EMU1.0decompiler.py

import base64

lookup = ["add", "add", "sub", "cmp", "or", "or", "xor", "xor", "and", "and", "sh/r", "shl", "shr", "ld", "st", "lbl", "jup", "jdn", "io", "mul"]
cmpluk = ["tr", "fa", "eq", "ne", "sl", "sg", "ul", "ug"]

def decode(instr):
    OPC = (instr & 0b0111111000000000000000000) >> 18
    A   = (instr & 0b0000000111111000000000000) >> 12
    B   = (instr & 0b0000000000000111111000000) >> 6
    C   = (instr & 0b0000000000000000000111111)
    if (OPC == 0): return "HALT"
    OPC -= 1
    op = OPC % 21
    co = OPC // 21
    cond = " "
    if co == 1: cond = "+"
    if co == 2: cond = "-"
    opS = lookup[op]
    aprev = "r"
    bprev = "r"
    cprev = "r"
    if op in [1, 5, 7, 9]: cprev = "i"
    if op == 18: bprev = "i"
    stri = f"{cond} {opS.ljust(3)}  {(aprev + str(A)).rjust(3)}, {(bprev + str(B)).rjust(3)}, {(cprev + str(C)).rjust(3)}"
    # exceptions
    if opS in ["lbl", "jup", "jdn"]:
        if opS == "lbl": cprev = ""
        stri = f"{cond} {opS.ljust(3)}  {str(64*A + B).rjust(8)}, {(cprev + str(C)).rjust(3)}"
    if opS == "cmp":
        cc = A % 8
        a = A // 8
        opS += cmpluk[cc]
        if a == 1: B,C = C,B
        if a == 2: cprev = "i"
        if a == 3: bprev = "i"
        stri = f"{cond} {opS.ljust(8)}  {(bprev + str(B)).rjust(3)}, {(cprev + str(C)).rjust(3)}"
    if opS == ["mul", "sh/r"]:
        # not neccessarry as not in rom
        pass
    return stri

bytesArr = []
with open("talkative-server-redacted.rom", "rb") as f:
    byte = f.read(1)
    while byte != b"":
        bytesArr.append(byte.decode())
        byte = f.read(1)
        
instArr = []
for i in range(0,len(bytesArr)-1, 4):
    base = bytesArr[i] + bytesArr[i+1] + bytesArr[i+2] + bytesArr[i+3]
    decoded = int.from_bytes(base64.b64decode(base), byteorder='big', signed=False)
    decoded = decode(decoded)

    print(decoded)

Disclaimer: This is not a full decompiler but just enough to get what is going on!