1# Protocol Buffers - Google's data interchange format
2# Copyright 2008 Google Inc.  All rights reserved.
3# https://developers.google.com/protocol-buffers/
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30
31TAG_TYPE_BITS = 3  # Number of bits used to hold type info in a proto tag.
32
33WIRETYPE_VARINT = 0
34WIRETYPE_FIXED64 = 1
35WIRETYPE_LENGTH_DELIMITED = 2
36WIRETYPE_START_GROUP = 3
37WIRETYPE_END_GROUP = 4
38WIRETYPE_FIXED32 = 5
39_WIRETYPE_MAX = 5
40
41def PackTag(field_number, wire_type):
42  """Returns an unsigned 32-bit integer that encodes the field number and
43  wire type information in standard protocol message wire format.
44
45  Args:
46    field_number: Expected to be an integer in the range [1, 1 << 29)
47    wire_type: One of the WIRETYPE_* constants.
48  """
49  if not 0 <= wire_type <= _WIRETYPE_MAX:
50    raise RuntimeError('Unknown wire type: %d' % wire_type)
51  return (field_number << TAG_TYPE_BITS) | wire_type
52
53