.TH REDCODE 6 5/20/84
.CM 3
.SH NAME
redcode \- assembler for mars game
.SH SYNOPSIS
.I redcode
.I file ...
.SH DESCRIPTION
.I Redcode
is an assembler for the
assembly language given by Kee Dewdney in the
`Computer Recreations',
.I Scientific American,
May, 1984.
The command line lists of source file names ending in
.LR .red .
They are assembled into corresponding
object files with names ending in
.LR .obj .
.PP
A source file consists of a
.L name
directive giving the program's name,
then any number of program and data statements,
then an
.L end
directive that gives the starting location of the program.
Statements have the following syntax:
.IP
[label] opcode arg1 [arg2] [; comment]
.PP
There are three addressing modes;
all address calculations are done modulo 8000.
.LP
.nf
.I
Syntax		Meaning
#[0-9]+		immediate
[0-9]+		relative
@[0-9]+		indirect, relative
.PP
The following opcodes are implemented, along with the corresponding
semantics specified in pseudo-C:
.PP
.nf
.I
Instruction	Mnem	Opcode	Args	Explanation
Move		mov	1	A B	B=A
Add		add	2	A B	B+=A
Subtract	sub	3	A B	B-=A
Jump		jmp	4	A	PC=A
Jump if zero	jmz	5	A B	PC=(B==0)?A:PC+1
Jump if greater	jmg	6	A B	PC=(B<4000)?A:PC+1
Dec, Jmp if 0	djz	7	A B	PC=(--B==0)?A:PC+1
Compare		cmp	8	A B	PC=(A==B)?PC+1:PC+2
.PP
The following non-executable directives may be used
to reserve and initialize data space:
.PP
.I
Directive	Mnem	Arg	Explanation
Buffer space	bss	n	Reserve n words
Data		data	A	Initialize 1 word
Name		name	't'	Name of program
End		end	start	Specify starting location
.PP
The program was written by Paul Milazzo at Rice.
For documentation on the object code format, see
.IR mars (6).
.SH EXAMPLES
.EX
	name	'dwarf'
site	data	-1		; address of last 0 'bomb'
start	add	#5	site	; move site forward
	mov	#0	@site	; write 0 'bomb'
	jmp	start		; loop
	end	start
.EE
.SH SEE ALSO
.IR mars (6)