mbarrett97 commented on a change in pull request #4543: [FRONTEND][TFLITE] Add
support for TFLite_Detection_PostProcess
URL: https://github.com/apache/incubator-tvm/pull/4543#discussion_r362410775
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File path: python/tvm/relay/frontend/tflite.py
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@@ -1565,6 +1676,91 @@ def get_tensor_name(subgraph, tensor_idx):
return subgraph.Tensors(tensor_idx).Name().decode("utf-8")
+def get_custom_options(op, option_names):
+ """Get the options of a custom operator.
+
+ This implements partial flexbuffer deserialization to be able
+ to read custom options. It is not intended to be a general
+ purpose flexbuffer deserializer and as such only supports a
+ limited number of types and assumes the data is a flat map.
+
+ Parameters
+ ----------
+ op:
+ A custom TFlite operator.
+ option_names: list
+ A complete list of the custom option names.
+
+ Returns
+ -------
+ options: dict
+ A dictionary of the custom options.
+
+ """
+ import struct
+ from enum import IntEnum
+
+ class _FlexBufferType(IntEnum):
+ """Flexbuffer type schema from flexbuffers.h"""
+ FBT_NULL = 0
+ FBT_INT = 1
+ FBT_UINT = 2
+ FBT_FLOAT = 3
+ # Types above stored inline, types below store an offset.
+ FBT_KEY = 4
+ FBT_STRING = 5
+ FBT_INDIRECT_INT = 6
+ FBT_INDIRECT_UINT = 7
+ FBT_INDIRECT_FLOAT = 8
+ FBT_MAP = 9
+ FBT_VECTOR = 10 # Untyped.
+ FBT_VECTOR_INT = 11 # Typed any size (stores no type table).
+ FBT_VECTOR_UINT = 12
+ FBT_VECTOR_FLOAT = 13
+ FBT_VECTOR_KEY = 14
+ FBT_VECTOR_STRING = 15
+ FBT_VECTOR_INT2 = 16 # Typed tuple (no type table, no size field).
+ FBT_VECTOR_UINT2 = 17
+ FBT_VECTOR_FLOAT2 = 18
+ FBT_VECTOR_INT3 = 19 # Typed triple (no type table, no size field).
+ FBT_VECTOR_UINT3 = 20
+ FBT_VECTOR_FLOAT3 = 21
+ FBT_VECTOR_INT4 = 22 # Typed quad (no type table, no size field).
+ FBT_VECTOR_UINT4 = 23
+ FBT_VECTOR_FLOAT4 = 24
+ FBT_BLOB = 25
+ FBT_BOOL = 26
+ FBT_VECTOR_BOOL = 36 # To Allow the same type of conversion of type to
vector type
+
+ buffer = op.CustomOptionsAsNumpy().tobytes()
+ value_vector_offset = buffer[-3]
+ buffer = buffer[:-3]
+ num_bytes = 4 # Assume all values are stored in 32 bit width
+ value_vector_size = struct.unpack(
+ "<i", buffer[-value_vector_offset - num_bytes:-value_vector_offset]
+ )[0]
+ type_offset = value_vector_size
+ types = buffer[-type_offset:]
+ values = []
+ for i, t in enumerate(types):
+ flex_type = _FlexBufferType(t >> 2)
+ value_offset = -value_vector_offset + i*num_bytes
+ value_bytes = buffer[value_offset:value_offset+num_bytes]
+ if flex_type == _FlexBufferType.FBT_BOOL:
+ value = True if value_bytes[0] else False
+ if flex_type == _FlexBufferType.FBT_INT:
Review comment:
This whole function is essentially a quick hack to get around there being no
python bindings for flexbuffers (the format custom options are stored in). For
the majority of cases I think we only need the types I've implemented, but I've
included the full schema in case we need to support additional types for other
operators later.
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