비트 논리 명령 문서의 검증 코드다. if __name__ == "__main__": 아래가 자체 테스트다.
"""비트 논리 명령 문서의 값 확인 (파이썬 흉내, 실제 MASM 실행 아님).
실행: python3 29_bitwise-instructions_verify.py"""
import re
# ---------------------------------------------------------------------------
# x86 흉내기: 이 파일에서 쓰는 만큼만 흉내 낸다 (MASM 문법의 일부를 그대로 읽는다).
# 레지스터 8·16·32비트, ZF/SF/CF/OF/PF, 리틀 엔디언 메모리, 스택, CALL/RET.
# 코드 주소는 실제 기계어 길이가 아니다. 줄 앞에 8자리 16진수를 쓰면 그 주소를 쓰고,
# 안 쓰면 CALL은 5, 나머지는 2씩 늘린다(문서 예시의 00000020 call → 00000025와 맞춘 값).
# ---------------------------------------------------------------------------
REG32 = ["eax", "ecx", "edx", "ebx", "esp", "ebp", "esi", "edi"]
REG16 = {"ax": "eax", "cx": "ecx", "dx": "edx", "bx": "ebx",
"sp": "esp", "bp": "ebp", "si": "esi", "di": "edi"}
REG8L = {"al": "eax", "cl": "ecx", "dl": "edx", "bl": "ebx"}
REG8H = {"ah": "eax", "ch": "ecx", "dh": "edx", "bh": "ebx"}
TYPES = {"byte": 1, "sbyte": 1, "word": 2, "sword": 2, "dword": 4, "sdword": 4}
STOP = 0xFFFFFFF0 # call_proc이 스택에 넣어 두는 가짜 복귀 주소
JCC = {
"jz": lambda f: f["ZF"], "je": lambda f: f["ZF"],
"jnz": lambda f: not f["ZF"], "jne": lambda f: not f["ZF"],
"jc": lambda f: f["CF"], "jb": lambda f: f["CF"], "jnae": lambda f: f["CF"],
"jnc": lambda f: not f["CF"], "jae": lambda f: not f["CF"], "jnb": lambda f: not f["CF"],
"jo": lambda f: f["OF"], "jno": lambda f: not f["OF"],
"js": lambda f: f["SF"], "jns": lambda f: not f["SF"],
"jp": lambda f: f["PF"], "jnp": lambda f: not f["PF"],
"ja": lambda f: not f["CF"] and not f["ZF"], "jnbe": lambda f: not f["CF"] and not f["ZF"],
"jbe": lambda f: f["CF"] or f["ZF"], "jna": lambda f: f["CF"] or f["ZF"],
"jg": lambda f: not f["ZF"] and f["SF"] == f["OF"],
"jnle": lambda f: not f["ZF"] and f["SF"] == f["OF"],
"jge": lambda f: f["SF"] == f["OF"], "jnl": lambda f: f["SF"] == f["OF"],
"jl": lambda f: f["SF"] != f["OF"], "jnge": lambda f: f["SF"] != f["OF"],
"jle": lambda f: f["ZF"] or f["SF"] != f["OF"],
"jng": lambda f: f["ZF"] or f["SF"] != f["OF"],
}
def signed(v, n):
"""n바이트 값 v를 부호 있는 정수로 읽는다."""
bits = 8 * n
return v - (1 << bits) if v >> (bits - 1) else v
class CPU:
def __init__(self, esp=0x1000):
self.r = {k: 0 for k in REG32}
self.r["esp"] = esp
self.f = dict(ZF=0, SF=0, CF=0, OF=0, PF=0)
self.mem = {} # 주소 -> 바이트
self.sym = {} # 변수 이름 -> (주소, 원소 크기, 원소 수)
self.const = {} # 기호 상수 -> 값
self.here = 0x4000 # 데이터 위치 카운터
self.code = [] # (주소, 연산, [피연산자], 원문)
self.label = {} # 레이블 -> 코드 주소
self.at = {} # 코드 주소 -> code 인덱스
self.hook = {} # 라이브러리 프로시저 흉내: 이름 -> 함수(cpu)
self.steps = 0
self.trace = None # 리스트를 넣어 두면 (원문, 레지스터, 플래그)를 쌓는다
self.calls = [] # 호출한 프로시저 이름 기록
# ---- 레지스터와 메모리 ----
def get(self, name):
name = name.lower()
if name in self.r:
return self.r[name]
if name in REG16:
return self.r[REG16[name]] & 0xFFFF
if name in REG8L:
return self.r[REG8L[name]] & 0xFF
if name in REG8H:
return (self.r[REG8H[name]] >> 8) & 0xFF
raise KeyError(name)
def put(self, name, v):
name = name.lower()
if name in self.r:
self.r[name] = v & 0xFFFFFFFF
elif name in REG16:
k = REG16[name]
self.r[k] = (self.r[k] & 0xFFFF0000) | (v & 0xFFFF)
elif name in REG8L:
k = REG8L[name]
self.r[k] = (self.r[k] & 0xFFFFFF00) | (v & 0xFF)
elif name in REG8H:
k = REG8H[name]
self.r[k] = (self.r[k] & 0xFFFF00FF) | ((v & 0xFF) << 8)
else:
raise KeyError(name)
@staticmethod
def regsize(name):
name = name.lower()
if name in REG32:
return 4
if name in REG16:
return 2
if name in REG8L or name in REG8H:
return 1
return None
def rd(self, addr, n):
"""리틀 엔디언: 낮은 주소에 낮은 바이트."""
return sum(self.mem.get(addr + i, 0) << (8 * i) for i in range(n))
def wr(self, addr, n, v):
for i in range(n):
self.mem[addr + i] = (v >> (8 * i)) & 0xFF
# ---- 데이터 정의 ----
def data(self, name, typ, values):
"""name TYPE values. 문자열은 글자마다 한 바이트, 레이블 이름은 그 코드 주소."""
n = TYPES[typ.lower()]
flat = []
for v in values:
if isinstance(v, str) and v in self.label:
flat.append(self.label[v])
elif isinstance(v, str):
flat.extend(ord(c) for c in v)
else:
flat.append(v)
addr = self.here
if name:
self.sym[name.lower()] = (addr, n, len(flat))
for v in flat:
self.wr(self.here, n, v)
self.here += n
return addr
# ---- 식과 피연산자 ----
def num(self, s):
"""상수식: 10진, 16진(h), 2진(b), 글자, 기호 상수, OFFSET/LENGTHOF/TYPE/SIZEOF, + - * / ( )."""
s = s.strip()
s = re.sub(r"'(.)'", lambda m: str(ord(m.group(1))), s)
def op(m):
a, n, c = self.sym[m.group(2).lower()]
return str({"offset": a, "lengthof": c, "type": n, "sizeof": n * c}[m.group(1).lower()])
s = re.sub(r"(?i)\b(offset|lengthof|type|sizeof)\s+(\w+)", op, s)
def tok(m):
t = m.group(0)
low = t.lower()
if re.fullmatch(r"[0-9][0-9a-f]*h", low):
return str(int(low[:-1], 16))
if re.fullmatch(r"[01]+b", low):
return str(int(low[:-1], 2))
if re.fullmatch(r"[0-9]+d?", low):
return str(int(low.rstrip("d")))
if low in self.const:
return str(self.const[low])
if low in self.label:
return str(self.label[low])
if t in self.label:
return str(self.label[t])
raise ValueError("모르는 이름: " + t)
s = re.sub(r"\w+", tok, s)
if not re.fullmatch(r"[0-9+\-*/() ]+", s):
raise ValueError("식을 못 읽음: " + s)
return int(eval(s.replace("/", "//")))
def operand(self, s):
"""('reg', 이름, 크기) / ('imm', 값, None) / ('mem', 주소, 크기 또는 None)"""
s = s.strip()
size = None
m = re.match(r"(?i)(byte|sbyte|word|sword|dword|sdword|near)\s+ptr\s+(.*)", s)
if m:
size = 4 if m.group(1).lower() == "near" else TYPES[m.group(1).lower()]
s = m.group(2).strip()
if self.regsize(s):
return ("reg", s.lower(), self.regsize(s))
m = re.fullmatch(r"(\w+)?\s*\[([^\]]+)\]", s)
if m:
addr = 0
if m.group(1):
a, n, _ = self.sym[m.group(1).lower()]
addr, size = a, size or n
for sign, term in re.findall(r"([+-]?)\s*([^+-]+)", m.group(2)):
term = term.strip()
v = self.get(term) if self.regsize(term) else self.num(term)
addr += -v if sign == "-" else v
return ("mem", addr & 0xFFFFFFFF, size)
m = re.fullmatch(r"(\w+)\s*(?:([+-])\s*(\w+))?", s)
if m and m.group(1).lower() in self.sym and not re.match(r"(?i)(offset|lengthof|type|sizeof)\b", s):
a, n, _ = self.sym[m.group(1).lower()]
if m.group(2):
d = self.num(m.group(3))
a += -d if m.group(2) == "-" else d
return ("mem", a, size or n)
return ("imm", self.num(s), None)
def val(self, o, n):
if o[0] == "reg":
return self.get(o[1])
if o[0] == "imm":
return o[1] & ((1 << (8 * n)) - 1)
return self.rd(o[1], n)
def store(self, o, n, v):
v &= (1 << (8 * n)) - 1
if o[0] == "reg":
self.put(o[1], v)
else:
self.wr(o[1], n, v)
# ---- 플래그 ----
def szp(self, v, n):
self.f["ZF"] = int(v == 0)
self.f["SF"] = (v >> (8 * n - 1)) & 1
self.f["PF"] = int(bin(v & 0xFF).count("1") % 2 == 0)
def add(self, a, b, n):
mask = (1 << (8 * n)) - 1
r = (a + b) & mask
top = 8 * n - 1
self.f["CF"] = int(a + b > mask)
self.f["OF"] = int((a >> top) == (b >> top) and (r >> top) != (a >> top))
self.szp(r, n)
return r
def sub(self, a, b, n):
mask = (1 << (8 * n)) - 1
r = (a - b) & mask
top = 8 * n - 1
self.f["CF"] = int(a < b)
self.f["OF"] = int((a >> top) != (b >> top) and (r >> top) != (a >> top))
self.szp(r, n)
return r
def logic(self, r, n):
self.f["CF"] = self.f["OF"] = 0
self.szp(r, n)
return r
# ---- 스택 ----
def push(self, v, n=4):
self.r["esp"] = (self.r["esp"] - n) & 0xFFFFFFFF
self.wr(self.r["esp"], n, v)
def pop(self, n=4):
v = self.rd(self.r["esp"], n)
self.r["esp"] = (self.r["esp"] + n) & 0xFFFFFFFF
return v
def eflags(self):
f = self.f
return f["CF"] | 2 | f["PF"] << 2 | f["ZF"] << 6 | f["SF"] << 7 | f["OF"] << 11
# ---- 코드 읽기 ----
def load(self, text, base=0):
cur = base
pending, uses = [], []
for raw in text.splitlines():
line = raw.split(";")[0].strip()
if not line or line.lower() in (".code", ".data"):
continue
m = re.match(r"([0-9A-Fa-f]{8})\s+(.*)", line)
if m:
cur, line = int(m.group(1), 16), m.group(2).strip()
m = re.fullmatch(r"(?i)(\w+)\s+PROC(?:\s+USES\s+(.*))?", line)
if m:
pending.append(m.group(1))
uses = m.group(2).split() if m.group(2) else []
for reg in uses: # USES가 만드는 push
cur = self._emit(cur, "push", [reg], "push " + reg, pending)
pending = []
continue
if re.fullmatch(r"(?i)\w+\s+ENDP", line):
uses = []
continue
m = re.match(r"(\w+)::?\s*(.*)", line)
if m and ":" in line.split()[0]:
pending.append(m.group(1))
line = m.group(2).strip()
if not line:
continue
parts = line.split(None, 1)
op = parts[0].lower()
args = [a.strip() for a in parts[1].split(",")] if len(parts) > 1 else []
if op == "ret":
for reg in reversed(uses): # USES가 만드는 pop
cur = self._emit(cur, "pop", [reg], "pop " + reg, pending)
pending = []
cur = self._emit(cur, op, args, line, pending)
pending = []
for name in pending: # 맨 끝의 레이블(next: 같은 것)
self.label[name] = self.label[name.lower()] = cur
self.end = cur
def _emit(self, cur, op, args, line, pending):
for name in pending:
self.label[name] = self.label[name.lower()] = cur
self.at[cur] = len(self.code)
self.code.append((cur, op, args, line))
return cur + (5 if op == "call" else 2)
def target(self, s):
if s in self.label:
return self.label[s]
if s.lower() in self.label:
return self.label[s.lower()]
o = self.operand(s)
return self.val(o, 4)
# ---- 실행 ----
def run(self, start=None, max_steps=10 ** 6):
eip = self.target(start) if isinstance(start, str) else (start if start is not None else self.code[0][0])
while eip in self.at:
self.steps += 1
if self.steps > max_steps:
raise RuntimeError("너무 오래 돈다")
i = self.at[eip]
addr, op, a, line = self.code[i]
nxt = self.code[i + 1][0] if i + 1 < len(self.code) else self.end
eip = self.step(op, a, nxt)
if self.trace is not None:
self.trace.append((line, dict(self.r), dict(self.f)))
if eip is None:
break
self.eip = eip
return self
def call_proc(self, name):
self.push(STOP)
return self.run(name)
def step(self, op, a, nxt):
f = self.f
if op in ("exit", "hlt"):
return None
if op == "nop":
return nxt
if op == "jmp":
return self.target(a[0])
if op in JCC:
return self.target(a[0]) if JCC[op](f) else nxt
if op == "jecxz":
return self.target(a[0]) if self.r["ecx"] == 0 else nxt
if op == "jcxz":
return self.target(a[0]) if self.get("cx") == 0 else nxt
if op in ("loop", "loope", "loopz", "loopne", "loopnz"):
self.r["ecx"] = (self.r["ecx"] - 1) & 0xFFFFFFFF # 플래그는 안 바뀐다
go = self.r["ecx"] != 0
if op in ("loope", "loopz"):
go = go and f["ZF"] == 1
if op in ("loopne", "loopnz"):
go = go and f["ZF"] == 0
return self.target(a[0]) if go else nxt
if op == "call":
if a[0] in self.hook:
self.calls.append(a[0])
self.hook[a[0]](self)
return nxt
t = self.target(a[0])
self.calls.append(a[0])
self.push(nxt)
return t
if op == "ret":
t = self.pop()
return None if t == STOP else t
if op == "push":
o = self.operand(a[0])
n = 2 if (o[0] == "reg" and o[2] == 2) or (o[0] == "mem" and o[2] == 2) else 4
self.push(self.val(o, n), n)
return nxt
if op == "pop":
o = self.operand(a[0])
n = 2 if o[2] == 2 else 4
self.store(o, n, self.pop(n))
return nxt
if op == "pushfd":
self.push(self.eflags())
return nxt
if op == "popfd":
v = self.pop()
f.update(CF=v & 1, PF=(v >> 2) & 1, ZF=(v >> 6) & 1, SF=(v >> 7) & 1, OF=(v >> 11) & 1)
return nxt
if op == "pushad":
old = self.r["esp"]
for k in ["eax", "ecx", "edx", "ebx"]:
self.push(self.r[k])
self.push(old)
for k in ["ebp", "esi", "edi"]:
self.push(self.r[k])
return nxt
if op == "popad":
for k in ["edi", "esi", "ebp"]:
self.r[k] = self.pop()
self.pop() # ESP 칸은 버린다
for k in ["ebx", "edx", "ecx", "eax"]:
self.r[k] = self.pop()
return nxt
# ---- 피연산자가 있는 명령 ----
d = self.operand(a[0])
s = self.operand(a[1]) if len(a) > 1 else None
n = d[2] or (s[2] if s else None)
if n is None:
raise ValueError("크기를 알 수 없다: " + " ".join(a))
if op in ("movzx", "movsx"):
sn = s[2]
v = self.val(s, sn)
self.store(d, d[2], signed(v, sn) if op == "movsx" else v)
return nxt
if s is not None and s[0] != "imm" and d[2] and s[2] and d[2] != s[2] and op not in ("shl", "sal", "shr", "sar"):
raise ValueError("크기가 다르다: " + " ".join(a))
x = self.val(d, n)
y = self.val(s, n) if s else None
top = 8 * n - 1
if op == "mov":
self.store(d, n, y)
elif op == "xchg":
self.store(d, n, y)
self.store(s, n, x)
elif op == "add":
self.store(d, n, self.add(x, y, n))
elif op == "sub":
self.store(d, n, self.sub(x, y, n))
elif op == "cmp":
self.sub(x, y, n) # 결과는 버린다
elif op == "inc":
c = f["CF"]
self.store(d, n, self.add(x, 1, n))
f["CF"] = c # INC는 CF를 안 건드린다
elif op == "dec":
c = f["CF"]
self.store(d, n, self.sub(x, 1, n))
f["CF"] = c
elif op == "neg":
self.store(d, n, self.sub(0, x, n))
elif op == "and":
self.store(d, n, self.logic(x & y, n))
elif op == "test":
self.logic(x & y, n) # 결과는 버린다
elif op == "or":
self.store(d, n, self.logic(x | y, n))
elif op == "xor":
self.store(d, n, self.logic(x ^ y, n))
elif op == "not":
self.store(d, n, ~x) # 플래그는 안 바뀐다
elif op in ("shl", "sal", "shr", "sar"):
c = self.val(s, 1) & 31
for _ in range(c):
if op in ("shl", "sal"):
f["CF"] = (x >> top) & 1
x = (x << 1) & ((1 << (8 * n)) - 1)
else:
f["CF"] = x & 1
x = (x >> 1) | ((x >> top) << top if op == "sar" else 0)
if c:
self.szp(x, n)
self.store(d, n, x)
else:
raise ValueError("모르는 명령: " + op)
return nxt
def machine(code, esp=0x1000, base=0):
c = CPU(esp)
c.load(code, base)
return c
def al(code, **reg):
c = machine(code)
for k, v in reg.items():
c.put(k, v)
return c.run()
def main():
# 1. 네 연산 표의 값
assert al("mov al,00111011b\nand al,00001111b").get("al") == 0b00001011
assert al("mov al,00111011b\nor al,00001111b").get("al") == 0b00111111
assert al("mov al,00111011b\nxor al,00001111b").get("al") == 0b00110100
assert al("mov al,00111011b\nnot al").get("al") == 0b11000100
# 2. 대문자로: 5번 비트 끄기. 소문자 26개 전부
assert al("mov al,'a'\nand al,11011111b").get("al") == 0b01000001 == ord("A")
for ch in "abcdefghijklmnopqrstuvwxyz":
assert chr(al("and al,11011111b", al=ord(ch)).get("al")) == ch.upper()
assert ord("a") - ord("A") == 32 == 1 << 5
# 3. 숫자를 글자로: 4·5번 비트 켜기. 0~9 전부
assert al("mov al,6\nor al,00110000b").get("al") == 0b00110110 == ord("6")
for d in range(10):
assert chr(al("or al,00110000b", al=d).get("al")) == str(d)
# 4. CapsLock: 6번 비트. 주소 0040:0017 = 00417h. 실행 확인 안 함(실주소 모드 전용), 계산만
assert 0x40 * 16 + 0x17 == 0x417 and (0b00000000 | 0b01000000) == 1 << 6
# 5. 짝수면 점프, 0이 아니면 점프: 전수
for v in list(range(0, 300)) + [0x7FFF, 0x8000, 0xFFFE, 0xFFFF]:
c = al("and ax,1\njz EvenValue\nmov bl,1\nEvenValue:", ax=v)
assert (c.get("bl") == 0) == (v % 2 == 0)
for v in range(256):
c = al("or al,al\njnz IsNotZero\nmov bl,1\nIsNotZero:", al=v)
assert (c.get("bl") == 0) == (v != 0) and c.get("al") == v
# Your turn: 음수면 점프. 두 가지 답, 16비트 전수
for v in range(0, 65536, 7):
neg = signed(v, 2) < 0
c = al("test ax,8000h\njnz IsNeg\nmov bl,1\nIsNeg:", ax=v)
assert (c.get("bl") == 0) == neg and c.get("ax") == v
c = al("or ax,ax\njs IsNeg\nmov bl,1\nIsNeg:", ax=v)
assert (c.get("bl") == 0) == neg and c.get("ax") == v
# 6. 0·1·3번 비트가 모두 켜졌나: 전수
for v in range(256):
c = al("and al,00001011b\ncmp al,00001011b\nje L1\nmov bl,1\nL1:", al=v)
assert (c.get("bl") == 0) == (v & 1 and v & 2 and v & 8 and True or False)
# 7. XOR 암호: 두 번 하면 돌아온다
enc = """mov ecx,bufSize
mov esi,0
L1:
xor buffer[esi],KEY
inc esi
loop L1"""
msg = b"Attack at dawn."
c = machine(enc)
b = c.data("buffer", "BYTE", list(msg) + [0])
c.data("bufSize", "DWORD", [len(msg)])
c.const["key"] = 239
c.run()
cipher = bytes(c.mem[b + i] for i in range(len(msg)))
assert cipher != msg and cipher == bytes(x ^ 239 for x in msg)
assert cipher[0] == 0xAE and ord("A") == 0x41 and 0x41 ^ 0xEF == 0xAE
c2 = machine(enc)
b2 = c2.data("buffer", "BYTE", list(cipher) + [0])
c2.data("bufSize", "DWORD", [len(msg)])
c2.const["key"] = 239
c2.run()
assert bytes(c2.mem[b2 + i] for i in range(len(msg))) == msg
assert all((x ^ k) ^ k == x for x in range(256) for k in range(256))
# 8. 플래그: AND/OR/XOR/TEST는 CF와 OF를 0으로, NOT은 플래그를 안 바꾼다. 8비트 전수
for x in range(256):
for y in (0, 1, 0x0F, 0x80, 0xFF, x):
for op, fn in (("and", lambda a, b: a & b), ("or", lambda a, b: a | b), ("xor", lambda a, b: a ^ b)):
c = machine("mov al,0FFh\nadd al,1\n%s bl,dl" % op) # 앞에서 CF = 1로 만들어 둔다
c.put("bl", x)
c.put("dl", y)
c.run()
r = fn(x, y)
assert c.get("bl") == r
assert (c.f["CF"], c.f["OF"], c.f["ZF"], c.f["SF"]) == (0, 0, int(r == 0), r >> 7)
c = machine("mov al,0FFh\nadd al,1\nnot bl")
c.put("bl", x)
c.run()
assert c.get("bl") == 255 - x and (c.f["CF"], c.f["ZF"]) == (1, 1)
# 9. 카드
assert al("mov al,10101100b\nand al,11110000b").get("al") == 0b10100000
assert al("mov al,10101100b\nor al,00000011b").get("al") == 0b10101111
assert al("mov al,10101100b\nxor al,11111111b").get("al") == 0b01010011
assert al("mov al,'Q'\nxor al,00100000b").get("al") == ord("q")
# 10. 소프트웨어 프로젝트 "비트 연산"의 과목별 관점: Java >> = SAR, >>> = SHR, << = SHL
def java_sar(x, s):
return x >> s
def java_shr(x, s):
return (x % 2 ** 32) >> s
for x in (-16, -8, -7, -1, 0, 1, 7, 45, 2 ** 31 - 1, -2 ** 31):
for s in range(0, 32):
c = machine("sar eax,%d" % s)
c.r["eax"] = x % 2 ** 32
assert signed(c.run().r["eax"], 4) == java_sar(x, s)
c = machine("shr eax,%d" % s)
c.r["eax"] = x % 2 ** 32
assert c.run().r["eax"] == java_shr(x, s)
c = machine("shl eax,%d" % s)
c.r["eax"] = x % 2 ** 32
assert c.run().r["eax"] == (x << s) % 2 ** 32
c = machine("sar eax,2")
c.r["eax"] = -16 % 2 ** 32
assert signed(c.run().r["eax"], 4) == -4
c = machine("shr eax,28")
c.r["eax"] = -16 % 2 ** 32
assert c.run().r["eax"] == 15
c = machine("shr eax,1")
c.r["eax"] = -8 % 2 ** 32
assert c.run().r["eax"] == 2147483644
# 시프트 예의 값: 80 shr 1 = 40, shr 2 = 10 / -80 sar 1 = -40, sar 2 = -10 / Your turn
assert al("mov dl,80\nshr dl,1\nshr dl,2").get("dl") == 10
assert signed(al("mov dl,-80\nsar dl,1\nsar dl,2").get("dl"), 1) == -10
assert al("mov al,6Bh\nshr al,1").get("al") == 0x35 and al("mov al,6Bh\nshr al,1\nshl al,3").get("al") == 0xA8
assert al("mov al,8Ch\nsar al,1").get("al") == 0xC6 and al("mov al,8Ch\nsar al,1\nsar al,3").get("al") == 0xF8
# 새 카드 C5: byte 값 -16(F0h)을 오른쪽으로 2칸
assert al("mov al,0F0h\nsar al,2").get("al") == 0xFC and signed(0xFC, 1) == -4
assert al("mov al,0F0h\nshr al,2").get("al") == 0x3C == 60
# 칸 수는 아래 5비트만 본다: 32칸 밀기는 0칸 밀기 (Java의 1 << 32 == 1과 같다)
c = machine("mov eax,1\nmov cl,32\nshl eax,cl").run()
assert c.r["eax"] == 1
c = machine("mov eax,1\nmov cl,33\nshl eax,cl").run()
assert c.r["eax"] == 2
if __name__ == "__main__":
main()
print("ALL CHECKS PASSED")