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C51: REENTRANCY ISSUES WITH THE DALLAS 390 MATH ACCELERATOR


Information in this article applies to:

  • All C51 Versions

QUESTION

Is the Dallas 390 math accelerator reentrant. In other words, can I use the math accelerator in my main C program and in an interrupt?

ANSWER

No. Math operations performed using the math accelerator are not reentrant. The following suggestions will help to guarantee that only one thread of execution uses the arithmetic processor.

  • Use the MODDA directive to compile either
    • Functions which are guaranteed to execute only in the main program,
    • or Functions used by one interrupt service routine.
  • Compile all remaining functions with the NOMODDA directive.

MORE INFORMATION

  • Refer to MODDA in the Cx51 User's Guide.
  • Refer to NOMODDA in the Cx51 User's Guide.

SEE ALSO

Last Reviewed: Thursday, October 6, 2005


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