"refactor(common): 重构序列化工具包，将serialize重命名为utils并添加bitset组件"

common/utils/sturc/README.md

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+[![Build Status](https://travis-ci.org/lunixbochs/struc.svg?branch=master)](https://travis-ci.org/lunixbochs/struc) [![GoDoc](https://godoc.org/github.com/lunixbochs/struc?status.svg)](https://godoc.org/github.com/lunixbochs/struc)
+
+struc
+====
+
+Struc exists to pack and unpack C-style structures from bytes, which is useful for binary files and network protocols. It could be considered an alternative to `encoding/binary`, which requires massive boilerplate for some similar operations.
+
+Take a look at an [example comparing `struc` and `encoding/binary`](https://bochs.info/p/cxvm9)
+
+Struc considers usability first. That said, it does cache reflection data and aims to be competitive with `encoding/binary` struct packing in every way, including performance.
+
+Example struct
+----
+
+```Go
+type Example struct {
+    Var   int `struc:"int32,sizeof=Str"`
+    Str   string
+    Weird []byte `struc:"[8]int64"`
+     Weird []byte `struc:"[32]byte"`
+    Var   []int `struc:"[]int32,little"`
+}
+```
+
+Struct tag format
+----
+
+ - ```Var []int `struc:"[]int32,little,sizeof=StringField"` ``` will pack Var as a slice of little-endian int32, and link it as the size of `StringField`.
+ - `sizeof=`: Indicates this field is a number used to track the length of a another field. `sizeof` fields are automatically updated on `Pack()` based on the current length of the tracked field, and are used to size the target field during `Unpack()`.
+ - Bare values will be parsed as type and endianness.
+
+Endian formats
+----
+
+ - `big` (default)
+ - `little`
+
+Recognized types
+----
+
+ - `pad` - this type ignores field contents and is backed by a `[length]byte` containing nulls
+ - `bool`
+ - `byte`
+ - `int8`, `uint8`
+ - `int16`, `uint16`
+ - `int32`, `uint32`
+ - `int64`, `uint64`
+ - `float32`
+ - `float64`
+
+Types can be indicated as arrays/slices using `[]` syntax. Example: `[]int64`, `[8]int32`.
+
+Bare slice types (those with no `[size]`) must have a linked `Sizeof` field.
+
+Private fields are ignored when packing and unpacking.
+
+Example code
+----
+
+```Go
+package main
+
+import (
+    "bytes"
+    "github.com/lunixbochs/struc"
+)
+
+type Example struct {
+    A int `struc:"big"`
+
+    // B will be encoded/decoded as a 16-bit int (a "short")
+    // but is stored as a native int in the struct
+    B int `struc:"int16"`
+
+    // the sizeof key links a buffer's size to any int field
+    Size int `struc:"int8,little,sizeof=Str"`
+    Str  string
+
+    // you can get freaky if you want
+    Str2 string `struc:"[5]int64"`
+}
+
+func main() {
+    var buf bytes.Buffer
+    t := &Example{1, 2, 0, "test", "test2"}
+    err := struc.Pack(&buf, t)
+    o := &Example{}
+    err = struc.Unpack(&buf, o)
+}
+```
+
+Benchmark
+----
+
+`BenchmarkEncode` uses struc. `Stdlib` benchmarks use equivalent `encoding/binary` code. `Manual` encodes without any reflection, and should be considered an upper bound on performance (which generated code based on struc definitions should be able to achieve).
+
+```
+BenchmarkEncode        1000000   1265 ns/op
+BenchmarkStdlibEncode  1000000   1855 ns/op
+BenchmarkManualEncode  5000000    284 ns/op
+BenchmarkDecode        1000000   1259 ns/op
+BenchmarkStdlibDecode  1000000   1656 ns/op
+BenchmarkManualDecode  20000000  89.0 ns/op
+```