一个UUID生成算法的C语言实现——WIN32版本
一个UUID生成算法的C语言实现——WIN32版本
cheungmine 2007-9-16
根据定义，UUID（Universally Unique IDentifier，也称GUID）在时间和空间都是唯一的。为保证空间的唯一性，每个UUID使用了一个48位的值来记录，一般是计算机的网卡地址。为保证时间上的唯一性，每个UUID具有一个60位的时间戳（timestamp）。这个时间戳表示自公元1582年（绝对不是1852，这是《COM技术内幕》，1999年3月第1版第89页中的一个错误）10月15号00：00：00：00以来的时间，是以100纳秒为单位的时间间隔。1纳秒（ns）=10-9秒（s）。UUID算法可以保证至大约公元3400年仍然唯一。UUID的C语言结构定义如下：
typedef struct _uuid_t {
unsigned long data1; unsigned short data2; unsigned short data3; unsigned char data4[8]; } uuid_t;
它的结构大小为16个字节。即sizeof(uuid_t)==16为TRUE。写成16进制字符串的格式，一般为：
\
上面的字符串形式，占用36个字符，不包括结尾空字符’\\0’。所以，要想容纳一个UUID字符串，必须声明为一个char[36+1]的字符数组。
以软件算法实现UUID非常有现实意义。参考RFC4122文档和其他一些开源代码，我写了一个WIN32下的UUID实现C语言程序——UUID32.c。程序符合RFC4122标准。程序不但实现创建UUID和UUID String，还可以对UUID进行字符和时间上的比较。还可以从UUID从提取时间戳（精度到秒）。头文件uuid32.h定义如下： /* uuid32.h
2007-09-15 Last created by cheungmine. Partly rights reserved by cheungmine. */
#ifndef UUID32_H_INCLUDED #define UUID32_H_INCLUDED
#include
#include
#include \
typedef struct _timestamp_t {
BYTE tm_sec; /* Seconds after minute (0 – 59). */ BYTE tm_min; /* Minutes after hour (0 – 59). */ BYTE tm_hour; /* Hours after midnight (0 – 23). */ BYTE tm_mday; /* Day of month (1 – 31). */
BYTE tm_mon; /* Month (0 – 11; January = 0). */ BYTE tm_wday; /* Day of week (0 – 6; Sunday = 0). */ short tm_year; /* Year (current year minus 1900). */
short tm_yday; /* Day of year (0 – 365; January 1 = 0). */ long tm_fraction; /* Fraction little than 1 second */ } timestamp_t;
typedef struct _uuid_t {
unsigned long data1; unsigned short data2; unsigned short data3; unsigned char data4[8]; } uuid_t;
/**
* Checks whether the given string matches the UUID format. * params:
* [in] uuid - the potential UUID string
* return
* TRUE if the given string is a UUID, FALSE otherwise **/
BOOL is_uuid_string(const char *uuid); /**
* Generates a new UUID. The UUID is a time-based time 1 UUID.
* A random per-process node identifier is used to avoid keeping global * state and maintaining inter-process synchronization. **/
void uuid_create(uuid_t* uuid); /**
* Generates a new UUID string. The returned UUID is a time-based time 1 U
UID.
* A random per-process node identifier is used to avoid keeping global * state and maintaining inter-process synchronization. * return UUID string (newly allocated) **/
char *uuid_create_string(void); /**
* Generates a name-based (type 3) UUID string from the given external * identifier. The special namespace UUID is used as the namespace of * the generated UUID. * params
* [in] external - the external identifier * return
* UUID string (newly allocated) **/
void uuid_create_external(const char *external, uuid_t* uuid); /**
* Translate a uuid_t to a uuid string * return UUID string **/
char *uuid_to_string(const uuid_t* uuid); /**
* Get timestamp from a UUID
**/
void uuid_to_timestamp(const uuid_t* uuid, timestamp_t* time);
/**
* Resurn a description of timestamp NOT including fraction **/
char* timestamp_to_string(const timestamp_t* time); /**
* Compare two UUID's lexically * return
* -1 u1 is lexically before u2 * 0 u1 is equal to u2
* 1 u1 is lexically after u2 */
int uuid_compare(const uuid_t *u1, const uuid_t *u2);
/**
* Compare two UUID's temporally * return
* -1 u1 is temporally before u2 * 0 u1 is equal to u2
* 1 u1 is temporally after u2 */
int uuid_compare_time(const uuid_t *u1, const uuid_t *u2);
#endif /* UUID32_H_INCLUDED */
其中，头文件\如下：
/* cdatatype.h
2008-09-15 Last created by cheungmine. All rights reserved by cheungmine. */
#ifndef CDATATYPE_H__ #define CDATATYPE_H__
/*============================================================================*/ typedef unsigned char uchar, byte, BYTE;
typedef unsigned short uint16, word_t, ushort;
typedef unsigned int uint, uint32, dword_t, size_t;
typedef unsigned long ulong;
typedef __int64 int64;
typedef unsigned __int64 uint64, qword_t;
#ifndef BOOL
#define BOOL int #define TRUE 1 #define FALSE 0 #endif
#ifndef RESULT
#define RESULT long #define SUCCESS 0 #define ERROR -1 #endif
#define SIZE_BYTE 1 #define SIZE_SHORT 2 #define SIZE_INT 4 #define SIZE_FLT 4 #define SIZE_DBL 8 #define SIZE_WORD 2 #define SIZE_DWORD 4 #define SIZE_QWORD 8 #define SIZE_LINT 8 #define SIZE_INT64 8 #define SIZE_UUID 16
/*============================================================================*/ #endif /*CDATATYPE_H__*/
MD5算法生成的文件有：md5.h和md5.c，分别罗列如下： #ifndef _MD5_H__
#define _MD5_H__
/* MD5.H - header file for MD5C.C */
/* Copyright (C) 1991-2, RSA Data Security, Inc. Created 1991. All rights reserved.
License to copy and use this software is granted provided that it is identified as the \ Algorithm\ or this function.
License is also granted to make and use derivative works provided that such works are identified as \ Security, Inc. MD5 Message-Digest Algorithm\ mentioning or referencing the derived work.
RSA Data Security, Inc. makes no representations concerning either the merchantability of this software or the suitability of this software for any particular purpose. It is provided \ without express or implied warranty of any kind.