use32
org 0x0

db 'MENUET01'
dd 1
dd start
dd i_end
dd mem_end
dd stack_top
dd param
dd 0

param rb 4096

path rb 256

drive db 0

msg_confirm db 'Format floppy in FAT32? (Y/N) ',0

msg_success db 10,'Formatted successfully. Press any key.',10,0

msg_error db 10,'Error: '

msg_invalid_path db 'Invalid path (use /fd0/1 or /fd1/1)',10,0

msg_not_floppy db 'Not a 1.44 MB floppy disk',10,0

msg_write_error db 'Write failed',10,0

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

sector_buffer rb 512 ; zero-filled

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
  mov eax, 3
  int 0x40
  mov [boot_sector + 0x27], eax

  ; Get file size to confirm floppy
  mov eax, 58
  mov ebx, 4
  mov ecx, 0
  mov edx, 0
  mov edi, sector_buffer ; reuse buffer for info
  mov ebp, path
  int 0x40
  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
  mov eax, 58
  mov ebx, 2
  mov ecx, 512
  mov edx, 0
  mov esi, 0
  mov edi, boot_sector
  mov ebp, path
  int 0x40
  cmp eax, 0
  jnz write_error

  ; Write FSInfo at 512
  mov edx, 512
  mov edi, fs_info
  int 0x40
  cmp eax, 0
  jnz write_error

  ; Write backup boot at 3072
  mov edx, 3072
  mov edi, boot_sector
  int 0x40
  cmp eax, 0
  jnz write_error

  ; Write backup FSInfo at 3584
  mov edx, 3584
  mov edi, fs_info
  int 0x40
  cmp eax, 0
  jnz write_error

  ; Write first FAT at 16384
  mov edx, 16384
  mov edi, fat_first
  int 0x40
  cmp eax, 0
  jnz write_error

  ; Write first FAT2 at 28160
  mov edx, 28160
  int 0x40
  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
  mov edi, sector_buffer
  int 0x40
  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
  mov edi, sector_buffer
  int 0x40
  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
  mov edi, sector_buffer
  int 0x40
  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:
  mov eax, -1
  int 0x40

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
  mov eax, 63
  mov ebx, 1
  int 0x40
  jmp print_string
.end:
  ret

get_key:
  mov eax, 2
  int 0x40
  shr eax, 8
  ret

i_end:
rb 1024 ; reserve for data if needed

stack_top:
rb 4096

mem_end: