99 bottles of beer in FASM bootsector

beer.asm

;=======================================================================
;   an x86 bootsector implementation of
;   99 bottles of beer
;   by Ivan Sukin <[email protected]>
;   based on template made by shoorick
;=======================================================================

;=======================================================================
;   Drive info
;=======================================================================
_bps equ 512 ; bytes per sector
_spt equ 18  ; sectors per track
_hds equ 2   ; number of heads
_trs equ 80  ; number of tracks
;=======================================================================
;   First 3 bytes of bootsector
;   Must be E9XXXX or EBXX90.
;   7C00h is the address where
;   bootsector is put by BIOS
;=======================================================================
    org 7C00h       ; starting address
    mov cx, 99      ; set CX to 99 right here
    jmp short start ; short jmp (EB XX)    
;=======================================================================
;   Bootsector record (1 byte after standard)
;=======================================================================
more db  "o more "       ; OEM name and version (8 B)
more_l = $ - more        ; !!! dirty hack
                         ; !!! I've put some string here
     dw  _bps            ; bytes per sector
     db  1               ; sectors per allocation unit
     dw  1               ; reserved sectors
     db  2               ; number of FATs
     dw  224             ; number of root dir entries
     dw  2880            ; total sectors in logical volume
     db  0F0h            ; media descriptor byte
     dw  9               ; number of sectors per FAT
     dw  _spt            ; sectors per track
     dw  _hds            ; number of heads
     dd  0               ; number of hidden sectors
     dd  0               ; total sectors in logical volume
                         ; if volume size > 32 MiB
     db  0               ; physical drive number
     db  0               ; reserved
     db  29h             ; Extended Boot Signature record (29h)
     dd  0               ; 32-bit binary volume ID
is   db  "Ivan Sukin "   ; volume label (11 B)
     db  "(C) 2011"      ; reserved (8 B)
is_l = $ - is            ; !!! dirty hack
                         ; !!! I've put my name here
;=======================================================================
;   Entry point
;=======================================================================
start:
; Point segment registers to the beginning of current segment
    mov  ax, cs
    mov  ds, ax
; loop: begin
@@:
    call put_cx_99
    cmp  cl, 1
    je   short cx_is_1
    call print_bott1
    call put_cx_99
    call print_bott2
    call print_endl1
    call print_bott3
; print cx - 1
    dec  cx
    call put_cx_99
; if next_value_of_cx == 1 then goto cx_will_be_1    
    cmp  cl, 1
    je   short cx_will_be_1
; else    
    call bott4_endl
    jmp  short @b
; loop: end
cx_will_be_1:
    mov  dx, b5_l
    call bott5_helper
    jmp  short @b
; loop: end
cx_is_1:
    mov  dx, b6_l
    call bott5_helper
    mov  al, ","
    call put_char
    mov  al, " "
    call put_char   
    call put_cx_99
    mov  dx, b7_l
    call bott5_helper
    call print_endl1
    call print_bott3
    mov  al, "N"
    call put_char
    call print_more
    call bott4_endl
cx_is_0:
    mov  ax, "N"
    call put_char
    call print_more
    call print_bott1
    mov  al, "n"
    call put_char
    call print_more
    call print_bott2
    call print_endl1
    mov  dx, store_l
    mov  si, stor
    call put_str

    mov  cx, 99
    call put_cx_99
    call bott4_endl 
    mov  dx, is_l
    mov  si, is
    call put_str

    xor   ah, ah
    int   16h           ; INT 16h -- function 00, Get keystroke
    int   19h           ; INT 19h -- Bootstrap loader
                        ; (reboot)


;=======================================================================
;   Many helper and printer procedures
;   written for code shortening
;=======================================================================

bott4_endl:
    call print_bott4
    call print_endl
    ret

print_more:
    mov dx, more_l
    mov si, more
    call put_str
    ret

bott1_helper:
    mov si, bott_1
    call put_str
    ret

bott5_helper:
    mov si, bott_5
    call put_str
    ret

print_bott1:
    mov dx, b1_l
    call bott1_helper
    ret

print_bott2:
    mov dx, b2_l
    call bott1_helper
    ret

print_bott3:
    mov dx, b3_l
    mov si, bott_3
    call put_str
    ret

print_bott4:
    mov dx, b4_l
    call bott1_helper
    ret 

print_endl:
    mov dx, endl_l
    mov si, endl
    call put_str
    ret

print_endl1:
    mov dx, endl_l1
    mov si, endl
    call put_str
    ret

;=======================================================================
;   Simple printing procedures
;=======================================================================

;=======================================================================
;   Procedure put_char
;   al -- character to output
;   Uses: ax
;=======================================================================
put_char:
    mov ah, 0Eh
    int 10h
    ret

;=======================================================================
;   Procedure put_cx_99
;   Puts a value of CX
;   assuming that it's in range
;   0 - 99
;   Uses: ax, bx
;=======================================================================
put_cx_99:
    mov  ax, cx
    mov  bl, 10
    div  bl
    mov  bh, ah
    test al, al
    jz   short @f 
    add  al, '0'
    call put_char    
@@:
    mov  al, bh
    add  al, '0'
    call put_char
    mov  al, " "
    call put_char
    ret

;=======================================================================
;   Procedure put_str
;   dx -- string lenth
;   ds:si -- string address
;   Uses: ah, dx
;=======================================================================
put_str:    
    lodsb
    call put_char
    dec  dx
    jnz  short put_str
    ret

;=======================================================================
;   String data needed for the song
;=======================================================================
    bott_1 db "bottles of beer on the wall, "
    b1_l    = $ - bott_1
    b2_l    = 15
    bott_3 db "Take one down pass it around, "
    b3_l    = $ - bott_3
    b4_l    = b1_l - 2
    bott_5 db "bottle of beer on the wall.", 13, 10, 10
    b5_l    = $ - bott_5
    b6_l    = b5_l - 4
    b7_l    = b5_l - 16
    endl    = $ - 4
    endl_l1 = 3
    endl_l  = 4
    stor db "Go to store and buy some more, "
    store_l = $ - stor


    rb 7E00h-2-$  ; reserve the rest of bootsector except last two bytes
    db 055h, 0AAh ; bootsector signature
;=======================================================================

You may build this code with FASM (http://flatassembler.net) and then write it to diskette or try in emulator (the best choice is DOSBox).