meos_app_start

udata
  param rb 4096
  path rb 256
  drive db 0
  sector_buffer rb 512
meos_app_end

data
  szZ msg_confirm, 'Format floppy in FAT32? (Y/N) '
  szZ msg_success, 10,'Formatted successfully. Press any key.',10
  szZ msg_error, 10,'Error: '
  szZ msg_invalid_path, 'Invalid path (use /fd0/1 or /fd1/1)',10
  szZ msg_not_floppy, 'Not a 1.44 MB floppy disk',10
  szZ msg_write_error, 'Write failed',10

  boot_sector:
    db 0xeb,0x58,0x90
    db 'MSWIN4.1'
    dw 512
    db 1
    dw 32
    db 2
    dw 0
    dw 0
    db 0xf0
    dw 0
    dw 2
    dd 0
    dd 2880
    dd 23
    dd 0
    dw 0
    dd 2
    dw 1
    dw 6
    times 12 db 0
    db 0
    db 0
    db 0x29
    dd 0x12345678 ; serial, will be set
    db 'NO NAME    '
    db 'FAT32   '
    times 420 db 0x90 ; boot code nop
    db 0x55,0xaa

  fs_info:
    dd 0x41615252
    times 480 db 0
    dd 0x61417272
    dd 2801 ; free clusters
    dd 3 ; last allocated
    times 12 db 0
    dd 0xaa550000

  fat_first:
    dd 0x0ffffff8
    dd 0x0fffffff
    dd 0x0fffffff
    times 512-12 db 0
data

code
start:
  mov esi, param
  call skip_spaces
  mov edi, path
  call copy_string

  ; Parse and validate path
  mov esi, path
  cmp byte [esi], '/'
  jne invalid_path
  inc esi
  cmp word [esi], 'fd'
  jne invalid_path
  add esi, 2
  mov al, [esi]
  sub al, '0'
  cmp al, 0
  jl invalid_path
  cmp al, 1
  jg invalid_path
  mov [drive], al
  inc esi
  cmp byte [esi], '/'
  jne invalid_path
  inc esi
  cmp byte [esi], '1'
  jne invalid_path
  inc esi
  cmp byte [esi], 0
  jne invalid_path

  ; Set drive number in boot sector
  mov al, [drive]
  mov [boot_sector + 0x24], al

  ; Set volume serial using system time
  mcall 3, 0, 0, 0, 0, 0, 0
  mov [boot_sector + 0x27], eax

  ; Get file size to confirm floppy
  mcall 58, 4, 0, 0, sector_buffer, path
  cmp eax, 0
  jnz write_error
  cmp dword [sector_buffer + 20], 0 ; size high
  jnz not_floppy
  cmp dword [sector_buffer + 16], 1474560 ; size low
  jnz not_floppy

  ; Confirm
  mov esi, msg_confirm
  call print_string
  call get_key
  or al, 0x20 ; to lowercase
  cmp al, 'y'
  jne exit

  ; Write boot sector at 0
  mcall 58, 2, 512, 0, 0, boot_sector, path
  cmp eax, 0
  jnz write_error

  ; Write FSInfo at 512
  mcall 58, 2, 512, 512, 0, fs_info, path
  cmp eax, 0
  jnz write_error

  ; Write backup boot at 3072
  mcall 58, 2, 512, 3072, 0, boot_sector, path
  cmp eax, 0
  jnz write_error

  ; Write backup FSInfo at 3584
  mcall 58, 2, 512, 3584, 0, fs_info, path
  cmp eax, 0
  jnz write_error

  ; Write first FAT at 16384
  mcall 58, 2, 512, 16384, 0, fat_first, path
  cmp eax, 0
  jnz write_error

  ; Write first FAT2 at 28160
  mcall 58, 2, 512, 28160, 0, fat_first, path
  cmp eax, 0
  jnz write_error

  ; Zero other FAT sectors (1 to 22 for each FAT)
  mov ecx, 22
  mov edx, 16384 + 512 ; FAT1 start +512
zero_fat1:
  push ecx
  mcall 58, 2, 512, edx, 0, sector_buffer, path
  cmp eax, 0
  jnz write_error
  add edx, 512
  pop ecx
  loop zero_fat1

  mov ecx, 22
  mov edx, 28160 + 512 ; FAT2
zero_fat2:
  push ecx
  mcall 58, 2, 512, edx, 0, sector_buffer, path
  cmp eax, 0
  jnz write_error
  add edx, 512
  pop ecx
  loop zero_fat2

  ; Zero data sectors (LBA 78 to 2879, position 78*512 to 2879*512)
  mov ecx, 2802 ; data sectors
  mov edx, 78 * 512 ; start data
zero_data:
  push ecx
  mcall 58, 2, 512, edx, 0, sector_buffer, path
  cmp eax, 0
  jnz write_error
  add edx, 512
  pop ecx
  loop zero_data

  mov esi, msg_success
  call print_string
  call get_key
  jmp exit

invalid_path:
  mov esi, msg_error
  call print_string
  mov esi, msg_invalid_path
  call print_string
  jmp exit

not_floppy:
  mov esi, msg_error
  call print_string
  mov esi, msg_not_floppy
  call print_string
  jmp exit

write_error:
  mov esi, msg_error
  call print_string
  mov esi, msg_write_error
  call print_string
  jmp exit

exit:
  mcall -1

skip_spaces:
  cmp byte [esi], ' '
  jne .end
  inc esi
  jmp skip_spaces
.end:
  ret

copy_string:
  lodsb
  stosb
  or al, al
  jnz copy_string
  ret

print_string:
  lodsb
  or al, al
  jz .end
  mov ah, 0
  mov ebx, eax
  mcall 63, 1
  jmp print_string
.end:
  ret

get_key:
  mcall 2
  shr eax, 8
  ret
code