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assembly language
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Language Assembler (Intel x86)
(really uses assembler instructions)
| Date: | 04/26/06 |
| Author: | Marcin Koziol |
| URL: | n/a |
| Comments: | 0 |
| Info: | n/a |
| Score: |  (3.50 in 32 votes) |
; Assembler (x86) version of 99 Bottles of beer
;
; This version is for NASM compiler but doesn't use any
; macros, just all basic instructions for x86 assembler.
; Also only putchar() function is used to print character
; onto screen, and the whole rest is in code.
;
; Compilation:
; nasm -fwin32 99.asm
; gcc -o 99.exe 99.obj
global _main
extern _putchar
segment .data
_line_1_1 db ' bottles of beer on the wall, ', 0
_line_1_2 db ' bottles of beer.', 13, 10, 0
_line_2_1 db 'Take one down and pass it around, ', 0
_line_2_2 db ' bottles of beer on the wall.', 13, 10, 13, 10, 0
_line_2_2_one db ' bottle of beer on the wall.', 13, 10, 13, 10, 0
_ending_lines db '1 bottle of beer on the wall, 1 bottle of beer.', 13, 10
db 'Take one down and pass it around, no more bottles of beer on the wall.', 13,
10, 13, 10
db 'No more bottles of beer on the wall, no more bottles of beer. ', 13, 10
db 'Go to the store and buy some more, 99 bottles of beer on the wall.', 13, 10,
0
segment .text
; this function converts integer in range 0-99 to string
_integer_to_string:
mov eax, dword [esp + 08h] ; get the vavlue
mov ecx, 10 ;
sub edx, edx
div ecx ; divide it by 10
mov ecx, dword [esp + 04h] ; get the output offset
test eax, eax ; is greater than 9
jz .skip_first_digit ; skip saving 0 char if no
add al, 030h ; convert number to ascii char
mov byte [ecx], al ; save
inc ecx ; increase pointer
jmp .dont_test_second_digit ;
.skip_first_digit: ; only if less then 10
test edx, edx
jz .skip_second_digit
.dont_test_second_digit: ; if it was greater than 10
add dl, 030h ; than second digit must by
mov byte [ecx], dl ; written at no condition
inc ecx
.skip_second_digit: ; only skip if value was 0
mov byte [ecx], ah ; save the null ending char
retn 4 ; ret and restore stack
; function prints null-terminated line to stdout
_show_line:
push edi ; function save registers
push esi
mov edi, dword [esp + 0Ch] ; get the pointer to string
sub eax, eax ; look for zeros
sub ecx, ecx
dec ecx ; set ecx to -1
repnz scasb ; search for 0 in string
neg ecx
sub ecx, 2 ; get the string length w/o zero
mov esi, dword [esp + 0Ch] ; get pointer once again
.putchar_loop:
push ecx ; keep the counter
lodsb ; get the char
push eax
call _putchar ; print char to stdout
add esp, 4 ; correct stack
pop ecx ; get back the counter
dec ecx
jnz .putchar_loop ; if not last char then get next
pop esi ; restore registers
pop edi
retn 4
; prints string for only one number
_bottles:
push ebp ; keep the offset to call params
mov ebp, esp
sub esp, 4 ; reserve one local variable
mov eax, dword [ebp + 08h] ; get number of bottles
dec eax ; is it 1?
jnz .more_than_one ; nope, it's not
push _ending_lines ; print the last lines
call _show_line
jmp .end ; exit function
.more_than_one:
inc eax ; get the original value
push eax ; convert it to string
lea eax, [ebp - 04h]
push eax ; string will be stored here
call _integer_to_string
lea eax, [ebp - 04h]
push eax
call _show_line ; 'xx'
push _line_1_1
call _show_line ; ' bottles of beer on the wall, '
lea eax, [ebp - 04h]
push eax
call _show_line ; 'xx'
push _line_1_2
call _show_line ; ' bottles of beer.'
mov eax, dword [ebp + 08h]
dec eax ; in second line the value is one less
push eax
lea eax, [ebp - 04h]
push eax
call _integer_to_string ; convert it to string
push _line_2_1
call _show_line ; 'Take one down and pass it around, '
lea eax, [ebp - 04h]
push eax
call _show_line ; 'xx'
cmp dword [ebp + 08h], 2
jnz .second_line_for_more_than_one
push _line_2_2_one ; ' bottle of beer on the wall.'
jmp .show_line
.second_line_for_more_than_one:
push _line_2_2 ; ' bottles of beer on the wall.'
.show_line:
call _show_line
.end:
leave
retn 4
; main function, the command line arguments are not important
_main:
pushad
mov ecx, 99 ; printf from 99
.main_loop:
push ecx
push ecx
call _bottles ; print lines for this value
pop ecx
loop .main_loop ; if still greater than zero
popad
sub eax, eax ; That's all folks!
retn
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