assembler.py

from syntax import syntax_check, is_label_decl, is_r_type, is_mem, is_beq
from translator import translate


def get_label(line):
    """Returns the label string of a label declaration. Does not check that the
    given string is indeed a label declaration or not."""
    return line[:-1]


def map_labels(args, lines):
    """Pass through the input lines once and create a map from label names to
    the offset in number of bytes from the first instruction of the input. This
    assumes that each instruction is 4 bytes long."""
    offset = 0
    result = {}
    for line in lines:
        if is_label_decl(line):
            result[get_label(line)] = offset
        else:
            offset += 4

    if args.debug:
        print("Labels map:", result)

    return result


def assemble(args, lines):
    """Converts the given list of RISC-V assembly lines into a list of RISC-V
    machine codes, one for each line. Each machine code is a string containing
    the machine code in hexadecimal representation (8 hex digits, no separation,
    no new lines).

    Returns None on failure."""
    lines = syntax_check(args, lines)
    if lines is None:
        return None

    labels_map = map_labels(args, lines)

    lines = translate(args, lines, labels_map)

    return lines