I have reordered time. I have turned the world upside down, and I have done it all for you!

Self-Generating

The following program will emit its own bytecode when run:

( uxncli gen.rom > gen-self.rom )
@q ;&end ;q &l LDAk #18 DEO INC2 GTH2k ?&l &end

The program above compiles to the resulting emitted bytecode:

a001 0fa0 0100 9480 1817 21aa 20ff f7

Self-Printing

The following program will emit a program that emits its own bytecode as hexadecimal ascii characters:

( uxncli pri.rom )
@q
	;end ;q
	&l LDA2k phex #2018 DEO INC2 INC2 GTH2k ?&l
	BRK
@phex ( short* -- )
	SWP phex/b
	&b DUP #04 SFT phex/c
	&c #0f AND DUP #09 GTH #27 MUL ADD [ LIT "0 ] ADD #18 DEO
	JMP2r
@end

Running the previous program generates the following hexadecimal values which are also valid source code:

a001 32a0 0100 b460 000b a020 1817 2121 
aa20 fff2 0004 6000 0006 8004 1f60 0000 
800f 1c06 8009 0a80 271a 1880 3018 8018 
176c

Maze

A small program to print the iconic Commodore 64 maze:

@maze ( -> )
	( seed ) #c5 DEI2 ,&seed STR2
	&w ( -- )
		[ LIT2 "/\ ] [ LIT2 &seed &x $1 &y $1 ]
		( rand x ) ADDk #50 SFT EOR DUP #03 SFT EOR DUP ,&x STR
		( rand y ) SUBk #01 SFT EOR EOR DUP ,&y STR
		( emit ) #01 AND [ JMP SWP POP ] #18 DEO !&w

Where Are We?

From anywhere during a program's execution, the location of the program counter can be pushed onto the working stack with the following snippet:

[ LITr 00 ] JSRr

• Self-Printing Machine Code