{{collection|99 Bottles of Beer}} [[implementation of task::99 Bottles of Beer| ]] [[99 Bottles of Beer]] done in any of the assembler-languages.

toc

360 Assembly

For maximum compatibility, this program uses only the basic instruction set.

```*        99 Bottles of Beer        04/09/2015
BOTTLES  CSECT
USING  BOTTLES,R12
LR     R12,R15
BEGIN    LA     R2,99              r2=99 number of bottles
LR     R3,R2
LOOP     BCTR   R3,0               r3=r2-1
CVD    R2,DW              binary to pack decimal
ED     ZN,DW+6            pack decimal (PL2) to char (CL4)
CH     R2,=H'1'           if r2<>1
BNE    NOTONE1            then goto notone1
MVI    PG1+13,C' '        1 bottle
MVI    PG2+13,C' '        1 bottle
NOTONE1  MVC    PG1+4(2),ZN+2      insert bottles
MVC    PG2+4(2),ZN+2      insert bottles
CVD    R3,DW              binary to pack decimal
ED     ZN,DW+6            pack decimal (PL2) to char (CL4)
MVC    PG4+4(2),ZN+2      insert bottles
WTO    MF=(E,PG1)
WTO    MF=(E,PG2)
WTO    MF=(E,PG3)
CH     R3,=H'1'           if r3<>1
BNE    NOTONE2            then goto notone2
MVI    PG4+13,C' '        1 bottle
NOTONE2  LTR    R3,R3              if r3=0
BZ     ZERO               then goto zero
WTO    MF=(E,PG4)
B      PR5
ZERO     WTO    MF=(E,PG4Z)
PR5      WTO    MF=(E,PG5)
BCT    R2,LOOP
RETURN   XR     R15,R15
BR     R14
CNOP   0,4
PG1      DC     H'40',H'0',CL40'xx bottles of beer on the wall'
PG2      DC     H'40',H'0',CL40'xx bottles of beer'
PG3      DC     H'40',H'0',CL40'Take one down, pass it around'
PG4      DC     H'40',H'0',CL40'xx bottles of beer on the wall'
PG5      DC     H'40',H'0',CL40' '
PG4Z     DC     H'40',H'0',CL40'No more bottles of beer on the wall'
DW       DS     0D,PL8             15num
ZN       DS     CL4
WTOMSG   CNOP   0,4
DC     H'80'              length of WTO buffer
DC     H'0'               must be binary zeroes
YREGS
END    BOTTLES
```

{{out}}

```...
5 bottles of beer on the wall
5 bottles of beer
Take one down, pass it around
4 bottles of beer on the wall

4 bottles of beer on the wall
4 bottles of beer
Take one down, pass it around
3 bottles of beer on the wall

3 bottles of beer on the wall
3 bottles of beer
Take one down, pass it around
2 bottles of beer on the wall

2 bottles of beer on the wall
2 bottles of beer
Take one down, pass it around
1 bottle  of beer on the wall

1 bottle  of beer on the wall
1 bottle  of beer
Take one down, pass it around
No more bottles of beer on the wall

```

## 6502 Assembly

IMPORTANT NOTE:  This assembly language solution is targeted at the Apple 1.

The Apple 1 was an innovative device for its time,
but it's quite primitive by modern standards,
and it had NO support for lower-case letters.

Therefore, the UPPER-CASE output of this example accurately represents
the only reasonable one for this device,
and cannot be "fixed" due to non-compliance, only deleted.

```6502 Assembly
.CR 6502
.TF AP1BEER.O,AP1
.LF AP1BEER.LST
.OR \$0BEE
;-------------------------------------;
; BEER SONG IN 6502 ASSEMBLY LANGUAGE ;
;       BY BARRYM 2010-05-30          ;
; THANKS TO SBPROJECTS.COM FOR LOTS   ;
;   OF VALUABLE INFORMATION AND A     ;
;   VERY NICE ASSEMBLER!              ;
;-------------------------------------;
; THE TARGET MACHINE FOR THIS PROGRAM ;
;   IS THE APPLE 1, BUT IT WOULD BE   ;
;   EASY TO MAKE IT RUN ON OTHER 65XX ;
;   MACHINES BY CHANGING THE NEXT TWO ;
;   EQUATES.  SOME MACHINE-TESTED     ;
;   EXAMPLES:                         ;
;   APPLE II, +, E, C: \$FDED, \$80     ;
;   COMMODORE 64:      \$FFD2, \$00     ;
;-------------------------------------;
ECHO     =  \$FFEF  ;EMIT A REG AS ASCII
ORMASK   =  \$80    ;(\$00 FOR + ASCII)
;
MAXBEER  =  99     ;INITIAL BEER COUNT
;-------------------------------------;
; X REG. IS THE BOTTLE COUNTER.       ;
; Y REG. IS THE STRING INDEX POINTER, ;
;   AND THE TENS DIGIT IN THE BINARY- ;
;   TO-ASCII CONVERSION ROUTINE.      ;
; A REG. HANDLES EVERYTHING ELSE WITH ;
;   A LITTLE HELP FROM THE STACK.     ;
; ZERO PAGE ISN'T DIRECTLY DISTURBED. ;
;-------------------------------------;
; EMIT COMPLETE CORRECT SONG ADJUSTED ;
;   FOR UPPER-CASE 40-COLUMN DISPLAY. ;
;-------------------------------------;
LDX #MAXBEER    ;X=MAXBEER
BNE PRSONG      ;SING THE SONG & RTS
;-------------------------------------;
; EMIT WHOLE SONG UP TO LAST SENTENCE.;
;-------------------------------------;
BEERME:
LDY #TAKE1-TXT  ;? "TAKE ... AROUND,"
JSR PRBOB       ;? X;" BOT ... WALL."
PRSONG: ;          ;?
LDY #CR-TXT     ;? X;" BOT ... WALL,"
JSR PRBOB       ;? X;" BOT ... BEER."
DEX             ;X=X-1
BPL BEERME      ;IF X>=0 THEN BEERME
;-------------------------------------;
; EMIT LAST SENTENCE AND FALL THROUGH.;
;-------------------------------------;
LDX #MAXBEER    ;X=MAXBEER:
;                  ;? "GO TO ... MORE,"
;-------------------------------------;
; PRINT A PROPERLY PUNCTUATED "BOTTLE ;
;   OF BEER" SENTENCE.                ;
;-------------------------------------;
PRBOB:
TYA
PHA             ;SAVE THE PRE\$ PTR
JSR PUTS        ;? PRE\$;
TXA             ;IF X=0 THEN
BEQ PRBOTT      ;   ? "NO MORE";
LDY #"0"-1      ;ELSE
SEC             ;(
DIV10:
SBC #10         ;   Y=INT(X/10)
INY
BCS DIV10
CPY #"0"
BEQ ONEDIG
PHA             ;   IF Y>0 THEN
TYA                   ? Y;
JSR PUTCH
PLA             ;   ? X MOD 10;
ONEDIG:
LDY #BOTTL-TXT  ;)
PRBOTT:
JSR PUTCH       ;? " BOTTLE";
CPX #1
BNE PLURAL
INY             ;IF X<>1 THEN ? "S";
PLURAL:
JSR PUTS        ;? " OF BEER";
PLA             ;RECALL THE PRE\$ PTR
CMP #COMCR-TXT
BEQ PRDOT
PHA             ;IF APPROPRIATE THEN
JSR PUTS        ;   ? " ON THE WALL";
PLA
LDY #COMCR-TXT  ;IF APPROPRIATE THEN
CMP #CR-TXT     ;   ? ",":
BEQ PRBOB       ;   ? X;" ... BEER";
PRDOT:
LDY #DOTCR-TXT  ;? "."
;-------------------------------------;
; EMIT A HI-BIT-SET TERMINATED STRING ;
;   @ OFFSET Y AND EXIT WITH Y @ THE  ;
;   BEGINNING OF THE NEXT STRING.     ;
;-------------------------------------;
PUTS:
LDA TXT,Y       ;GRAB A STRING CHAR
PUTCH:
PHA
AND #ORMASK+127 ;FORMAT CHAR FOR ECHO
JSR ECHO        ;SHOOT IT TO CONSOLE
PLA
BPL PUTS        ;LOOP IF APPROPRIATE
RTS
;-------------------------------------;
; OPTIMIZED SONG LYRIC STRINGS.       ;
;-------------------------------------;
TXT:
TAKE1:
.AS "TAKE ONE DOWN AND"
.AS " PASS IT AROUND"
COMCR:
.AS ","
CR:
.AT #13
.AS "NO MORE"
BOTTL:
.AT " BOTTLE"
.AT "S OF BEER"
.AT " ON THE WALL"
DOTCR:
.AT ".",#13
.AS "GO TO THE STORE AND"
.EN
;-------------------------------------;
; APPLE 1 MONITOR HEX DUMP FOLLOWS.   ;
; ENTER THE 200 BYTES AS SHOWN INTO   ;
;   WOZMON AND LET THE BEER FLOW!!    ;
;-------------------------------------;
0BEE
:A2 63 D0 05 A0 00 20 01 0C A0 21 20 01
:0C CA 10 F3 A2 63 98 48 20 3C 0C 8A F0
:16 A0 AF 38 E9 0A C8 B0 FB 69 3A C0 B0
:F0 06 48 98 20 40 0C 68 A0 29 20 40 0C
:E0 01 D0 01 C8 20 3C 0C 68 C9 20 F0 0B
:48 20 3C 0C 68 A0 20 C9 21 F0 C7 A0 45
:B9 4C 0C C8 48 09 80 29 FF 20 EF FF 68
:10 F1 60 54 41 4B 45 20 4F 4E 45 20 44
:4F 57 4E 20 41 4E 44 20 50 41 53 53 20
:49 54 20 41 52 4F 55 4E 44 2C 8D 4E 4F
:20 4D 4F 52 45 20 42 4F 54 54 4C C5 53
:20 4F 46 20 42 45 45 D2 20 4F 4E 20 54
:48 45 20 57 41 4C CC 2E 8D 47 4F 20 54
:4F 20 54 48 45 20 53 54 4F 52 45 20 41
:4E 44 20 42 55 59 20 53 4F 4D 45 20 4D
:4F 52 45 2C 8D
BEER
```

## 6800 Assembly

```6800 Assembly
.cr  6800
.tf  beer6800.obj,AP1
.lf  beer6800
;
### ===============================================
;
;    Beer Song for the Motorola 6800 microprocessor   ;
;                 by barrym 2011-04-19                ;
;-----------------------------------------------------;
; Prints the correct, complete song lyrics to a full  ;
;   ascii terminal (console) connected to a 1970s     ;
;   vintage SWTPC 6800 system, which is the target    ;
;   device for this assembly.                         ;
; Many thanks to:                                     ;
;   swtpc.com for hosting Michael Holley's documents! ;
;   sbprojects.com for a very nice assembler!         ;
;   swtpcemu.com for a very capable emulator!         ;
; The 6800 microprocessor is the slightly older, less ;
;   popular, and more expensive step-brother of the   ;
;   6502.  Numerous similarities exist between the    ;
;   assembly languages of the two, but the 6800 has   ;
;   its own distinct flavor, which is (judging by how ;
;   compact the code ended up) well suited to this    ;
;   type of small program.  I am especially impressed ;
;   with the two-byte 'bsr' instruction, and I make   ;
;   extensive use of it here.                         ;
; Effort was made to keep the code footprint as small ;
;   as possible by re-using substrings and code in a  ;
;   hacker-like style that makes the program flow a   ;
;   bit strange to the human eye (the 6800 gobbles it ;
;   up without complaint).  The final tally: 97 bytes ;
;   of instructions, 108 bytes of text, and about 11  ;
;   bytes of stack.  This includes integer-to-ascii   ;
;   conversion, blank line between verses, removal of ;
;   "s" from "1 bottles", substitution of "no more"   ;
;   for "0", and proper capitalization of "No more".  ;
; reg b is the beer counter                           ;
; reg x is the string pointer                         ;
; reg a handles everything else (with a little help   ;
;                             from the system stack)  ;
;-----------------------------------------------------;
outeee   =   \$e1d1      ;ROM: console putchar routine
stbeer   =   99         ;Must be in the range [0..99]
.or  \$0f00
;
### ===============================================
;
; Initialize, sing the song, and exit                 ;
;-----------------------------------------------------;
main    ldab #stbeer    ;Beer count = stbeer
bsr  prsong     ;Sing the entire song
;
### ===============================================
;
; Emit the entire song up to the last sentence        ;
;-----------------------------------------------------;
beerme  bsr  prbob2     ;Emit second sentence of verse
prsong  ldx  #nline     ;Blank line between verses
ldaa #'N'       ;First sentence type = 'N'
bsr  prbob      ;Emit 1st sentence of verse
decb            ;Beer count -= 1
bpl  beerme     ;If beer count >= 0 then beerme
;
### ===============================================
;
; Set up the last sentence and fall through to prbob2 ;
;-----------------------------------------------------;
ldab #stbeer    ;Beer count = stbeer
ldx  #store     ;x\$ = "Go to the store ..."
;
### ===============================================
;
; Emit a properly punctuated bottle-of-beer sentence, ;
;   using beer counter in reg b, pre-string pointer   ;
;   in reg x, and the sentence type in reg a ('N' =   ;
;   sentence 1, 'o' = sentence 1.5, 'n' = sentence 2) ;
;-----------------------------------------------------;
prbob2  ldaa #'n'       ;Second sentence type = 'n'
prbob   psha            ;Stack sentence type for later
bsr  puts       ;Emit pre-string
pula            ;Check sentence type and use
psha            ;  it to prepare the upper- or
anda #'n'       ;  lower-case of "no more"
ldx  #omore     ;x\$ = "o more bottle"
tstb            ;If beer count = 0 then
beq  prbott     ;  skip over the i-to-a
ldx  #bottl     ;x\$ = " bottle"
;
### ===============================================
;
; I-to-A (inline): convert int in b to ascii and emit ;
;    with leading zero suppression (0 <= # <= 99)!    ;
;-----------------------------------------------------;
pshb            ;Stack beer count
ldaa #-1        ;  (divten trashes it)
divten  subb #10        ;b = ones digit - 10
inca            ;a = tens digit
bcc  divten     ;If a = 0 then
beq  onedig     ;  suppress leading zero
adda #"0"       ;else translate tens digit to
bsr  putch      ;  shifted ascii and emit
onedig  addb #'0'+10    ;Translate ones digit to ascii
tba             ;  and leave it in a for putch
pulb            ;Restore beer count
;-----------------------------------------------------;
prbott  bsr  putch      ;Emit a;x\$;
cmpb #1         ;If beer count = 1
bne  plural     ;then
inx             ;  skip over the "s"
plural  bsr  puts       ;Emit " ... beer";
pula            ;Restore sentence type
cmpa #'o'       ;If type <> 'o'
beq  putdot     ;then
psha            ;  emit " on the wall";
bsr  puts       ;  if type = 'N' then loop
pula            ;    back to finish the
adda #33        ;    first sentence with
bpl  prbob      ;    type = 'o', x\$ = ", "
putdot  ldx  #dotnl     ;x\$ = ".\n"
;
### ===============================================
;
; Emit string @ x and leave x @ start of next string  ;
;-----------------------------------------------------;
puts    ldaa 0,x        ;a = raw character removed
inx             ;  from the beginning of x\$
;
### ===============================================
;
; Emit a as ascii and loop into x\$ if hi-bit is clear ;
;-----------------------------------------------------;
putch   psha            ;Stack raw char
anda #\$7f       ;Mask off the hi-bit
jsr  outeee     ;Emit a as 7-bit ascii
pula            ;Restore raw char
tsta            ;If hi-bit is clear then
bpl  puts       ;  loop back into x\$
rts             ;All 8 'bsr's use this 'rts'!
;
### ===============================================
;
; Optimized song lyric strings, carefully arranged to ;
;   allow the prbob subroutine to take full advantage ;
;   of the x register side-effects of puts            ;
;-----------------------------------------------------;
omore   .as  "o more"
bottl   .at  " bottle"
.at  "s of beer"
.at  " on the wall"
.at  ", "
dotnl   .as  "."
nline   .at  #13,#10
.at  "Take one down and pass it around, "
store   .at  "Go to the store and buy some more, "
.en
;
### ===============================================
;
; The following is a hex dump of the object file,     ;
;   suitable for copying and pasting into the 6800    ;
;   emulator available at swtpcemu.com!               ;
;-----------------------------------------------------;
e0F00 C6 63 8D 03 3F 8D 0F CE 0F 86 86 4E 8D 0A 5A 2A
e0F10 F4 C6 63 CE 0F AA 86 6E 36 8D 38 32 36 84 6E CE
e0F20 0F 61 5D 27 15 CE 0F 67 37 86 FF C0 0A 4C 24 FB
e0F30 27 04 8B B0 8D 20 17 8B 3A 33 8D 1A C1 01 26 01
e0F40 08 8D 10 32 81 6F 27 08 36 8D 08 32 8B 21 2A C8
e0F50 CE 0F 85 A6 00 08 36 84 7F BD E1 D1 32 4D 2A F3
e0F60 39 6F 20 6D 6F 72 65 20 62 6F 74 74 6C E5 73 20
e0F70 6F 66 20 62 65 65 F2 20 6F 6E 20 74 68 65 20 77
e0F80 61 6C EC 2C A0 2E 0D 8A 54 61 6B 65 20 6F 6E 65
e0F90 20 64 6F 77 6E 20 61 6E 64 20 70 61 73 73 20 69
e0FA0 74 20 61 72 6F 75 6E 64 2C A0 47 6F 20 74 6F 20
e0FB0 74 68 65 20 73 74 6F 72 65 20 61 6E 64 20 62 75
e0FC0 79 20 73 6F 6D 65 20 6D 6F 72 65 2C A0
j0F00
```

## ARM Assembly

.global main

main:
mov r0, #99

loop:
push {r0}
mov r1, r0
mov r2, r0
sub r3, r0, #1
ldr r0, =lyric
bl printf
pop {r0}

sub r0, r0, #1
cmp r0, #0
bgt loop

ldr r0, =last_lyric
bl printf

mov r7, #1
swi 0

lyric:
.ascii "%d bottles of beer on the wall\n"
.ascii "%d bottles of beer\n"
.ascii "Take one down, pass it around\n"
.ascii "%d bottles of beer on the wall\n\n\000"

last_lyric:
.ascii "No more bottles of beer on the wall, no more bottles of beer.\n"
.ascii "Go to the store and buy some more, 99 bottles of beer on the wall\n\000"

```

## LLVM

```llvm
; "99 Bottles of Beer on the Wall" in LLVM Assembly

; This is not strictly LLVM, as it uses the C library function "printf".
; LLVM does not provide a way to print values, so the alternative would be
; to just load the string into memory, and that would be boring.

; The song lyrics are global constants.
; Lyrics for plural verses:
@pluralVerse = private constant [120 x i8]
c"%d bottles of beer on the wall, %d bottles of beer.\0ATake one down and pass it around, %d bottles of beer on the wall.\0A\0A\00"
; Lyrics for the singular verse:
@singularVerse = private constant [121 x i8]
c"1 bottle of beer on the wall, 1 bottle of beer.\0ATake one down and pass it around, no more bottles of beer on the wall.\0A\0A\00"
; Lyrics for the final verse:
@finalVerse = private constant [130 x i8]
c"No more bottles of beer on the wall, no more bottles of beer.\0AGo to the store and buy some more, %d bottles of beer on the wall.\0A\00"

; Initial number of bottles of beer.
; This must be a natural number.
@initialVerseNumber = private constant i32 99

; The declaration for the external C printf function.
declare i32 @printf(i8*, ...)

; Prints a verse, with %numberOfBottles being the initial number of bottles
; in that verse.
define fastcc void @printVerse(i32 %numberOfBottles) {
switch i32 %numberOfBottles,
label %pluralVerse
[ i32 1, label %singularVerse
i32 0, label %finalVerse ]

pluralVerse:
%pluralVersePointer = getelementptr [120 x i8]* @pluralVerse, i64 0, i64 0
%newNumberOfBottles = sub i32 %numberOfBottles, 1
call i32(i8*, ...)* @printf(
i8* %pluralVersePointer,
i32 %numberOfBottles,
i32 %numberOfBottles,
i32 %newNumberOfBottles)
ret void

singularVerse:
%singularVersePointer = getelementptr [121 x i8]* @singularVerse,i64 0,i64 0
call i32(i8*, ...)* @printf(i8* %singularVersePointer)
ret void

finalVerse:
%finalVersePointer = getelementptr [130 x i8]* @finalVerse, i64 0, i64 0
call i32(i8*, ...)* @printf(i8* %finalVersePointer,i32 %initialVerseNumberL)
ret void
}

define i32 @main() {
br label %loop ; This br terminates the first basic block.
loop:
%verseNumber =
phi i32 [%initialVerseNumberL, %loopHeader], [%nextVerseNumber, %do]
%cond = icmp eq i32 -1, %verseNumber
br i1 %cond, label %break, label %do
do:
call fastcc void @printVerse(i32 %verseNumber)
%nextVerseNumber = sub i32 %verseNumber, 1
br label %loop
break:
ret i32 0
}
```

## OASYS Assembler

The following example demonstrates the use of pointer variables (the argument ,^# to the &VERSE# method), and therefore may not be as efficient as one which does not use pointer variables.

; Beer program with OASYS assembler.

[&]
%@*>"Type 'beer' for beer.~Type 'quit' to quit.~"PS

['BEER]
,#99>:+,#&VERSE#/"No more bottles of beer on the wall.~"PS

[&VERSE#,^#]
,^#<,^#<<\
,^#<// Compiles with `gcc -nostdlib`
#define SYS_EXIT    \$60
#define SYS_WRITE   \$1

#define STDOUT          \$1

// Some numbers:
#define START_BOTTLES   99
#define NUM_LOCALS      \$8
#define WRL1_LEN        \$30
#define WRL2_LEN        \$53
#define WRL3_LEN        \$31

.global _start
.text

.macro WRITE
movq    STDOUT, %rdi
movq    SYS_WRITE, %rax
syscall
.endm

.macro WRITENUM
movq    8(%rsp), %rdx
movq    (%rsp), %rsi
WRITE
.endm

/* void* itoa(long, char *)
0q     8q
- char * points to the *back* of the string. itoa writes from ls digit.
- clobbers rdi, rax, rdx
- returns pointer to beginning of string
*/
itoa:
pushq   %rbp
movq    %rsp, %rbp

movq    16(%rsp), %rdi
movq    24(%rsp), %rax

cycledigits:
xorq    %rdx, %rdx
divq    decimal
movb    %dl, (%rdi)     // Copy char
decq    %rdi            // Next digit
cmpq    \$0, %rax
jg      cycledigits     // No more digits?

leaq    1(%rdi), %rax       // return value

popq    %rbp
ret

_start:
// Set up stack
movq    %rsp, %rbp
/*
bptr = itoa(counter, numstring)
do
{
write(stdout, bptr, bptr-numstring+1) // number
write(stdout, regstring, 30)
write(stdout, bptr, bptr-numstring+1) // number
write(stdout, regstring2, 52)
counter-=1
bptr = itoa(counter, numstring)
write(stdout, bptr, bptr-numstring+1) // number
write(stdout, regstring3, 30)
} while(counter>0)
*/
subq    NUM_LOCALS, %rsp
pushq   counter
pushq   \$numstring
precall:
call    itoa
addq    \$16, %rsp       // clean args
movq    %rax, (%rsp)      // bptr = itoa(counter, numstring)

subq    \$numstring, %rax
negq    %rax
leaq    1(%rax), %rdx
movq    %rdx, 8(%rsp)   // Save the calculation

printloop:
WRITENUM       // write(stdout, bptr, bptr-numstring+1)

writeline1:
movq    WRL1_LEN, %rdx
movq    \$regstring, %rsi
WRITE               // write(stdout, regstring, 30)

WRITENUM       // write(stdout, bptr, bptr-numstring+1)

writeline2:
movq    WRL2_LEN, %rdx
movq    \$regstring2, %rsi
WRITE               // write(stdout, regstring2, 52)
decq    counter     // counter--

pluralcheck:
cmpq    \$1, counter
jg      norm
cmpq    \$0, counter
je      zeroconfirm

oneconfirm:
movq    \$regstring, %rdx
movb    \$0x20 , 7(%rdx)
movq    \$regstring2, %rdx
movb    \$0x20 , 7(%rdx)
movq    \$regstring3, %rdx
movb    \$0x20 , 7(%rdx)
jg      norm

zeroconfirm:
movq    \$regstring, %rdx
movb    \$'s, 7(%rdx)
movq    \$regstring2, %rdx
movb    \$'s , 7(%rdx)
movq    \$regstring3, %rdx
movb    \$'s , 7(%rdx)

norm:
pushq   counter
pushq   \$numstring
call    itoa
movq    %rax, (%rsp)    // bptr = itoa(counter, numstring)

write3:
subq    \$numstring, %rax
negq    %rax
leaq    1(%rax), %rdx
movq    %rdx, 8(%rsp)
movq    (%rsp), %rsi
WRITE               // write(stdout, bptr, bptr-numstring+1)

writeline3:
movq    WRL3_LEN, %rdx
movq    \$regstring3, %rsi
WRITE               // write(stdout, regstring, 30)

cmpq    \$0, counter
jg      printloop

exit:
movq    SYS_EXIT, %rax
xorq    %rdi, %rdi              // The exit code.
syscall

.data
/* Begin Data Section: */
decimal:  // base 10
counter:
buffer:
.ascii "xxx"     /* Separated out because want back of string */
numstring:
.byte 'x
regstring:
.ascii " bottles of beer on the wall,\n"
regstring2:
.ascii " bottles of beer.\nTake one down, and pass it around:\n"
regstring3:
.ascii " bottles of beer on the wall.\n\n"

```

## Z80 Assembly

For Sinclair ZX Spectrum.

```z80
org 32768

start:
ld      a, 2                  ; Spectrum: channel 2 = "S" for screen
call    \$1601                 ; Spectrum: Select print channel using ROM

loopstart:
call printc                   ; Print the number of bottles
ld hl,line1                   ; Print the rest of the first line
call printline

call printc                   ; Print the number of bottles
ld hl,line2_3                 ; Print rest of the 2nd and 3rd lines
call printline

dec c                         ; Take one bottle away
call printc                   ; Print the number of bottles
ld hl,line4                   ; Print the rest of the fourth line
call printline

ld a,c
cp 0                          ; Out of beer bottles?
jp nz,loopstart               ; If not, loop round again

printc:                        ; Routine to print C register as ASCII decimal
ld a,c
call dtoa2d                   ; Split A register into D and E

ld a,d                        ; Print first digit in D
cp '0'                        ; Don't bother printing leading 0
jr z,printc2
rst 16                        ; Spectrum: Print the character in 'A'

printc2:
ld a,e                        ; Print second digit in E
rst 16                        ; Spectrum: Print the character in 'A'
ret

printline:                     ; Routine to print out a line
ld a,(hl)                     ; Get character to print
cp '\$'                        ; See if it '\$' terminator
jp z,printend                 ; We're done if it is
rst 16                        ; Spectrum: Print the character in 'A'
inc hl                        ; Move onto the next character
jp printline                  ; Loop round

printend:
ret

dtoa2d:                        ; Decimal to ASCII (2 digits only), in: A, out: DE
ld d,'0'                      ; Starting from ASCII '0'
dec d                         ; Because we are inc'ing in the loop
ld e,10                       ; Want base 10 please
and a                         ; Clear carry flag

dtoa2dloop:
inc d                         ; Increase the number of tens
sub e                         ; Take away one unit of ten from A
jr nc,dtoa2dloop              ; If A still hasn't gone negative, do another
add a,e                       ; Decreased it too much, put it back
add a,'0'                     ; Convert to ASCII
ld e,a                        ; Stick remainder in E
ret

; Data
line1:    defb ' bottles of beer on the wall,',13,'\$'
line2_3:  defb ' bottles of beer,',13,'Take one down, pass it around,',13,'\$'
line4:    defb ' bottles of beer on the wall.',13,13,'\$'
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