https://github.com/tensorflow/tensorflow/blob/master/tensorflow/contrib/lite/g3doc/rpi.md
安装交叉编译工具链
sudo apt-get install crossbuild-essential-armhf
下载依赖
./tensorflow/contrib/lite/tools/make/download_dependencies.sh
download_and_extract "${EIGEN_URL}" "${DOWNLOADS_DIR}/eigen"
https://bitbucket.org/eigen/eigen/overview
Eigen is a C++ template library for linear algebra: matrices, vectors, numerical solvers, and related algorithms.
Eigen是用于线性代数，矩阵和向量运算，几何变换，数值求解器和相关算法的模板头的高级C ++库。
download_and_extract "${GEMMLOWP_URL}" "${DOWNLOADS_DIR}/gemmlowp"
https://github.com/google/gemmlowp/blob/master/doc/design.md
低精度的矩阵乘法
gemmlowp: a small self-contained low-precision GEMM library
This is not a full linear algebra library, only a GEMM library: it only does general matrix multiplication ("GEMM").
download_and_extract "${GOOGLETEST_URL}" "${DOWNLOADS_DIR}/googletest"
download_and_extract "${ABSL_URL}" "${DOWNLOADS_DIR}/absl"
https://github.com/abseil/abseil-cpp
Abseil is an open-source collection of C++ library code designed to augment the C++ standard library.
The Abseil library code is collected from Google's own C++ code base,
has been extensively tested and used in production, and is the same code we depend on in our daily coding lives.
https://abseil.io/about/philosophy
Why the world has room for another collection of C++ utility libraries
There are a few main reasons we recommend Abseil as your first choice for utility code when starting a new C++ project:
1.Compatibility with current and future C++ standards, and planned evolution over time
2.Compatibility with Google OSS projects - these are the foundational types for things like Protocol Buffers, gRPC, and TensorFlow
3.Upgrade Support - make it easy to live at head
download_and_extract "${NEON_2_SSE_URL}" "${DOWNLOADS_DIR}/neon_2_sse"
https://github.com/intel/ARM_NEON_2_x86_SSE/
SSE stands for Streaming SIMD Extensions. It is essentially the floating-point equivalent of the MMX instructions.
The SSE registers are 128 bits, and can be used to perform operations on a variety of data sizes and types.
Unlike MMX, the SSE registers do not overlap with the floating point stack.
ARM NEON 是适用于ARM Cortex-A和Cortex-R52系列处理器的一种128位SIMD（single instruction multiple data, 单指令多数据）扩展结构。
ARM CPU最开始只有普通的寄存器，可以进行基本数据类型的基本运算。自ARMv5开始引入了VFP(Vector Floating Point)指令，该指令用于向量化加速浮点运算。自ARMv7开始正式引入NEON指令，NEON性能远超VFP，因此VFP指令被废弃。类似于Intel CPU下的MMX/SSE/AVX/FMA指令，ARM CPU的NEON指令同样是通过向量化来进行速度优化。
download_and_extract "${FARMHASH_URL}" "${DOWNLOADS_DIR}/farmhash"
https://github.com/google/farmhash
FarmHash, a family of hash functions.
download_and_extract "${FLATBUFFERS_URL}" "${DOWNLOADS_DIR}/flatbuffers"
FlatBuffers is a cross platform serialization library architected for maximum memory efficiency.
It allows you to directly access serialized data without parsing/unpacking it first,
while still having great forwards/backwards compatibility.
download_and_extract "${FFT2D_URL}" "${DOWNLOADS_DIR}/fft2d"
FFT (Fast Fourier/Cosine/Sine Transform)快速傅里叶变换
编译
./tensorflow/contrib/lite/tools/make/build_rpi_lib.sh
CORE_CC_ALL_SRCS := \ $(wildcard tensorflow/contrib/lite/*.cc) \ $(wildcard tensorflow/contrib/lite/*.c) \ $(wildcard tensorflow/contrib/lite/c/*.c) \ $(wildcard tensorflow/contrib/lite/core/api/*.cc) ifneq ($(BUILD_TYPE),micro) CORE_CC_ALL_SRCS += \ $(wildcard tensorflow/contrib/lite/kernels/*.cc) \ $(wildcard tensorflow/contrib/lite/kernels/internal/*.cc) \ $(wildcard tensorflow/contrib/lite/kernels/internal/optimized/*.cc) \ $(wildcard tensorflow/contrib/lite/kernels/internal/reference/*.cc) \
$(PROFILER_SRCS) \ $(wildcard tensorflow/contrib/lite/kernels/*.c) \ $(wildcard tensorflow/contrib/lite/kernels/internal/*.c) \ $(wildcard tensorflow/contrib/lite/kernels/internal/optimized/*.c) \ $(wildcard tensorflow/contrib/lite/kernels/internal/reference/*.c) \ $(wildcard tensorflow/contrib/lite/tools/make/downloads/farmhash/src/farmhash.cc) \ $(wildcard tensorflow/contrib/lite/tools/make/downloads/fft2d/fftsg.c)
ifeq ($(BUILD_TYPE),micro) CORE_CC_EXCLUDE_SRCS += \ tensorflow/contrib/lite/mmap_allocation.cc \ tensorflow/contrib/lite/nnapi_delegate.cc endif
# This library is the main target for this makefile. It will contain a minimal # runtime that can be linked in to other programs. LIB_NAME := libtensorflow-lite.a
现在没有看明白libtensorflow-lite.a是由那些文件生成的，上面的只是大概率猜猜