kolibrios-gitea/kernel/trunk/fs/fat12.inc
Evgeny Grechnikov (Diamond) c1783c769f 1. Execution of files with long names (function 70.7).
2. Function 70 now supports folders on ramdisk.


git-svn-id: svn://kolibrios.org@91 a494cfbc-eb01-0410-851d-a64ba20cac60
2006-06-26 12:13:58 +00:00

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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; ;;
;; FAT12.INC ;;
;; (C) 2005 Mario79, License: GPL ;;
;; ;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
n_sector dd 0 ; temporary save for sector value
flp_status dd 0
clust_tmp_flp dd 0 ; used by analyze_directory and analyze_directory_to_write
path_pointer_flp dd 0
pointer_file_name_flp dd 0
save_root_flag db 0
save_flag db 0
root_read db 0 ; 0-necessary to load root, 1-not to load root
flp_fat db 0 ; 0-necessary to load fat, 1-not to load fat
flp_number db 0 ; 1- Floppy A, 2-Floppy B
old_track db 0 ; old value track
flp_label rb 15 ; Label and ID of inserted floppy disk
reserve_flp:
cli
cmp [flp_status],0
je reserve_flp_ok
sti
call change_task
jmp reserve_flp
reserve_flp_ok:
push eax
mov eax,[0x3000]
shl eax,5
mov eax,[eax+0x3000+4]
mov [flp_status],eax
pop eax
sti
ret
floppy_free_space:
;---------------------------------------------
;
; returns free space in edi
;
;---------------------------------------------
push eax ebx ecx
call read_flp_fat
cmp [FDC_Status],0
jne fdc_status_error_2
mov eax,0x282000
xor edi,edi
mov ecx,2847 ;1448000/512
rdfs1_1:
mov ebx,[eax]
and ebx,4095
jne rdfs2_1
add edi,512
rdfs2_1:
add eax,2
loop rdfs1_1
fdc_status_error_2:
pop ecx ebx eax
ret
floppy_fileread:
;----------------------------------------------------------------
;
; fileread - sys floppy
;
; eax points to filename 11 chars - for root directory
; ebx first wanted block ; 1+ ; if 0 then set to 1
; ecx number of blocks to read ; 1+ ; if 0 then set to 1
; edx mem location to return data
; esi length of filename 12*X
; edi pointer to path /fd/1/...... - for all files in nested directories
;
; ret ebx = size or 0xffffffff file not found
; eax = 0 ok read or other = errormsg
; 10 = access denied
;--------------------------------------------------------------
mov [save_flag],0
mov [path_pointer_flp],edi
cmp esi,0 ; return ramdisk root
jne fr_noroot_1
cmp ebx,224/16
jbe fr_do_1
mov eax,5
mov ebx,0
mov [flp_status],0
ret
fr_do_1:
push ebx ecx edx
call read_flp_root
pop edx ecx ebx
cmp [FDC_Status],0
jne fdc_status_error_1
mov edi,edx
dec ebx
shl ebx,9
mov esi,0x8000
add esi,ebx
shl ecx,9
cld
rep movsb
mov eax,0 ; ok read
mov ebx,0
mov [flp_status],0
ret
fdc_status_error_1:
mov [flp_status],0
mov eax,10
mov ebx,-1
ret
fr_noroot_1:
sub esp,32
call expand_filename
frfloppy_1:
cmp ebx,0
jne frfl5_1
mov ebx,1
frfl5_1:
cmp ecx,0
jne frfl6_1
mov ecx,1
frfl6_1:
dec ebx
push eax
push eax ebx ecx edx esi edi
call read_flp_fat
cmp [FDC_Status],0
jne fdc_status_error_3_1
mov [FDD_Track],0 ; <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
mov [FDD_Head],1 ; <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
mov [FDD_Sector],2 ; <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
call SeekTrack
mov dh,14
l.20_1:
call ReadSectWithRetr
cmp [FDC_Status],0
jne fdc_status_error_3_1
mov dl,16
mov edi,0xD000
inc [FDD_Sector]
l.21_1:
mov esi,eax ;Name of file we want
mov ecx,11
cld
rep cmpsb ;Found the file?
je fifound_1 ;Yes
add ecx,21
add edi, ecx ;Advance to next entry
dec dl
cmp dl,0
jne l.21_1
dec dh
cmp dh,0
jne l.20_1
fdc_status_error_3:
mov eax,5 ; file not found ?
mov ebx,-1
add esp,32+28
mov [flp_status],0
ret
fdc_status_error_3_2:
cmp [FDC_Status],0
je fdc_status_error_3
fdc_status_error_3_1:
add esp,32+28
jmp fdc_status_error_1
fifound_1:
mov eax,[path_pointer_flp]
cmp [eax+36],byte 0
je fifound_2
add edi,0xf
mov eax,[edi]
and eax,65535
mov ebx,[path_pointer_flp]
add ebx,36
call get_cluster_of_a_path_flp
jc fdc_status_error_3_2
mov ebx,[ebx-11+28] ;file size
mov [esp+20],ebx
mov [esp+24],ebx
jmp fifound_3
fifound_2:
mov ebx,[edi-11+28] ;file size
mov [esp+20],ebx
mov [esp+24],ebx
add edi,0xf
mov eax,[edi]
fifound_3:
and eax,65535
mov [n_sector],eax ;eax=cluster
frnew_1:
add eax,31 ;bootsector+2*fat+filenames
cmp [esp+16],dword 0 ; wanted cluster ?
jne frfl7_1
call read_chs_sector
cmp [FDC_Status],0
jne fdc_status_error_5
mov edi,[esp+8]
call give_back_application_data_1
add [esp+8],dword 512
dec dword [esp+12] ; last wanted cluster ?
cmp [esp+12],dword 0
je frnoread_1
jmp frfl8_1
frfl7_1:
dec dword [esp+16]
frfl8_1:
mov edi,[n_sector]
shl edi,1 ;find next cluster from FAT
add edi,0x282000
mov eax,[edi]
and eax,4095
mov edi,eax
mov [n_sector],edi
cmp edi,4095 ;eof - cluster
jz frnoread2_1
cmp [esp+24],dword 512 ;eof - size
jb frnoread_1
sub [esp+24],dword 512
jmp frnew_1
read_chs_sector:
call calculate_chs
call ReadSectWithRetr
ret
frnoread2_1:
cmp [esp+16],dword 0 ; eof without read ?
je frnoread_1
mov [fdc_irq_func],fdc_null
pop edi esi edx ecx
add esp,4
pop ebx ; ebx <- eax : size of file
add esp,36
mov eax,6 ; end of file
mov [flp_status],0
ret
frnoread_1:
pop edi esi edx ecx
add esp,4
pop ebx ; ebx <- eax : size of file
add esp,36
mov eax,0
mov [flp_status],0
ret
fdc_status_error_5:
pop edi esi edx ecx
add esp,4
pop ebx ; ebx <- eax : size of file
add esp,36
jmp fdc_status_error_1
read_flp_root:
pusha
call check_label
cmp [FDC_Status],0
jne unnecessary_root_read
cmp [root_read],1
je unnecessary_root_read
mov [FDD_Track],0 ; <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
mov [FDD_Head],1 ; <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
mov [FDD_Sector],2 ; <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
mov edi,0x8000
call SeekTrack
read_flp_root_1:
call ReadSectWithRetr
cmp [FDC_Status],0
jne unnecessary_root_read
push edi
call give_back_application_data_1
pop edi
add edi,512
inc [FDD_Sector]
cmp [FDD_Sector],16
jne read_flp_root_1
mov [root_read],1
unnecessary_root_read:
popa
ret
read_flp_fat:
pusha
call check_label
cmp [FDC_Status],0
jne unnecessary_flp_fat
cmp [flp_fat],1
je unnecessary_flp_fat
mov [FDD_Track],0 ; <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
mov [FDD_Head],0 ; <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
mov [FDD_Sector],2 ; <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
mov edi,0x8000
call SeekTrack
read_flp_fat_1:
call ReadSectWithRetr
cmp [FDC_Status],0
jne unnecessary_flp_fat
push edi
call give_back_application_data_1
pop edi
add edi,512
inc [FDD_Sector]
cmp [FDD_Sector],19
jne read_flp_fat_1
mov [FDD_Sector],1
mov [FDD_Head],1
call ReadSectWithRetr
cmp [FDC_Status],0
jne unnecessary_flp_fat
call give_back_application_data_1
call calculatefatchain_flp
mov [root_read],0
mov [flp_fat],1
unnecessary_flp_fat:
popa
ret
calculatefatchain_flp:
pushad
mov esi,0x8000
mov edi,0x282000
fcnew_1:
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
add edi,4
mov dword [edi],ebx
add edi,4
mov dword [edi],ecx
add edi,4
mov dword [edi],edx
add edi,4
add esi,12
cmp edi,0x282000+2856*2 ;2849 clusters
jnz fcnew_1
popad
ret
check_label:
pushad
mov [FDD_Track],0 ; <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
mov [FDD_Head],0 ; <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
mov [FDD_Sector],1 ; <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
call SetUserInterrupts
call FDDMotorON
call RecalibrateFDD
cmp [FDC_Status],0
jne fdc_status_error
call SeekTrack
cmp [FDC_Status],0
jne fdc_status_error
call ReadSectWithRetr
cmp [FDC_Status],0
jne fdc_status_error
mov esi,flp_label
mov edi,0xD000+39
mov ecx,15
cld
rep cmpsb
je same_label
mov [root_read],0
mov [flp_fat],0
same_label:
mov esi,0xD000+39
mov edi,flp_label
mov ecx,15
cld
rep movsb
popad
ret
fdc_status_error:
popad
ret
save_flp_root:
pusha
call check_label
cmp [FDC_Status],0
jne unnecessary_root_save
cmp [root_read],0
je unnecessary_root_save
mov [FDD_Track],0 ; <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
mov [FDD_Head],1 ; <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
mov [FDD_Sector],2 ; <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
mov esi,0x8000
call SeekTrack
save_flp_root_1:
push esi
call take_data_from_application_1
pop esi
add esi,512
call WriteSectWithRetr
cmp [FDC_Status],0
jne unnecessary_root_save
inc [FDD_Sector]
cmp [FDD_Sector],16
jne save_flp_root_1
unnecessary_root_save:
mov [fdc_irq_func],fdc_null
popa
ret
save_flp_fat:
pusha
call check_label
cmp [FDC_Status],0
jne unnecessary_flp_fat_save
cmp [flp_fat],0
je unnecessary_flp_fat_save
call restorefatchain_flp
mov [FDD_Track],0 ; <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
mov [FDD_Head],0 ; <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
mov [FDD_Sector],2 ; <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
mov esi,0x8000
call SeekTrack
save_flp_fat_1:
push esi
call take_data_from_application_1
pop esi
add esi,512
call WriteSectWithRetr
cmp [FDC_Status],0
jne unnecessary_flp_fat_save
inc [FDD_Sector]
cmp [FDD_Sector],19
jne save_flp_fat_1
mov [FDD_Sector],1
mov [FDD_Head],1
call take_data_from_application_1
call WriteSectWithRetr
cmp [FDC_Status],0
jne unnecessary_flp_fat_save
mov [root_read],0
unnecessary_flp_fat_save:
mov [fdc_irq_func],fdc_null
popa
ret
restorefatchain_flp: ; restore fat chain
pushad
mov esi,0x282000
mov edi,0x8000
fcnew2_1:
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
add edi,4
mov word [edi],bx
add edi,2
add esi,8
cmp edi,0x8000+0x1200 ;4274 bytes - all used FAT
jb fcnew2_1
mov esi,0x8000 ; duplicate fat chain
mov edi,0x8000+0x1200
mov ecx,0x1200/4
cld
rep movsd
popad
ret
floppy_filedelete:
;--------------------------------------------
;
; filedelete - sys floppy
; in:
; eax - filename 11 chars - for root directory
; edi pointer to path /fd/1/...... - for all files in nested directories
;
; out:
; eax - 0 = successful, 1 = file not found, 10 = access denied
;
;--------------------------------------------
mov [path_pointer_flp],edi
mov [save_flag],0
mov ebp,1 ; file not found as default
filedelete_newtry_1:
sub esp,32
call expand_filename
push eax ebx ecx edx esi edi
call read_flp_fat
cmp [FDC_Status],0
jne frnoreadd_1
mov [FDD_Track],0 ; <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
mov [FDD_Head],1 ; <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
mov [FDD_Sector],2 ; <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
call SeekTrack
mov dh,14
l.20_2:
call ReadSectWithRetr
cmp [FDC_Status],0
jne fdc_status_error_4
mov dl,16
mov edi,0xD000
inc [FDD_Sector]
l.21_2:
mov esi,eax ;Name of file we want
mov ecx,11
cld
rep cmpsb ;Found the file?
je fifoundd_1 ;Yes
add ecx,21
add edi, ecx ;Advance to next entry
dec dl
jne l.21_2
dec dh
jne l.20_2
jmp frnoreadd_1
fdc_status_error_4:
pop edi esi edx ecx ebx eax
add esp,32
jmp fdc_status_error_1
fifoundd_1:
mov eax,[path_pointer_flp]
cmp [eax+36],byte 0
je fifoundd_2
movzx eax, word [edi+0xf]
mov ebx,[path_pointer_flp]
add ebx,36
call get_cluster_of_a_path_flp
jc frnoreadd_1_1
mov edi,ebx
add edi,11
jmp fifoundd_2_1
fifoundd_2:
dec [FDD_Sector]
fifoundd_2_1:
mov [edi-11],byte 0xE5 ;mark filename deleted
movzx edi, word [edi+0xf] ;edi = cluster
frnewd_1:
shl edi,1 ;find next cluster from FAT
add edi,0x282000
mov eax,[edi]
mov [edi],word 0x0 ;clear fat chain cluster
and eax,4095
mov edi,eax
cmp edi,dword 4095 ;last cluster ?
jz frnoreadd2_1
jmp frnewd_1
frnoreadd2_1:
call WriteSectWithRetr
cmp [FDC_Status],0
jne fdc_status_error_4
call save_flp_fat
cmp [FDC_Status],0
jne fdc_status_error_4
; pop edi esi edx ecx ebx eax
; add esp,32
mov ebp,0 ; file found
; jmp filedelete_newtry_1
jmp frnoreadd_1
frnoreadd_1_1:
cmp [FDC_Status],0
jne fdc_status_error_4
frnoreadd_1:
pop edi esi edx ecx ebx eax
add esp,32
mov eax,ebp
ret
floppy_filesave:
;----------------------------------------------------------
;
; filesave - sys floppy
;
; eax ; pointer to file name 11 chars - for root directory
; ebx ; buffer
; ecx ; count to write in bytes
; edx ; 0 create new , 1 append
; edi pointer to path /fd/1/...... - for all files in nested directories
;
; output : eax = 0 - ok
; 5 - file not found / directory not found
; 8 - disk full
; 10 - access denied
;-----------------------------------------------------------
mov [path_pointer_flp],edi
sub esp,32
call expand_filename
cmp edx,0
jnz fsdel_1
pusha
call floppy_filedelete
cmp [FDC_Status],0
jne fdc_status_error_6
popa
mov [save_flag],1
fsdel_1:
call floppy_free_space
cmp [FDC_Status],0
jne fdc_status_error_6
cmp ecx,edi
jb rd_do_save_1
add esp,32
mov eax,8 ; not enough free space
mov [flp_status],0
ret
fdc_status_error_6:
popa
add esp,32
jmp fdc_status_error_1
rd_do_save_1:
push eax ebx ecx edx esi edi
call read_flp_fat
cmp [FDC_Status],0
jne fdc_status_error_7
push eax
mov eax,[path_pointer_flp]
cmp [eax+36],byte 0
jne fifoundds_2
pop eax
mov [save_root_flag],1
call read_flp_root
cmp [FDC_Status],0
jne fdc_status_error_7
mov edi,0x8000 ;Point at directory
mov edx,224 +1
; find an empty spot for filename in the root dir
l20ds_1:
sub edx,1
jz frnoreadds_1
l21ds_1:
cmp [edi],byte 0xE5
jz fifoundds_1
cmp [edi],byte 0x0
jz fifoundds_1
add edi,32 ; Advance to next entry
jmp l20ds_1
fifoundds_2:
pop eax
mov [save_root_flag],0
mov [FDD_Track],0 ; <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
mov [FDD_Head],1 ; <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
mov [FDD_Sector],2 ; <EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
call SeekTrack
mov dh,14
l.20_3:
call ReadSectWithRetr
cmp [FDC_Status],0
jne fdc_status_error_7
mov dl,16
mov edi,0xD000
inc [FDD_Sector]
l.21_3:
mov esi,eax ;Name of file we want
mov ecx,11
cld
rep cmpsb ;Found the file?
je fifoundds_3 ;Yes
add ecx,21
add edi, ecx ;Advance to next entry
dec dl
jne l.21_3
dec dh
jne l.20_3
fdc_status_error_8:
pop edi esi edx ecx ebx eax
mov eax,5 ; file not found ?
mov ebx,-1
add esp,32
mov [flp_status],0
ret
fifoundds_3:
add edi,0xf
mov eax,[edi]
and eax,65535
mov ebx,[path_pointer_flp]
add ebx,36
call get_cluster_of_a_path_flp
jc fdc_status_error_7_1
found_directory_for_writing_flp:
call analyze_directory_to_write_flp
jc fdc_status_error_7_1
mov edi,ebx
fifoundds_1:
push edi ; move the filename to root dir
mov esi,[esp+4+20]
cmp [save_root_flag],0
jne fifoundds_4
mov esi,[pointer_file_name_flp]
fifoundds_4:
mov ecx,11
cld
rep movsb
pop edi
mov edx,edi
add edx,11+0xf ; edx <- cluster save position
mov ebx,[esp+12] ; save file size
mov [edi+28],ebx
mov [edi+11],byte 0x20 ; attribute
call get_date_for_file ; from FAT32.INC
mov [edi+24],ax ; date
mov [edi+18],ax ; date
call get_time_for_file ; from FAT32.INC
mov [edi+22],ax ; time
xor ax,ax
mov [edi+20],ax
mov ebx,1 ; first cluster
cmp [save_root_flag],0
jne frnewds_1
call frnewds_2
pusha
call WriteSectWithRetr
popa
cmp [FDC_Status],0
jne fdc_status_error_7
jmp frnewds_3
frnewds_1:
call frnewds_2
frnewds_3:
pusha ; move save to floppy cluster
add ebx,31
mov eax,ebx
mov esi,[esp+32+16]
call take_data_from_application_1
call save_chs_sector
cmp [FDC_Status],0
jne fdc_status_error_7
popa
mov eax,[esp+12]
cmp eax,512
jb flnsa_1
sub eax,512
mov [esp+12],eax
mov eax,[esp+16]
add eax,512
mov [esp+16],eax
jmp frnewds_1
frnewds_2:
add ebx,1
mov edi,ebx ; find free cluster in FAT
shl edi,1
add edi,0x282000
mov eax,[edi]
and eax,4095
jnz frnewds_2
mov [edx],bx ; save next cluster pos. to prev cl.
mov edx,edi ; next save pos abs mem add
ret
flnsa_1:
mov [edi],word 4095 ; mark end of file - last cluster
cmp [save_root_flag],1
jne flnsa_2
call save_flp_root
cmp [FDC_Status],0
jne fdc_status_error_7
flnsa_2:
call save_flp_fat
cmp [FDC_Status],0
jne fdc_status_error_7
frnoreadds_1:
pop edi esi edx ecx ebx eax
add esp,32
mov eax,0
mov [flp_status],0
ret
fdc_status_error_7_1:
cmp [FDC_Status],0
je fdc_status_error_8
fdc_status_error_7:
pop edi esi edx ecx ebx eax
add esp,32
jmp fdc_status_error_1
save_chs_sector:
call calculate_chs
call WriteSectWithRetr
ret
calculate_chs:
mov bl,[FDD_Track]
mov [old_track],bl
mov ebx,18
xor edx,edx
div ebx
inc edx
mov [FDD_Sector],dl
xor edx,edx
mov ebx,2
div ebx
mov [FDD_Track],al
mov [FDD_Head],0
cmp edx,0
je no_head_2
inc [FDD_Head]
no_head_2:
mov dl,[old_track]
cmp dl,[FDD_Track]
je no_seek_track_1
call SeekTrack
no_seek_track_1:
ret
get_cluster_of_a_path_flp:
;---------------------------------------------------------
; input : EBX = pointer to a path string
; (example: the path "/files/data/document" become
; "files......data.......document...0"
; '.' = space char
; '0' = char(0) (ASCII=0) !!! )
; output : if (CARRY=1) -> ERROR in the PATH
; if (CARRY=0) -> EAX=cluster
;---------------------------------------------------------
push edx
mov edx,ebx
search_end_of_path_flp:
cmp [save_flag],0
jne search_end_of_path_flp_1
cmp byte [edx],0
je found_end_of_path_flp
jmp search_end_of_path_flp_2
search_end_of_path_flp_1:
cmp byte [edx+12],0
je found_end_of_path_flp
search_end_of_path_flp_2:
inc edx ; '/'
call analyze_directory_flp
jc directory_not_found_flp
mov eax,[ebx+20-2] ; read the HIGH 16bit cluster field
mov ax,[ebx+26] ; read the LOW 16bit cluster field
and eax,0xfff ;[fatMASK]
add edx,11 ; 8+3 (name+extension)
jmp search_end_of_path_flp
found_end_of_path_flp:
inc edx
mov [pointer_file_name_flp],edx
pop edx
clc ; no errors
ret
directory_not_found_flp:
pop edx
stc ; errors occour
ret
analyze_directory_flp:
;--------------------------------
; input : EAX = first cluster of the directory
; EBX = pointer to filename
; output : IF CARRY=0 EAX = sector where th file is found
; EBX = pointer in buffer
; [buffer .. buffer+511]
; ECX,EDX,EDI,EDI not changed
; IF CARRY=1
;--------------------------------
push ebx ;[esp+16]
push ecx
push edx
push esi
push edi
adr56_flp:
mov [clust_tmp_flp],eax
add eax,31
pusha
call read_chs_sector
popa
cmp [FDC_Status],0
jne not_found_file_analyze_flp
mov ecx,512/32
mov ebx,0xD000
adr1_analyze_flp:
mov esi,edx ;[esp+16]
mov edi,ebx
cld
push ecx
mov ecx,11
rep cmpsb
pop ecx
je found_file_analyze_flp
add ebx,32
loop adr1_analyze_flp
mov eax,[clust_tmp_flp]
shl eax,1 ;find next cluster from FAT
add eax,0x282000
mov eax,[eax]
and eax,4095
cmp eax,0x0ff8
jb adr56_flp
not_found_file_analyze_flp:
pop edi
pop esi
pop edx
pop ecx
add esp,4
stc ;file not found
ret
found_file_analyze_flp:
pop edi
pop esi
pop edx
pop ecx
add esp,4
clc ;file found
ret
analyze_directory_to_write_flp:
;--------------------------------
; input : EAX = first cluster of the directory
; output : IF CARRY=0 EAX = sector where the file is found
; EBX = pointer in buffer
; [buffer .. buffer+511]
; ECX,EDX,EDI,EDI not changed
; IF CARRY=1
;--------------------------------
push ecx
push edx
push esi
adr561:
mov [clust_tmp_flp],eax
add eax,31
pusha
call read_chs_sector
popa
cmp [FDC_Status],0
jne error_found_file_analyze1
mov ecx,512/32
mov ebx,0xD000
adr1_analyze1:
cmp byte [ebx],0x00
je found_file_analyze1
cmp byte [ebx],0xe5
je found_file_analyze1
avanti:
add ebx,32
loop adr1_analyze1
mov eax,[clust_tmp_flp]
shl eax,1 ;find next cluster from FAT
add eax,0x282000
mov eax,[eax]
and eax,4095
cmp eax,0x0ff8
jb adr561
call get_free_FAT ;this block of code add a new cluster
;for the directory because the directory
;is full
mov [edi],word 0x0fff
mov eax,[clust_tmp_flp]
shl eax,1 ;find next cluster from FAT
add eax,0x282000
sub edi,0x282000
mov [eax],di
pusha
mov ecx,512/4
xor eax,eax
mov edi,0xD000
cld
rep stosd
popa
mov eax,edi
add eax,31
pusha
call save_chs_sector
popa
cmp [FDC_Status],0
jne error_found_file_analyze1
mov ebx,0xD000
found_file_analyze1:
pop esi
pop edx
pop ecx
clc ;file found
ret
error_found_file_analyze1:
pop esi
pop edx
pop ecx
stc
ret
get_free_FAT_flp:
;------------------------------------------
; input : EAX = # cluster for start the searching
; output : EAX = # first cluster found free
;-------------------------------------------
push ebx
mov ebx,1
check_new_flp:
add ebx,1
mov edi,ebx ; find free cluster in FAT
shl edi,1
add edi,0x282000
mov eax,[edi]
and eax,4095
cmp eax,0x0
jnz check_new_flp
pop ebx
ret
; \begin{diamond}
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
; 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
mov ebp, esp
push 0 ; for fat_get_name: read ASCII name
.l1:
call fat_get_name
jc .l2
call fat_compare_name
jz .found
.l2:
lea eax, [esp+0Ch+20h+262*2+4]
call dword [eax-8]
jnc .l1
add esp, 262*2+4
.reterr:
stc
popa
ret
.found:
add esp, 262*2+4
; 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
flp_root_next:
cmp edi, 0xD200-0x20
jae @f
add edi, 0x20
ret ; CF=0
@@:
; read next sector
inc dword [eax]
cmp dword [eax], 14
jae flp_root_first.readerr
flp_root_first:
mov eax, [eax]
pusha
add eax, 19
call read_chs_sector
popa
cmp [FDC_Status], 0
jnz .readerr
mov edi, 0xD000
ret ; CF=0
.readerr:
stc
ret
flp_rootmem_first:
mov edi, 0x8000
clc
ret
flp_rootmem_next:
add edi, 0x20
cmp edi, 0x8000+14*0x200
cmc
flp_rootmem_next_write:
flp_rootmem_begin_write:
flp_rootmem_end_write:
ret
flp_rootmem_extend_dir:
stc
ret
flp_notroot_next:
cmp edi, 0xD200-0x20
jae flp_notroot_next_sector
add edi, 0x20
ret ; CF=0
flp_notroot_next_sector:
push ecx
mov ecx, [eax]
mov ecx, [ecx*2+0x282000]
and ecx, 0xFFF
cmp ecx, 2849
jae flp_notroot_first.err2
mov [eax], ecx
pop ecx
flp_notroot_first:
mov eax, [eax]
cmp eax, 2
jb .err
cmp eax, 2849
jae .err
pusha
add eax, 31
call read_chs_sector
popa
mov edi, 0xD000
cmp [FDC_Status], 0
jnz .err
ret ; CF=0
.err2:
pop ecx
.err:
stc
ret
flp_notroot_begin_write:
pusha
mov eax, [eax]
add eax, 31
call read_chs_sector
popa
ret
flp_notroot_end_write:
pusha
mov eax, [eax]
add eax, 31
call save_chs_sector
popa
ret
flp_notroot_next_write:
cmp edi, 0xD200
jae @f
ret
@@:
call flp_notroot_end_write
jmp flp_notroot_next_sector
flp_notroot_extend_dir:
; find free cluster in FAT
pusha
xor eax, eax
mov edi, 0x282000
mov ecx, 2849
repnz scasw
jnz .notfound
mov word [edi-2], 0xFFF ; mark as last cluster
sub edi, 0x282000
shr edi, 1
dec edi
mov eax, [esp+28]
mov ecx, [eax]
mov [0x282000+ecx*2], di
mov [eax], edi
xor eax, eax
mov edi, 0xD000
mov ecx, 128
rep stosd
popa
call flp_notroot_end_write
mov edi, 0xD000
clc
ret
.notfound:
popa
stc
ret
fd_find_lfn:
; in: esi->name
; out: CF=1 - file not found
; else CF=0 and edi->direntry, eax=directory cluster (0 for root)
push esi edi
push 0
push flp_root_first
push flp_root_next
.loop:
call fat_find_lfn
jc .notfound
cmp byte [esi], 0
jz .found
test byte [edi+11], 10h
jz .notfound
movzx eax, word [edi+26] ; cluster
mov [esp+8], eax
mov dword [esp+4], flp_notroot_first
mov dword [esp], flp_notroot_next
jmp .loop
.notfound:
add esp, 12
pop edi esi
stc
ret
.found:
mov eax, [esp+8]
add esp, 16 ; CF=0
pop esi
ret
;----------------------------------------------------------------
;
; fs_FloppyRead - LFN variant for reading floppy
;
; esi points to filename
; ebx pointer to 64-bit number = first wanted byte, 0+
; may be ebx=0 - start from first byte
; ecx number of bytes to read, 0+
; edx mem location to return data
;
; ret ebx = bytes read or 0xffffffff file not found
; eax = 0 ok read or other = errormsg
;
;--------------------------------------------------------------
fs_FloppyRead:
call read_flp_fat
cmp byte [esi], 0
jnz @f
or ebx, -1
mov eax, 10 ; access denied
ret
@@:
push edi
call fd_find_lfn
jnc .found
pop edi
or ebx, -1
mov eax, 5 ; file not found
ret
.found:
test ebx, ebx
jz .l1
cmp dword [ebx+4], 0
jz @f
xor ebx, ebx
.reteof:
mov eax, 6 ; EOF
pop edi
ret
@@:
mov ebx, [ebx]
.l1:
push ecx edx
push 0
mov eax, [edi+28]
sub eax, ebx
jb .eof
cmp eax, ecx
jae @f
mov ecx, eax
mov byte [esp], 6 ; EOF
@@:
movzx edi, word [edi+26]
.new:
jecxz .done
test edi, edi
jz .eof
cmp edi, 0xFF8
jae .eof
lea eax, [edi+31]
pusha
call read_chs_sector
popa
cmp [FDC_Status], 0
jnz .err
sub ebx, 512
jae .skip
lea eax, [0xD000+ebx+512]
neg ebx
push ecx
cmp ecx, ebx
jbe @f
mov ecx, ebx
@@:
mov ebx, edx
call memmove
add edx, ecx
sub [esp], ecx
pop ecx
xor ebx, ebx
.skip:
movzx edi, word [edi*2+0x282000]
jmp .new
.done:
mov ebx, edx
pop eax edx ecx edi
sub ebx, edx
ret
.eof:
mov ebx, edx
pop eax edx ecx
jmp .reteof
.err:
mov ebx, edx
pop eax edx ecx edi
sub ebx, edx
mov al, 11
ret
;----------------------------------------------------------------
;
; fs_FloppyReadFolder - LFN variant for reading floppy folders
;
; esi points to filename
; ebx pointer to structure: 32-bit number = first wanted block, 0+
; & flags (bitfields)
; flags: bit 0: 0=ANSI names, 1=UNICODE names
; ecx number of blocks to read, 0+
; edx mem location to return data
;
; ret ebx = blocks read or 0xffffffff folder not found
; eax = 0 ok read or other = errormsg
;
;--------------------------------------------------------------
fs_FloppyReadFolder:
call read_flp_fat
push edi
cmp byte [esi], 0
jz .root
call fd_find_lfn
jnc .found
pop edi
or ebx, -1
mov eax, ERROR_FILE_NOT_FOUND
ret
.found:
test byte [edi+11], 0x10 ; do not allow read files
jnz .found_dir
pop edi
or ebx, -1
mov eax, ERROR_ACCESS_DENIED
ret
.found_dir:
movzx eax, word [edi+26]
add eax, 31
push 0
jmp .doit
.root:
mov eax, 19
push 14
.doit:
push ecx ebp
sub esp, 262*2 ; reserve space for LFN
mov ebp, esp
push dword [ebx+4] ; for fat_get_name: read ANSI/UNICODE names
mov ebx, [ebx]
; init header
push eax ecx
mov edi, edx
mov ecx, 32/4
xor eax, eax
rep stosd
pop ecx eax
mov byte [edx], 1 ; version
mov esi, edi ; esi points to BDFE
.main_loop:
pusha
call read_chs_sector
popa
cmp [FDC_Status], 0
jnz .error
mov edi, 0xD000
push eax
.l1:
call fat_get_name
jc .l2
cmp byte [edi+11], 0xF
jnz .do_bdfe
add edi, 0x20
cmp edi, 0xD200
jb .do_bdfe
pop eax
inc eax
dec byte [esp+262*2+12]
jz .done
jns @f
; read next sector from FAT
mov eax, [(eax-31-1)*2+0x282000]
and eax, 0xFFF
cmp eax, 0xFF8
jae .done
add eax, 31
mov byte [esp+262*2+12], 0
@@:
pusha
call read_chs_sector
popa
cmp [FDC_Status], 0
jnz .error
mov edi, 0xD000
push eax
.do_bdfe:
inc dword [edx+8] ; new file found
dec ebx
jns .l2
dec ecx
js .l2
inc dword [edx+4] ; new file block copied
call fat_entry_to_bdfe
.l2:
add edi, 0x20
cmp edi, 0xD200
jb .l1
pop eax
inc eax
dec byte [esp+262*2+12]
jz .done
jns @f
; read next sector from FAT
mov eax, [(eax-31-1)*2+0x282000]
and eax, 0xFFF
cmp eax, 0xFF8
jae .done
add eax, 31
mov byte [esp+262*2+12], 0
@@:
jmp .main_loop
.error:
add esp, 262*2+4
pop ebp ecx edi edi
or ebx, -1
mov eax, ERROR_FILE_NOT_FOUND
ret
.done:
add esp, 262*2+4
pop ebp
mov ebx, [edx+4]
xor eax, eax
dec ecx
js @f
mov al, ERROR_END_OF_FILE
@@:
pop ecx edi edi
ret
;----------------------------------------------------------------
;
; fs_FloppyRewrite - LFN variant for writing sys floppy
;
; esi points to filename
; ebx ignored (reserved)
; ecx number of bytes to write, 0+
; edx mem location to data
;
; ret ebx = number of written bytes
; eax = 0 ok read or other = errormsg
;
;--------------------------------------------------------------
@@:
mov eax, ERROR_ACCESS_DENIED
xor ebx, ebx
ret
fsfrfe2:
popad
fsfrfe:
mov eax, 11
xor ebx, ebx
ret
fs_FloppyRewrite:
cmp byte [esi], 0
jz @b
call read_flp_fat
cmp [FDC_Status], 0
jnz fsfrfe
pushad
xor ebp, ebp
push esi
@@:
lodsb
test al, al
jz @f
cmp al, '/'
jnz @b
lea ebp, [esi-1]
jmp @b
@@:
pop esi
test ebp, ebp
jnz .noroot
call read_flp_root
cmp [FDC_Status], 0
jnz fsfrfe2
push flp_rootmem_extend_dir
push flp_rootmem_end_write
push flp_rootmem_next_write
push flp_rootmem_begin_write
xor ebp, ebp
push ebp
push flp_rootmem_first
push flp_rootmem_next
jmp .common1
.noroot:
; check existence
mov byte [ebp], 0
call fd_find_lfn
mov byte [ebp], '/'
lea esi, [ebp+1]
jnc @f
mov eax, ERROR_FILE_NOT_FOUND
.ret1:
mov [esp+28], eax
popad
xor ebx, ebx
ret
@@:
test byte [edi+11], 0x10 ; must be directory
mov eax, ERROR_ACCESS_DENIED
jz .ret1
movzx ebp, word [edi+26] ; ebp=cluster
mov eax, ERROR_FAT_TABLE
cmp ebp, 2
jb .ret1
cmp ebp, 2849
jae .ret1
push flp_notroot_extend_dir
push flp_notroot_end_write
push flp_notroot_next_write
push flp_notroot_begin_write
push ebp
push flp_notroot_first
push flp_notroot_next
.common1:
call fat_find_lfn
jc .notfound
; found; must not be directory
test byte [edi+11], 10h
jz @f
add esp, 28
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
xchg ax, word [edi+26] ; start cluster
test eax, eax
jz .done1
@@:
cmp eax, 0xFF8
jae .done1
lea edi, [0x282000 + eax*2] ; position in FAT
xor eax, eax
xchg ax, [edi]
jmp @b
.done1:
pop edi
call get_time_for_file
mov [edi+22], ax
call get_date_for_file
mov [edi+24], ax
mov [edi+18], ax
or byte [edi+11], 20h ; set 'archive' attribute
jmp .doit
.notfound:
; file is not found; generate short name
call fat_name_is_legal
jc @f
add esp, 28
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 [eax], ebp
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+28
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
push 1
pop eax ; 1 entry
jnz .notilde
; we need ceil(strlen(esi)/13) additional entries = floor((strlen(esi)+12+13)/13) total
xor eax, eax
@@:
cmp byte [esi], 0
jz @f
inc esi
inc eax
jmp @b
@@:
sub esi, eax
add eax, 12+13
mov ecx, 13
push edx
cdq
div ecx
pop edx
.notilde:
push -1
push -1
; find <eax> successive entries in directory
xor ecx, ecx
push eax
lea eax, [esp+12+8+12+8]
mov [eax], ebp
call dword [eax-4]
pop eax
jnc .scan_dir
.fsfrfe3:
add esp, 8+8+12+28
popad
mov eax, 11
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+12+8+12+8]
call dword [eax-8]
pop eax
jnc .scan_dir
cmp [FDC_Status], 0
jnz .fsfrfe3
push eax
lea eax, [esp+12+8+12+8]
call dword [eax+16] ; extend directory
pop eax
jnc .scan_dir
add esp, 8+8+12+28
popad
mov eax, ERROR_DISK_FULL
xor ebx, ebx
ret
.free:
test ecx, ecx
jnz @f
mov [esp], edi
mov ecx, [esp+8+8+12+8]
mov [esp+4], ecx
xor ecx, ecx
@@:
inc ecx
cmp ecx, eax
jb .scan_cont
; found!
; calculate name checksum
push esi ecx
mov esi, [esp+8+8]
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+8]
; 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+4] ; 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 fs_RamdiskRewrite.read_symbols
mov ax, 0xF
stosw
mov al, [esp+4]
stosb
mov cl, 6
call fs_RamdiskRewrite.read_symbols
xor eax, eax
stosw
mov cl, 2
call fs_RamdiskRewrite.read_symbols
pop ecx
lea eax, [esp+8+8+12+8]
call dword [eax+8] ; next write
xor eax, eax
loop .writelfn
pop eax
pop esi
; lea eax, [esp+8+12+8]
; call dword [eax+12] ; 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
and word [edi+20], 0 ; high word of cluster
and word [edi+26], 0 ; low word of cluster - to be filled
and dword [edi+28], 0 ; file size - to be filled
.doit:
lea eax, [esp+8]
call dword [eax+12] ; flush directory
push ecx
push edi
add edi, 26 ; edi points to low word of cluster
push edi
mov esi, edx
jecxz .done
mov ecx, 2849
mov edi, 0x282000
push 0 ; first cluster
.write_loop:
; allocate new cluster
xor eax, eax
repnz scasw
mov al, ERROR_DISK_FULL
jnz .ret
dec edi
dec edi
lea eax, [edi-0x282000]
shr eax, 1 ; eax = cluster
mov word [edi], 0xFFF ; mark as last cluster
cmp dword [esp], 0
jz .first
xchg edi, [esp+4]
stosw
mov edi, [esp+4]
jmp @f
.first:
mov [esp], eax
@@:
inc ecx
; write data
push ecx edi
mov ecx, 512
cmp dword [esp+20], ecx
jae @f
mov ecx, [esp+20]
@@:
push ecx
mov edi, 0xD000
rep movsb
pop ecx
push ecx
sub ecx, 512
neg ecx
push eax
xor eax, eax
rep stosb
pop eax
add eax, 31
pusha
call save_chs_sector
popa
pop ecx
cmp [FDC_Status], 0
jnz .diskerr
sub [esp+20], ecx
pop edi ecx
jnz .write_loop
.done:
xor eax, eax
.ret:
pop ebx edi edi ecx
mov [esp+28+28], eax
lea eax, [esp+8]
call dword [eax+4]
mov [edi+26], bx
mov ebx, esi
sub ebx, edx
mov [edi+28], ebx
call dword [eax+12]
mov [esp+28+16], ebx
test ebp, ebp
jnz @f
call save_flp_root
@@:
add esp, 28
cmp [FDC_Status], 0
jnz .err3
call save_flp_fat
cmp [FDC_Status], 0
jnz .err3
popa
ret
.err3:
popa
mov al, 11
xor ebx, ebx
ret
.diskerr:
sub esi, ecx
mov eax, 11
pop edi ecx
jmp .ret
fs_FloppyGetFileInfo:
call read_flp_fat
cmp [FDC_Status], 0
jnz ret11
cmp byte [esi], 0
jnz @f
mov eax, 2 ; unsupported
ret
@@:
push edi
call fd_find_lfn
jmp fs_GetFileInfo_finish
ret11:
mov eax, 11
ret
fs_FloppySetFileInfo:
call read_flp_fat
cmp [FDC_Status], 0
jnz ret11
cmp byte [esi], 0
jnz @f
mov eax, 2 ; unsupported
ret
@@:
push edi
call fd_find_lfn
jnc @f
pop edi
mov eax, ERROR_FILE_NOT_FOUND
ret
@@:
push eax
call bdfe_to_fat_entry
pop eax
test eax, eax
jz .root
add eax, 31
pusha
call save_chs_sector
popa
jmp .cmn
.root:
call save_flp_root
.cmn:
pop edi
xor eax, eax
cmp [FDC_Status], 0
jz @f
mov al, 11
@@:
ret
;----------------------------------------------------------------
;
; fs_FloppyExecute - LFN variant for executing from floppy
;
; esi points to floppy filename (e.g. 'dir1/name')
; ebp points to full filename (e.g. '/fd/1/dir1/name')
; dword [ebx] = flags
; dword [ebx+4] = cmdline
;
; ret ebx,edx destroyed
; eax > 0 - PID, < 0 - error
;
;--------------------------------------------------------------
fs_FloppyExecute:
mov edx, [ebx]
mov ebx, [ebx+4]
test ebx, ebx
jz @f
add ebx, std_application_base_address
@@:
;----------------------------------------------------------------
;
; fs_FloppyExecute.flags - second entry
;
; esi points to floppy filename (kernel address)
; ebp points to full filename
; edx flags
; ebx cmdline (kernel address)
;
; ret eax > 0 - PID, < 0 - error
;
;--------------------------------------------------------------
.flags:
call read_flp_fat
cmp byte [esi], 0
jnz @f
; cannot execute root!
mov eax, -ERROR_ACCESS_DENIED
ret
@@:
push edi
call fd_find_lfn
jnc .found
pop edi
mov eax, -ERROR_FILE_NOT_FOUND
ret
.found:
movzx eax, word [edi+26] ; cluster
push eax
push dword [edi+28] ; size
push .DoRead
call fs_execute
add esp, 12
pop edi
ret
.DoRead:
; read next block
; in: eax->parameters, edi->buffer
; out: eax = error code
pushad
cmp dword [eax], 0 ; file size
jz .eof
mov eax, [eax+4] ; cluster
add eax, 31
call read_chs_sector
cmp [FDC_Status], 0
jnz .err
pop edi
mov esi, 0xD000
push edi
mov ecx, 512/4
rep movsd
mov eax, [esp+28]
mov ecx, [eax]
sub ecx, 512
jae @f
add edi, ecx
neg ecx
push eax
xor eax, eax
rep stosb
pop eax
@@:
mov [eax], ecx
mov edx, [eax+4]
mov dx, [edx*2+0x282000]
mov [eax+4], dx ; high word is already zero
popad
xor eax, eax
ret
.eof:
popad
mov eax, 6
ret
.err:
popad
mov eax, 11
ret
; \end{diamond}