Fixes builds for cpp examples.

- Upgrade to latest libedgetpu with matching tensorflow library
- Use bazel and share WORKSPACE for both examples
- Added docker with cross compile supports

.gitignore

@@ -0,0 +1 @@
+*.idea

cpp/examples/.gitignore

@@ -0,0 +1,7 @@
+.bazelrc
+/bazel-*
+/out
+
+** Editors **
+*.swp
+*.idea

cpp/examples/Makefile

@@ -0,0 +1,82 @@
+# Copyright 2022 Google LLC
+#
+# 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
+#
+#     https://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.
+SHELL := /bin/bash
+MAKEFILE_DIR := $(realpath $(dir $(lastword $(MAKEFILE_LIST))))
+OS := $(shell uname -s)
+
+# Allowed CPU values: k8, armv7a, aarch64
+ifeq ($(OS),Linux)
+CPU ?= k8
+else
+$(error $(OS) is not supported)
+endif
+ifeq ($(filter $(CPU),k8 armv7a aarch64),)
+$(error CPU must be k8, armv7a, aarch64)
+endif
+
+# Allowed COMPILATION_MODE values: opt, dbg
+COMPILATION_MODE ?= opt
+ifeq ($(filter $(COMPILATION_MODE),opt dbg),)
+$(error COMPILATION_MODE must be opt or dbg)
+endif
+
+BAZEL_OUT_DIR :=  $(MAKEFILE_DIR)/bazel-out/$(CPU)-$(COMPILATION_MODE)/bin
+BAZEL_BUILD_FLAGS := --crosstool_top=@crosstool//:toolchains \
+                     --compiler=gcc \
+                     --compilation_mode=$(COMPILATION_MODE) \
+                     --copt=-DNPY_NO_DEPRECATED_API=NPY_1_7_API_VERSION \
+                     --copt=-std=c++14 \
+                     --verbose_failures \
+                     --cpu=$(CPU) \
+                     --experimental_repo_remote_exec
+
+ifeq ($(COMPILATION_MODE), opt)
+BAZEL_BUILD_FLAGS += --linkopt=-Wl,--strip-all
+else ifeq ($(COMPILATION_MODE), dbg)
+# for now, disable arm_neon in dbg.
+# see: https://github.com/tensorflow/tensorflow/issues/33360
+BAZEL_BUILD_FLAGS += --cxxopt -DTF_LITE_DISABLE_X86_NEON
+endif
+
+ifeq ($(CPU),k8)
+BAZEL_BUILD_FLAGS += --copt=-includeglibc_compat.h
+else ifeq ($(CPU),aarch64)
+BAZEL_BUILD_FLAGS += --copt=-ffp-contract=off
+else ifeq ($(CPU),armv7a)
+BAZEL_BUILD_FLAGS += --copt=-ffp-contract=off
+endif
+
+
+DEMO_OUT_DIR    := $(MAKEFILE_DIR)/out/$(CPU)/
+
+.PHONY: all lstpu classify clean
+
+
+examples:
+	bazel build $(BAZEL_BUILD_FLAGS) //classification:classify
+	bazel build $(BAZEL_BUILD_FLAGS) //lstpu:lstpu
+	mkdir -p $(DEMO_OUT_DIR)
+	cp -f $(BAZEL_OUT_DIR)/classification/classify \
+              $(DEMO_OUT_DIR)
+	cp -f $(BAZEL_OUT_DIR)/lstpu/lstpu \
+              $(DEMO_OUT_DIR)
+	rm -rf $(MAKEFILE_DIR)/bazel-*
+
+clean:
+	rm -rf $(MAKEFILE_DIR)/out
+
+DOCKER_WORKSPACE=$(MAKEFILE_DIR)
+DOCKER_CPUS=k8 armv7a aarch64 armv6
+DOCKER_TAG_BASE=tflite-coral-examples
+include $(MAKEFILE_DIR)/docker/docker.mk

cpp/examples/README.md

@@ -0,0 +1,14 @@
+# Simple C++ code example
+
+These examples show how to build a simple C++ program that uses the EdgeTPU
+runtime library. This subdirectory contains 2 different examples:
+
+- lstpu: 
+  - lists available Edge TPU devices (It does not perform inference).
+- classification: 
+  - classify a bmp image using a classification model.
+
+## Compile the examples
+```bash
+$ make DOCKER_TARGET=examples DOCKER_CPUS=k8 docker-build
+```

cpp/examples/WORKSPACE

@@ -0,0 +1,49 @@
+# Copyright 2020 Google LLC
+#
+# 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
+#
+#     https://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.
+workspace(name = "tflite_examples")
+
+load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
+
+TENSORFLOW_COMMIT = "48c3bae94a8b324525b45f157d638dfd4e8c3be1"
+TENSORFLOW_SHA256 = "363420a67b4cfa271cd21e5c8fac0d7d91b18b02180671c3f943c887122499d8"
+
+# These values come from the Tensorflow workspace. If the TF commit is updated,
+# these should be updated to match.
+IO_BAZEL_RULES_CLOSURE_COMMIT = "308b05b2419edb5c8ee0471b67a40403df940149"
+IO_BAZEL_RULES_CLOSURE_SHA256 = "5b00383d08dd71f28503736db0500b6fb4dda47489ff5fc6bed42557c07c6ba9"
+
+CORAL_CROSSTOOL_COMMIT = "142e930ac6bf1295ff3ba7ba2b5b6324dfb42839"
+CORAL_CROSSTOOL_SHA256 = "088ef98b19a45d7224be13636487e3af57b1564880b67df7be8b3b7eee4a1bfc"
+
+# Configure libedgetpu and downstream libraries (TF and Crosstool).
+http_archive(
+  name = "libedgetpu",
+  sha256 = "d76d18c5a96758dd620057028cdd4e129bd885480087a5c7334070bba3797e58",
+  strip_prefix = "libedgetpu-14eee1a076aa1af7ec1ae3c752be79ae2604a708",
+  urls = [
+    "https://github.com/google-coral/libedgetpu/archive/14eee1a076aa1af7ec1ae3c752be79ae2604a708.tar.gz"
+  ],
+)
+
+load("@libedgetpu//:workspace.bzl", "libedgetpu_dependencies")
+libedgetpu_dependencies(TENSORFLOW_COMMIT, TENSORFLOW_SHA256,
+                        IO_BAZEL_RULES_CLOSURE_COMMIT,IO_BAZEL_RULES_CLOSURE_SHA256,
+                        CORAL_CROSSTOOL_COMMIT,CORAL_CROSSTOOL_SHA256)
+
+
+load("@org_tensorflow//tensorflow:workspace.bzl", "tf_workspace")
+tf_workspace(tf_repo_name = "org_tensorflow")
+
+load("@coral_crosstool//:configure.bzl", "cc_crosstool")
+cc_crosstool(name = "crosstool", additional_system_include_directories=["//docker/include"])

cpp/examples/classification/BUILD

@@ -0,0 +1,23 @@
+# Copyright 2019 Google LLC
+#
+# 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
+#
+#     https://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.
+cc_binary(
+    name = "classify",
+    srcs = ["classify.cc"],
+    deps = [
+        "@libedgetpu//tflite/public:oss_edgetpu_direct_all",
+        "@org_tensorflow//tensorflow/lite:builtin_op_data",
+        "@org_tensorflow//tensorflow/lite:framework",
+        "@org_tensorflow//tensorflow/lite/kernels:builtin_ops",
+    ],
+)

cpp/examples/classification/classify.cc

@@ -8,10 +8,11 @@
 #include <utility>
 #include <vector>
 
-#include "edgetpu_c.h"
+#include "tensorflow/lite/builtin_op_data.h"
 #include "tensorflow/lite/interpreter.h"
 #include "tensorflow/lite/kernels/register.h"
 #include "tensorflow/lite/model.h"
+#include "tflite/public/edgetpu.h"
 
 namespace {
 constexpr size_t kBmpFileHeaderSize = 14;
@@ -130,17 +131,6 @@ int main(int argc, char* argv[]) {
   const std::string image_file = argv[3];
   const float threshold = std::stof(argv[4]);
 
-  // Find TPU device.
-  size_t num_devices;
-  std::unique_ptr<edgetpu_device, decltype(&edgetpu_free_devices)> devices(
-      edgetpu_list_devices(&num_devices), &edgetpu_free_devices);
-
-  if (num_devices == 0) {
-    std::cerr << "No connected TPU found" << std::endl;
-    return 1;
-  }
-  const auto& device = devices.get()[0];
-
   // Load labels.
   auto labels = ReadLabels(label_file);
   if (labels.empty()) {
@@ -164,17 +154,19 @@ int main(int argc, char* argv[]) {
     return 1;
   }
 
-  // Create interpreter.
+  // Get edgetpu context.
+  auto edgetpu_context = edgetpu::EdgeTpuManager::GetSingleton()->OpenDevice();
   tflite::ops::builtin::BuiltinOpResolver resolver;
+  resolver.AddCustom(edgetpu::kCustomOp, edgetpu::RegisterCustomOp());
+
+  // Create interpreter.
   std::unique_ptr<tflite::Interpreter> interpreter;
   if (tflite::InterpreterBuilder(*model, resolver)(&interpreter) != kTfLiteOk) {
     std::cerr << "Cannot create interpreter" << std::endl;
-    return 1;
+    exit(EXIT_FAILURE);
   }
-
-  auto* delegate =
-      edgetpu_create_delegate(device.type, device.path, nullptr, 0);
-  interpreter->ModifyGraphWithDelegate({delegate, edgetpu_free_delegate});
+  interpreter->SetExternalContext(kTfLiteEdgeTpuContext, edgetpu_context.get());
+  interpreter->SetNumThreads(1);
 
   // Allocate tensors.
   if (interpreter->AllocateTensors() != kTfLiteOk) {

cpp/examples/docker/Dockerfile

@@ -0,0 +1,66 @@
+# Copyright 2021 Google LLC
+#
+# 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.
+
+ARG IMAGE
+FROM ${IMAGE}
+
+COPY update_sources.sh /
+RUN /update_sources.sh
+
+RUN dpkg --add-architecture armhf
+RUN dpkg --add-architecture arm64
+RUN apt-get update && apt-get install -y \
+  sudo \
+  debhelper \
+  build-essential \
+  crossbuild-essential-armhf \
+  crossbuild-essential-arm64 \
+  libusb-1.0-0-dev \
+  libusb-1.0-0-dev:arm64 \
+  libusb-1.0-0-dev:armhf \
+  libglib2.0-dev \
+  libglib2.0-dev:armhf \
+  libglib2.0-dev:arm64 \
+  libgstreamer1.0-dev \
+  libgstreamer1.0-dev:armhf \
+  libgstreamer1.0-dev:arm64 \
+  libgstreamer-plugins-base1.0-dev \
+  libgstreamer-plugins-base1.0-dev:armhf \
+  libgstreamer-plugins-base1.0-dev:arm64 \
+  libgtk-3-dev \
+  libgtk-3-dev:arm64 \
+  libgtk-3-dev:armhf \
+  python \
+  python3-all \
+  python3-six \
+  zlib1g-dev \
+  zlib1g-dev:armhf \
+  zlib1g-dev:arm64 \
+  pkg-config \
+  zip \
+  unzip \
+  curl \
+  wget \
+  git \
+  subversion \
+  vim \
+  python3-numpy
+
+ARG BAZEL_VERSION=2.1.0
+RUN wget -O /bazel https://github.com/bazelbuild/bazel/releases/download/${BAZEL_VERSION}/bazel-${BAZEL_VERSION}-installer-linux-x86_64.sh && \
+    bash /bazel && \
+    rm -f /bazel
+
+RUN svn export https://github.com/google-coral/edgetpu/trunk/libedgetpu /libedgetpu
+

cpp/examples/docker/docker.mk

@@ -0,0 +1,39 @@
+DOCKER_MK_DIR := $(realpath $(dir $(lastword $(MAKEFILE_LIST))))
+
+# Docker
+DOCKER_CPUS ?= k8 armv7a armv6 aarch64
+DOCKER_TARGETS ?=
+DOCKER_IMAGE ?= debian:buster
+DOCKER_TAG_BASE ?= "bazel-cross"
+DOCKER_TAG := "$(DOCKER_TAG_BASE)-$(subst :,-,$(DOCKER_IMAGE))"
+DOCKER_SHELL_COMMAND ?=
+
+ifndef DOCKER_WORKSPACE
+$(error DOCKER_WORKSPACE is not defined)
+endif
+
+WORKSPACE := /workspace
+MAKE_COMMAND := \
+for cpu in $(DOCKER_CPUS); do \
+    make CPU=\$${cpu} COMPILATION_MODE=$(COMPILATION_MODE) -C /workspace $(DOCKER_TARGETS) || exit 1; \
+done
+
+define run_command
+chmod a+w /; \
+groupadd --gid $(shell id -g) $(shell id -g -n); \
+useradd -m -e '' -s /bin/bash --gid $(shell id -g) --uid $(shell id -u) $(shell id -u -n); \
+echo '$(shell id -u -n) ALL=(ALL) NOPASSWD:ALL' >> /etc/sudoers; \
+su $(shell id -u -n) $(if $(1),-c '$(1)',)
+endef
+
+docker-image:
+	docker build $(DOCKER_IMAGE_OPTIONS) -t $(DOCKER_TAG) \
+	    --build-arg IMAGE=$(DOCKER_IMAGE) $(DOCKER_MK_DIR)
+
+docker-shell: docker-image
+	docker run --rm -i --tty -v $(DOCKER_WORKSPACE):$(WORKSPACE) --workdir $(WORKSPACE) \
+	    $(DOCKER_TAG) /bin/bash -c "$(call run_command,$(DOCKER_SHELL_COMMAND))"
+
+docker-build: docker-image
+	docker run --rm -i $(shell tty -s && echo --tty) -v $(DOCKER_WORKSPACE):$(WORKSPACE) \
+	    $(DOCKER_TAG) /bin/bash -c "$(call run_command,$(MAKE_COMMAND))"