1 files changed, 81 insertions, 0 deletions
diff --git a/external/construct/lib/bitstream.py b/external/construct/lib/bitstream.py
new file mode 100644
index 0000000..3b51f66
--- /dev/null
+++ b/external/construct/lib/bitstream.py
@@ -0,0 +1,81 @@
+import six
+from construct.lib.binary import encode_bin, decode_bin
+
+try:
+    bytes
+except NameError:
+    bytes = str
+
+class BitStreamReader(object):
+    __slots__ = ["substream", "buffer", "total_size"]
+
+    def __init__(self, substream):
+        self.substream = substream
+        self.total_size = 0
+        self.buffer = six.b("")
+
+    def close(self):
+        if self.total_size % 8 != 0:
+            raise ValueError("total size of read data must be a multiple of 8",
+                self.total_size)
+
+    def tell(self):
+        return self.substream.tell()
+
+    def seek(self, pos, whence = 0):
+        self.buffer = six.b("")
+        self.total_size = 0
+        self.substream.seek(pos, whence)
+
+    def read(self, count):
+        if count < 0:
+            raise ValueError("count cannot be negative")
+
+        l = len(self.buffer)
+        if count == 0:
+            data = six.b("")
+        elif count <= l:
+            data = self.buffer[:count]
+            self.buffer = self.buffer[count:]
+        else:
+            data = self.buffer
+            count -= l
+            count_bytes = count // 8
+            if count & 7:
+                count_bytes += 1
+            buf = encode_bin(self.substream.read(count_bytes))
+            data += buf[:count]
+            self.buffer = buf[count:]
+        self.total_size += len(data)
+        return data
+
+class BitStreamWriter(object):
+    __slots__ = ["substream", "buffer", "pos"]
+
+    def __init__(self, substream):
+        self.substream = substream
+        self.buffer = []
+        self.pos = 0
+
+    def close(self):
+        self.flush()
+
+    def flush(self):
+        raw = decode_bin(six.b("").join(self.buffer))
+        self.substream.write(raw)
+        self.buffer = []
+        self.pos = 0
+
+    def tell(self):
+        return self.substream.tell() + self.pos // 8
+
+    def seek(self, pos, whence = 0):
+        self.flush()
+        self.substream.seek(pos, whence)
+
+    def write(self, data):
+        if not data:
+            return
+        if not isinstance(data, bytes):
+            raise TypeError("data must be a string, not %r" % (type(data),))
+        self.buffer.append(data)