Support for DECODE operator

python/tflite_micro/python_ops_resolver.cc

@@ -40,6 +40,7 @@ PythonOpsResolver::PythonOpsResolver() {
   AddConv2D();
   AddCos();
   AddCumSum();
+  AddDecode();
   AddDelay();
   AddDepthToSpace();
   AddDepthwiseConv2D();

tensorflow/lite/micro/kernels/BUILD

@@ -236,6 +236,11 @@ tflm_kernel_cc_library(
         "conv.cc",
         "conv_common.cc",
         "cumsum.cc",
+        "decode.cc",
+        "decode_state.cc",
+        "decode_state_huffman.cc",
+        "decode_state_lut.cc",
+        "decode_state_prune.cc",
         "depth_to_space.cc",
         "depthwise_conv.cc",
         "depthwise_conv_common.cc",
@@ -327,6 +332,10 @@ tflm_kernel_cc_library(
         "batch_matmul.h",
         "circular_buffer.h",
         "conv.h",
+        "decode_state.h",
+        "decode_state_huffman.h",
+        "decode_state_lut.h",
+        "decode_state_prune.h",
         "depthwise_conv.h",
         "dequantize.h",
         "ethosu.h",
@@ -643,6 +652,21 @@ tflm_cc_test(
     ],
 )
 
+tflm_cc_test(
+    name = "decode_test",
+    srcs = [
+        "decode_test.cc",
+    ],
+    deps = [
+        ":kernel_runner",
+        "//tensorflow/lite/c:common",
+        "//tensorflow/lite/micro:debug_log",
+        "//tensorflow/lite/micro:op_resolvers",
+        "//tensorflow/lite/micro:test_helpers",
+        "//tensorflow/lite/micro/testing:micro_test",
+    ],
+)
+
 tflm_cc_test(
     name = "decompress_test",
     srcs = [

tensorflow/lite/micro/kernels/Makefile.inc

@@ -123,6 +123,7 @@ $(TENSORFLOW_ROOT)tensorflow/lite/micro/kernels/ceil_test.cc \
 $(TENSORFLOW_ROOT)tensorflow/lite/micro/kernels/comparisons_test.cc \
 $(TENSORFLOW_ROOT)tensorflow/lite/micro/kernels/concatenation_test.cc \
 $(TENSORFLOW_ROOT)tensorflow/lite/micro/kernels/cumsum_test.cc \
+$(TENSORFLOW_ROOT)tensorflow/lite/micro/kernels/decode_test.cc \
 $(TENSORFLOW_ROOT)tensorflow/lite/micro/kernels/depth_to_space_test.cc \
 $(TENSORFLOW_ROOT)tensorflow/lite/micro/kernels/depthwise_conv_test.cc \
 $(TENSORFLOW_ROOT)tensorflow/lite/micro/kernels/dequantize_test.cc \

tensorflow/lite/micro/kernels/decode.cc

@@ -0,0 +1,160 @@
+/* Copyright 2025 The TensorFlow Authors. All Rights Reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+==============================================================================*/
+
+#include "tensorflow/lite/c/common.h"
+#include "tensorflow/lite/kernels/internal/compatibility.h"
+#include "tensorflow/lite/kernels/kernel_util.h"
+#include "tensorflow/lite/micro/kernels/decode_state.h"
+#include "tensorflow/lite/micro/kernels/kernel_util.h"
+#include "tensorflow/lite/micro/micro_context.h"
+#include "tensorflow/lite/micro/micro_log.h"
+
+namespace tflite {
+namespace {
+
+TfLiteStatus Prepare(TfLiteContext* context, TfLiteNode* node) {
+  const size_t num_inputs = NumInputs(node);
+  const size_t num_outputs = NumOutputs(node);
+  TF_LITE_ENSURE(context, num_outputs > 0);
+  TF_LITE_ENSURE_EQ(context, num_inputs, num_outputs * 2);
+
+  MicroContext* const micro_context = GetMicroContext(context);
+
+  node->user_data = micro_context->AllocatePersistentBuffer(
+      num_outputs * sizeof(DecodeState*));
+  TF_LITE_ENSURE(context, node->user_data != nullptr);
+  DecodeState** const dsp_arr =
+      reinterpret_cast<DecodeState**>(node->user_data);
+
+  TfLiteTensor* input = nullptr;
+  TfLiteTensor* ancillary = nullptr;
+  TfLiteTensor* output = nullptr;
+  TfLiteStatus status = kTfLiteOk;
+
+  for (size_t i = 0; i < num_inputs; i += 2) {
+    input = micro_context->AllocateTempInputTensor(node, i);
+    if (input == nullptr) {
+      MicroPrintf("failed to allocate input tensor %u", i);
+      status = kTfLiteError;
+      break;
+    }
+    ancillary = micro_context->AllocateTempInputTensor(node, i + 1);
+    if (ancillary == nullptr) {
+      MicroPrintf("failed to allocate ancillary tensor %u", i + 1);
+      status = kTfLiteError;
+      break;
+    }
+    output = micro_context->AllocateTempOutputTensor(node, i / 2);
+    if (output == nullptr) {
+      MicroPrintf("failed to allocate output tensor %u", i / 2);
+      status = kTfLiteError;
+      break;
+    }
+
+    TF_LITE_ENSURE(context, IsConstantTensor(input));
+    TF_LITE_ENSURE(context, IsConstantTensor(ancillary));
+
+    if (DecodeState::Version(*ancillary) != 1) {
+      MicroPrintf("version %u != 1", DecodeState::Version(*ancillary));
+      status = kTfLiteError;
+      break;
+    }
+
+    DecodeState* dsp = nullptr;
+    switch (DecodeState::Type(*ancillary)) {
+      case DecodeState::kDcmTypeLUT:
+        dsp = DecodeState::CreateDecodeStateLUT(
+            context, micro_context->GetAlternateProfiler());
+        break;
+      case DecodeState::kDcmTypePrune:
+        dsp = DecodeState::CreateDecodeStatePrune(
+            context, micro_context->GetAlternateProfiler());
+        break;
+      case DecodeState::kDcmTypeHuffman:
+        dsp = DecodeState::CreateDecodeStateHuffman(
+            context, micro_context->GetAlternateProfiler());
+        break;
+      case DecodeState::kDcmTypeCustom:
+        MicroPrintf("Custom decode type not yet supported");
+        break;
+      default:
+        MicroPrintf("unsupported decode type %u",
+                    DecodeState::Type(*ancillary));
+        break;
+    }
+
+    if (dsp != nullptr) {
+      status = dsp->Setup(*input, *ancillary, *output);
+      if (status != kTfLiteOk) {
+        break;
+      }
+      dsp_arr[i / 2] = dsp;
+    } else {
+      MicroPrintf("failed to allocate DecodeState[%u]", i / 2);
+      status = kTfLiteError;
+      break;
+    }
+
+    micro_context->DeallocateTempTfLiteTensor(input);
+    micro_context->DeallocateTempTfLiteTensor(ancillary);
+    micro_context->DeallocateTempTfLiteTensor(output);
+    input = nullptr;
+    ancillary = nullptr;
+    output = nullptr;
+  }
+
+  if (input != nullptr) {
+    micro_context->DeallocateTempTfLiteTensor(input);
+  }
+  if (ancillary != nullptr) {
+    micro_context->DeallocateTempTfLiteTensor(ancillary);
+  }
+  if (output != nullptr) {
+    micro_context->DeallocateTempTfLiteTensor(output);
+  }
+
+  return status;
+}
+
+TfLiteStatus Eval(TfLiteContext* context, TfLiteNode* node) {
+  const size_t num_inputs = NumInputs(node);
+  DecodeState** const dsp_arr =
+      reinterpret_cast<DecodeState**>(node->user_data);
+
+  for (size_t i = 0; i < num_inputs; i += 2) {
+    const TfLiteEvalTensor* input =
+        tflite::micro::GetEvalInput(context, node, i);
+    TF_LITE_ENSURE(context, input != nullptr);
+    const TfLiteEvalTensor* ancillary =
+        tflite::micro::GetEvalInput(context, node, i + 1);
+    TF_LITE_ENSURE(context, ancillary != nullptr);
+    const TfLiteEvalTensor* output =
+        tflite::micro::GetEvalOutput(context, node, i / 2);
+    TF_LITE_ENSURE(context, output != nullptr);
+
+    TfLiteStatus status = dsp_arr[i / 2]->Decode(*input, *ancillary, *output);
+    TF_LITE_ENSURE(context, status == kTfLiteOk);
+  }
+
+  return kTfLiteOk;
+}
+
+}  // namespace
+
+TFLMRegistration Register_DECODE() {
+  return tflite::micro::RegisterOp(nullptr, Prepare, Eval);
+}
+
+}  // namespace tflite

tensorflow/lite/micro/kernels/decode_state.cc

@@ -0,0 +1,64 @@
+/* Copyright 2025 The TensorFlow Authors. All Rights Reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+==============================================================================*/
+
+#include "tensorflow/lite/micro/kernels/decode_state.h"
+
+#include "tensorflow/lite/micro/kernels/decode_state_huffman.h"
+#include "tensorflow/lite/micro/kernels/decode_state_lut.h"
+#include "tensorflow/lite/micro/kernels/decode_state_prune.h"
+#include "tensorflow/lite/micro/micro_context.h"
+
+namespace tflite {
+
+DecodeState* DecodeState::CreateDecodeStateLUT(
+    const TfLiteContext* context, MicroProfilerInterface* profiler) {
+  MicroContext* const micro_context = GetMicroContext(context);
+  void* buffer =
+      micro_context->AllocatePersistentBuffer(sizeof(DecodeStateLUT));
+  if (buffer == nullptr) {
+    return nullptr;
+  }
+  DecodeState* dsp = new (buffer) DecodeStateLUT(context, profiler);
+
+  return dsp;
+}
+
+DecodeState* DecodeState::CreateDecodeStatePrune(
+    const TfLiteContext* context, MicroProfilerInterface* profiler) {
+  MicroContext* const micro_context = GetMicroContext(context);
+  void* buffer =
+      micro_context->AllocatePersistentBuffer(sizeof(DecodeStatePrune));
+  if (buffer == nullptr) {
+    return nullptr;
+  }
+  DecodeState* dsp = new (buffer) DecodeStatePrune(context, profiler);
+
+  return dsp;
+}
+
+DecodeState* DecodeState::CreateDecodeStateHuffman(
+    const TfLiteContext* context, MicroProfilerInterface* profiler) {
+  MicroContext* const micro_context = GetMicroContext(context);
+  void* buffer =
+      micro_context->AllocatePersistentBuffer(sizeof(DecodeStateHuffman));
+  if (buffer == nullptr) {
+    return nullptr;
+  }
+  DecodeState* dsp = new (buffer) DecodeStateHuffman(context, profiler);
+
+  return dsp;
+}
+
+}  // namespace tflite

tensorflow/lite/micro/kernels/decode_state.h

@@ -0,0 +1,93 @@
+/* Copyright 2025 The TensorFlow Authors. All Rights Reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+==============================================================================*/
+
+#ifndef TENSORFLOW_LITE_MICRO_MICRO_KERNELS_DECODE_STATE_H_
+#define TENSORFLOW_LITE_MICRO_MICRO_KERNELS_DECODE_STATE_H_
+
+#include <cstdint>
+
+#include "tensorflow/lite/c/common.h"
+#include "tensorflow/lite/core/c/c_api_types.h"
+#include "tensorflow/lite/kernels/kernel_util.h"
+#include "tensorflow/lite/micro/compatibility.h"
+#include "tensorflow/lite/micro/kernels/kernel_util.h"
+#include "tensorflow/lite/micro/micro_profiler_interface.h"
+
+namespace tflite {
+
+struct DecodeState {
+  DecodeState() = delete;
+
+  DecodeState(const TfLiteContext* context, MicroProfilerInterface* profiler)
+      : context_(context), micro_profiler_(profiler) {}
+
+  virtual TfLiteStatus Setup(const TfLiteTensor& input,
+                             const TfLiteTensor& ancillary,
+                             const TfLiteTensor& output) = 0;
+  virtual TfLiteStatus Decode(const TfLiteEvalTensor& input,
+                              const TfLiteEvalTensor& ancillary,
+                              const TfLiteEvalTensor& output) = 0;
+
+  static DecodeState* CreateDecodeStateLUT(const TfLiteContext* context,
+                                           MicroProfilerInterface* profiler);
+  static DecodeState* CreateDecodeStatePrune(const TfLiteContext* context,
+                                             MicroProfilerInterface* profiler);
+  static DecodeState* CreateDecodeStateHuffman(
+      const TfLiteContext* context, MicroProfilerInterface* profiler);
+
+  static uint8_t Type(const TfLiteTensor& ancillary) {
+    return GetTensorData<uint8_t>(&ancillary)[kDcmDecodeTypeOffset];
+  }
+
+  static uint8_t Type(const TfLiteEvalTensor& ancillary) {
+    return micro::GetTensorData<uint8_t>(&ancillary)[kDcmDecodeTypeOffset];
+  }
+
+  static uint8_t Version(const TfLiteTensor& ancillary) {
+    return GetTensorData<uint8_t>(&ancillary)[kDcmVersionOffset];
+  }
+
+  static uint8_t Version(const TfLiteEvalTensor& ancillary) {
+    return micro::GetTensorData<uint8_t>(&ancillary)[kDcmVersionOffset];
+  }
+
+ protected:
+  virtual ~DecodeState() = default;
+
+  // Decode Common Metadata constants
+ public:
+  static constexpr uint8_t kDcmTypeLUT = 0;
+  static constexpr uint8_t kDcmTypeHuffman = 1;
+  static constexpr uint8_t kDcmTypePrune = 2;
+  static constexpr uint8_t kDcmTypeCustom = 127;
+
+  static constexpr size_t kDcmSizeInBytes = 16;
+
+ private:
+  static constexpr size_t kDcmDecodeTypeOffset = 0;
+  static constexpr size_t kDcmVersionOffset = 1;
+
+  // DecodeState vars
+ protected:
+  const TfLiteContext* context_;
+  MicroProfilerInterface* micro_profiler_;
+
+ private:
+  TF_LITE_REMOVE_VIRTUAL_DELETE
+};
+
+}  // namespace tflite
+
+#endif  // TENSORFLOW_LITE_MICRO_MICRO_KERNELS_DECODE_STATE_H_