Quines : Programs that copy themselves

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bitRAKE

Joined: 21 Jul 2003
Posts: 4428
Location: vpcmpistri

bitRAKE 22 Jan 2026, 07:25

In fasmg not only does an empty file copy itself, but "file __FILE__" also copies itself. Moving beyond these trivial examples (305 bytes):

Code:

virtual
A::db 'virtual|A::db ~|end virtual|repeat sizeof A|load a:1 from A:%-1|if a=7Eh|load a:%% from A:0|db 27h,a,27h|else if a=7Ch|db 10|else|db a|end if|end repeat'
end virtual
repeat sizeof A
load a:1 from A:%-1
if a=7Eh
load a:%% from A:0
db 27h,a,27h
else if a=7Ch
db 10
else
db a
end if
end repeat

... you'll need to use Unix (10) line endings. Basically, a tag character is used to self-copy within the string of bytes, and a few exceptions are handled. Greater explanation is probably best done by another's video (he also explains how trojans can be hidden in compilers).

(Of course, a smaller version is possible - down to 291.)

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Last edited by bitRAKE on 01 Apr 2026, 02:09; edited 1 time in total

22 Jan 2026, 07:25

Tomasz Grysztar

Joined: 16 Jun 2003
Posts: 8524
Location: Kraków, Poland

Tomasz Grysztar 22 Jan 2026, 10:10

How about something more unique to fasmg?

Code:

a
macro a
calminstruction ?!n&
match,n
jyes x
take m,m
arrange m,n
stringify m
emit lengthof m,m
emit 1,10
jno x
assemble n
x:
end calminstruction
a
end macro

22 Jan 2026, 10:10

bitRAKE

Joined: 21 Jul 2003
Posts: 4428
Location: vpcmpistri

bitRAKE 22 Jan 2026, 12:11

That's bonkers - yet, insightful.

Three distinctly different corner cases.

22 Jan 2026, 12:11

bitRAKE

Joined: 21 Jul 2003
Posts: 4428
Location: vpcmpistri

bitRAKE 21 Mar 2026, 02:12

A slight re-arrangement allows removing special handling for the empty line.

Code:

a
macro a
calminstruction ?!n&
take m,m
jno y
emit 1,10
y:
arrange m,n
stringify m
emit lengthof m,m
jno x
assemble n
x:
end calminstruction
a
end macro

Note: the final newline is no longer needed (152 bytes), but also is allowed. Very Happy

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21 Mar 2026, 02:12

Tomasz Grysztar

Joined: 16 Jun 2003
Posts: 8524
Location: Kraków, Poland

Tomasz Grysztar 21 Mar 2026, 09:34

I was hoping you would improve it! Smile

21 Mar 2026, 09:34

bitRAKE

Joined: 21 Jul 2003
Posts: 4428
Location: vpcmpistri

bitRAKE 21 Mar 2026, 21:33

Fold conditions together, reduce first line test/track (138 bytes):

Code:

a
macro a
calminstruction ?!n&
take,b
jno z
emit 1,10
assemble n
z:
stringify n
emit lengthof n,n
take b,n
end calminstruction
a
end macro

... still feel I'm missing something.

It seems something like,

Code:

a
macro a
macro ?!b&
match,c
b
end match
c equ
c equ
db`b,10
end macro
a
end macro

... would work. It finishes without the unconditional modifier on the ? macro, but only processes the "a".

21 Mar 2026, 21:33

bitRAKE

Joined: 21 Jul 2003
Posts: 4428
Location: vpcmpistri

bitRAKE 01 Apr 2026, 01:09

It just occurred to me there is no in-place replace -- that would be a very fasm/fasmg style solution.

Another potential would be larger integer manipulation.

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01 Apr 2026, 01:09

bitRAKE

Joined: 21 Jul 2003
Posts: 4428
Location: vpcmpistri

bitRAKE 03 Apr 2026, 15:53

Code:

DB 'i\jkXikflk![Y79[Y7>9CXCJPCHGC>cfX[7XQ;7]ifd7G>CHGC>\mXc7jki`e^7XD?DH@YjnXg7;F;]]AIJ>'
LOAD A:$ FROM 0
EVAL STRING A-(-1)BSWAP $/$FF*23

138 bytes, big integer filter eval. Very Happy

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Last edited by bitRAKE on 03 Apr 2026, 16:32; edited 1 time in total

03 Apr 2026, 15:53

Tomasz Grysztar

Joined: 16 Jun 2003
Posts: 8524
Location: Kraków, Poland

Tomasz Grysztar 03 Apr 2026, 16:30

Nice!
I was thinking about using EVAL to distil the classic quine idea:

Code:

A='db "A=",39,A,39,10,"EVAL A"'
EVAL A

Still, making use of fasmg's multi-pass feels more fun.

03 Apr 2026, 16:30

bitRAKE

Joined: 21 Jul 2003
Posts: 4428
Location: vpcmpistri

bitRAKE 03 Apr 2026, 17:04

You're right - I still had my head in the load/store in-place replace version.
Should just do:

Code:

A="[Y7>XT9>CXCJKCHGC>\mXc7jki`e^7XD?DH@YjnXg7LIF;]]AIJ>"
EVAL STRING A-(-1)BSWAP 52/$FF*23

... focused on the theme, 90 bytes.

03 Apr 2026, 17:04

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