stosb
        push    eax
        mov     cl, 6
        call    .read_symbols
        xor     eax, eax
        stosw
        mov     cl, 2
        call    .read_symbols
        pop     eax ecx
        sub     edi, 0x20
        loop    .writelfn
        pop     edi
        pop     esi
.nolfn:
        xchg    esi, [esp]
        mov     ecx, 11
        rep     movsb
        mov     word [edi], 20h         ; attributes
        sub     edi, 11
        pop     esi ecx
        add     esp, 12
        mov     byte [edi+13], 0        ; tenths of a second at file creation time
        call    get_time_for_file
        mov     [edi+14], ax            ; creation time
        mov     [edi+22], ax            ; last write time
        call    get_date_for_file
        mov     [edi+16], ax            ; creation date
        mov     [edi+24], ax            ; last write date
        mov     [edi+18], ax            ; last access date
        and     word [edi+20], 0        ; high word of cluster
        and     word [edi+26], 0        ; low word of cluster - to be filled
        and     dword [edi+28], 0       ; file size - to be filled
.doit:
        push    ecx edx
        push    ecx
        push    edi
        add     edi, 26         ; edi points to low word of cluster
        push    edi
        jecxz   .done
        mov     ecx, 2849
        mov     edi, 0x280000
.write_loop:
; allocate new cluster
        xor     eax, eax
        repnz   scasw
        jnz     .disk_full2
        dec     edi
        dec     edi
        lea     eax, [edi-0x280000]
        shr     eax, 1                  ; eax = cluster
        mov     word [edi], 0xFFF       ; mark as last cluster
        xchg    edi, [esp]
        stosw
        pop     edi
        push    edi
        inc     ecx
; write data
        shl     eax, 9
        add     eax, 0x100000+31*512
        mov     ebx, edx
        xchg    eax, ebx
        push    ecx
        mov     ecx, 512
        cmp     dword [esp+12], ecx
        jae     @f
        mov     ecx, [esp+12]
@@:
        call    memmove
        add     edx, ecx
        sub     [esp+12], ecx
        pop     ecx
        jnz     .write_loop
.done:
        mov     ebx, edx
        pop     edi edi ecx edx ecx
        sub     ebx, edx
        mov     [edi+28], ebx
        pop     edi
        xor     eax, eax
        ret
.disk_full2:
        mov     ebx, edx
        pop     edi edi ecx edx ecx
        sub     ebx, edx
        mov     [edi+28], ebx
        pop     edi
        push    ERROR_DISK_FULL
        pop     eax
        ret

.read_symbol:
        or      ax, -1
        test    esi, esi
        jz      .retFFFF
        lodsb
        test    al, al
        jnz     ansi2uni_char
        xor     eax, eax
        xor     esi, esi
.retFFFF:
        ret

.read_symbols:
        call    .read_symbol
        stosw
        loop    .read_symbols
        ret

; \end{diamond}