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function pointer

Anh Phan

hi all,

do you think i can work around function pointers as following:

extern void a(void);
extern void b(void);

void fptr(void *fp)
{
if (fp == a)
a();
if (fp == b)
b();
}

void main(void)
{
void *fp;
fp = (void *)a; //or b
fptr(fp);
}

Parents
  • 0 in reply to Dan Henry

    "Would this solve function pointer problem?"

    Possibly, but in a very wasteful way, and no more maintainable than using the Linker directives.

    You are effectively just using the function pointer as an index - so why not just use a plain byte index instead?

    void func_caller ( unsigned char index )
{
   unsigned char i;
   for (i = 0; i < 10; i++)
   {
      switch( index )
      {
         case 1: func1(i);
                 break;
         case 2: func2(i);
                 break;
         case 3: func3(i);
                 break;
         // etc
      }
   }
}
    You could, of course, define an enum to make things clearer.

    BTW: note the use of the < pre > and < /pre > tags to retain the formatting - see the instructions when you make a post.

Reply
  • 0 in reply to Dan Henry

    "Would this solve function pointer problem?"

    Possibly, but in a very wasteful way, and no more maintainable than using the Linker directives.

    You are effectively just using the function pointer as an index - so why not just use a plain byte index instead?

    void func_caller ( unsigned char index )
{
   unsigned char i;
   for (i = 0; i < 10; i++)
   {
      switch( index )
      {
         case 1: func1(i);
                 break;
         case 2: func2(i);
                 break;
         case 3: func3(i);
                 break;
         // etc
      }
   }
}
    You could, of course, define an enum to make things clearer.

    BTW: note the use of the < pre > and < /pre > tags to retain the formatting - see the instructions when you make a post.

Children
  • 0 in reply to Andy Neil

    Function pointers is a wonderful means of achieveing certain things on processors with a suitable architecture.

    Here in the '51 community we often see someone trying to force the '51 to "behave".

    Darn it, the '51 is NOT a PC. Accept the challenges/limitations or stick with your PC.

    Function pointers is a nightmare in the '51 architecture, not in Keil C.

    Erik