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C166: PAG AND POF FROM POINTERS


Information in this article applies to:

  • C166 Version 6 or higher

QUESTION

I have a function that was initially written for the Tasking Compiler. This function uses specific Tasking extensions that are not available in the ANSI standard:

void TskInit (unsigned int *stk, void (*task) (void), void far *p)  {
  *stk-- = _sof(task);
  *stk-- = _seg(task);

  *stk-- = _pof(p);
  *stk-- = _pag(p);
}

ANSWER

You may convert:

  • __sof: into a int cast operation.
  • __seg: into a int cast operation with shift.
  • __pag/pof: into a standard pointer assignment.

The function below has exactly the same effect and does not need any non ANSI extensions:

void TskInit (unsigned int *stk, void (*task) (void), void far *p)  {
  *stk-- = (unsigned int) task;
  *stk-- = (unsigned int) ((unsigned long) task >> 16);

  *((void far **) stk) = p;
  stk -= 2;
}

Even better would be to define a struct that represents the stack layout of the Task Control Block. However this might be a bigger change in the system.

MORE INFORMATION

SEE ALSO

Last Reviewed: Wednesday, November 15, 2006


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