tiny-assembler 0.0.1

A basic assembler for educational processors.

Tiny Assembler

A customizable assembler for cores developed in introductory VLSI courses.

This project is licensed under the terms of the MIT license.

Installation

    pip install tiny_assembler

Usage

To assemble example.asm based on isa.json. The output will be written to example.mem.

    python tiny_assembler.py isa.json example.asm

Instruction Set Architecture (ISA)

ISA's are defined in a json file:

	"metadata":{
		"version": "0.0.1"
	},
	"properties":{
		"INST_WIDTH": 16,
		"DATA_WIDTH": 16,
		"OPCODE_WIDTH": 4,
		"REG_COUNT": 16,
		"LABEL_WIDTH": 10,
		"IMM_WIDTH": 8
	},
	"opcodes":{
		"ADD" : 0,
		"SLL" : 1,
		"SLR" : 2,
		"NOT" : 3,
		"AND" : 4,
		"OR"  : 5,
		"XOR" : 6,
		"NOP" : 7,
		"JMP"  : 8,
		"JZ"   : 8,
		"JNZ"  : 8,
		"LD"   : 10,
		"ST"   : 11,
		"ADDI" : 12,
		"SLLI" : 13,
		"SLRI" : 14,
		"NOTI" : 15
	},
	"subopcodes":{
		"JMP": 0,
		"JZ":  1,
		"JNZ": 2
	},
	"grammar":{
		"RRR":["ADD", "SLL", "SLR", "AND", "OR", "XOR"],
		"RR": ["NOT", "LD", "ST"],
		"RI": ["ADDI", "SLL", "SLR", "NOT"],
		"SL": ["JMP", "JZ", "JNZ"],
		"NON": ["NOP"]
	}
}

Assembly File Example

start:
NOP 
NOP
ADDI R1, #1 ; Address Incrementer
ADDI R5, #4 ; Upper address limit

read:
LD R3, R4 ; Load Mem[R4] to R3
ADD R4, R4, R1 ; R4 is the loop variable
XOR R6, R5, R4 ; See if we reach the address limit (R4 == R5)
JNZ $read
XOR R4, R4, R4; Clear R4

write:
; First read the content of the destination (Mem[2])
ADDI R2, #2; Address
LD R3, R2 ; Load Mem[R2] to R3
ADD R4, R4, R1; Data to store (incremented by 1 every step
ST R4, R2 ; Store the new data back to Mem[2]
XOR R6, R5, R4 ; See if we reach the end of loop (R4 == R5)
JNZ $write
JMP $start