Added code for parsing tflite customops (#1281)

Signed-off-by: Tom Wildenhain <[email protected]>

Author: TomWildenhain-Microsoft

tf2onnx/flexbuffers.py

@@ -0,0 +1,140 @@
+# SPDX-License-Identifier: Apache-2.0
+
+
+"""
+tf2onnx.flexbuffers - Code for parsing flexbuffers
+"""
+
+import struct
+
+
+class FlexbufferParseException(Exception):
+    pass
+
+
+def read_int(buffer, offset, bit_size):
+    size = 1 << bit_size
+    format_char = 'bhiq'[bit_size]
+    return struct.unpack('<' + format_char, buffer[offset:offset+size])[0]
+
+
+def read_uint(buffer, offset, bit_size):
+    size = 1 << bit_size
+    format_char = 'BHIQ'[bit_size]
+    return struct.unpack('<' + format_char, buffer[offset:offset+size])[0]
+
+
+def read_float(buffer, offset, bit_size):
+    if bit_size == 2:
+        return struct.unpack('<f', buffer[offset:offset+4])[0]
+    if bit_size == 3:
+        return struct.unpack('<d', buffer[offset:offset+8])[0]
+    raise FlexbufferParseException("Invalid bit size for flexbuffer float: %d" % bit_size)
+
+
+def read_string(buffer, offset, size):
+    return buffer[offset:offset+size].decode('utf-8')
+
+
+def read_indirect(buffer, offset, bit_size):
+    return offset - read_uint(buffer, offset, bit_size)
+
+
+def read_bytes(buffer, offset, size):
+    return buffer[offset:offset+size]
+
+
+def read_array(buffer, offset, length, bit_size, packed_type):
+    byte_size = 1 << bit_size
+    arr = []
+    for i in range(length):
+        item_offset = offset + (i * byte_size)
+        arr.append(read_buffer(buffer, item_offset, bit_size, packed_type))
+    return arr
+
+
+def read_buffer(buffer, offset, parent_bit_size, packed_type):
+    """Recursively decode flatbuffer object into python representation"""
+    bit_size = packed_type & 3
+    value_type = packed_type >> 2
+    byte_size = 1 << bit_size
+
+    if value_type == 0x0:
+        return None
+    if value_type in [0x1, 0x2, 0x3]:
+        read_fn = {0x1: read_int, 0x2: read_uint, 0x3: read_float}[value_type]
+        return read_fn(buffer, offset, parent_bit_size)
+    if value_type in [0x4, 0x5]:
+        str_offset = read_indirect(buffer, offset, parent_bit_size)
+        size = 0
+        while read_int(buffer, str_offset + size, 0) != 0:
+            size += 1
+        return read_string(buffer, str_offset, size)
+    if value_type == 0x5:
+        str_offset = read_indirect(buffer, offset, parent_bit_size)
+        size_byte_size = 1 << bit_size
+        size = read_uint(buffer, str_offset - size_byte_size, bit_size)
+        while read_int(buffer, str_offset + size, 0) != 0:
+            size_byte_size <<= 1
+            size = read_uint(buffer, str_offset - size_byte_size, bit_size)
+        return read_string(buffer, str_offset, size)
+    if value_type in [0x6, 0x7, 0x8]:
+        read_fn = {0x6: read_int, 0x7: read_uint, 0x8: read_float}[value_type]
+        data_offset = read_indirect(buffer, offset, parent_bit_size)
+        return read_fn(buffer, data_offset, bit_size)
+    if value_type == 0x9:
+        length = read_uint(buffer, read_indirect(buffer, offset, parent_bit_size) - byte_size, bit_size)
+        keys_offset = read_indirect(buffer, offset, parent_bit_size) - (byte_size * 3)
+        keys_vector_offset = read_indirect(buffer, keys_offset, bit_size)
+        key_byte_size = read_uint(buffer, keys_offset + byte_size, bit_size)
+        key_bit_size = {1: 0, 2: 1, 4: 2, 8: 3, 16: 4}[key_byte_size]
+        values_offset = read_indirect(buffer, offset, parent_bit_size)
+        packed_types_offset = values_offset + length * byte_size
+        obj = {}
+        for i in range(length):
+            key_offset = keys_vector_offset + i * key_byte_size
+            key = read_buffer(buffer, key_offset, key_bit_size, (0x4 << 2) | key_bit_size)
+            value_offset = values_offset + i * byte_size
+            value_packed_type = read_uint(buffer, packed_types_offset + i, 0)
+            value = read_buffer(buffer, value_offset, bit_size, value_packed_type)
+            obj[key] = value
+        return obj
+    if value_type == 0xa:
+        length = read_uint(buffer, read_indirect(buffer, offset, parent_bit_size) - byte_size, bit_size)
+        arr = []
+        items_offset = read_indirect(buffer, offset, parent_bit_size)
+        packed_types_offset = items_offset + (length * byte_size)
+        for i in range(length):
+            item_offset = items_offset + (i * byte_size)
+            packed_type = read_uint(buffer, packed_types_offset + i, 0)
+            arr.append(read_buffer(buffer, item_offset, bit_size, packed_type))
+        return arr
+    if value_type in [0xb, 0xc, 0xd, 0xe, 0xf, 0x24]:
+        length_offset = read_indirect(buffer, offset, parent_bit_size) - byte_size
+        length = read_uint(buffer, length_offset, bit_size)
+        item_value_type = value_type - 0xb + 0x1
+        packed_type = item_value_type << 2
+        items_offset = read_indirect(buffer, offset, parent_bit_size)
+        return read_array(buffer, items_offset, length, bit_size, packed_type)
+    if 0x10 <= value_type <= 0x18:
+        length = (value_type - 0x10) // 3 + 2
+        value_type = ((value_type - 0x10) % 3) + 1
+        packed_type = value_type << 2
+        items_offset = read_indirect(buffer, offset, parent_bit_size)
+        return read_array(buffer, items_offset, length, bit_size, packed_type)
+    if value_type == 0x19:
+        data_offset = read_indirect(buffer, offset, parent_bit_size)
+        size_offset = data_offset - byte_size
+        size = read_uint(buffer, size_offset, bit_size)
+        return read_bytes(buffer, data_offset, size)
+    if value_type == 0x1a:
+        return read_uint(buffer, offset, parent_bit_size) > 0
+    raise FlexbufferParseException("Invalid flexbuffer value type %r" % value_type)
+
+
+def read_flexbuffer(buffer):
+    byte_size = read_uint(buffer, len(buffer) - 1, 0)
+    bit_size = {1: 0, 2: 1, 4: 2, 8: 3, 16: 4}[byte_size]
+    packed_type = read_uint(buffer, len(buffer) - 2, 0)
+    offset = len(buffer) - 2 - byte_size
+    return read_buffer(buffer, offset, bit_size, packed_type)

tf2onnx/tflite_utils.py

@@ -13,6 +13,7 @@
 from tensorflow.python.framework import tensor_util
 from tf2onnx.tflite.TensorType import TensorType as TFLiteTensorType
 from tf2onnx.tflite.Model import Model
+from tf2onnx.flexbuffers import read_flexbuffer
 
 
 TFLITE_TO_ONNX_DTYPE = {
@@ -133,6 +134,8 @@ def read_tflite_model(tflite_path):
         code = lookup_enum(op_code.DeprecatedBuiltinCode(), 'BuiltinOperator')
         if code == 'PLACEHOLDER_FOR_GREATER_OP_CODES':
             code = lookup_enum(op_code.BuiltinCode(), 'BuiltinOperator')
+        if code == 'CUSTOM':
+            code = op_code.CustomCode().decode()
         opcodes_map[i] = code
     tflite_graphs = [model.Subgraphs(i) for i in range(model.SubgraphsLength())]
     return tflite_graphs, opcodes_map, model
@@ -257,6 +260,10 @@ def get_prequant(tensor_name):
                 attr['scale'] = quant.ScaleAsNumpy().tolist()
                 attr['zero_point'] = quant.ZeroPointAsNumpy().tolist()
                 attr['quantized_dimension'] = quant.QuantizedDimension()
+        if not op.CustomOptionsIsNone():
+            custom_ops_format = lookup_enum(op.CustomOptionsFormat(), 'CustomOptionsFormat')
+            if custom_ops_format == 'FLEXBUFFERS':
+                attr.update(read_flexbuffer(op.CustomOptionsAsNumpy().tobytes()))
         if option_class is not None:
             options = option_class()
             options.Init(op.BuiltinOptions().Bytes, op.BuiltinOptions().Pos)