RASM

Assembler for RISC-ALX architecture.

Usage

./rasm <INPUT_FILE> INPUT_FILE must be valid RASM code. Machine code will be sent to stdout.

Language

There are four kinds of statements in RASM:

• Section declarations
• Register declarations
• Symbol declarations
• Instructions

Section Declarations

Either .data or .text. The statement .data must be the first line of code in the file and precede .text.

Register Declarations

Register name followed by the integer value it is initialized to. Can only exist in .data section. Example: tmp 10.

Symbol Declarations

Symbol name followed by a colon. Can only exist in .text section. Example: _start:.

Instructions

An instruction from the following list followed by its operands.

Name	Operand 1	Operand 2	Description
jmp	Dest		Sets instruction pointer to Dest
jz	Dest	Source	Jumps to Dest if [Source] = 0
jnz	Dest	Source	Jumps to Dest if [Source] != 0
cmp	Addr1	Addr2	To be followed by je, jne, jg, jge, jl, or jle
je	Dest		Jump to Dest if [Addr1] = [Addr2]
jne	Dest		Jump to Dest if [Addr1] != [Addr2]
jg	Dest		Jump to Dest if [Addr1] > [Addr2]
jge	Dest		Jump to Dest if [Addr1] >= [Addr2]
jl	Dest		Jump to Dest if [Addr1] < [Addr2]
jle	Dest		Jump to Dest if [Addr1] <= [Addr2]
inc	Dest		Increments [Dest]
add	Dest	Source	Stores [Dest] + [Source] into [Dest]
sub	Dest	Source	Stores [Dest] - [Source] into [Dest] (Stores 0 if [Source] >= [Dest])
mov	Dest	Source	Copies [Source] to [Dest]
drs	Dest	Source	Copies [[Source]] to [Dest]
drt	Dest	Source	Copies [Source] to [[Dest]]
out	Source		Outputs [Source]
inp	Dest		Inputs into [Dest]
hlt			Halts
An operand can either be a register name, a symbol name, or a non-negative integer preceded by a dollar sign indicating a numerical constant.
The symbol _start must be defined for all programs, as it acts as the starting point of execution.
The symbol __ram is a special symbol that is predefined and indicates the beginning of available memory. All memory past this point is free to alter without repercussion.

Example

An example of a program designed to list the first n fibonacci numbers where n is the given input:

.data

cur 0
next 1
tmp 0
count 0

.text

_start:
    inp count

_repeat:
    out cur
    mov tmp next
    add next cur
    mov cur tmp
    sub count $1
    jnz _repeat count

_finish:
    hlt

RISC-ALX Specification

See RISC-ALX.md.

Syntax Highlighting

Support for syntax highlighting is provided through the VSCode extension syntax.vsix.