Initial public release of JustOneCacophony

src/evo_unpack.py

@@ -0,0 +1,76 @@
+"""解包 EVO MD-set evolution 载荷，返回各 payload ID 的字节数据和位偏移。"""
+_MARK = "1001001000000"
+
+# 各子载荷字段: (id, 头部前缀, 同步标记, 后缀常量, 尺寸域位数, 是否有转义)
+# 头部前缀 = 5 位 id 的 MSB 二进制（id11 字段前另有 5 位容器前导 00000）
+# 尺寸域单位 = nibble（4 位）。id14 有转义：9 位值=0 → 再读 9 位 = 字节数。
+_LAYOUT = [
+    (11, "0000001011", "010000000000000", 8, False),
+    (14, "01110",      "01000000000000",  9, True),
+    (2,  "00010",      "000100",          7, False),
+    (1,  "00001",      "1110000000000000000000000000", 4, False),
+    (30, "11110",      "1110000000000000000000000000", 4, False),
+]
+
+
+def _msb_bits(data: bytes):
+    return [(x >> (7 - i)) & 1 for x in data for i in range(8)]
+
+
+def _val(bits, off, n):
+    v = 0
+    for b in bits[off:off + n]:
+        v = (v << 1) | b
+    return v
+
+
+class _LooseSkip(Exception):
+    def __init__(self, ident):
+        self.ident = ident
+
+
+def unpack_evolution(payload: bytes, loose=False):
+    """解包 evolution 载荷 → (subs, offsets)。subs 键为 id 整数。
+    loose=True 时对每个 id 的 (前缀+标记+后缀) 全模式做位流重同步扫描
+    （不同编码流的子载荷次序/内部常量可有合法差异，如 kanata 的 id11）。"""
+    bits = _msb_bits(payload)
+    pos = 0
+    subs = {}
+    offsets = {}
+    for ident, pref, suff, sbits, escape in _LAYOUT:
+        pat = pref + _MARK + suff
+        if loose:
+            hit = -1
+            for i in range(pos, len(bits) - len(pat)):
+                if ''.join(map(str, bits[i:i + len(pat)])) == pat:
+                    hit = i
+                    break
+            if hit < 0:
+                continue
+            pos = hit + len(pat)
+        else:
+            for name, const, expect in (("前缀", bits[pos:pos + len(pref)], pref),
+                                        ("标记", bits[pos + len(pref):pos + len(pref) + len(_MARK)], _MARK),
+                                        ("后缀", bits[pos + len(pref) + len(_MARK):
+                                                     pos + len(pref) + len(_MARK) + len(suff)], suff)):
+                got = ''.join(map(str, const))
+                if got != expect:
+                    raise ValueError(f"id={ident}: {name}常量不匹配 @bit{pos} got={got} want={expect}")
+            pos += len(pref) + len(_MARK) + len(suff)
+        n_nib = _val(bits, pos, sbits)
+        pos += sbits
+        if escape and n_nib == 1:
+            n_nib = 512 + _val(bits, pos, sbits)
+            pos += sbits
+        n_bits = n_nib * 4
+        body = bits[pos:pos + n_bits]
+        pos += n_bits
+        b = bytearray(len(body) // 8)
+        for i in range(0, len(body) // 8 * 8, 8):
+            v = 0
+            for x in body[i:i + 8]:
+                v = (v << 1) | x
+            b[i // 8] = v
+        subs[ident] = bytes(b)
+        offsets[ident] = pos
+    return subs, offsets