RT-Thread finsh源码分析: finsh_var.h

/*
*  Variable implementation in finsh shell.
*
* COPYRIGHT (C) 2006 - 2013, RT-Thread Development Team
*
*  This file is part of RT-Thread (http://www.rt-thread.org)
*  Maintainer: bernard.xiong <bernard.xiong at gmail.com>
*
*  All rights reserved.
*
*  This program is free software; you can redistribute it and/or modify
*  it under the terms of the GNU General Public License as published by
*  the Free Software Foundation; either version 2 of the License, or
*  (at your option) any later version.
*
*  This program is distributed in the hope that it will be useful,
*  but WITHOUT ANY WARRANTY; without even the implied warranty of
*  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
*  GNU General Public License for more details.
*
*  You should have received a copy of the GNU General Public License along
*  with this program; if not, write to the Free Software Foundation, Inc.,
*  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Change Logs:
* Date           Author       Notes
* 2010-03-22     Bernard      first version
*/
#ifndef __FINSH_VAR_H__
#define __FINSH_VAR_H__

#include <finsh.h>

/*
* The variable in finsh is put in data segment as a global variable.
* The 'finsh_var' structure presents the structure of variable in data segment.
*/

/*
* finsh_var是全局变量，属于数据段
*/
struct finsh_var
{
//数组长度加1，可以在循环中避免>=或者<=临界问题，增加代码可读性
char name[FINSH_NAME_MAX + 1];/* the name of variable */

//错误类型
u_char type;/* the type of variable */

//联合，模糊定义，动态扩展
/* variable value */
union {
char char_value;
short short_value;
intint_value;
longlong_value;
void*ptr;
}value;
};
//声明为全局数据，注意数组未初始化，应该放在.bss段
extern struct finsh_var global_variable[];

int finsh_var_init(void);  //数组global_variable初始化
int finsh_var_insert(const char* name, int type); //插入var到数组global_variable
int finsh_var_delete(const char* name);  //从数组移出var
struct finsh_var* finsh_var_lookup(const char* name);  //查找var

#endif