.TH REDCODE 1 5/20/84
.CM 3
.SH NAME
redcode \- assembler for
.IR mars (1)
.SH SYNOPSIS
redcode
.I 
file1 file2 ...
.SH DESCRIPTION
.PP
.I redcode
is an assembler for the 
.I redcode
assembly language specified by Dr. Kee Dewdney in the
"Computer Recreations" column in the May 1984 issue of
.I Scientific American. 
The command line contains a list of source file names (including
the extension ".red") to be assembled.  The result is a corresponding
number of object files with extension ".obj".
For example, the following command:
.sp
	redcode dwarf.red gemini.red imp.red
.sp
would assemble these three programs and create files
.I
dwarf.obj gemini.obj imp.obj.
.SH SOURCE FILES
.PP
A source file consists of a 
.I name
directive which specifies the program's name, 
followed by any number of program and data statements,
followed by an
.I end
directive which specifies the starting location of the program.
Statements have the following syntax:
.sp
	[label] opcode arg1 [arg2] [; comment]
.SH ADDRESSING MODES
There are three addressing modes; 
all address calculations are done modulo 8000.
.sp
.I
Syntax		Meaning
.sp
#[0-9]+		immediate
.br
[0-9]+		relative
.br
@[0-9]+		indirect, relative
.SH OPCODES
.PP
The following opcodes are implemented, along with the corresponding
semantics specified in pseudo-C:
.I
Instruction	Mnem	Opcode	Args	Explanation
.sp
Move		mov	1	A B	B=A
.br
Add		add	2	A B	B+=A
.br
Subtract	sub	3	A B	B-=A
.br
Jump		jmp	4	A	PC=A
.br
Jump if zero	jmz	5	A B	PC=(B==0)?A:PC+1
.br
Jump if greater	jmg	6	A B	PC=(B<4000)?A:PC+1
.br
Dec, Jmp if 0	djz	7	A B	PC=(--B==0)?A:PC+1
.br
Compare		cmp	8	A B	PC=(A==B)?PC+1:PC+2
.SH PSEUDO-OPS
.PP
The following non-executable directives may be used
to reserve and initialize data space:
.sp
.I
Directive	Mnem	Arg	Explanation
.sp
Buffer space	bss	n	Reserve n words
.br
Data		data	A	Initialize 1 word
.br
Name		name	't'	Name of program
.br
End		end	start	Specify starting location
.SH A SAMPLE REDCODE PROGRAM
.sp
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
.br
;;; Dwarf, a sample Redcode program
.br
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
.br

.br
	name	'dwarf'
.br
site	data	-1		; address of last 0 'bomb'
.br
start	add	#5	site	; move site forward
.br
	mov	#0	@site	; write 0 'bomb'
.br
	jmp	start		; loop
.br
	end	start
.SH OBJECT FILES
.PP
For documentation on the object code format, see 
.IR mars (1).
.SH SEE ALSO
mars(1)
.SH HISTORY
.TP
20-May-84 Paul Milazzo (milazzo) at RICE
Created.