#!/usr/bin/env python3
import sys


def task01() -> None:
    instr = 0xFFC30293
    opcode = instr & 0x7F
    rd = (instr >> 7) & 0x1F
    funct3 = (instr >> 12) & 0x7
    rs1 = (instr >> 15) & 0x1F
    imm = (instr >> 20) & 0xFFF
    imm = imm - 0x1000 if imm & 0x800 else imm
    assert (opcode, rd, funct3, rs1, imm) == (0x13, 5, 0, 6, -4)
    print("PASS task01 instr=ffc30293 opcode=13 rd=5 rs1=6 funct3=0 imm=-4")


def task02() -> None:
    classes = {0x13: "alu_imm", 0x33: "alu_reg", 0x03: "load", 0x23: "store", 0x63: "branch", 0x6F: "jump", 0x67: "jump"}
    assert len(classes) == 7 and 0x7F not in classes
    print("PASS task02 legal=7 jump_opcodes=6f,67 illegal_7f=1")


def task03() -> None:
    regs = [0] * 32
    regs[5] = 0x12345678
    attempted_x0 = 0xFFFFFFFF
    if 0 != 0:
        regs[0] = attempted_x0
    assert regs[5] == 0x12345678 and regs[0] == 0
    print("PASS task03 x5=12345678 x0=00000000 dual_read=1")


TASKS = {"task01_instruction_fields": task01, "task02_opcode_decoder": task02, "task03_register_file": task03}
if len(sys.argv) != 2 or sys.argv[1] not in TASKS: raise SystemExit(f"usage: {sys.argv[0]} {'|'.join(TASKS)}")
TASKS[sys.argv[1]]()