梳理caffe代码blob(三)

#ifndef CAFFE_BLOB_HPP_
#define CAFFE_BLOB_HPP_

#include <algorithm>
#include <string>
#include <vector>

#include "caffe/common.hpp"
#include "caffe/proto/caffe.pb.h"
#include "caffe/syncedmem.hpp"
#include "caffe/util/math_functions.hpp"

const int kMaxBlobAxes = INT_MAX;//blob最大维数目

namespace caffe {

/**
* @brief A wrapper around SyncedMemory holders serving as the basic
*        computational unit through which Layer%s, Net%s, and Solver%s
*        interact.
*
* TODO(dox): more thorough description.
*/

template <typename Dtype>
class Blob {
public:
Blob()//默认构造函数
: data_(), diff_(), count_(0), capacity_(0) {}

/// @brief Deprecated; use <code>Blob(const vector<int>& shape)</code>.
//explicit关键字的作用是禁止单参数构造函数的隐式转换
explicit Blob(const int num, const int channels, const int height,
const int width);
explicit Blob(const vector<int>& shape);

/// @brief Deprecated; use <code>Reshape(const vector<int>& shape)</code>.
/*
Reshape函数将num,channels,height,width传递给vector shape_
*/
void Reshape(const int num, const int channels, const int height,
const int width);
/**
*Blob作为一个最基础的类，其中构造函数开辟一个内存空间来存储数据，Reshape函数在Layer中的
*reshape或者forward 操作中来adjust the dimensions of a top blob。同时在改变Blob大小时，
*内存将会被重新分配如果内存大小不够了，并且额外的内存将不会被释放。对input的blob进行reshape,
*如果立马调用Net::Backward是会出错的，因为reshape之后，要么Net::forward或者Net::Reshape就会
*被调用来将新的input shape 传播到高层
*/
//根据shape来初始化shape_和shape_data_，以及为data_ 和diff_ 分配空间。
void Reshape(const vector<int>& shape);
void Reshape(const BlobShape& shape);
void ReshapeLike(const Blob& other);
//iniline主要是将代码进行复制，扩充，会使代码总量上升，好处就是可以节省调用的开销,以string形式获取shape_，用于打印blob的log
inline string shape_string() const {
ostringstream stream;
for (int i = 0; i < shape_.size(); ++i) {
stream << shape_[i] << " ";
}
stream << "(" << count_ << ")";
return stream.str();
}
//获取shape_
inline const vector<int>& shape() const { return shape_; }
/**
* @brief Returns the dimension of the index-th axis (or the negative index-th
*        axis from the end, if index is negative).
*
* @param index the axis index, which may be negative as it will be
*        "canonicalized" using CanonicalAxisIndex.
*        Dies on out of range index.
*/
//获取index维的大小，返回某一维的尺寸
inline int shape(int index) const {
return shape_[CanonicalAxisIndex(index)];
}
//获取维的个数
inline int num_axes() const { return shape_.size(); }
//获取当前data的大小
inline int count() const { return count_; }

/**
* @brief Compute the volume of a slice; i.e., the product of dimensions
*        among a range of axes.
*
* @param start_axis The first axis to include in the slice.
*
* @param end_axis The first axis to exclude from the slice.
*/
/*多个count()函数，主要还是为了统计Blob的容量（volume），或者是某一片（slice），
从某个axis到具体某个axis的shape乘积。
*/
//获取某几维数据的大小
inline int count(int start_axis, int end_axis) const {
CHECK_LE(start_axis, end_axis);
CHECK_GE(start_axis, 0);
CHECK_GE(end_axis, 0);
CHECK_LE(start_axis, num_axes());
CHECK_LE(end_axis, num_axes());
int count = 1;
for (int i = start_axis; i < end_axis; ++i) {
count *= shape(i);
}
return count;
}
/**
* @brief Compute the volume of a slice spanning from a particular first
*        axis to the final axis.
*
* @param start_axis The first axis to include in the slice.
*/
//获取某一维到结束数据的大小
inline int count(int start_axis) const {
return count(start_axis, num_axes());
}

/**
* @brief Returns the 'canonical' version of a (usually) user-specified axis,
*        allowing for negative indexing (e.g., -1 for the last axis).
*
* @param index the axis index.
*        If 0 <= index < num_axes(), return index.
*        If -num_axes <= index <= -1, return (num_axes() - (-index)),
*        e.g., the last axis index (num_axes() - 1) if index == -1,
*        the second to last if index == -2, etc.
*        Dies on out of range index.
*/
//Blob的Index是可以从负坐标开始读的,标准化索引，主要是对参数索引进行标准化，以满足要求，转换坐标轴索引[-N，N]为[0，N]
inline int CanonicalAxisIndex(int axis_index) const {
CHECK_GE(axis_index, -num_axes())
<< "axis " << axis_index << " out of range for " << num_axes()
<< "-D Blob with shape " << shape_string();
CHECK_LT(axis_index, num_axes())
<< "axis " << axis_index << " out of range for " << num_axes()
<< "-D Blob with shape " << shape_string();
if (axis_index < 0) {
return axis_index + num_axes();
}
return axis_index;
}
//Blob中的4个基本变量num,channel,height,width可以直接通过shape(0),shape(1),shape(2),shape(3)来访问
/// @brief Deprecated legacy shape accessor num: use shape(0) instead.
inline int num() const { return LegacyShape(0); }
/// @brief Deprecated legacy shape accessor channels: use shape(1) instead.
inline int channels() const { return LegacyShape(1); }
/// @brief Deprecated legacy shape accessor height: use shape(2) instead.
inline int height() const { return LegacyShape(2); }
/// @brief Deprecated legacy shape accessor width: use shape(3) instead.
inline int width() const { return LegacyShape(3); }
//data_维数不大于4时才能使用，功能同shape()类似。
inline int LegacyShape(int index) const {
CHECK_LE(num_axes(), 4)
<< "Cannot use legacy accessors on Blobs with > 4 axes.";
CHECK_LT(index, 4);
CHECK_GE(index, -4);
if (index >= num_axes() || index < -num_axes()) {
// Axis is out of range, but still in [0, 3] (or [-4, -1] for reverse
// indexing) -- this special case simulates the one-padding used to fill
// extraneous axes of legacy blobs.
return 1;
}
return shape(index);
}
//计算offset,offset计算的方式也支持两种方式，一种直接指定n,c,h,w或者放到一个vector中进行计算，
//偏移量是根据对应的n,c,h,w，返回的offset是((n*channels()+c)*height()+h)*width()+w
inline int offset(const int n, const int c = 0, const int h = 0,
const int w = 0) const {
CHECK_GE(n, 0);
CHECK_LE(n, num());
CHECK_GE(channels(), 0);
CHECK_LE(c, channels());
CHECK_GE(height(), 0);
CHECK_LE(h, height());
CHECK_GE(width(), 0);
CHECK_LE(w, width());
return ((n * channels() + c) * height() + h) * width() + w;
}

inline int offset(const vector<int>& indices) const {
CHECK_LE(indices.size(), num_axes());
int offset = 0;
for (int i = 0; i < num_axes(); ++i) {
offset *= shape(i);
if (indices.size() > i) {
CHECK_GE(indices[i], 0);
CHECK_LT(indices[i], shape(i));
offset += indices[i];
}
}
return offset;
}
/**
* @brief Copy from a source Blob.
*
* @param source the Blob to copy from
* @param copy_diff if false, copy the data; if true, copy the diff
* @param reshape if false, require this Blob to be pre-shaped to the shape
*        of other (and die otherwise); if true, Reshape this Blob to other's
*        shape if necessary
*/
//按值拷贝blob到当前blob。一个blob中copy数据 ，通过开关控制是否copy_diff,如果是False则copy data。reshape控制是否需要reshape
void CopyFrom(const Blob<Dtype>& source, bool copy_diff = false,
bool reshape = false);
/*这一部分函数主要通过给定的位置访问数据，根据位置计算与数据起始
的偏差offset，在通过cpu_data*指针获得地址
*/
//获取某位置的data_数据
inline Dtype data_at(const int n, const int c, const int h,
const int w) const {
return cpu_data()[offset(n, c, h, w)];
}
//获取某位置的diff_数据
inline Dtype diff_at(const int n, const int c, const int h,
const int w) const {
return cpu_diff()[offset(n, c, h, w)];
}

inline Dtype data_at(const vector<int>& index) const {
return cpu_data()[offset(index)];
}

inline Dtype diff_at(const vector<int>& index) const {
return cpu_diff()[offset(index)];
}
//获取data_
inline const shared_ptr<SyncedMemory>& data() const {
CHECK(data_);
return data_;
}
//获取diff_
inline const shared_ptr<SyncedMemory>& diff() const {
CHECK(diff_);
return diff_;
}
//这里有data和diff两类数据，而这个diff就是我们所熟知的偏差，前者主要存储
//前向传递的数据，而后者存储的是反向传播中的梯度
const Dtype* cpu_data() const;//只读获取data_ cpu指针
void set_cpu_data(Dtype* data);//设置data_的cpu指针，只是修改了指针
const Dtype* gpu_data() const;//获取data_的gpu指针
const Dtype* cpu_diff() const;//获取diff_的cpu指针
const Dtype* gpu_diff() const;//获取diff_的gpu指针
Dtype* mutable_cpu_data();//见SyncedMemory的mutable_cpu_data()，mutable是可读写访问
Dtype* mutable_gpu_data();//见SyncedMemory的mutable_gpu_data();
Dtype* mutable_cpu_diff();//见SyncedMemory的mutable_cpu_data();
Dtype* mutable_gpu_diff();//见SyncedMemory的mutable_gpu_data();
//更新data_的数据,减去diff_的数据，就是合并data和diff
void Update();
/*
其中用到math_functions.hpp中的函数caffe_axpy(),该函数封装了cblas_saxpy，实现的是Y=alpha*X+Y。
由此，知该函数的功能是data_=(data_-diff_)。另外，该函数只实现了对double和float型数据，
对于unsigned int和int由于该函数主要是在Net中被调用，只有Blob<float>和Blob<double>型式，
因此没有定义unsigned int和int。从proto中恢复一个blob对象
*/
void FromProto(const BlobProto& proto, bool reshape = true);
/*
由BlobProto对Blob进行赋值操作。reshape代表是否允许修改shape_的大小。
需要注意的是再这里有double和float两种类型的数据 ，将blob序列化为proto，在代码中可以看到具体的体现
*/
void ToProto(BlobProto* proto, bool write_diff = false) const;

/// @brief Compute the sum of absolute values (L1 norm) of the data.
/*
功能：计算L1范数
说明：其中用到了math_function.hpp中的函数caffe_cpu_asum()和caffe_gpu_asum，实现的功能是对向量X求其每个元素绝对值的和，不同的是X分别在cpu和gpu中。
*/
Dtype asum_data() const;
/// @brief Compute the sum of absolute values (L1 norm) of the diff.
Dtype asum_diff() const;
/// @brief Compute the sum of squares (L2 norm squared) of the data.
/*
功能：计算L2范数。
说明：用到了math_function.hpp中的caffe_cpu_dot(),caffe_cpu_strided_dot(),caffe_gpu_dot(), caffe_gpu_strided_dot()。具体就是就向量X的平方和。
*/
Dtype sumsq_data() const;
/// @brief Compute the sum of squares (L2 norm squared) of the diff.
Dtype sumsq_diff() const;

/// @brief Scale the blob data by a constant factor.
/*
功能：正规化data_。
说明：用到math_function.hpp中的caffe_scal()和caffe_gpu_scal()函数，就是对向量X乘上一个因子。
*/
void scale_data(Dtype scale_factor);
/// @brief Scale the blob diff by a constant factor.
void scale_diff(Dtype scale_factor);

/**
* @brief Set the data_ shared_ptr to point to the SyncedMemory holding the
*        data_ of Blob other -- useful in Layer%s which simply perform a copy
*        in their Forward pass.
*
* This deallocates the SyncedMemory holding this Blob's data_, as
* shared_ptr calls its destructor when reset with the "=" operator.
*/
void ShareData(const Blob& other);//本Blob共享other的data_
/**
* @brief Set the diff_ shared_ptr to point to the SyncedMemory holding the
*        diff_ of Blob other -- useful in Layer%s which simply perform a copy
*        in their Forward pass.
*
* This deallocates the SyncedMemory holding this Blob's diff_, as
* shared_ptr calls its destructor when reset with the "=" operator.
*/
void ShareDiff(const Blob& other);//本Blob共享other的diff_

bool ShapeEquals(const BlobProto& other);//判断other与本Blob形状是否相同。

protected:
//data_指针，指针类型是shared_ptr，属于boost库的一个智能指针，这一部分主要用来申请内存存储data，data主要是正向传播的时候用的
shared_ptr<SyncedMemory> data_;
//diff_主要用来存储偏差，update data
shared_ptr<SyncedMemory> diff_;
//shape_存储Blob的形状
vector<int> shape_;
//count_表示Blob中的元素个数，也就是个数*通道数*高度*宽度
int count_;
//capacity表示当前的元素个数，因为Blob可能会reshape
int capacity_;

DISABLE_COPY_AND_ASSIGN(Blob);//禁止拷贝和赋值运算
};  // class Blob

}  // namespace caffe

#endif  // CAFFE_BLOB_HPP_

#include <climits>
#include <vector>

#include "caffe/blob.hpp"
#include "caffe/common.hpp"
#include "caffe/syncedmem.hpp"
#include "caffe/util/math_functions.hpp"

namespace caffe {

template <typename Dtype>
//该函数将num,channels,height,width传递给vector shape_
void Blob<Dtype>::Reshape(const int num, const int channels, const int height,
const int width) {
vector<int> shape(4);
shape[0] = num;
shape[1] = channels;
shape[2] = height;
shape[3] = width;
Reshape(shape);
}

template <typename Dtype>
void Blob<Dtype>::Reshape(const vector<int>& shape) {
CHECK_LE(shape.size(), kMaxBlobAxes);
count_ = 1;
shape_.resize(shape.size());//重新定义vector shape_ 的size
for (int i = 0; i < shape.size(); ++i) {
CHECK_GE(shape[i], 0);//确保shape 每个元素为正数
CHECK_LE(shape[i], INT_MAX / count_) << "blob size exceeds INT_MAX";
count_ *= shape[i];
shape_[i] = shape[i];
}
//由于count_超过了当前capacity_ 因此需要重新分配内存空间
if (count_ > capacity_) {
capacity_ = count_;
data_.reset(new SyncedMemory(capacity_ * sizeof(Dtype)));
diff_.reset(new SyncedMemory(capacity_ * sizeof(Dtype)));
}
}

template <typename Dtype>// BlobShape 在caffe.proto 中定义
void Blob<Dtype>::Reshape(const BlobShape& shape) {
CHECK_LE(shape.dim_size(), kMaxBlobAxes);
vector<int> shape_vec(shape.dim_size());
for (int i = 0; i < shape.dim_size(); ++i) {
shape_vec[i] = shape.dim(i);//dim 包含num，channels，height， width
}
Reshape(shape_vec);//用protobuf传递来dim 对shape_ 进行reshape
}
//用已知的Blob的shape来对shape_ 进行reshape
template <typename Dtype>
void Blob<Dtype>::ReshapeLike(const Blob<Dtype>& other) {
Reshape(other.shape());
}
//用num，channels，height， width 初始化
template <typename Dtype>
Blob<Dtype>::Blob(const int num, const int channels, const int height,
const int width)
// capacity_ must be initialized before calling Reshape
: capacity_(0) {
Reshape(num, channels, height, width);
}
//用shape 初始化
template <typename Dtype>
Blob<Dtype>::Blob(const vector<int>& shape)
// capacity_ must be initialized before calling Reshape
: capacity_(0) {
Reshape(shape);
}
//返回cpu 中的数据
template <typename Dtype>
const Dtype* Blob<Dtype>::cpu_data() const {
CHECK(data_);
return (const Dtype*)data_->cpu_data();
}
// 清空cpu 数据
template <typename Dtype>
void Blob<Dtype>::set_cpu_data(Dtype* data) {
CHECK(data);
data_->set_cpu_data(data);
}
//返回gpu 中的数据
template <typename Dtype>
const Dtype* Blob<Dtype>::gpu_data() const {
CHECK(data_);
return (const Dtype*)data_->gpu_data();
}
//反向传播导数diff_ 操作函数,返回cpu 中的数据
template <typename Dtype>
const Dtype* Blob<Dtype>::cpu_diff() const {
CHECK(diff_);
return (const Dtype*)diff_->cpu_data();
}
//返回gpu 中的数据
template <typename Dtype>
const Dtype* Blob<Dtype>::gpu_diff() const {
CHECK(diff_);
return (const Dtype*)diff_->gpu_data();
}

template <typename Dtype>
Dtype* Blob<Dtype>::mutable_cpu_data() {
CHECK(data_);
return static_cast<Dtype*>(data_->mutable_cpu_data());
}

template <typename Dtype>
Dtype* Blob<Dtype>::mutable_gpu_data() {
CHECK(data_);
return static_cast<Dtype*>(data_->mutable_gpu_data());
}

template <typename Dtype>
Dtype* Blob<Dtype>::mutable_cpu_diff() {
CHECK(diff_);
return static_cast<Dtype*>(diff_->mutable_cpu_data());
}

template <typename Dtype>
Dtype* Blob<Dtype>::mutable_gpu_diff() {
CHECK(diff_);
return static_cast<Dtype*>(diff_->mutable_gpu_data());
}
//当前的blob 的data_ 指向已知blob的数据
template <typename Dtype>
void Blob<Dtype>::ShareData(const Blob& other) {
CHECK_EQ(count_, other.count());
data_ = other.data();
}
//当前的blob 的diff_ 指向已知blob的反向传播导数
template <typename Dtype>
void Blob<Dtype>::ShareDiff(const Blob& other) {
CHECK_EQ(count_, other.count());
diff_ = other.diff();
}

// The "update" method is used for parameter blobs in a Net, which are stored
// as Blob<float> or Blob<double> -- hence we do not define it for
// Blob<int> or Blob<unsigned int>.
template <> void Blob<unsigned int>::Update() { NOT_IMPLEMENTED; }
template <> void Blob<int>::Update() { NOT_IMPLEMENTED; }
//Updata函数用于参数blob的更新（weight，bias 等减去对应的导数）
template <typename Dtype>
void Blob<Dtype>::Update() {
// We will perform update based on where the data is located.
switch (data_->head()) {
case SyncedMemory::HEAD_AT_CPU://数据在cpu上，则在cpu上进行计算
// perform computation on CPU
caffe_axpy<Dtype>(count_, Dtype(-1),
static_cast<const Dtype*>(diff_->cpu_data()),
static_cast<Dtype*>(data_->mutable_cpu_data()));
break;
case SyncedMemory::HEAD_AT_GPU:
case SyncedMemory::SYNCED:
#ifndef CPU_ONLY//如果没有定义CPU_ONLY，且数据在gpu上，则在gpu上进行计算
// perform computation on GPU
caffe_gpu_axpy<Dtype>(count_, Dtype(-1),
static_cast<const Dtype*>(diff_->gpu_data()),
static_cast<Dtype*>(data_->mutable_gpu_data()));
#else
NO_GPU;
#endif
break;
default:
LOG(FATAL) << "Syncedmem not initialized.";
}
}

template <> unsigned int Blob<unsigned int>::asum_data() const {
NOT_IMPLEMENTED;
return 0;
}

template <> int Blob<int>::asum_data() const {
NOT_IMPLEMENTED;
return 0;
}
//返回data_ 中所有 element 的绝对值之和
template <typename Dtype>
Dtype Blob<Dtype>::asum_data() const {
if (!data_) { return 0; }
switch (data_->head()) {
case SyncedMemory::HEAD_AT_CPU:
return caffe_cpu_asum(count_, cpu_data());
case SyncedMemory::HEAD_AT_GPU:
case SyncedMemory::SYNCED:
#ifndef CPU_ONLY
{
Dtype asum;
caffe_gpu_asum(count_, gpu_data(), &asum);
return asum;
}
#else
NO_GPU;
#endif
case SyncedMemory::UNINITIALIZED:
return 0;
default:
LOG(FATAL) << "Unknown SyncedMemory head state: " << data_->head();
}
return 0;
}

template <> unsigned int Blob<unsigned int>::asum_diff() const {
NOT_IMPLEMENTED;
return 0;
}

template <> int Blob<int>::asum_diff() const {
NOT_IMPLEMENTED;
return 0;
}
//返回diff_ 中所有 element 的绝对值之和
template <typename Dtype>
Dtype Blob<Dtype>::asum_diff() const {
if (!diff_) { return 0; }
switch (diff_->head()) {
case SyncedMemory::HEAD_AT_CPU:
return caffe_cpu_asum(count_, cpu_diff());
case SyncedMemory::HEAD_AT_GPU:
case SyncedMemory::SYNCED:
#ifndef CPU_ONLY
{
Dtype asum;
caffe_gpu_asum(count_, gpu_diff(), &asum);
return asum;
}
#else
NO_GPU;
#endif
case SyncedMemory::UNINITIALIZED:
return 0;
default:
LOG(FATAL) << "Unknown SyncedMemory head state: " << diff_->head();
}
return 0;
}

template <> unsigned int Blob<unsigned int>::sumsq_data() const {
NOT_IMPLEMENTED;
return 0;
}

template <> int Blob<int>::sumsq_data() const {
NOT_IMPLEMENTED;
return 0;
}
//返回 data_ 中所有 element 的平方和
template <typename Dtype>
Dtype Blob<Dtype>::sumsq_data() const {
Dtype sumsq;
const Dtype* data;
if (!data_) { return 0; }
switch (data_->head()) {
case SyncedMemory::HEAD_AT_CPU:
data = cpu_data();
sumsq = caffe_cpu_dot(count_, data, data);
break;
case SyncedMemory::HEAD_AT_GPU:
case SyncedMemory::SYNCED:
#ifndef CPU_ONLY
data = gpu_data();
caffe_gpu_dot(count_, data, data, &sumsq);
#else
NO_GPU;
#endif
break;
case SyncedMemory::UNINITIALIZED:
return 0;
default:
LOG(FATAL) << "Unknown SyncedMemory head state: " << data_->head();
}
return sumsq;
}

template <> unsigned int Blob<unsigned int>::sumsq_diff() const {
NOT_IMPLEMENTED;
return 0;
}

template <> int Blob<int>::sumsq_diff() const {
NOT_IMPLEMENTED;
return 0;
}
//返回 diff_ 中所有 element 的平方和
template <typename Dtype>
Dtype Blob<Dtype>::sumsq_diff() const {
Dtype sumsq;
const Dtype* diff;
if (!diff_) { return 0; }
switch (diff_->head()) {
case SyncedMemory::HEAD_AT_CPU:
diff = cpu_diff();
sumsq = caffe_cpu_dot(count_, diff, diff);
break;
case SyncedMemory::HEAD_AT_GPU:
case SyncedMemory::SYNCED:
#ifndef CPU_ONLY
diff = gpu_diff();
caffe_gpu_dot(count_, diff, diff, &sumsq);
break;
#else
NO_GPU;
#endif
case SyncedMemory::UNINITIALIZED:
return 0;
default:
LOG(FATAL) << "Unknown SyncedMemory head state: " << data_->head();
}
return sumsq;
}

template <> void Blob<unsigned int>::scale_data(unsigned int scale_factor) {
NOT_IMPLEMENTED;
}

template <> void Blob<int>::scale_data(int scale_factor) {
NOT_IMPLEMENTED;
}
// 给data乘以scale_factor
template <typename Dtype>
void Blob<Dtype>::scale_data(Dtype scale_factor) {
Dtype* data;
if (!data_) { return; }
switch (data_->head()) {
case SyncedMemory::HEAD_AT_CPU:
data = mutable_cpu_data();
caffe_scal(count_, scale_factor, data);
return;
case SyncedMemory::HEAD_AT_GPU:
case SyncedMemory::SYNCED:
#ifndef CPU_ONLY
data = mutable_gpu_data();
caffe_gpu_scal(count_, scale_factor, data);
return;
#else
NO_GPU;
#endif
case SyncedMemory::UNINITIALIZED:
return;
default:
LOG(FATAL) << "Unknown SyncedMemory head state: " << data_->head();
}
}

template <> void Blob<unsigned int>::scale_diff(unsigned int scale_factor) {
NOT_IMPLEMENTED;
}

template <> void Blob<int>::scale_diff(int scale_factor) {
NOT_IMPLEMENTED;
}
// 给diff乘以scale_factor
template <typename Dtype>
void Blob<Dtype>::scale_diff(Dtype scale_factor) {
Dtype* diff;
if (!diff_) { return; }
switch (diff_->head()) {
case SyncedMemory::HEAD_AT_CPU:
diff = mutable_cpu_diff();
caffe_scal(count_, scale_factor, diff);
return;
case SyncedMemory::HEAD_AT_GPU:
case SyncedMemory::SYNCED:
#ifndef CPU_ONLY
diff = mutable_gpu_diff();
caffe_gpu_scal(count_, scale_factor, diff);
return;
#else
NO_GPU;
#endif
case SyncedMemory::UNINITIALIZED:
return;
default:
LOG(FATAL) << "Unknown SyncedMemory head state: " << diff_->head();
}
}
//BlobProto 是定义在caffe.proto 中的一个message，其字段有 data,diff,shape,num,channels,height,width
template <typename Dtype>
bool Blob<Dtype>::ShapeEquals(const BlobProto& other) {
if (other.has_num() || other.has_channels() ||
other.has_height() || other.has_width()) {
// Using deprecated 4D Blob dimensions --
// shape is (num, channels, height, width).
// Note: we do not use the normal Blob::num(), Blob::channels(), etc.
// methods as these index from the beginning of the blob shape, where legacy
// parameter blobs were indexed from the end of the blob shape (e.g., bias
// Blob shape (1 x 1 x 1 x N), IP layer weight Blob shape (1 x 1 x M x N)).
return shape_.size() <= 4 &&
LegacyShape(-4) == other.num() &&
LegacyShape(-3) == other.channels() &&
LegacyShape(-2) == other.height() &&
LegacyShape(-1) == other.width();
}
vector<int> other_shape(other.shape().dim_size());
for (int i = 0; i < other.shape().dim_size(); ++i) {
other_shape[i] = other.shape().dim(i);
}
return shape_ == other_shape;
}//检查当前的blob和已知的 other 的 shape 是否相同，相同返回true

template <typename Dtype>
void Blob<Dtype>::CopyFrom(const Blob& source, bool copy_diff, bool reshape) {
if (source.count() != count_ || source.shape() != shape_) {
if (reshape) {
ReshapeLike(source);
} else {
LOG(FATAL) << "Trying to copy blobs of different sizes.";
}
}
switch (Caffe::mode()) {
case Caffe::GPU:
if (copy_diff) {
caffe_copy(count_, source.gpu_diff(),
static_cast<Dtype*>(diff_->mutable_gpu_data()));
} else {
caffe_copy(count_, source.gpu_data(),
static_cast<Dtype*>(data_->mutable_gpu_data()));
}
break;
case Caffe::CPU:
if (copy_diff) {
caffe_copy(count_, source.cpu_diff(),
static_cast<Dtype*>(diff_->mutable_cpu_data()));
} else {
caffe_copy(count_, source.cpu_data(),
static_cast<Dtype*>(data_->mutable_cpu_data()));
}
break;
default:
LOG(FATAL) << "Unknown caffe mode.";
}
}//从source 拷贝数据,copy_diff控制是拷贝diff还是data

template <typename Dtype>
void Blob<Dtype>::FromProto(const BlobProto& proto, bool reshape) {
if (reshape) {
vector<int> shape;
if (proto.has_num() || proto.has_channels() ||
proto.has_height() || proto.has_width()) {
// Using deprecated 4D Blob dimensions --
// shape is (num, channels, height, width).
shape.resize(4);
shape[0] = proto.num();
shape[1] = proto.channels();
shape[2] = proto.height();
shape[3] = proto.width();
} else {
shape.resize(proto.shape().dim_size());
for (int i = 0; i < proto.shape().dim_size(); ++i) {
shape[i] = proto.shape().dim(i);
}
}
Reshape(shape);
} else {//如果不做reshape要求当前的blob的shape和proto传入的shape相同
CHECK(ShapeEquals(proto)) << "shape mismatch (reshape not set)";
}
// copy data
Dtype* data_vec = mutable_cpu_data();
for (int i = 0; i < count_; ++i) {
data_vec[i] = proto.data(i);
}//将proto传入的data拷贝到cpu数据
if (proto.diff_size() > 0) {
Dtype* diff_vec = mutable_cpu_diff();
for (int i = 0; i < count_; ++i) {
diff_vec[i] = proto.diff(i);
}//将proto传入的diff 拷贝到cpu数据
}
}

template <typename Dtype>
void Blob<Dtype>::ToProto(BlobProto* proto, bool write_diff) const {
proto->clear_shape();
for (int i = 0; i < shape_.size(); ++i) {
proto->mutable_shape()->add_dim(shape_[i]);
}
proto->clear_data();
proto->clear_diff();
const Dtype* data_vec = cpu_data();
for (int i = 0; i < count_; ++i) {
proto->add_data(data_vec[i]);//将data写入proto
}
if (write_diff) {
const Dtype* diff_vec = cpu_diff();
for (int i = 0; i < count_; ++i) {
proto->add_diff(diff_vec[i]);//将diff写入proto
}
}
}

INSTANTIATE_CLASS(Blob);
template class Blob<int>;
template class Blob<unsigned int>;

}  // namespace caffe