C51: INDIRECTLY CALLED REENTRANT FUNCTIONS

Information in this article applies to:

• C51 All Version
• Cx51 All Version

QUESTION

I have problems passing lots of parameters to indirectly called functions. I tried to use the reentrant attribute but I could not make it work. Can you give me an example?

ANSWER

The example below shows the correct definition for reentrant functions that are called via function pointers. Both the function pointer and the function itself must contain the reentrant attribute. In addition, you must setup the reentrant stack pointer in the startup code (STARTUP.A51).

long* (*indirect_func) (long l, long* lp, int i) reentrant;

long* func (long l, long* lp, int i) reentrant {
  lp += i;              // just for demonstration
  *lp = l;
  return (lp);
}

long xdata larray[100];
long *lp;

void main (void)  {
  indirect_func = func;

  lp = indirect_func (500000L, larray, 5);
  while (1);
}

MORE INFORMATION

• Refer to Data Overlaying in the BL51 User's Guide.
• Refer to Application Note 129: Function Pointers in C51 for a complete discussion of all the ramifications of using function pointers with the C51 compiler.

SEE ALSO

• BL51: CALL TREE USING POINTERS TO FUNCTIONS
• BL51: AVOIDING FUNCTION POINTER PROBLEMS WITH NOOVERLAY
• BL51: WARNING L16 (UNCALLED FUNCTION) USING CODE BANKING
• C51: INDIRECT FUNCTION CALLS WITH CODE BANKING
• C51: PASSING PARAMETERS TO INDIRECTLY CALLED FUNCTIONS

Last Reviewed: Monday, July 18, 2005