可否让一个函数的返回值可以是任意值呢?(USMART设计中遇到的问题)

正点原子 · 发表于 2011-4-28 14:23:22

在USMART(一个串口调试互交组建)的设计过程中,需要一个通用的函数原型,来匹配各种函数(不包含指针参量,即参数和返回值都不为指针类型).以达到函数受usmart管理的目的.
下面是核心定义:

//定义一个通用的函数类型
//usmart_func的返回值为u32，参数待定.
typedef u32(*usmart_func)();//定义函数类型
//函数名列表
struct _m_usmart_nametab
{
usmart_func func;  //函数指针
const u8* name;  //函数名(查找串)
};
//usmart控制管理器
struct _m_usmart_dev
{
struct _m_usmart_nametab *funs; //函数名指针
void (*init)(void);    //初始化
u8 (*cmd_rec)(u8*str);   //识别函数名及参数
void (*exe)(void);     //执行
void (*scan)(void);             //扫描
u8 fnum;         //函数数量
u8 pnum;                        //参数数量
u8 id;       //函数id
u32 parm[MAX_PARM];           //函数的参数(最大参数)
};
extern struct _m_usmart_nametab usmart_nametab[]; //在usmart_config.c里面定义
extern struct _m_usmart_dev usmart_dev;    //在usmart_config.c里面定义

上面,我把通用的函数原型定义为u32的返回类型,以适应最大返回值的情况.但是这样的定义,在函数返回值为void或者u8，u16的时候,会产生警告.不知道有没有办法让函数原型可以返回任意值,而不产生警告呢?

在另外一个.c文件里面,通过如下方法初始化函数名列表:
//函数名列表初始化(用户自己添加)
//用户直接在这里输入要执行的函数名及其查找串
struct _m_usmart_nametab usmart_nametab[]=
{
delay_ms,"delay_ms",
delay_us,"delay_us",
SPI_Flash_ReadID,"SPI_Flash_ReadID",
Seg_Show_Num,"Seg_Show_Num",
Seg_Show_Char,"Seg_Show_Char",
RTC_Set,"RTC_Set",
Seg_Clear,"Seg_Clear",
Seg_Show_Str,"Seg_Show_Str",
EXIO_Set,"EXIO_Set",
EXIO_Scan,"EXIO_Scan",
Seg_Dot_Set,"Seg_Dot_Set",
ATR_TEST,"ATR_TEST",
Test_Read,"Test_Read",
MRAM_Read,"MRAM_Read",
RAM_Read,"PRAM_Read",
Start_Transaction,"Start_Transaction",
TEST_RD_REC,"TEST_RD_REC",
TEST_WR_REC,"TEST_WR_REC",
Sle_WR_Cmd,"Sle_WR_Cmd",
Flash_Get_Recnum,"Flash_Get_Recnum",
   SPI_Flash_Erase_Chip,"SPI_Flash_Erase_Chip",
TEST_WR_ALL,"TEST_WR_ALL",
Test_Write,"Test_Write",
TEST_Ver,"TEST_Ver",

};

以上各个函数,有的返回void,有的返回u8有的返回u16.导致很多警告.希望高人指点一下,如何能去掉这些警告?
下面是编译后的警告:

图片不清晰,看下面的:
..\USMART\usmart_config.c(22): warning: #144-D: a value of type "void (*)(u16)" cannot be used to initialize an entity of type "usmart_func"
..\USMART\usmart_config.c(23): warning: #144-D: a value of type "void (*)(u32)" cannot be used to initialize an entity of type "usmart_func"
..\USMART\usmart_config.c(24): warning: #144-D: a value of type "u16 (*)(void)" cannot be used to initialize an entity of type "usmart_func"
..\USMART\usmart_config.c(25): warning: #144-D: a value of type "void (*)(u8, u32, u8)" cannot be used to initialize an entity of type "usmart_func"
..\USMART\usmart_config.c(26): warning: #144-D: a value of type "void (*)(u8, u8)" cannot be used to initialize an entity of type "usmart_func"
..\USMART\usmart_config.c(27): warning: #144-D: a value of type "u8 (*)(u16, u8, u8, u8, u8, u8)" cannot be used to initialize an entity of type "usmart_func"
..\USMART\usmart_config.c(28): warning: #144-D: a value of type "void (*)(void)" cannot be used to initialize an entity of type "usmart_func"
..\USMART\usmart_config.c(29): warning: #144-D: a value of type "void (*)(u8, u8 *)" cannot be used to initialize an entity of type "usmart_func"
..\USMART\usmart_config.c(30): warning: #144-D: a value of type "void (*)(u8, u8)" cannot be used to initialize an entity of type "usmart_func"
..\USMART\usmart_config.c(31): warning: #144-D: a value of type "u8 (*)(void)" cannot be used to initialize an entity of type "usmart_func"
..\USMART\usmart_config.c(32): warning: #144-D: a value of type "void (*)(u8, u8)" cannot be used to initialize an entity of type "usmart_func"
..\USMART\usmart_config.c(33): warning: #144-D: a value of type "void (*)(void)" cannot be used to initialize an entity of type "usmart_func"
..\USMART\usmart_config.c(34): warning: #144-D: a value of type "u8 (*)(u8, u8)" cannot be used to initialize an entity of type "usmart_func"
..\USMART\usmart_config.c(35): warning: #144-D: a value of type "void (*)(void)" cannot be used to initialize an entity of type "usmart_func"
..\USMART\usmart_config.c(36): warning: #144-D: a value of type "void (*)(void)" cannot be used to initialize an entity of type "usmart_func"
..\USMART\usmart_config.c(37): warning: #144-D: a value of type "void (*)(void)" cannot be used to initialize an entity of type "usmart_func"
..\USMART\usmart_config.c(38): warning: #144-D: a value of type "void (*)(u32)" cannot be used to initialize an entity of type "usmart_func"
..\USMART\usmart_config.c(39): warning: #144-D: a value of type "void (*)(u32)" cannot be used to initialize an entity of type "usmart_func"
..\USMART\usmart_config.c(40): warning: #144-D: a value of type "void (*)(u8, u8, u8)" cannot be used to initialize an entity of type "usmart_func"
..\USMART\usmart_config.c(42): warning: #144-D: a value of type "void (*)(void)" cannot be used to initialize an entity of type "usmart_func"
..\USMART\usmart_config.c(43): warning: #144-D: a value of type "void (*)(void)" cannot be used to initialize an entity of type "usmart_func"
..\USMART\usmart_config.c(44): warning: #144-D: a value of type "u8 (*)(u8, u8, u8)" cannot be used to initialize an entity of type "usmart_func"
..\USMART\usmart_config.c(45): warning: #144-D: a value of type "u8 (*)(u8, u8, u8)" cannot be used to initialize an entity of type "usmart_func"

正点原子 · 发表于 2011-4-28 14:29:01

在百度上搜到,有人说可以用联合体,但是我试过,警告依旧.(测试软件是MDK3.80A).

aozima · 发表于 2011-5-23 22:14:58

#include <stdio.h>
#include <stdlib.h>
struct _m_usmart_nametab
{
void * func;  //函数指针
char * name;  //函数名(查找串)
};
void test1(void)
{
printf("fun test1 done!\r\n");
return;
}
int test2(void)
{
printf("fun test2 done!\r\n");
return 2;
}
int test3(int arg)
{
printf("arg is :%d\r\n",arg);
printf("fun test3 done!\r\n");
return arg*2;
}
unsigned long test4(int arg1,unsigned long arg2)
{
printf("arg1 is :%d\r\n",arg1);
printf("arg2 is :0x%X\r\n",arg2);
printf("fun test4 done!\r\n");
return arg2+1;
}
struct _m_usmart_nametab usmart_nametab[]=
{
{test1,"void test1(void)",},
{test2,"int test2(void)",},
{test3,"int test3(int arg)",},
{test4,"unsigned long test4(int arg1,unsigned long arg2)",},
};
int main()
{
unsigned long return_value = 0;
unsigned int return_long = 0;
// 函数类型 (*指针变量名)(形参列表);
printf("function name: %s\r\n",usmart_nametab[0].name);
test1();
printf("***\r\nfunction table:\r\n");
return_value = (*(unsigned long(*)())usmart_nametab[0].func)();
printf("return_value is : %d\r\n",return_value);
printf("\r\nfunction name: %s\r\n",usmart_nametab[1].name);
printf("return_value is : %d\r\n",test2());
printf("***\r\nfunction table:\r\n");
return_value = (*(int(*)())usmart_nametab[1].func)();
printf("return_value is : %d\r\n",return_value);
printf("\r\nfunction name: %s\r\n",usmart_nametab[2].name);
printf("return_value is : %d\r\n",test3(4));
printf("***\r\nfunction table:\r\n");
return_value = (*(int(*)(int))usmart_nametab[2].func)(5);
printf("return_value is : %d\r\n",return_value);
printf("\r\nfunction name: %s\r\n",usmart_nametab[3].name);
printf("return_value is : %X\r\n",test4(4,0xFFFFFFF7));
printf("***\r\nfunction table:\r\n");
return_long = (*(unsigned long(*)(int,unsigned long))usmart_nametab[3].func)(5,0xFFFFFFF8);
printf("return_long is : %X\r\n",return_long);
return 0;
}

复制代码

正点原子 · 发表于 2011-5-23 23:07:13

回复【3楼】aozima:
---------------------------------
谢谢.后来给我的代码可用.
struct _m_usmart_nametab
{
    void * func;  //函数指针
    char * name;  //函数名(查找串)
};

void test1(void)
{
    printf("fun test1 done!\r\n");
    return;
}

int test2(void)
{
    printf("fun test2 done!\r\n");
    return 2;
}

int test3(int arg)
{
    printf("arg is:%d\r\n",arg);
    printf("fun test3 done!\r\n");
    return arg*2;
}

unsigned long test4(int arg1,unsigned long arg2)
{
    printf("arg1 is:%d\r\n",arg1);
    printf("arg2 is:0x%X\r\n",arg2);
    printf("fun test4 done!\r\n");
    return arg2+1;
}

struct _m_usmart_nametab usmart_nametab[]=
{
    {(void*)test1,"void test1(void)",},
    {(void*)test2,"int test2(void)",},
    {(void*)test3,"int test3(int arg)",},
    {(void*)test4,"unsigned long test4(int arg1,unsigned long arg2)",},
};

int main(void)
{
    //启用PLL运行在72M
//    SystemInit();

     printf("hello");

    // 测试
    {
        unsigned long return_value = 0;
        unsigned int return_long = 0;

        // 函数类型 (*指针变量名)(形参列表);

        printf("function name: %s\r\n",usmart_nametab[0].name);
        test1();
        printf("***\r\nfunction table:\r\n");
        return_value = (*(unsigned long(*)())usmart_nametab[0].func)();
        printf("return_value is: %d\r\n",return_value);

        printf("\r\nfunction name: %s\r\n",usmart_nametab[1].name);
        printf("return_value is: %d\r\n",test2());
        printf("***\r\nfunction table:\r\n");
        return_value = (*(int(*)())usmart_nametab[1].func)();
        printf("return_value is: %d\r\n",return_value);

        printf("\r\nfunction name: %s\r\n",usmart_nametab[2].name);
        printf("return_value is: %d\r\n",test3(4));
        printf("***\r\nfunction table:\r\n");
        return_value = (*(int(*)(int))usmart_nametab[2].func)(5);
        printf("return_value is: %d\r\n",return_value);

        printf("\r\nfunction name: %s\r\n",usmart_nametab[3].name);
        printf("return_value is: %X\r\n",test4(4,0xFFFFFFF7));
        printf("***\r\nfunction table:\r\n");
        return_long = (*(unsigned long(*)(int,unsigned long))usmart_nametab[3].func)(5,0xFFFFFFF8);
        printf("return_long is: %X\r\n",return_long);
    }
    // 测试
}

正点原子 · 发表于 2011-5-23 23:10:26

在aozima的帮助下,过几天我会公布USMARTV1.4的源码.
V1.4的主要新特性:
1,支持字符串参数.
2,优化参数存储方式,内存占用显著减小.
3,自适应参数长度(连函数名,总数不超过64个字节.ps:只需要自行修改usart.c的部分内容,即可支持大于64字节.)
4,去掉了警告(在aozima帮助下解决,特此感谢!).