| 0,0 → 1,327 |
|---|
| ; FAT-specific code for tmpdisk.asm. |
| ; Formats a disk to FAT16 or FAT32, depending on size. |
| ; Note: formatting is adjusted for memory-based disks. Although the resulting |
| ; image is a valid FAT32 volume, it has no "spare" sectors, e.g. second copy |
| ; of FAT or place for second sector of MS FAT32 bootloader. |
| |
| ; Some constants |
| FAT16_ROOTDIR_SECTORS = 16 ; can be changed, but why not? |
| ; FAT16: |
| ; 1 bootsector, |
| ; min 0xFF5 sectors for data, |
| ; min (0xFF5*2/512) = 16 sectors per FAT, we use only one copy, |
| ; FAT16_ROOTDIR_SECTORS for root directory |
| MIN_FAT16_SIZE = 1 + 16 + FAT16_ROOTDIR_SECTORS + 0xFF5 |
| ; FAT32: |
| ; 1 bootsector, |
| ; 1 sector for fsinfo, |
| ; min 0xFFF5 sectors for data, |
| ; min (0xFFF5*4/512) = 512 sectors per FAT, we use only one copy |
| MIN_FAT32_SIZE = 1 + 1 + 512 + 0xFFF5 |
| MAX_SIZE = 1 shl (30 - 9) ; 1G in 512-byte sectors |
| |
| ; Initializes FATxx structures on the disk. |
| ; Called with edi = pointer to disk data, esi = size of disk. |
| proc format_disk |
| ; Determine FAT type and jump to the corresponding handler. |
| cmp esi, MIN_FAT32_SIZE |
| jae format_disk_fat32 |
| ; Fall through to format_disk_fat16. |
| endp |
| |
| ; Structure of FAT16 bootsector. Field names are from MS spec. |
| struc FAT16BOOT |
| { |
| .BS_jmpBoot rb 3 |
| .BS_OEMName rb 8 |
| .BPB_BytsPerSec dw ? |
| .BPB_SecsPerClus db ? |
| .BPB_RsvdSecCnt dw ? |
| .BPB_NumFATs db ? |
| .BPB_RootEntCnt dw ? |
| .BPB_TotSec16 dw ? |
| .BPB_Media db ? |
| .BPB_FATSz16 dw ? |
| .BPB_SecPerTrk dw ? |
| .BPB_NumHeads dw ? |
| .BPB_HiddSec dd ? |
| .BPB_TotSec32 dd ? |
| .BS_DrvNum db ? |
| .BS_Reserved1 db ? |
| .BS_BootSig db ? |
| .BS_VolID dd ? |
| .BS_VolLab rb 11 |
| .BS_FilSysType rb 8 |
| } |
| virtual at 0 |
| FAT16BOOT FAT16BOOT |
| end virtual |
| |
| ; Initializes FAT16 structures on the disk. |
| ; Called with edi = pointer to disk data, esi = size of disk. |
| format_disk_fat16: |
| ; 1. Calculate number of clusters. |
| ; 1a. There are fixed-sized areas and there are data+FAT; |
| ; every cluster uses 512 bytes in data area and 2 bytes in FAT area. |
| lea eax, [esi-1-FAT16_ROOTDIR_SECTORS] |
| ; two following lines are equivalent to edx = floor(eax*512/514) |
| mov ecx, 0xFF00FF01 |
| mul ecx ; edx = number of clusters |
| ; 1b. Force the number be less than 0xfff5. |
| mov eax, 0xFFF4 |
| cmp edx, eax |
| jb @f |
| mov edx, eax |
| @@: |
| ; 2. Zero all system areas on the disk. |
| lea ecx, [256*(1+FAT16_ROOTDIR_SECTORS)+edx+255] |
| and ecx, not 255 |
| shr ecx, 1 |
| xor eax, eax |
| push edi |
| rep stosd |
| pop edi |
| ; 3. Generate the bootsector. |
| ; 3a. Copy static stub. |
| push esi edi |
| mov esi, fat16bootsector_stub |
| mov ecx, fat16bootsector_stub_size |
| rep movsb |
| pop edi esi |
| mov word [edi+510], 0xAA55 |
| ; 3b. Set fields which depend on size. |
| cmp esi, 0x10000 |
| jae .size_is_32bit |
| mov [edi+FAT16BOOT.BPB_TotSec16], si |
| jmp .size_written |
| .size_is_32bit: |
| mov [edi+FAT16BOOT.BPB_TotSec32], esi |
| .size_written: |
| lea eax, [edx+255] |
| shr eax, 8 |
| mov [edi+FAT16BOOT.BPB_FATSz16], ax |
| ; 3c. Generate volume ID. |
| call generate_volume_id |
| mov [edi+FAT16BOOT.BS_VolID], eax |
| ; 4. Initialize FAT. |
| mov dword [edi+512], 0xFFFFFFF8 |
| ; 5. Return. |
| ret |
| |
| ; Structure of FAT32 bootsector. Field names are from MS spec. |
| struc FAT32BOOT |
| { |
| .BS_jmpBoot rb 3 |
| .BS_OEMName rb 8 |
| .BPB_BytsPerSec dw ? |
| .BPB_SecsPerClus db ? |
| .BPB_RsvdSecCnt dw ? |
| .BPB_NumFATs db ? |
| .BPB_RootEntCnt dw ? |
| .BPB_TotSec16 dw ? |
| .BPB_Media db ? |
| .BPB_FATSz16 dw ? |
| .BPB_SecPerTrk dw ? |
| .BPB_NumHeads dw ? |
| .BPB_HiddSec dd ? |
| .BPB_TotSec32 dd ? |
| .BPB_FATSz32 dd ? |
| .BPB_ExtFlags dw ? |
| .BPB_FSVer dw ? |
| .BPB_RootClus dd ? |
| .BPB_FSInfo dw ? |
| .BPB_BkBootSec dw ? |
| .BPB_Reserved rb 12 |
| .BS_DrvNum db ? |
| .BS_Reserved1 db ? |
| .BS_BootSig db ? |
| .BS_VolID dd ? |
| .BS_VolLab rb 11 |
| .BS_FilSysType rb 8 |
| } |
| virtual at 0 |
| FAT32BOOT FAT32BOOT |
| end virtual |
| |
| ; Initializes FAT32 structures on the disk. |
| ; Called with edi = pointer to disk data, esi = size of disk. |
| format_disk_fat32: |
| ; 1. Calculate number of clusters. |
| ; 1a. There is fixed-sized area and there are data+FAT; |
| ; every cluster uses 512 bytes in data area and 4 bytes in FAT area. |
| lea eax, [esi-1-1] |
| ; two following lines are equivalent to edx=floor(eax*512/516) if eax<10000000h |
| mov ecx, 0xFE03F810 |
| mul ecx ; edx = number of clusters |
| ; 2. Zero all system areas on the disk and first cluster of data, |
| ; used for root directory. |
| lea ecx, [128*(1+1+1)+edx+127] |
| and ecx, not 127 |
| xor eax, eax |
| push edi |
| rep stosd |
| pop edi |
| ; 3. Generate the bootsector. |
| ; 3a. Copy static stub. |
| push esi edi |
| mov esi, fat32bootsector_stub |
| mov ecx, fat32bootsector_stub_size |
| rep movsb |
| pop edi esi |
| mov word [edi+510], 0xAA55 |
| ; 3b. Set fields which depend on size. |
| mov [edi+FAT32BOOT.BPB_TotSec32], esi |
| lea eax, [edx+127] |
| shr eax, 7 |
| mov [edi+FAT32BOOT.BPB_FATSz32], eax |
| ; 3c. Generate volume ID. |
| call generate_volume_id |
| mov [edi+FAT32BOOT.BS_VolID], eax |
| ; 4. Initialize fsinfo sector. |
| mov dword [edi+512], 'RRaA' |
| mov dword [edi+512+484], 'rrAa' |
| dec edx ; one cluster is occupied by root dir |
| mov dword [edi+512+488], edx ; free count |
| mov byte [edi+512+492], 3 ; first free cluster |
| mov word [edi+512+510], 0xAA55 |
| ; 5. Initialize FAT. |
| mov dword [edi+512*2], 0x0FFFFFF8 |
| mov dword [edi+512*2+4], 0x0FFFFFFF |
| mov dword [edi+512*2+8], 0x0FFFFFFF |
| ; 6. Return. |
| ret |
| |
| ; Generate volume serial number, which should try to be unique for each volume. |
| ; Use CMOS date+time, copy-pasted from fat32.inc. |
| generate_volume_id: |
| call get_time_for_file |
| mov cx, ax |
| call get_date_for_file |
| shl eax, 16 |
| mov ax, cx |
| ret |
| |
| ; Three following procedures are copy-pasted from fat32.inc. |
| 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 |
| |
| ; some data |
| fat16bootsector_stub: |
| db 0EBh, 3Ch, 90h ; BS_jmpBoot |
| db 'KOLIBRI ' ; BS_OEMName |
| dw 512 ; BPB_BytsPerSec |
| db 1 ; BPB_SecsPerClus |
| dw 1 ; BPB_RsvdSecCnt |
| db 1 ; BPB_NumFATs |
| dw FAT16_ROOTDIR_SECTORS*16 ; BPB_RootEntCnt |
| dw 0 ; BPB_TotSec16, filled in format_disk_fat16 |
| db 0F8h ; BPB_Media |
| dw 0 ; BPB_FATSz16, filled in format_disk_fat16 |
| dw 32 ; BPB_SecPerTrk |
| dw 128 ; BPB_NumHeads |
| dd 0 ; BPB_HiddSec |
| dd 0 ; BPB_TotSec32, filled in format_disk_fat16 |
| db 80h ; BS_DrvNum |
| db 0 ; BS_Reserved1 |
| db 29h ; BS_BootSig |
| dd 0 ; BS_VolID, filled in format_disk_fat16 |
| db 'NO NAME ' ; BS_VolLab |
| db 'FAT16 ' ; BS_FilSysType |
| ; just in case add some meaningful bytes if someone tries to boot |
| db 0CDh, 19h, 0EBh, 0FEh ; int 19h, jmp $ |
| fat16bootsector_stub_size = $ - fat16bootsector_stub |
| fat32bootsector_stub: |
| db 0EBh, 58h, 90h ; BS_jmpBoot |
| db 'KOLIBRI ' ; BS_OEMName |
| dw 512 ; BPB_BytsPerSec |
| db 1 ; BPB_SecsPerClus |
| dw 2 ; BPB_RsvdSecCnt |
| db 1 ; BPB_NumFATs |
| dw 0 ; BPB_RootEntCnt |
| dw 0 ; BPB_TotSec16 |
| db 0F8h ; BPB_Media |
| dw 0 ; BPB_FATSz16 |
| dw 32 ; BPB_SecPerTrk |
| dw 128 ; BPB_NumHeads |
| dd 0 ; BPB_HiddSec |
| dd 0 ; BPB_TotSec32, filled in format_disk_fat32 |
| dd 0 ; BPB_FATSz32, filled in format_disk_fat32 |
| dw 0 ; BPB_ExtFlags |
| dw 0 ; BPB_FSVer |
| dd 2 ; BPB_RootClus |
| dw 1 ; BPB_FSInfo |
| dw 0 ; BPB_BkBootSec |
| rb 12 ; BPB_Reserved |
| db 80h ; BS_DrvNum |
| db 0 ; BS_Reserved1 |
| db 29h ; BS_BootSig |
| dd 0 ; BS_VolID, filled in format_disk_fat32 |
| db 'NO NAME ' ; BS_VolLab |
| db 'FAT32 ' ; BS_FilSysType |
| ; same bytes as in fat16bootsector_stub |
| db 0CDh, 19h, 0EBh, 0FEh ; int 19h, jmp $ |
| fat32bootsector_stub_size = $ - fat32bootsector_stub |
| Property changes: |
|---|
| Added: svn:eol-style |
|---|
| +native |
|---|
| \ No newline at end of property |
|---|