kolibrios/kernel/trunk/fs/fat.inc

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;                                                              ;;
;; Copyright (C) KolibriOS team 2004-2015. All rights reserved. ;;
;; Distributed under terms of the GNU General Public License    ;;
;;                                                              ;;
;;  FAT functions for KolibriOS                                 ;;
;;                                                              ;;
;;  Copyright 2002 Paolo Minazzi, paolo.minazzi@inwind.it       ;;
;;                                                              ;;
;;  See file COPYING for details                                ;;
;;  06.2015 fs_read64 - pathoswithin                            ;;
;;  04.02.2007 LFN create folder - diamond                      ;;
;;  08.10.2006 LFN delete file/folder - diamond                 ;;
;;  20.08.2006 LFN set file size (truncate/extend) - diamond    ;;
;;  17.08.2006 LFN write/append to file - diamond               ;;
;;  23.06.2006 LFN start application - diamond                  ;;
;;  15.06.2006 LFN get/set file/folder info - diamond           ;;
;;  27.05.2006 LFN create/rewrite file - diamond                ;;
;;  04.05.2006 LFN read folder - diamond                        ;;
;;  29.04.2006 Elimination of hangup after the                  ;;
;;             expiration hd_wait_timeout - Mario79             ;;
;;  23.04.2006 LFN read file - diamond                          ;;
;;  28.01.2006 find all Fat16/32 partition in all input point   ;;
;;             to MBR, see file part_set.inc - Mario79          ;;
;;  15.01.2005 get file size/attr/date, file_append - ATV       ;;
;;  04.12.2004 skip volume label, file delete bug fixed - ATV   ;;
;;  29.11.2004 get_free_FAT changed, append dir bug fixed - ATV ;;
;;  23.11.2004 don't allow overwrite dir with file - ATV        ;;
;;  18.11.2004 get_disk_info and more error codes - ATV         ;;
;;  17.11.2004 set_FAT/get_FAT and disk cache rewritten - ATV   ;;
;;  10.11.2004 removedir clear whole directory structure - ATV  ;;
;;  08.11.2004 rename - ATV                                     ;;
;;  30.10.2004 file_read return also dirsize in bytes - ATV     ;;
;;  20.10.2004 Makedir/Removedir - ATV                          ;;
;;  14.10.2004 Partition chain/Fat16 - ATV (thanks drh3xx)      ;;
;;  06.09.2004 Fix free space - Mario79                         ;;
;;  24.05.2004 Write back buffer for File_write - VT            ;;
;;  20.05.2004 File_read function to work with syscall 58 - VT  ;;
;;  30.03.2004 Error parameters at function return - VT         ;;
;;  29.06.2002 Improved fat32 verification - VT                 ;;
;;  20.05.2002 Hd status check - VT                             ;;
;;  01.05.2002 Bugfix in device write - VT                      ;;
;;                                                              ;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

$Revision$

cache_max equ 1919      ; max. is 1919*512+0x610000=0x6ffe00

PUSHAD_EAX equ [esp+28]
PUSHAD_ECX equ [esp+24]
PUSHAD_EDX equ [esp+20]
PUSHAD_EBX equ [esp+16]
PUSHAD_EBP equ [esp+8]
PUSHAD_ESI equ [esp+4]
PUSHAD_EDI equ [esp+0]

; Internal data for every FAT partition.
struct FAT PARTITION
fs_type              db ?
fat16_root           db 0       ; flag for fat16 rootdir
fat_change           db 0       ; 1=fat has changed
                     rb 1
Lock            MUTEX   ?       ; currently operations with one partition
; can not be executed in parallel since the legacy code is not ready
SECTORS_PER_FAT      dd 0x1f3a
NUMBER_OF_FATS       dd 0x2
SECTORS_PER_CLUSTER  dd 0x8
BYTES_PER_SECTOR     dd 0x200   ; Note: if BPS <> 512 need lots of changes
ROOT_CLUSTER         dd 2       ; first rootdir cluster
FAT_START            dd 0       ; start of fat table
ROOT_START           dd 0       ; start of rootdir (only fat16)
ROOT_SECTORS         dd 0       ; count of rootdir sectors (only fat16)
DATA_START           dd 0       ; start of data area (=first cluster 2)
LAST_CLUSTER         dd 0       ; last availabe cluster
ADR_FSINFO           dd 0       ; used only by fat32

fatRESERVED          dd 0x0FFFFFF6
fatBAD               dd 0x0FFFFFF7
fatEND               dd 0x0FFFFFF8
fatMASK              dd 0x0FFFFFFF

fatStartScan         dd 2
cluster_tmp          dd 0       ; used by analyze_directory
                                ; and analyze_directory_to_write
longname_sec1        dd 0       ; used by analyze_directory to save 2 previous
longname_sec2        dd 0       ; directory sectors for delete long filename
fat_in_cache         dd -1

; For FAT16/FAT32, this points to 512-byte buffer for the current sector of FAT.
; For FAT12, the entire FAT structure is read
; and unpacked from 12bit per cluster to word per cluster.

; Note: work with unpacked copy of FAT12 means
; additional memory and additional code for packing/unpacking.
; I'm not sure that the economy justifies the cost, but anyway,
; there is how work was done before my edits, and I'm just keeping the principle.
fat_cache_ptr        dd ?
fat12_unpacked_ptr   dd ?
buffer               rb 512
fsinfo_buffer        rb 512
ends

uglobal
align 4
partition_count      dd 0       ; partitions found by set_FAT32_variables
hd_error             dd 0
hd_setup             dd 0
hd_wait_timeout      dd 0
cache_search_start   dd 0       ; used by find_empty_slot
endg

uglobal
align 4
Sector512:      ; label for dev_hdcd.inc
buffer:
rb 512
endg

iglobal
align 4
fat_user_functions:
        dd      fat_free
        dd      (fat_user_functions_end - fat_user_functions - 4) / 4
        dd      fat_Read
        dd      fat_ReadFolder
        dd      fat_Rewrite
        dd      fat_Write
        dd      fat_SetFileEnd
        dd      fat_GetFileInfo
        dd      fat_SetFileInfo
        dd      0
        dd      fat_Delete
        dd      fat_CreateFolder
fat_user_functions_end:
endg

; these labels are located before the main function to make
; most of jumps to these be short
fat_create_partition.free_return0:
        mov     eax, ebp
        call    free
        pop     ebp
fat_create_partition.return0:
        xor     eax, eax
        ret
fat_create_partition:
; sector size must be 512
        cmp     dword [esi+DISK.MediaInfo.SectorSize], 512
        jnz     .return0
; bootsector must have been successfully read
        cmp     dword [esp+4], 0
        jnz     .return0
; bootsector signature must be correct
        cmp     word [ebx+0x1fe], 0xaa55
        jnz     .return0
; sectors per cluster must be nonzero
        cmp     byte [ebx+0xd], 0
        jz      .return0
; bytes per sector must be 0x200
        cmp     word [ebx+0xb], 0x200
        jnz     .return0
; number of fats must be nonzero
        cmp     byte [ebx+0x10], 0
        jz      .return0
; The only reason to be invalid partition now is FAT12. Since the test for
; FAT size requires knowledge of some calculated values, which are also used
; in the normal operation, let's hope for the best and allocate data now; if
; it will prove wrong, just deallocate it.
        movi    eax, sizeof.FAT
        call    malloc
        test    eax, eax
        jz      .return0
        mov     ecx, dword [ebp+PARTITION.FirstSector]
        mov     dword [eax+FAT.FirstSector], ecx
        mov     ecx, dword [ebp+PARTITION.FirstSector+4]
        mov     dword [eax+FAT.FirstSector+4], ecx
        mov     ecx, dword [ebp+PARTITION.Length]
        mov     dword [eax+FAT.Length], ecx
        mov     ecx, dword [ebp+PARTITION.Length+4]
        mov     dword [eax+FAT.Length+4], ecx
        mov     ecx, [ebp+PARTITION.Disk]
        mov     [eax+FAT.Disk], ecx
        mov     [eax+FAT.FSUserFunctions], fat_user_functions
        or      [eax+FAT.fat_in_cache], -1
        mov     [eax+FAT.fat_change], 0
        push    ebp
        mov     ebp, eax

        lea     ecx, [ebp+FAT.Lock]
        call    mutex_init

        movzx   eax, word [ebx+0xe]     ; sectors reserved
        mov     [ebp+FAT.FAT_START], eax

        movzx   eax, byte [ebx+0xd]     ; sectors per cluster
        mov     [ebp+FAT.SECTORS_PER_CLUSTER], eax

        movzx   ecx, word [ebx+0xb]     ; bytes per sector
        mov     [ebp+FAT.BYTES_PER_SECTOR], ecx

        movzx   eax, word [ebx+0x11]    ; count of rootdir entries (=0 fat32)
        shl     eax, 5                  ; mul 32
        dec     ecx
        add     eax, ecx                ; round up if not equal count
        inc     ecx                     ; bytes per sector
        xor     edx, edx
        div     ecx
        mov     [ebp+FAT.ROOT_SECTORS], eax     ; count of rootdir sectors

        movzx   eax, word [ebx+0x16]    ; sectors per fat <65536
        test    eax, eax
        jnz     @f
        mov     eax, [ebx+0x24]         ; sectors per fat
@@:
        mov     [ebp+FAT.SECTORS_PER_FAT], eax

        movzx   eax, byte [ebx+0x10]    ; number of fats
        mov     [ebp+FAT.NUMBER_OF_FATS], eax
        mul     [ebp+FAT.SECTORS_PER_FAT]
        test    edx, edx
        jnz     .free_return0
        add     eax, [ebp+FAT.FAT_START]
        jc      .free_return0
        mov     [ebp+FAT.ROOT_START], eax       ; rootdir = fat_start + fat_size * fat_count
        add     eax, [ebp+FAT.ROOT_SECTORS]     ; rootdir sectors should be 0 on fat32
        jc      .free_return0
        mov     [ebp+FAT.DATA_START], eax       ; data area = rootdir + rootdir_size

        movzx   eax, word [ebx+0x13]    ; total sector count <65536
        test    eax, eax
        jnz     @f
        mov     eax, [ebx+0x20]         ; total sector count
@@:
; total sector count must not exceed partition size
        cmp     dword [ebp+FAT.Length+4], 0
        jnz     @f
        cmp     eax, dword [ebp+FAT.Length]
        ja      .free_return0
@@:
        mov     dword [ebp+FAT.Length], eax
        and     dword [ebp+FAT.Length+4], 0
        sub     eax, [ebp+FAT.DATA_START]       ; eax = count of data sectors
        jc      .free_return0
        xor     edx, edx
        div     [ebp+FAT.SECTORS_PER_CLUSTER]
        inc     eax
        mov     [ebp+FAT.LAST_CLUSTER], eax
        dec     eax                     ; cluster count
        jz      .free_return0
        mov     [ebp+FAT.fatStartScan], 2

        ; limits by Microsoft Hardware White Paper v1.03
        cmp     eax, 4085               ; 0xff5
        jb      .fat12
        cmp     eax, 65525              ; 0xfff5
        jb      .fat16
.fat32:
        mov     eax, [ebx+0x2c]         ; rootdir cluster
        mov     [ebp+FAT.ROOT_CLUSTER], eax
        movzx   eax, word [ebx+0x30]
        mov     [ebp+FAT.ADR_FSINFO], eax
        push    ebx
        add     ebx, 512
        call    fs_read32_sys
        test    eax, eax
        jnz     @f
        mov     eax, [ebx+0x1ec]
        cmp     eax, -1
        jz      @f
        mov     [ebp+FAT.fatStartScan], eax
@@:
        pop     ebx
        mov     [ebp+FAT.fatRESERVED], 0x0FFFFFF6
        mov     [ebp+FAT.fatBAD], 0x0FFFFFF7
        mov     [ebp+FAT.fatEND], 0x0FFFFFF8
        mov     [ebp+FAT.fatMASK], 0x0FFFFFFF
        mov     al, 32
.fat_not_12_finalize:
        mov     [ebp+FAT.fs_type], al
; For FAT16 and FAT32, allocate 512 bytes for FAT cache.
        mov     eax, 512
        call    malloc
        test    eax, eax
        jz      .free_return0
        mov     [ebp+FAT.fat_cache_ptr], eax
        mov     eax, ebp
        pop     ebp
        ret
.fat16:
        and     [ebp+FAT.ROOT_CLUSTER], 0
        mov     [ebp+FAT.fatRESERVED], 0x0000FFF6
        mov     [ebp+FAT.fatBAD], 0x0000FFF7
        mov     [ebp+FAT.fatEND], 0x0000FFF8
        mov     [ebp+FAT.fatMASK], 0x0000FFFF
        mov     al, 16
        jmp     .fat_not_12_finalize
.fat12:
        and     [ebp+FAT.ROOT_CLUSTER], 0
        mov     [ebp+FAT.fatRESERVED], 0xFF6
        mov     [ebp+FAT.fatBAD], 0xFF7
        mov     [ebp+FAT.fatEND], 0xFFF
        mov     [ebp+FAT.fatMASK], 0xFFF
        mov     al, 12
        mov     [ebp+FAT.fs_type], al
; For FAT12, allocate&read data for entire table:
; calculate A = ALIGN_UP(NUM_CLUSTERS, 8),
; calculatefatchain/restorefatchain will process A items,
; allocate ALIGN_UP(A*3/2, 512) bytes for FAT table plus A*2 bytes for unpacked data.
        mov     eax, [ebp+FAT.LAST_CLUSTER]
        and     eax, not 7
        add     eax, 8
        mov     edx, eax
        lea     eax, [eax*3]
        add     eax, 512*2-1
        shr     eax, 10
        shl     eax, 9
        lea     eax, [eax+edx*2]
        call    malloc
        test    eax, eax
        jz      .free_return0
; Read ALIGN_UP(NUM_CLUSTERS*3/2, 512) bytes.
; Note that this can be less than allocated, this is ok,
; overallocation simplifies calculatefatchain/restorefatchain.
        push    ebx
        mov     [ebp+FAT.fat_cache_ptr], eax
        mov     edx, [ebp+FAT.LAST_CLUSTER]
        lea     edx, [(edx+1)*3 + 512*2-1]
        shr     edx, 10
        xchg    eax, ebx
        xor     eax, eax
.read_fat:
        push    eax
        add     eax, [ebp+FAT.FAT_START]
        call    fs_read32_sys
        test    eax, eax
        pop     eax
        jz      @f
        dbgstr 'Failed to read FAT table'
        mov     eax, [ebp+FAT.fat_cache_ptr]
        call    free
        pop     ebx
        jmp     .free_return0
@@:
        add     ebx, 512
        inc     eax
        cmp     eax, edx
        jb      .read_fat
        mov     [ebp+FAT.fat12_unpacked_ptr], ebx
        call    calculatefatchain
        pop     ebx
        mov     eax, ebp
        pop     ebp
        ret

fat_free:
        push    eax
        mov     eax, [eax+FAT.fat_cache_ptr]
        call    free
        pop     eax
        jmp     free

calculatefatchain:

        pushad

        mov     esi, [ebp+FAT.fat_cache_ptr]
        mov     edi, [ebp+FAT.fat12_unpacked_ptr]

        mov     edx, [ebp+FAT.LAST_CLUSTER]
        and     edx, not 7
        lea     edx, [edi+(edx+8)*2]
        push    edx

 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, [esp]
        jnz     fcnew
        pop     eax

        popad
        ret


restorefatchain:   ; restore fat chain

        pushad

        mov     esi, [ebp+FAT.fat12_unpacked_ptr]
        mov     edi, [ebp+FAT.fat_cache_ptr]

        mov     edx, [ebp+FAT.LAST_CLUSTER]
        and     edx, not 7
        lea     edx, [esi+(edx+8)*2]

  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     esi, edx
        jb      fcnew2

        mov     esi, [ebp+FAT.NUMBER_OF_FATS]
        mov     edx, [ebp+FAT.LAST_CLUSTER]
        lea     edx, [(edx+1)*3 + 512*2-1]
        shr     edx, 10
        push    [ebp+FAT.FAT_START]

.write_fats:
        xor     eax, eax
        mov     ebx, [ebp+FAT.fat_cache_ptr]
.loop1:
        push    eax
        add     eax, [esp+4]
        call    fs_write32_sys
        test    eax, eax
        pop     eax
        jnz     .fail
        add     ebx, 512
        inc     eax
        cmp     eax, edx
        jb      .loop1
        pop     eax
        add     eax, [ebp+FAT.SECTORS_PER_FAT]
        push    eax
        dec     esi
        jnz     .write_fats
        pop     eax

        popad
        ret
.fail:
        dbgstr 'Failed to save FAT'
        popad
        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
        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]
        add     dword [esp], 8
        jmp     .zerorest
.break:
        jecxz   .noplace
        inc     edi
        mov     al, '1'
@@:
        xchg    al, [edi]
        inc     edi
        cmp     al, ' '
        mov     al, '0'
        jnz     @b
.succ:
        pop     edi
        popad
        clc
        ret
.noplace:
        dec     edi
        cmp     edi, [esp]
        jz      .err
        add     dword [esp], 8
        mov     word [edi], '~1'
        inc     edi
        inc     edi
@@:
        mov     byte [edi], '0'
.zerorest:
        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
        movi    ebx, 8
        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     ebx, ecx
        jb      @f
        pop     ebx
        push    ecx
@@:
        cmp     edi, ecx
        jbe     .skip
@@:
        dec     edi
        mov     al, [edi]
        dec     ebx
        mov     [ebx], al
        mov     byte [edi], ' '
        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

fat12_free_space:
;---------------------------------------------
;
; returns free space in edi
; rewr.by Mihasik
;---------------------------------------------

        push    eax ebx ecx

        mov     edi, [ebp+FAT.fat12_unpacked_ptr];start of FAT
        xor     ax, ax;Free cluster=0x0000 in FAT
        xor     ebx, ebx;counter
        mov     ecx, [ebp+FAT.LAST_CLUSTER]
        inc     ecx
        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



set_FAT:
;--------------------------------
; input  : EAX = cluster
;          EDX = value to save
;          EBP = pointer to FAT structure
; output : EDX = old value
;--------------------------------
; out: CF set <=> error
        push    eax ebx esi

        cmp     eax, 2
        jb      sfc_error
        cmp     eax, [ebp+FAT.LAST_CLUSTER]
        ja      sfc_error
        cmp     [ebp+FAT.fs_type], 12
        je      set_FAT12
        cmp     [ebp+FAT.fs_type], 16
        je      sfc_1
        add     eax, eax
  sfc_1:
        add     eax, eax
        mov     esi, 511
        and     esi, eax        ; esi = position in fat sector
        shr     eax, 9          ; eax = fat sector
        add     eax, [ebp+FAT.FAT_START]
        mov     ebx, [ebp+FAT.fat_cache_ptr]

        cmp     eax, [ebp+FAT.fat_in_cache]; is fat sector already in memory?
        je      sfc_in_cache    ; yes

        cmp     [ebp+FAT.fat_change], 0; is fat changed?
        je      sfc_no_change   ; no
        call    write_fat_sector; yes. write it into disk
        jc      sfc_error

  sfc_no_change:
        mov     [ebp+FAT.fat_in_cache], eax; save fat sector
        call    fs_read32_sys
        test    eax, eax
        jne     sfc_error


  sfc_in_cache:
        cmp     [ebp+FAT.fs_type], 16
        jne     sfc_test32

  sfc_set16:
        xchg    [ebx+esi], dx   ; save new value and get old value
        jmp     sfc_write

  sfc_test32:
        mov     eax, [ebp+FAT.fatMASK]

  sfc_set32:
        and     edx, eax
        xor     eax, -1         ; mask for high bits
        and     eax, [ebx+esi]  ; get high 4 bits
        or      eax, edx
        mov     edx, [ebx+esi]  ; get old value
        mov     [ebx+esi], eax  ; save new value

  sfc_write:
        mov     [ebp+FAT.fat_change], 1; fat has changed

  sfc_nonzero:
        and     edx, [ebp+FAT.fatMASK]

  sfc_return:
        pop     esi ebx eax
        ret
  sfc_error:
        stc
        jmp     sfc_return

  set_FAT12:
        test    edx, 0xF000
        jnz     sfc_error
        mov     ebx, [ebp+FAT.fat12_unpacked_ptr]
        xchg    [ebx+eax*2], dx
        mov     [ebp+FAT.fat_change], 1
        pop     esi ebx eax
        clc
        ret

get_FAT:
;--------------------------------
; input  : EAX = cluster
;          EBP = pointer to FAT structure
; output : EAX = next cluster
;--------------------------------
; out: CF set <=> error
        push    ebx esi

        cmp     [ebp+FAT.fs_type], 12
        je      get_FAT12

        cmp     [ebp+FAT.fs_type], 16
        je      gfc_1
        add     eax, eax
  gfc_1:
        add     eax, eax
        mov     esi, 511
        and     esi, eax        ; esi = position in fat sector
        shr     eax, 9          ; eax = fat sector
        add     eax, [ebp+FAT.FAT_START]
        mov     ebx, [ebp+FAT.fat_cache_ptr]

        cmp     eax, [ebp+FAT.fat_in_cache]; is fat sector already in memory?
        je      gfc_in_cache

        cmp     [ebp+FAT.fat_change], 0; is fat changed?
        je      gfc_no_change   ; no
        call    write_fat_sector; yes. write it into disk
        jc      hd_error_01

  gfc_no_change:
        mov     [ebp+FAT.fat_in_cache], eax
        call    fs_read32_sys
        test    eax, eax
        jne     hd_error_01

  gfc_in_cache:
        mov     eax, [ebx+esi]
        and     eax, [ebp+FAT.fatMASK]
  gfc_return:
        pop     esi ebx
        ret
 hd_error_01:
        stc
        jmp     gfc_return

get_FAT12:
        mov     ebx, [ebp+FAT.fat12_unpacked_ptr]
        movzx   eax, word [ebx+eax*2]
        pop     esi ebx
        clc
        ret


get_free_FAT:
;-----------------------------------------------------------
; output : if CARRY=0 EAX = # first cluster found free
;          if CARRY=1 disk full
; Note   : for more speed need to use fat_cache directly
;-----------------------------------------------------------
        push    ecx
        mov     ecx, [ebp+FAT.LAST_CLUSTER]; counter for full disk
        mov     eax, [ebp+FAT.fatStartScan]
        cmp     [ebp+FAT.fs_type], 12
        jz      get_free_FAT12
        dec     ecx
        cmp     eax, 2
        jb      gff_reset

  gff_test:
        cmp     eax, [ebp+FAT.LAST_CLUSTER]; if above last cluster start at cluster 2
        jbe     gff_in_range
  gff_reset:
        mov     eax, 2

  gff_in_range:
        push    eax
        call    get_FAT         ; get cluster state
        jc      gff_not_found_1

        test    eax, eax        ; is it free?
        pop     eax
        je      gff_found       ; yes
        inc     eax             ; next cluster
        dec     ecx             ; is all checked?
        jnz     gff_test        ; no

  gff_not_found:
        pop     ecx             ; yes. disk is full
        stc
        ret

  gff_not_found_1:
        pop     eax
        jmp     gff_not_found

  gff_found:
        lea     ecx, [eax+1]
        mov     [ebp+FAT.fatStartScan], ecx
        pop     ecx
        clc
        ret

get_free_FAT12:
        push    edx edi
        mov     edi, [ebp+FAT.fat12_unpacked_ptr]
        cmp     eax, 2
        jb      .reset
        cmp     eax, ecx
        jbe     @f
.reset:
        mov     eax, 2
@@:
        mov     edx, eax
        lea     edi, [edi+eax*2]
        sub     ecx, eax
        inc     ecx
        xor     eax, eax
        repnz scasw
        jz      .found
        cmp     edx, 2
        jz      .notfound
        mov     edi, [ebp+FAT.fat12_unpacked_ptr]
        lea     ecx, [edx-2]
        repnz scasw
        jnz     .notfound
.found:
        sub     edi, [ebp+FAT.fat12_unpacked_ptr]
        shr     edi, 1
        mov     [ebp+FAT.fatStartScan], edi
        lea     eax, [edi-1]
        pop     edi edx ecx
        ret
.notfound:
        pop     edi edx ecx
        stc
        ret


write_fat_sector:
;-----------------------------------------------------------
; write changed fat to disk
;-----------------------------------------------------------
        push    eax ebx ecx

        mov     [ebp+FAT.fat_change], 0
        mov     eax, [ebp+FAT.fat_in_cache]
        cmp     eax, -1
        jz      write_fat_not_used
        mov     ebx, [ebp+FAT.fat_cache_ptr]
        mov     ecx, [ebp+FAT.NUMBER_OF_FATS]

  write_next_fat:
        push    eax
        call    fs_write32_sys
        test    eax, eax
        pop     eax
        jnz     write_fat_not_used

        add     eax, [ebp+FAT.SECTORS_PER_FAT]
        dec     ecx
        jnz     write_next_fat

  write_fat_not_used:
        pop     ecx ebx eax
        ret





bcd2bin:
;----------------------------------
; input  : AL=BCD number (eg. 0x11)
; output : AH=0
;          AL=decimal number (eg. 11)
;----------------------------------
        xor     ah, ah
        shl     ax, 4
        shr     al, 4
        aad
        ret


get_date_for_file:
;-----------------------------------------------------
; Get date from CMOS and pack day,month,year in AX
; DATE   bits  0..4   : day of month 0..31
;              5..8   : month of year 1..12
;              9..15  : count of years from 1980
;-----------------------------------------------------
        mov     al, 0x7 ;day
        out     0x70, al
        in      al, 0x71
        call    bcd2bin
        ror     eax, 5

        mov     al, 0x8 ;month
        out     0x70, al
        in      al, 0x71
        call    bcd2bin
        ror     eax, 4

        mov     al, 0x9 ;year
        out     0x70, al
        in      al, 0x71
        call    bcd2bin
        add     ax, 20  ;because CMOS return only the two last
                        ;digit (eg. 2000 -> 00 , 2001 -> 01) and we
        rol     eax, 9  ;need the difference with 1980 (eg. 2001-1980)
        ret


get_time_for_file:
;-----------------------------------------------------
; Get time from CMOS and pack hour,minute,second in AX
; TIME   bits  0..4   : second (the low bit is lost)
;              5..10  : minute 0..59
;              11..15 : hour 0..23
;-----------------------------------------------------
        mov     al, 0x0 ;second
        out     0x70, al
        in      al, 0x71
        call    bcd2bin
        ror     eax, 6

        mov     al, 0x2 ;minute
        out     0x70, al
        in      al, 0x71
        call    bcd2bin
        ror     eax, 6

        mov     al, 0x4 ;hour
        out     0x70, al
        in      al, 0x71
        call    bcd2bin
        rol     eax, 11
        ret


set_current_time_for_entry:
;-----------------------------------------------------
; Set current time/date for file entry
; input  : ebx = file entry pointer
;-----------------------------------------------------
        push    eax
        call    get_time_for_file; update files date/time
        mov     [ebx+22], ax
        call    get_date_for_file
        mov     [ebx+24], ax
        pop     eax
        ret



add_disk_free_space:
;-----------------------------------------------------
; input  : ecx = cluster count
; Note   : negative = remove clusters from free space
;          positive = add clusters to free space
;-----------------------------------------------------
        test    ecx, ecx        ; no change
        je      add_dfs_no
        cmp     [ebp+FAT.fs_type], 32  ; free disk space only used by fat32
        jne     add_dfs_no

        push    eax ebx
        mov     eax, [ebp+FAT.ADR_FSINFO]
        lea     ebx, [ebp+FAT.fsinfo_buffer]
        call    fs_read32_sys
        test    eax, eax
        jnz     add_not_fs

        cmp     dword [ebx+0x1fc], 0xaa550000; check sector id
        jne     add_not_fs

        add     [ebx+0x1e8], ecx
        push    [ebp+FAT.fatStartScan]
        pop     dword [ebx+0x1ec]
        mov     eax, [ebp+FAT.ADR_FSINFO]
        call    fs_write32_sys
;    jc    add_not_fs

  add_not_fs:
        pop     ebx eax

  add_dfs_no:
        ret



clear_cluster_chain:
;-----------------------------------------------------
; input  : eax = first cluster
;-----------------------------------------------------
        push    eax ecx edx
        xor     ecx, ecx        ; cluster count

  clean_new_chain:
        cmp     eax, [ebp+FAT.LAST_CLUSTER]; end of file
        ja      delete_OK
        cmp     eax, 2          ; unfinished fat chain or zero length file
        jb      delete_OK
        cmp     eax, [ebp+FAT.ROOT_CLUSTER]; don't remove root cluster
        jz      delete_OK

        xor     edx, edx
        call    set_FAT         ; clear fat entry
        jc      access_denied_01

        inc     ecx             ; update cluster count
        mov     eax, edx        ; old cluster
        jmp     clean_new_chain

  delete_OK:
        call    add_disk_free_space; add clusters to free disk space
        clc
  access_denied_01:
        pop     edx ecx eax
        ret


if 0
get_hd_info:
;-----------------------------------------------------------
; output : eax = 0 - ok
;                3 - unknown FS
;               10 - access denied
;          edx = cluster size in bytes
;          ebx = total clusters on disk
;          ecx = free clusters on disk
;-----------------------------------------------------------
        cmp     [ebp+FAT.fs_type], 16
        jz      info_fat_ok
        cmp     [ebp+FAT.fs_type], 32
        jz      info_fat_ok
        xor     edx, edx
        xor     ebx, ebx
        xor     ecx, ecx
        mov     eax, ERROR_UNKNOWN_FS
        ret

  info_fat_ok:
;    call  reserve_hd1

        xor     ecx, ecx        ; count of free clusters
        mov     eax, 2
        mov     ebx, [ebp+FAT.LAST_CLUSTER]

  info_cluster:
        push    eax
        call    get_FAT         ; get cluster info
        jc      info_access_denied

        test    eax, eax        ; is it free?
        jnz     info_used       ; no
        inc     ecx

  info_used:
        pop     eax
        inc     eax
        cmp     eax, ebx        ; is above last cluster?
        jbe     info_cluster    ; no. test next cluster

        dec     ebx             ; cluster count
        imul    edx, [ebp+FAT.SECTORS_PER_CLUSTER], 512; cluster size in bytes
        xor     eax, eax
        ret

  info_access_denied:
        add     esp, 4
        xor     edx, edx
        xor     ebx, ebx
        xor     ecx, ecx
        mov     eax, ERROR_ACCESS_DENIED
        ret
end if

update_disk:
        cmp     [ebp+FAT.fat_change], 0 ; is fat changed?
        je      upd_no_change
        cmp     [ebp+FAT.fs_type], 12
        jz      .fat12
;-----------------------------------------------------------
; write changed fat and cache to disk
;-----------------------------------------------------------

        call    write_fat_sector
        jc      update_disk_acces_denied
        jmp     upd_no_change
.fat12:
        call    restorefatchain
        mov     [ebp+FAT.fat_change], 0

  upd_no_change:

        push    esi
        mov     esi, [ebp+PARTITION.Disk]
        call    disk_sync
        pop     esi
  update_disk_acces_denied:
        ret

fat_lock:
        lea     ecx, [ebp+FAT.Lock]
        jmp     mutex_lock
fat_unlock:
        lea     ecx, [ebp+FAT.Lock]
        jmp     mutex_unlock

; \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, 0xF0 ; 'Ё'
        jmp     .doit
.yo2:
        mov     al, 0xF1 ; 'ё'
        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, 0xF0 ; 'Ё'
        jz      .yo1
        cmp     al, 0xF1 ; 'ё'
        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, 0xF1 ; 'ё'
        jz      .yo1
        cmp     al, 0xA0 ; 'а'
        jb      .ret
        cmp     al, 0xE0 ; 'р'
        jb      .rus1
        cmp     al, 0xEF ; 'я'
        ja      .ret
; 0xE0-0xEF -> 0x90-0x9F
        sub     al, 0xE0-0x90
.ret:
        ret
.rus1:
; 0xA0-0xAF -> 0x80-0x8F
.az:
        and     al, not 0x20
        ret
.yo1:
; 0xF1 -> 0xF0
        dec     ax
        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
        test    byte [edi+11], 8
        jnz     .no
        push    ecx
        push    edi ebp
        test    byte [ebp-4], 1
        jnz     .unicode_short

        mov     eax, [edi]
        mov     ecx, [edi+4]
        mov     [ebp], eax
        mov     [ebp+4], ecx

        mov     ecx, 8
@@:
        cmp     byte [ebp+ecx-1], ' '
        loope   @b

        mov     eax, [edi+8]
        cmp     al, ' '
        je      .done
        shl     eax, 8
        mov     al, '.'

        lea     ebp, [ebp+ecx+1]
        mov     [ebp], eax
        mov     ecx, 3
@@:
        rol     eax, 8
        cmp     al, ' '
        jne     .done
        loop    @b
        dec     ebp
.done:
        and     byte [ebp+ecx+1], 0   ; CF=0
        pop     ebp edi ecx
        ret
.unicode_short:
        mov     ecx, 8
        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
@@:
        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_find_lfn:
; in: esi->name
;     [esp+4] = next
;     [esp+8] = first
;     [esp+C]... - possibly parameters for first and next
; out: CF=1 - file not found, eax=error code
;      else CF=0, esi->next name component, edi->direntry
        pusha
        lea     eax, [esp+0Ch+20h]
        call    dword [eax-4]
        jc      .reterr
        sub     esp, 262*2      ; reserve place for LFN
        push    0               ; for fat_get_name: read ASCII name
.l1:
        lea     ebp, [esp+4]
        call    fat_get_name
        jc      .l2
        call    fat_compare_name
        jz      .found
.l2:
        mov     ebp, [esp+8+262*2+4]
        lea     eax, [esp+0Ch+20h+262*2+4]
        call    dword [eax-8]
        jnc     .l1
        add     esp, 262*2+4
.reterr:
        mov     [esp+28], eax
        stc
        popa
        ret
.found:
        add     esp, 262*2+4
        mov     ebp, [esp+8]
; if this is LFN entry, advance to true entry
        cmp     byte [edi+11], 0xF
        jnz     @f
        lea     eax, [esp+0Ch+20h]
        call    dword [eax-8]
        jc      .reterr
@@:
        add     esp, 8          ; CF=0
        push    esi
        push    edi
        popa
        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

bdfe_to_fat_time:
        push    edx
        mov     edx, eax
        shr     eax, 16
        and     dh, 0x3F
        shl     eax, 6
        or      al, dh
        shr     dl, 1
        and     dl, 0x1F
        shl     eax, 5
        or      al, dl
        pop     edx
        ret

bdfe_to_fat_date:
        push    edx
        mov     edx, eax
        shr     eax, 16
        sub     ax, 1980
        and     dh, 0xF
        shl     eax, 4
        or      al, dh
        and     dl, 0x1F
        shl     eax, 5
        or      al, dl
        pop     edx
        ret

fat_entry_to_bdfe:
; convert FAT entry at edi to BDFE (block of data of folder entry) at esi, advance esi
; destroys eax
        mov     eax, [ebp-4]
        mov     [esi+4], eax    ; ASCII/UNICODE name
fat_entry_to_bdfe2:
        movzx   eax, byte [edi+11]
        mov     [esi], eax      ; attributes
        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)
        test    ebp, ebp
        jz      .ret
        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:
        ret
.ansi:
        mov     ecx, 264/4
        rep movsd
        mov     [edi-1], al
        jmp     @b

bdfe_to_fat_entry:
; convert BDFE at edx to FAT entry at edi
; destroys eax
; attributes byte
        test    byte [edi+11], 8        ; volume label?
        jnz     @f
        mov     al, [edx]
        and     al, 0x27
        and     byte [edi+11], 0x10
        or      byte [edi+11], al
@@:
        mov     eax, [edx+8]
        call    bdfe_to_fat_time
        mov     [edi+14], ax            ; creation time
        mov     eax, [edx+12]
        call    bdfe_to_fat_date
        mov     [edi+16], ax            ; creation date
        mov     eax, [edx+20]
        call    bdfe_to_fat_date
        mov     [edi+18], ax            ; last access date
        mov     eax, [edx+24]
        call    bdfe_to_fat_time
        mov     [edi+22], ax            ; last write time
        mov     eax, [edx+28]
        call    bdfe_to_fat_date
        mov     [edi+24], ax            ; last write date
        ret

hd_find_lfn:
; in: ebp -> FAT structure
; in: esi+[esp+4] -> name
; out: CF=1 - file not found, eax=error code
;      else CF=0 and edi->direntry, eax=sector
; destroys eax
        push    esi edi
        push    0
        push    0
        push    fat1x_root_first
        push    fat1x_root_next
        mov     eax, [ebp+FAT.ROOT_CLUSTER]
        cmp     [ebp+FAT.fs_type], 32
        jz      .fat32
.loop:
        and     [ebp+FAT.longname_sec1], 0
        and     [ebp+FAT.longname_sec2], 0
        call    fat_find_lfn
        jc      .notfound
        cmp     byte [esi], 0
        jz      .found
.continue:
        test    byte [edi+11], 10h
        jz      .notfound
        and     dword [esp+12], 0
        mov     eax, [edi+20-2]
        mov     ax, [edi+26]    ; cluster
.fat32:
        mov     [esp+8], eax
        mov     dword [esp+4], fat_notroot_first
        mov     dword [esp], fat_notroot_next
        jmp     .loop
.notfound:
        add     esp, 16
        pop     edi esi
        stc
        ret     4
.found:
        lea     eax, [esp+4+24]
        cmp     dword [eax], 0
        jz      @f
        mov     esi, [eax]
        and     dword [eax], 0
        jmp     .continue
@@:
        lea     eax, [esp+8]
        cmp     dword [eax], 0
        jz      .root
        call    fat_get_sector
        jmp     .cmn
.root:
        mov     eax, [eax+4]
        add     eax, [ebp+FAT.ROOT_START]
.cmn:
        add     esp, 20         ; CF=0
        pop     esi
        ret     4

;----------------------------------------------------------------
; fat_Read - FAT implementation of reading a file
; in:  ebp = pointer to FAT structure
; in:  esi+[esp+4] = name
; in:  ebx = pointer to parameters from sysfunc 70
; out: eax, ebx = return values for sysfunc 70
;----------------------------------------------------------------
fat_Read:
        call    fat_lock
        push    edi
        cmp     byte [esi], 0
        jnz     @f
.noaccess:
        pop     edi
        call    fat_unlock
        or      ebx, -1
        mov     eax, ERROR_ACCESS_DENIED
        ret
@@:
        stdcall hd_find_lfn, [esp+8]
        jnc     .found
        pop     edi
        push    eax
        call    fat_unlock
        pop     eax
        or      ebx, -1
        ret
.found:
        test    byte [edi+11], 0x10     ; do not allow read directories
        jnz     .noaccess
        cmp     dword [ebx+8], 0
        jz      @f
        xor     ebx, ebx
        call    fat_unlock
        mov     eax, ERROR_END_OF_FILE
        pop     edi
        ret
@@:
        mov     edx, [ebx+4]    ; file offset
        mov     ecx, [ebx+12]   ; size
        mov     ebx, [ebx+16]   ; buffer
        push    ebx
        push    0
        test    ecx, ecx
        jz      .done
        mov     eax, [edi+28]
        sub     eax, edx
        jb      .fileEnd
        cmp     eax, ecx
        jae     @f
        mov     ecx, eax
        mov     byte [esp], 6
@@:
        mov     eax, [edi+20-2]
        mov     ax, [edi+26]
; now eax=cluster, ebx=buffer for data, ecx=count, edx=position
        mov     edi, [ebp+FAT.SECTORS_PER_CLUSTER]
        shl     edi, 9
@@:
        cmp     eax, 2
        jb      .fileEnd
        cmp     eax, [ebp+FAT.fatRESERVED]
        jae     .fileEnd
        sub     edx, edi
        jc      @f
        call    get_FAT
        jc      .noaccess2
        jmp     @b
@@:
        mov     esi, eax
        dec     eax
        dec     eax
        imul    eax, [ebp+FAT.SECTORS_PER_CLUSTER]
        add     eax, [ebp+FAT.DATA_START]
        add     edx, edi
        jz      .alignedCluster
        mov     edi, edx
        shr     edi, 9
        add     eax, edi
        and     edx, 511
        cmp     ecx, 512
        jc      .sectorPiece
        test    edx, edx
        jz      .alignedSector
.sectorPiece:
        push    eax ebx
        lea     ebx, [ebp+FAT.buffer]
        call    fs_read32_app
        test    eax, eax
        mov     eax, ebx
        pop     ebx
        jne     .noaccess3
        add     eax, edx
        push    ecx
        add     ecx, edx
        cmp     ecx, 512
        jbe     @f
        mov     ecx, 512
@@:
        sub     ecx, edx
        call    memmove
        sub     [esp], ecx
        add     ebx, ecx
        pop     ecx eax
        xor     edx, edx
        inc     edi
        inc     eax
        test    ecx, ecx
        jz      .done
.alignedSector:
        shl     edi, 9
        add     ecx, edi
        mov     edi, [ebp+FAT.SECTORS_PER_CLUSTER]
        shl     edi, 9
.alignedCluster:
        cmp     ecx, 512
        jc      .sectorPiece
        mov     edx, eax
        mov     eax, esi
@@:
        sub     ecx, edi
        jbe     .readEnd
        call    get_FAT
        jc      .noaccess4
        cmp     eax, 2
        jb      .fileEnd2
        cmp     eax, [ebp+FAT.fatRESERVED]
        jae     .fileEnd2
        inc     esi
        cmp     eax, esi
        jz      @b
.fragmentEnd:
        xchg    eax, esi
        dec     eax
        dec     eax
        imul    eax, [ebp+FAT.SECTORS_PER_CLUSTER]
        add     eax, [ebp+FAT.DATA_START]
        push    ecx
        mov     ecx, eax
        mov     eax, esi
        dec     eax
        dec     eax
        imul    eax, [ebp+FAT.SECTORS_PER_CLUSTER]
        add     eax, [ebp+FAT.DATA_START]
        push    eax
.readFragment:
        sub     ecx, edx
        mov     eax, edx
        xor     edx, edx
        call    fs_read64_app
        shl     ecx, 9
        add     ebx, ecx
        test    eax, eax
        pop     eax
        jnz     .noaccess3
        pop     ecx
        xor     edx, edx
        jecxz   .done
        jmp     .alignedCluster
.readEnd:
        add     ecx, edi
        mov     edi, ecx
        and     ecx, 511
        shr     edi, 9
        dec     eax
        dec     eax
        imul    eax, [ebp+FAT.SECTORS_PER_CLUSTER]
        add     eax, [ebp+FAT.DATA_START]
        add     eax, edi
        push    ecx
        push    eax
        mov     ecx, eax
        jmp     .readFragment
.noaccess3:
        pop     eax
.noaccess2:
        mov     byte [esp], ERROR_DEVICE
.done:
        call    fat_unlock
        pop     eax edx edi
        sub     ebx, edx
        ret
.fileEnd:
        mov     byte [esp], ERROR_END_OF_FILE
        jmp     .done
.noaccess4:
        mov     byte [esp], ERROR_DEVICE
        jmp     @f
.fileEnd2:
        mov     byte [esp], ERROR_END_OF_FILE
@@:
        inc     esi
        xor     ecx, ecx
        jmp     .fragmentEnd

;----------------------------------------------------------------
; fat_ReadFolder - FAT implementation of reading a folder
; in:  ebp = pointer to FAT structure
; in:  esi+[esp+4] = name
; in:  ebx = pointer to parameters from sysfunc 70
; out: eax, ebx = return values for sysfunc 70
;----------------------------------------------------------------
fat_ReadFolder:
        call    fat_lock
        mov     eax, [ebp+FAT.ROOT_CLUSTER]
        push    edi
        cmp     byte [esi], 0
        jz      .doit
        stdcall hd_find_lfn, [esp+4+4]
        jnc     .found
        pop     edi
        push    eax
        call    fat_unlock
        pop     eax
        or      ebx, -1
        ret
.found:
        test    byte [edi+11], 0x10     ; do not allow read files
        jnz     .found_dir
        pop     edi
        call    fat_unlock
        or      ebx, -1
        mov     eax, ERROR_ACCESS_DENIED
        ret
.found_dir:
        mov     eax, [edi+20-2]
        mov     ax, [edi+26]    ; eax=cluster
.doit:
        push    esi
        sub     esp, 262*2      ; reserve space for LFN
        push    dword [ebx+8]   ; for fat_get_name: read ANSI/UNICODE name
        mov     edx, [ebx+16]   ; pointer to buffer
; init header
        push    eax
        mov     edi, edx
        mov     ecx, 32/4
        xor     eax, eax
        rep stosd
        pop     eax
        mov     byte [edx], 1   ; version
        mov     esi, edi        ; esi points to BDFE
        mov     ecx, [ebx+12]   ; number of blocks to read
        mov     ebx, [ebx+4]    ; index of the first block
.new_cluster:
        mov     [ebp+FAT.cluster_tmp], eax
        test    eax, eax
        jnz     @f
        cmp     [ebp+FAT.fs_type], 32
        jz      .notfound
        mov     eax, [ebp+FAT.ROOT_START]
        push    [ebp+FAT.ROOT_SECTORS]
        push    ebx
        jmp     .new_sector
@@:
        dec     eax
        dec     eax
        imul    eax, [ebp+FAT.SECTORS_PER_CLUSTER]
        push    [ebp+FAT.SECTORS_PER_CLUSTER]
        add     eax, [ebp+FAT.DATA_START]
        push    ebx
.new_sector:
        lea     ebx, [ebp+FAT.buffer]
        mov     edi, ebx
        push    eax
        call    fs_read32_sys
        test    eax, eax
        pop     eax
        jnz     .notfound2
        add     ebx, 512
        push    eax
.l1:
        push    ebp
        lea     ebp, [esp+20]
        call    fat_get_name
        pop     ebp
        jc      .l2
        cmp     byte [edi+11], 0xF
        jnz     .do_bdfe
        add     edi, 0x20
        cmp     edi, ebx
        jb      .do_bdfe
        pop     eax
        inc     eax
        dec     dword [esp+4]
        jnz     @f
        mov     eax, [ebp+FAT.cluster_tmp]
        test    eax, eax
        jz      .done
        call    get_FAT
        jc      .notfound2
        cmp     eax, 2
        jb      .done
        cmp     eax, [ebp+FAT.fatRESERVED]
        jae     .done
        push    eax
        mov     eax, [ebp+FAT.SECTORS_PER_CLUSTER]
        mov     [esp+8], eax
        pop     eax
        mov     [ebp+FAT.cluster_tmp], eax
        dec     eax
        dec     eax
        imul    eax, [ebp+FAT.SECTORS_PER_CLUSTER]
        add     eax, [ebp+FAT.DATA_START]
@@:
        lea     ebx, [ebp+FAT.buffer]
        mov     edi, ebx
        push    eax
        call    fs_read32_sys
        test    eax, eax
        pop     eax
        jnz     .notfound2
        add     ebx, 512
        push    eax
.do_bdfe:
        inc     dword [edx+8]   ; new file found
        dec     dword [esp+4]
        jns     .l2
        dec     ecx
        js      .l2
        inc     dword [edx+4]   ; new file block copied
        push    ebp
        lea     ebp, [esp+20]
        call    fat_entry_to_bdfe
        pop     ebp
.l2:
        add     edi, 0x20
        cmp     edi, ebx
        jb      .l1
        pop     eax
        inc     eax
        dec     dword [esp+4]
        jnz     .new_sector
        mov     eax, [ebp+FAT.cluster_tmp]
        test    eax, eax
        jz      .done
        call    get_FAT
        jc      .notfound2
        cmp     eax, 2
        jb      .done
        cmp     eax, [ebp+FAT.fatRESERVED]
        jae     .done
        push    eax
        mov     eax, [ebp+FAT.SECTORS_PER_CLUSTER]
        mov     [esp+8], eax
        pop     eax
        pop     ebx
        add     esp, 4
        jmp     .new_cluster
.notfound2:
        add     esp, 8
.notfound:
        add     esp, 262*2+4
        pop     esi edi
        mov     ebx, [edx+4]
        call    fat_unlock
        mov     eax, ERROR_DEVICE
        ret
.done:
        add     esp, 262*2+4+8
        mov     ebx, [edx+4]
        xor     eax, eax
        dec     ecx
        js      @f
        mov     al, ERROR_END_OF_FILE
@@:
        push    eax
        call    fat_unlock
        pop     eax
        pop     esi edi
        ret

fat1x_root_next:
        push    ecx
        lea     ecx, [ebp+FAT.buffer+0x200-0x20]
        cmp     edi, ecx
        jae     fat1x_root_next_sector
        pop     ecx
        add     edi, 0x20
        ret     ; CF=0
fat1x_root_next_sector:
; read next sector
        push    [ebp+FAT.longname_sec2]
        pop     [ebp+FAT.longname_sec1]
        mov     ecx, [eax+4]
        push    ecx
        add     ecx, [ebp+FAT.ROOT_START]
        mov     [ebp+FAT.longname_sec2], ecx
        pop     ecx
        inc     ecx
        mov     [eax+4], ecx
        cmp     ecx, [ebp+FAT.ROOT_SECTORS]
        pop     ecx
        jb      fat1x_root_first
        mov     eax, ERROR_FILE_NOT_FOUND
        stc
        ret
fat1x_root_first:
        mov     eax, [eax+4]
        add     eax, [ebp+FAT.ROOT_START]
        push    ebx
        lea     edi, [ebp+FAT.buffer]
        mov     ebx, edi
        call    fs_read32_sys
        pop     ebx
        test    eax, eax
        jnz     .readerr
        ret     ; CF=0
.readerr:
        mov     eax, ERROR_DEVICE
        stc
        ret
.notfound:
        mov     eax, ERROR_FILE_NOT_FOUND
        stc
        ret
fat1x_root_begin_write:
        push    edi eax
        call    fat1x_root_first
        pop     eax edi
        ret
fat1x_root_end_write:
        pusha
        mov     eax, [eax+4]
        add     eax, [ebp+FAT.ROOT_START]
        lea     ebx, [ebp+FAT.buffer]
        call    fs_write32_sys
        popa
        ret
fat1x_root_next_write:
        push    ecx
        lea     ecx, [ebp+FAT.buffer+0x200]
        cmp     edi, ecx
        jae     @f
        pop     ecx
        ret
@@:
        call    fat1x_root_end_write
        jmp     fat1x_root_next_sector
fat1x_root_extend_dir:
        stc
        ret

fat_notroot_next:
        push    ecx
        lea     ecx, [ebp+FAT.buffer+0x200-0x20]
        cmp     edi, ecx
        jae     fat_notroot_next_sector
        pop     ecx
        add     edi, 0x20
        ret     ; CF=0
fat_notroot_next_sector:
        push    [ebp+FAT.longname_sec2]
        pop     [ebp+FAT.longname_sec1]
        push    eax
        call    fat_get_sector
        mov     [ebp+FAT.longname_sec2], eax
        pop     eax
        mov     ecx, [eax+4]
        inc     ecx
        cmp     ecx, [ebp+FAT.SECTORS_PER_CLUSTER]
        jae     fat_notroot_next_cluster
        mov     [eax+4], ecx
        jmp     @f
fat_notroot_next_cluster:
        push    eax
        mov     eax, [eax]
        call    get_FAT
        mov     ecx, eax
        pop     eax
        jc      fat_notroot_first.deverr
        cmp     ecx, 2
        jb      fat_notroot_next_err
        cmp     ecx, [ebp+FAT.fatRESERVED]
        jae     fat_notroot_next_err
        mov     [eax], ecx
        and     dword [eax+4], 0
@@:
        pop     ecx
fat_notroot_first:
        call    fat_get_sector
        push    ebx
        lea     edi, [ebp+FAT.buffer]
        mov     ebx, edi
        call    fs_read32_sys
        pop     ebx
        test    eax, eax
        jz      .ret ; CF=0
        push    ecx
.deverr:
        pop     ecx
        mov     eax, ERROR_DEVICE
        stc
.ret:
        ret
fat_notroot_next_err:
        pop     ecx
        mov     eax, ERROR_FILE_NOT_FOUND
        stc
        ret
fat_notroot_begin_write:
        push    eax edi
        call    fat_notroot_first
        pop     edi eax
        ret
fat_notroot_end_write:
        call    fat_get_sector
        push    ebx
        lea     ebx, [ebp+FAT.buffer]
        call    fs_write32_sys
        pop     ebx
        ret
fat_notroot_next_write:
        push    ecx
        lea     ecx, [ebp+FAT.buffer+0x200]
        cmp     edi, ecx
        jae     @f
        pop     ecx
        ret
@@:
        push    eax
        call    fat_notroot_end_write
        pop     eax
        jmp     fat_notroot_next_sector
fat_notroot_extend_dir:
        push    eax
        call    get_free_FAT
        jnc     .found
        pop     eax
        ret     ; CF=1
.found:
        push    edx
        mov     edx, [ebp+FAT.fatEND]
        call    set_FAT
        jc      .writeerr
        mov     edx, eax
        mov     eax, [esp+4]
        mov     eax, [eax]
        push    edx
        call    set_FAT
        pop     edx
        jnc     @f
.writeerr:
        pop     edx
        pop     eax
        stc
        ret
@@:
        push    ecx
        or      ecx, -1
        call    add_disk_free_space
; zero new cluster
        mov     ecx, 512/4
        lea     edi, [ebp+FAT.buffer]
        push    edi
        xor     eax, eax
        rep stosd
        pop     edi
        pop     ecx
        mov     eax, [esp+4]
        mov     [eax], edx
        and     dword [eax+4], 0
        pop     edx
        mov     eax, [eax]
        dec     eax
        dec     eax
        push    ebx ecx
        mov     ecx, [ebp+FAT.SECTORS_PER_CLUSTER]
        imul    eax, ecx
        add     eax, [ebp+FAT.DATA_START]
        mov     ebx, edi
@@:
        push    eax
        call    fs_write32_sys
        pop     eax
        inc     eax
        loop    @b
        pop     ecx ebx eax
        clc
        ret

fat_get_sector:
        push    ecx
        mov     ecx, [eax]
        dec     ecx
        dec     ecx
        imul    ecx, [ebp+FAT.SECTORS_PER_CLUSTER]
        add     ecx, [ebp+FAT.DATA_START]
        add     ecx, [eax+4]
        mov     eax, ecx
        pop     ecx
        ret

fshrad:
        call    fat_unlock
        mov     eax, ERROR_ACCESS_DENIED
        xor     ebx, ebx
        ret

;----------------------------------------------------------------
; fat_CreateFolder - FAT implementation of creating a folder
; in:  ebp = pointer to FAT structure
; in:  esi+[esp+4] = name
; in:  ebx = pointer to parameters from sysfunc 70
; out: eax, ebx = return values for sysfunc 70
;----------------------------------------------------------------
fat_CreateFolder:
        push    1
        jmp     fat_Rewrite.common

;----------------------------------------------------------------
; fat_Rewrite - FAT implementation of creating a new file
; in:  ebp = pointer to FAT structure
; in:  esi+[esp+4] = name
; in:  ebx = pointer to parameters from sysfunc 70
; out: eax, ebx = return values for sysfunc 70
;----------------------------------------------------------------
fat_Rewrite:
        push    0
.common:
        call    fat_lock
        pop     eax
        cmp     byte [esi], 0
        jz      fshrad
        mov     ecx, [ebx+12]
        mov     edx, [ebx+16]
        pushad
        xor     edi, edi
        mov     edx, [esp+4+20h]
        push    esi
        test    edx, edx
        jz      @f
        mov     esi, edx
@@:
        lodsb
        test    al, al
        jz      @f
        cmp     al, '/'
        jnz     @b
        lea     edi, [esi-1]
        jmp     @b
@@:
        pop     esi
        test    edi, edi
        jnz     .noroot
        test    edx, edx
        jnz     .hasebp
        mov     edx, [ebp+FAT.ROOT_CLUSTER]
        cmp     [ebp+FAT.fs_type], 32
        jz      .pushnotroot
        xor     edx, edx
        push    edx
        push    fat1x_root_extend_dir
        push    fat1x_root_end_write
        push    fat1x_root_next_write
        push    fat1x_root_begin_write
        push    edx
        push    edx
        push    fat1x_root_first
        push    fat1x_root_next
        jmp     .common1
.hasebp:
        mov     eax, ERROR_ACCESS_DENIED
        cmp     byte [edx], 0
        jz      .ret1
        stdcall hd_find_lfn, 0
        mov     esi, [esp+4+20h]
        jc      .ret1
        jmp     .common0
.noroot:
        mov     eax, ERROR_ACCESS_DENIED
        cmp     byte [edi+1], 0
        jz      .ret1
; check existence
        mov     byte [edi], 0
        push    edi
        stdcall hd_find_lfn, [esp+4+24h]
        pop     esi
        mov     byte [esi], '/'
        jnc     @f
.notfound0:
        mov     eax, ERROR_FILE_NOT_FOUND
.ret1:
        mov     [esp+28], eax
        call    fat_unlock
        popad
        xor     ebx, ebx
        ret
@@:
        inc     esi
.common0:
        test    byte [edi+11], 0x10     ; must be directory
        mov     eax, ERROR_ACCESS_DENIED
        jz      .ret1
        mov     edx, [edi+20-2]
        mov     dx, [edi+26]            ; ebp=cluster
        mov     eax, ERROR_FAT_TABLE
        cmp     edx, 2
        jb      .ret1
.pushnotroot:
        push    edx
        push    fat_notroot_extend_dir
        push    fat_notroot_end_write
        push    fat_notroot_next_write
        push    fat_notroot_begin_write
        push    0
        push    edx
        push    fat_notroot_first
        push    fat_notroot_next
.common1:
        call    fat_find_lfn
        jc      .notfound
; found
        test    byte [edi+11], 10h
        jz      .exists_file
; found directory; if we are creating directory, return OK,
;                  if we are creating file, say "access denied"
        add     esp, 36
        call    fat_unlock
        popad
        test    al, al
        mov     eax, ERROR_ACCESS_DENIED
        jz      @f
        mov     al, 0
@@:
        xor     ebx, ebx
        ret
.exists_file:
; found file; if we are creating directory, return "access denied",
;             if we are creating file, delete existing file and continue
        cmp     byte [esp+36+28], 0
        jz      @f
        add     esp, 36
        call    fat_unlock
        popad
        mov     eax, ERROR_ACCESS_DENIED
        xor     ebx, ebx
        ret
@@:
; delete FAT chain
        push    edi
        xor     eax, eax
        mov     dword [edi+28], eax     ; zero size
        xor     ecx, ecx
        mov     eax, [edi+20-2]
        mov     ax, [edi+26]
        mov     word [edi+20], cx
        mov     word [edi+26], cx
        test    eax, eax
        jz      .done1
@@:
        cmp     eax, [ebp+FAT.fatRESERVED]
        jae     .done1
        push    edx
        xor     edx, edx
        call    set_FAT
        mov     eax, edx
        pop     edx
        jc      .done1
        inc     ecx
        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
        add     esp, 36
        call    fat_unlock
        popad
        mov     eax, ERROR_FILE_NOT_FOUND
        xor     ebx, ebx
        ret
@@:
        sub     esp, 12
        mov     edi, esp
        call    fat_gen_short_name
.test_short_name_loop:
        push    esi edi ecx
        mov     esi, edi
        lea     eax, [esp+12+12+8]
        mov     edx, [eax+24]
        mov     [eax], edx
        and     dword [eax+4], 0
        call    dword [eax-4]
        jc      .found
.test_short_name_entry:
        cmp     byte [edi+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:
        lea     eax, [esp+12+12+8]
        call    dword [eax-8]
        jnc     .test_short_name_entry
        jmp     .found
.short_name_found:
        pop     ecx edi esi
        call    fat_next_short_name
        jnc     .test_short_name_loop
.disk_full:
        add     esp, 12+36
        call    fat_unlock
        popa
        mov     eax, ERROR_DISK_FULL
        xor     ebx, ebx
        ret
.found:
        pop     ecx edi esi
; 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
        movi    eax, 1     ; 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:
        push    -1
        push    -1
        push    -1
; find <eax> successive entries in directory
        xor     ecx, ecx
        push    eax
        lea     eax, [esp+16+8+12+8]
        mov     edx, [eax+24]
        mov     [eax], edx
        and     dword [eax+4], 0
        call    dword [eax-4]
        pop     eax
        jnc     .scan_dir
.fsfrfe3:
        add     esp, 12+8+12+36
        call    fat_unlock
        popad
        mov     eax, ERROR_DEVICE
        xor     ebx, ebx
        ret
.scan_dir:
        cmp     byte [edi], 0
        jz      .free
        cmp     byte [edi], 0xE5
        jz      .free
        xor     ecx, ecx
.scan_cont:
        push    eax
        lea     eax, [esp+16+8+12+8]
        call    dword [eax-8]
        mov     edx, eax
        pop     eax
        jnc     .scan_dir
        cmp     edx, ERROR_DEVICE
        jz      .fsfrfe3
        push    eax
        lea     eax, [esp+16+8+12+8]
        call    dword [eax+20]          ; extend directory
        pop     eax
        jnc     .scan_dir
        add     esp, 12+8+12+36
        call    fat_unlock
        popad
        mov     eax, ERROR_DISK_FULL
        xor     ebx, ebx
        ret
.free:
        test    ecx, ecx
        jnz     @f
        mov     [esp], edi
        mov     ecx, [esp+12+8+12+8]
        mov     [esp+4], ecx
        mov     ecx, [esp+12+8+12+12]
        mov     [esp+8], ecx
        xor     ecx, ecx
@@:
        inc     ecx
        cmp     ecx, eax
        jb      .scan_cont
; found!
        push    esi ecx
; If creating a directory, allocate one data cluster now and fail immediately
; if this is impossible. This prevents from creating an invalid directory entry
; on a full disk.
; yup, the argument is quite non-intuitive... but what should I do if
; the entire function uses such arguments? BTW, it refers to al from pushad,
; which in turn is filled with 0 in fat_Rewrite and 1 in fat_CreateFolder.
        cmp     byte [esp+8+12+8+12+36+28], 0
        jz      .no.preallocate.folder.data
        call    get_free_FAT
        jnc     @f
        add     esp, 8+12+8
        jmp     .disk_full
@@:
        mov     [esp+8+12+8+12+36+20], eax ; store the cluster somewhere
.no.preallocate.folder.data:
; calculate name checksum
        mov     esi, [esp+8+12]
        mov     ecx, 11
        xor     eax, eax
@@:
        ror     al, 1
        add     al, [esi]
        inc     esi
        loop    @b
        pop     ecx esi
        pop     edi
        pop     dword [esp+8+12+12]
        pop     dword [esp+8+12+12]
; edi points to first entry in free chunk
        dec     ecx
        jz      .nolfn
        push    esi
        push    eax
        lea     eax, [esp+8+8+12+8]
        call    dword [eax+8]         ; begin write
        mov     al, 40h
.writelfn:
        or      al, cl
        mov     esi, [esp+4]
        push    ecx
        dec     ecx
        imul    ecx, 13
        add     esi, ecx
        stosb
        mov     cl, 5
        call    fat_read_symbols
        mov     ax, 0xF
        stosw
        mov     al, [esp+4]
        stosb
        mov     cl, 6
        call    fat_read_symbols
        xor     eax, eax
        stosw
        mov     cl, 2
        call    fat_read_symbols
        pop     ecx
        lea     eax, [esp+8+8+12+8]
        call    dword [eax+12]         ; next write
        xor     eax, eax
        loop    .writelfn
        pop     eax
        pop     esi
;        lea     eax, [esp+8+12+8]
;        call    dword [eax+16]          ; end write
.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
        xor     ecx, ecx
        mov     word [edi+20], cx       ; high word of cluster
        mov     word [edi+26], cx       ; low word of cluster - to be filled
        mov     dword [edi+28], ecx     ; file size - to be filled
        cmp     byte [esp+36+28], cl
        jz      .doit
; create directory
        mov     byte [edi+11], 10h      ; attributes: folder
        mov     esi, edi
        lea     eax, [esp+8]
        call    dword [eax+16]  ; flush directory
        mov     eax, [esp+36+20] ; extract saved cluster
        mov     [esp+36+20], edi ; this is needed for calculating arg of add_disk_free_space!
        push    ecx
        mov     ecx, [ebp+FAT.SECTORS_PER_CLUSTER]
        shl     ecx, 9
        push    ecx
        push    edi
        jmp     .doit2
.doit:
        mov     esi, [esp+36+20]
        lea     eax, [esp+8]
        call    dword [eax+16]  ; flush directory
        push    ecx
        mov     ecx, [esp+4+36+24]
        push    ecx
        push    edi
        test    ecx, ecx
        jz      .done
        call    get_free_FAT
        jc      .diskfull
.doit2:
        push    eax
        mov     [edi+26], ax
        shr     eax, 16
        mov     [edi+20], ax
        lea     eax, [esp+16+8]
        call    dword [eax+16]  ; flush directory
        pop     eax
        push    edx
        mov     edx, [ebp+FAT.fatEND]
        call    set_FAT
        pop     edx
.write_cluster:
        push    eax
        dec     eax
        dec     eax
        imul    eax, [ebp+FAT.SECTORS_PER_CLUSTER]
        add     eax, [ebp+FAT.DATA_START]
        push    [ebp+FAT.SECTORS_PER_CLUSTER]
; write data
.write_sector:
        cmp     byte [esp+20+36+28], 0
        jnz     .writedir
        mov     ecx, 512
        cmp     dword [esp+12], ecx
        jb      .writeshort
; we can write directly from given buffer
        mov     ebx, esi
        add     esi, ecx
        jmp     .writecommon
.writeshort:
        mov     ecx, [esp+12]
        push    ecx
        lea     edi, [ebp+FAT.buffer]
        mov     ebx, edi
        rep movsb
.writedircont:
        lea     ecx, [ebp+FAT.buffer+0x200]
        sub     ecx, edi
        push    eax
        xor     eax, eax
        rep stosb
        pop     eax
        pop     ecx
.writecommon:
        push    eax
        call    fs_write32_app
        test    eax, eax
        pop     eax
        jnz     .writeerr
        inc     eax
        sub     dword [esp+12], ecx
        jz      .writedone
        dec     dword [esp]
        jnz     .write_sector
        pop     eax
; allocate new cluster
        pop     eax
        mov     ecx, eax
        call    get_free_FAT
        jc      .diskfull
        push    edx
        mov     edx, [ebp+FAT.fatEND]
        call    set_FAT
        xchg    eax, ecx
        mov     edx, ecx
        call    set_FAT
        pop     edx
        xchg    eax, ecx
        jmp     .write_cluster
.diskfull:
        mov     eax, ERROR_DISK_FULL
        jmp     .ret
.writeerr:
        pop     eax eax
        sub     esi, ecx
        mov     eax, ERROR_DEVICE
        jmp     .ret
.writedone:
        pop     eax eax
.done:
        xor     eax, eax
.ret:
        pop     edi ecx
        sub     esi, [esp+4+36+20]
        mov     [esp+4+36+28], eax
        mov     [esp+4+36+16], esi
        lea     eax, [esp+12]
        call    dword [eax+8]
        mov     [edi+28], esi
        call    dword [eax+16]
        mov     [esp+36+16], ebx
        lea     eax, [esi+511]
        shr     eax, 9
        mov     ecx, [ebp+FAT.SECTORS_PER_CLUSTER]
        lea     eax, [eax+ecx-1]
        xor     edx, edx
        div     ecx
        pop     ecx
        sub     ecx, eax
        call    add_disk_free_space
        add     esp, 36
        call    update_disk
        call    fat_unlock
        popad
        ret
.writedir:
        push    512
        lea     edi, [ebp+FAT.buffer]
        mov     ebx, edi
        mov     ecx, [ebp+FAT.SECTORS_PER_CLUSTER]
        shl     ecx, 9
        cmp     ecx, [esp+16]
        jnz     .writedircont
        dec     dword [esp+20]
        push    esi
        mov     ecx, 32/4
        rep movsd
        pop     esi
        mov     dword [edi-32], '.   '
        mov     dword [edi-32+4], '    '
        mov     dword [edi-32+8], '    '
        mov     byte [edi-32+11], 10h
        push    esi
        mov     ecx, 32/4
        rep movsd
        pop     esi
        mov     dword [edi-32], '..  '
        mov     dword [edi-32+4], '    '
        mov     dword [edi-32+8], '    '
        mov     byte [edi-32+11], 10h
        mov     ecx, [esp+20+36]
        cmp     ecx, [ebp+FAT.ROOT_CLUSTER]
        jnz     @f
        xor     ecx, ecx
@@:
        mov     word [edi-32+26], cx
        shr     ecx, 16
        mov     [edi-32+20], cx
        jmp     .writedircont

fat_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

fat_read_symbols:
        call    fat_read_symbol
        stosw
        loop    fat_read_symbols
        ret


fat_Write.access_denied:
        push    ERROR_ACCESS_DENIED
fat_Write.ret0:
        pop     eax
        xor     ebx, ebx
        ret

fat_Write.ret11:
        push    ERROR_DEVICE
        jmp     fat_Write.ret0

;----------------------------------------------------------------
; fat_Write - FAT implementation of writing to file
; in:  ebp = pointer to FAT structure
; in:  esi+[esp+4] = name
; in:  ebx = pointer to parameters from sysfunc 70
; out: eax, ebx = return values for sysfunc 70
;----------------------------------------------------------------
fat_Write:
        cmp     byte [esi], 0
        jz      .access_denied
        call    fat_lock
        push    edi
        stdcall hd_find_lfn, [esp+4+4]
        jnc     .found
        pop     edi
        push    eax
        call    fat_unlock
        jmp     .ret0
.found:
; FAT does not support files larger than 4GB
        cmp     dword [ebx+8], 0
        jz      @f
.eof:
        pop     edi
        push    ERROR_END_OF_FILE
        call    fat_unlock
        jmp     .ret0
@@:
        mov     ecx, [ebx+12]
        mov     edx, [ebx+16]
        mov     ebx, [ebx+4]
; now edi points to direntry, ebx=start byte to write,
; ecx=number of bytes to write, edx=data pointer

; extend file if needed
        add     ecx, ebx
        jc      .eof    ; FAT does not support files larger than 4GB
        push    edx
        push    eax     ; save directory sector
        push    0       ; return value=0

        call    get_time_for_file
        mov     [edi+22], ax            ; last write time
        call    get_date_for_file
        mov     [edi+24], ax            ; last write date
        mov     [edi+18], ax            ; last access date

        push    dword [edi+28]          ; save current file size
        cmp     ecx, [edi+28]
        jbe     .length_ok
        cmp     ecx, ebx
        jz      .length_ok
        call    hd_extend_file
        jnc     .length_ok
        mov     [esp+4], eax
; hd_extend_file can return three error codes: FAT table error, device error or disk full.
; First two cases are fatal errors, in third case we may write some data
        cmp     al, ERROR_DISK_FULL
        jz      .disk_full
        call    fat_unlock
        pop     eax
        pop     eax
        pop     ecx
        pop     edx
        pop     edi
        xor     ebx, ebx
        ret
.disk_full:
; correct number of bytes to write
        mov     ecx, [edi+28]
        cmp     ecx, ebx
        ja      .length_ok
        push    0
.ret:
        pop     eax
        sub     edx, [esp+12]
        mov     ebx, edx        ; ebx=number of written bytes
        call    update_disk
        test    eax, eax
        jz      @f
        mov     byte [esp+4], ERROR_DEVICE
@@:
        call    fat_unlock
        pop     eax
        pop     eax
        pop     ecx
        pop     edx
        pop     edi
        ret
.length_ok:
        mov     esi, [edi+28]
        mov     eax, [edi+20-2]
        mov     ax, [edi+26]
        mov     edi, eax        ; edi=current cluster
        push    0               ; current sector in cluster
; save directory
        mov     eax, [esp+12]
        push    ebx
        lea     ebx, [ebp+FAT.buffer]
        call    fs_write32_sys
        pop     ebx
        test    eax, eax
        jz      @f
.device_err:
        mov     byte [esp+8], ERROR_DEVICE
        jmp     .ret
.fat_err:
        mov     byte [esp+8], ERROR_FAT_TABLE
        jmp     .ret
@@:

; now ebx=start pos, ecx=end pos, both lie inside file
        sub     ecx, ebx
        jz      .ret
.write_loop:
; skip unmodified sectors
        cmp     dword [esp+4], 0x200
        jb      .modify
        sub     ebx, 0x200
        jae     .skip
        add     ebx, 0x200
.modify:
; get length of data in current sector
        push    ecx
        sub     ebx, 0x200
        jb      .hasdata
        neg     ebx
        xor     ecx, ecx
        jmp     @f
.hasdata:
        neg     ebx
        cmp     ecx, ebx
        jbe     @f
        mov     ecx, ebx
@@:
; get current sector number
        mov     eax, edi
        dec     eax
        dec     eax
        imul    eax, [ebp+FAT.SECTORS_PER_CLUSTER]
        add     eax, [ebp+FAT.DATA_START]
        add     eax, [esp+4]
; load sector if needed
        cmp     dword [esp+8], 0        ; we don't need to read uninitialized data
        jz      .noread
        cmp     ecx, 0x200      ; we don't need to read sector if it is fully rewritten
        jz      .noread
        cmp     ecx, esi        ; (same for the last sector)
        jz      .noread
        push    eax ebx
        lea     ebx, [ebp+FAT.buffer]
        call    fs_read32_app
        test    eax, eax
        pop     ebx eax
        jz      @f
.device_err2:
        pop     ecx
        jmp     .device_err
@@:
.noread:
; zero uninitialized data if file was extended (because hd_extend_file does not this)
        push    eax ecx edi
        xor     eax, eax
        mov     ecx, 0x200
        sub     ecx, [esp+8+12]
        jbe     @f
        lea     edi, [ebp+FAT.buffer]
        add     edi, [esp+8+12]
        rep stosb
@@:
; zero uninitialized data in the last sector
        mov     ecx, 0x200
        sub     ecx, esi
        jbe     @f
        lea     edi, [ebp+FAT.buffer+esi]
        rep stosb
@@:
        pop     edi ecx
; copy new data
        mov     eax, edx
        neg     ebx
        jecxz   @f
        lea     ebx, [ebp+FAT.buffer+0x200+ebx]
        call    memmove
        xor     ebx, ebx
@@:
        pop     eax
; save sector
        push    ebx
        lea     ebx, [ebp+FAT.buffer]
        call    fs_write32_app
        pop     ebx
        test    eax, eax
        jnz     .device_err2
        add     edx, ecx
        sub     [esp], ecx
        pop     ecx
        jz      .ret
.skip:
; next sector
        pop     eax
        inc     eax
        push    eax
        cmp     eax, [ebp+FAT.SECTORS_PER_CLUSTER]
        jb      @f
        and     dword [esp], 0
        mov     eax, edi
        call    get_FAT
        mov     edi, eax
        jc      .device_err
        cmp     edi, 2
        jb      .fat_err
        cmp     edi, [ebp+FAT.fatRESERVED]
        jae     .fat_err
@@:
        sub     esi, 0x200
        jae     @f
        xor     esi, esi
@@:
        sub     dword [esp+4], 0x200
        jae     @f
        and     dword [esp+4], 0
@@:
        jmp     .write_loop

hd_extend_file.zero_size:
        xor     eax, eax
        jmp     hd_extend_file.start_extend

; extends file on hd to given size (new data area is undefined)
; in: edi->direntry, ecx=new size
; out: CF=0 => OK, eax=0
;      CF=1 => error, eax=code (ERROR_FAT_TABLE or ERROR_DISK_FULL or ERROR_DEVICE)
hd_extend_file:
        push    esi
        mov     esi, [ebp+FAT.SECTORS_PER_CLUSTER]
        imul    esi, [ebp+FAT.BYTES_PER_SECTOR]
        push    ecx
; find the last cluster of file
        mov     eax, [edi+20-2]
        mov     ax, [edi+26]
        mov     ecx, [edi+28]
        jecxz   .zero_size
.last_loop:
        sub     ecx, esi
        jbe     .last_found
        call    get_FAT
        jnc     @f
.device_err:
        pop     ecx
.device_err2:
        pop     esi
        push    ERROR_DEVICE
.ret_err:
        pop     eax
        stc
        ret
@@:
        cmp     eax, 2
        jb      .fat_err
        cmp     eax, [ebp+FAT.fatRESERVED]
        jb      .last_loop
.fat_err:
        pop     ecx esi
        push    ERROR_FAT_TABLE
        jmp     .ret_err
.last_found:
        push    eax
        call    get_FAT
        jnc     @f
        pop     eax
        jmp     .device_err
@@:
        cmp     eax, [ebp+FAT.fatRESERVED]
        pop     eax
        jb      .fat_err
; set length to full number of clusters
        sub     [edi+28], ecx
.start_extend:
        pop     ecx
; now do extend
        push    edx
        mov     edx, 2          ; start scan from cluster 2
.extend_loop:
        cmp     [edi+28], ecx
        jae     .extend_done
; add new cluster
        push    eax
        call    get_free_FAT
        jc      .disk_full
        mov     edx, [ebp+FAT.fatEND]
        call    set_FAT
        mov     edx, eax
        pop     eax
        test    eax, eax
        jz      .first_cluster
        push    edx
        call    set_FAT
        pop     edx
        jmp     @f
.first_cluster:
        ror     edx, 16
        mov     [edi+20], dx
        ror     edx, 16
        mov     [edi+26], dx
@@:
        push    ecx
        mov     ecx, -1
        call    add_disk_free_space
        pop     ecx
        mov     eax, edx
        add     [edi+28], esi
        jmp     .extend_loop
.extend_done:
        mov     [edi+28], ecx
        pop     edx esi
        xor     eax, eax        ; CF=0
        ret
.device_err3:
        pop     edx
        jmp     .device_err2
.disk_full:
        pop     eax edx esi
        movi    eax, ERROR_DISK_FULL
        stc
        ret

fat_update_datetime:
        call    get_time_for_file
        mov     [edi+22], ax            ; last write time
        call    get_date_for_file
        mov     [edi+24], ax            ; last write date
        mov     [edi+18], ax            ; last access date
        ret


;----------------------------------------------------------------
; fat_SetFileEnd - FAT implementation of setting end-of-file
; in:  ebp = pointer to FAT structure
; in:  esi+[esp+4] = name
; in:  ebx = pointer to parameters from sysfunc 70
; out: eax, ebx = return values for sysfunc 70
;----------------------------------------------------------------
fat_SetFileEnd:
        call    fat_lock
        push    edi
        cmp     byte [esi], 0
        jnz     @f
.access_denied:
        push    ERROR_ACCESS_DENIED
.ret:
        call    fat_unlock
        pop     eax
        pop     edi
        ret
@@:
        stdcall hd_find_lfn, [esp+4+4]
        jnc     @f
.reteax:
        push    eax
        jmp     .ret
@@:
; must not be directory
        test    byte [edi+11], 10h
        jnz     .access_denied
; file size must not exceed 4 Gb
        cmp     dword [ebx+8], 0
        jz      @f
        push    ERROR_END_OF_FILE
        jmp     .ret
@@:
        push    eax     ; save directory sector
; set file modification date/time to current
        call    fat_update_datetime
        mov     eax, [ebx+4]
        cmp     eax, [edi+28]
        jb      .truncate
        ja      .expand
        pop     eax
        lea     ebx, [ebp+FAT.buffer]
        call    fs_write32_sys
        test    eax, eax
        jz      @f
        push    ERROR_DEVICE
        jmp     .ret
@@:
        push    0
        jmp     .ret
.expand:
        push    ebx ebp ecx
        push    dword [edi+28]  ; save old size
        mov     ecx, eax
        call    hd_extend_file
        push    eax             ; return code
        jnc     .expand_ok
        cmp     al, ERROR_DISK_FULL
        jz      .disk_full
.pop_ret:
        call    update_disk
        pop     eax ecx ecx ebp ebx ecx
        jmp     .reteax
.expand_ok:
.disk_full:
; save directory
        mov     eax, [edi+28]
        xchg    eax, [esp+20]
        lea     ebx, [ebp+FAT.buffer]
        call    fs_write32_sys
        test    eax, eax
        mov     eax, [edi+20-2]
        mov     ax, [edi+26]
        mov     edi, eax
        jz      @f
.pop_ret11:
        mov     byte [esp], ERROR_DEVICE
        jmp     .pop_ret
@@:
        test    edi, edi
        jz      .pop_ret
; now zero new data
        push    0
; edi=current cluster, [esp]=sector in cluster
; [esp+24]=new size, [esp+8]=old size, [esp+4]=return code
.zero_loop:
        cmp     edi, 2
        jb      .error_fat
        cmp     edi, [ebp+FAT.fatRESERVED]
        jae     .error_fat
        sub     dword [esp+8], 0x200
        jae     .next_cluster
        lea     eax, [edi-2]
        imul    eax, [ebp+FAT.SECTORS_PER_CLUSTER]
        add     eax, [ebp+FAT.DATA_START]
        add     eax, [esp]
        cmp     dword [esp+8], -0x200
        jz      .noread
        push    eax
        lea     ebx, [ebp+FAT.buffer]
        call    fs_read32_app
        test    eax, eax
        pop     eax
        jnz     .err_next
.noread:
        mov     ecx, [esp+8]
        neg     ecx
        push    edi
        lea     edi, [ebp+FAT.buffer+0x200]
        add     edi, [esp+12]
        push    eax
        xor     eax, eax
        mov     [esp+16], eax
        rep stosb
        pop     eax
        pop     edi
        call    fs_write32_app
        test    eax, eax
        jz      .next_cluster
.err_next:
        mov     byte [esp+4], ERROR_DEVICE
.next_cluster:
        pop     eax
        sub     dword [esp+20], 0x200
        jbe     .pop_ret
        inc     eax
        push    eax
        cmp     eax, [ebp+FAT.SECTORS_PER_CLUSTER]
        jb      .zero_loop
        and     dword [esp], 0
        mov     eax, edi
        call    get_FAT
        mov     edi, eax
        jnc     .zero_loop
        pop     eax
        jmp     .pop_ret11
.truncate:
        mov     [edi+28], eax
        push    ecx
        mov     ecx, [edi+20-2]
        mov     cx, [edi+26]
        push    eax
        test    eax, eax
        jz      .zero_size
; find new last cluster
@@:
        cmp     ecx, 2
        jb      .error_fat2
        cmp     ecx, [ebp+FAT.fatRESERVED]
        jae     .error_fat2
        mov     eax, [ebp+FAT.SECTORS_PER_CLUSTER]
        shl     eax, 9
        sub     [esp], eax
        jbe     @f
        mov     eax, ecx
        call    get_FAT
        mov     ecx, eax
        jnc     @b
.device_err3:
        pop     eax ecx eax edi
        call    update_disk
        call    fat_unlock
        movi    eax, ERROR_DEVICE
        ret
@@:
; we will zero data at the end of last sector - remember it
        push    ecx
; terminate FAT chain
        push    edx
        mov     eax, ecx
        mov     edx, [ebp+FAT.fatEND]
        call    set_FAT
        mov     eax, edx
        pop     edx
        jnc     @f
.device_err4:
        pop     ecx
        jmp     .device_err3
.zero_size:
        and     word [edi+20], 0
        and     word [edi+26], 0
        push    0
        mov     eax, ecx
@@:
; delete FAT chain
        call    clear_cluster_chain
        jc      .device_err4
; save directory
        mov     eax, [esp+12]
        push    ebx
        lea     ebx, [ebp+FAT.buffer]
        call    fs_write32_sys
        pop     ebx
        test    eax, eax
        jnz     .device_err4
; zero last sector, ignore errors
        pop     ecx
        pop     eax
        dec     ecx
        imul    ecx, [ebp+FAT.SECTORS_PER_CLUSTER]
        add     ecx, [ebp+FAT.DATA_START]
        push    eax
        sar     eax, 9
        add     ecx, eax
        pop     eax
        and     eax, 0x1FF
        jz      .truncate_done
        push    ebx eax
        mov     eax, ecx
        lea     ebx, [ebp+FAT.buffer]
        call    fs_read32_app
        pop     eax
        lea     edi, [ebp+FAT.buffer+eax]
        push    ecx
        mov     ecx, 0x200
        sub     ecx, eax
        xor     eax, eax
        rep stosb
        pop     eax
        call    fs_write32_app
        pop     ebx
.truncate_done:
        pop     ecx eax edi
        call    update_disk
        call    fat_unlock
        xor     eax, eax
        ret
.error_fat:
        pop     eax
        mov     byte [esp], ERROR_FAT_TABLE
        jmp     .pop_ret
.error_fat2:
        pop     eax ecx eax edi
        call    update_disk
        call    fat_unlock
        movi    eax, ERROR_FAT_TABLE
        ret

;----------------------------------------------------------------
; fat_GetFileInfo - FAT implementation of getting file info
; in:  ebp = pointer to FAT structure
; in:  esi+[esp+4] = name
; in:  ebx = pointer to parameters from sysfunc 70
; out: eax, ebx = return values for sysfunc 70
;----------------------------------------------------------------
fat_GetFileInfo:
        cmp     byte [esi], 0
        jnz     @f
        mov     eax, 2
        ret
@@:
        push    edi
        call    fat_lock
        stdcall hd_find_lfn, [esp+4+4]
        jc      .error
        push    ebp
        xor     ebp, ebp
        mov     esi, [ebx+16]
        mov     dword [esi+4], ebp
        call    fat_entry_to_bdfe2
        pop     ebp
        call    fat_unlock
        xor     eax, eax
        pop     edi
        ret
.error:
        push    eax
        call    fat_unlock
        pop     eax
        pop     edi
        ret

;----------------------------------------------------------------
; fat_SetFileInfo - FAT implementation of setting file info
; in:  ebp = pointer to FAT structure
; in:  esi+[esp+4] = name
; in:  ebx = pointer to parameters from sysfunc 70
; out: eax, ebx = return values for sysfunc 70
;----------------------------------------------------------------
fat_SetFileInfo:
        cmp     byte [esi], 0
        jnz     @f
        mov     eax, 2
        ret
@@:
        push    edi
        call    fat_lock
        stdcall hd_find_lfn, [esp+4+4]
        jc      .error
        push    eax
        mov     edx, [ebx+16]
        call    bdfe_to_fat_entry
        pop     eax
        lea     ebx, [ebp+FAT.buffer]
        call    fs_write32_sys
        call    update_disk
        call    fat_unlock
        pop     edi
        xor     eax, eax
        ret
.error:
        push    eax
        call    fat_unlock
        pop     eax
        pop     edi
        ret

;----------------------------------------------------------------
; fat_Delete - FAT implementation of deleting a file/folder
; in:  ebp = pointer to FAT structure
; in:  esi+[esp+4] = name
; in:  ebx = pointer to parameters from sysfunc 70
; out: eax, ebx = return values for sysfunc 70
;----------------------------------------------------------------
fat_Delete:
        call    fat_lock
        cmp     byte [esi], 0
        jnz     @f
; cannot delete root!
.access_denied:
        push    ERROR_ACCESS_DENIED
.pop_ret:
        call    fat_unlock
        pop     eax
        xor     ebx, ebx
        ret
@@:
        and     [ebp+FAT.longname_sec1], 0
        and     [ebp+FAT.longname_sec2], 0
        push    edi
        stdcall hd_find_lfn, [esp+4+4]
        jnc     .found
        pop     edi
        push    ERROR_FILE_NOT_FOUND
        jmp     .pop_ret
.found:
        cmp     dword [edi], '.   '
        jz      .access_denied2
        cmp     dword [edi], '..  '
        jz      .access_denied2
        test    byte [edi+11], 10h
        jz      .dodel
; we can delete only empty folders!
        pushad
        mov     esi, [edi+20-2]
        mov     si, [edi+26]
        xor     ecx, ecx
        lea     eax, [esi-2]
        imul    eax, [ebp+FAT.SECTORS_PER_CLUSTER]
        add     eax, [ebp+FAT.DATA_START]
        lea     ebx, [ebp+FAT.buffer]
        call    fs_read32_sys
        test    eax, eax
        jnz     .err1
        lea     eax, [ebx+0x200]
        add     ebx, 2*0x20
.checkempty:
        cmp     byte [ebx], 0
        jz      .empty
        cmp     byte [ebx], 0xE5
        jnz     .notempty
        add     ebx, 0x20
        cmp     ebx, eax
        jb      .checkempty
        inc     ecx
        cmp     ecx, [ebp+FAT.SECTORS_PER_CLUSTER]
        jb      @f
        mov     eax, esi
        call    get_FAT
        jc      .err1
        cmp     eax, 2
        jb      .error_fat
        cmp     eax, [ebp+FAT.fatRESERVED]
        jae     .empty
        mov     esi, eax
        xor     ecx, ecx
@@:
        lea     eax, [esi-2]
        imul    eax, [ebp+FAT.SECTORS_PER_CLUSTER]
        add     eax, [ebp+FAT.DATA_START]
        add     eax, ecx
        lea     ebx, [ebp+FAT.buffer]
        call    fs_read32_sys
        test    eax, eax
        lea     eax, [ebx+0x200]
        jz      .checkempty
.err1:
        popad
.err2:
        pop     edi
        call    fat_unlock
        movi    eax, ERROR_DEVICE
        ret
.error_fat:
        popad
        pop     edi
        call    fat_unlock
        movi    eax, ERROR_FAT_TABLE
        ret
.notempty:
        popad
.access_denied2:
        pop     edi
        call    fat_unlock
        movi    eax, ERROR_ACCESS_DENIED
        ret
.empty:
        popad
        push    eax ebx
        lea     ebx, [ebp+FAT.buffer]
        call    fs_read32_sys
        test    eax, eax
        pop     ebx eax
        jnz     .err2
.dodel:
        push    eax
        mov     eax, [edi+20-2]
        mov     ax, [edi+26]
        xchg    eax, [esp]
; delete folder entry
        mov     byte [edi], 0xE5
; delete LFN (if present)
.lfndel:
        lea     edx, [ebp+FAT.buffer]
        cmp     edi, edx
        ja      @f
        cmp     [ebp+FAT.longname_sec2], 0
        jz      .lfndone
        push    [ebp+FAT.longname_sec2]
        push    [ebp+FAT.longname_sec1]
        pop     [ebp+FAT.longname_sec2]
        and     [ebp+FAT.longname_sec1], 0
        push    ebx
        mov     ebx, edx
        call    fs_write32_sys
        mov     eax, [esp+4]
        call    fs_read32_sys
        pop     ebx
        pop     eax
        lea     edi, [ebp+FAT.buffer+0x200]
@@:
        sub     edi, 0x20
        cmp     byte [edi], 0xE5
        jz      .lfndone
        cmp     byte [edi+11], 0xF
        jnz     .lfndone
        mov     byte [edi], 0xE5
        jmp     .lfndel
.lfndone:
        push    ebx
        lea     ebx, [ebp+FAT.buffer]
        call    fs_write32_sys
        pop     ebx
; delete FAT chain
        pop     eax
        call    clear_cluster_chain
        call    update_disk
        call    fat_unlock
        pop     edi
        xor     eax, eax
        ret

; \end{diamond}