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A166: Using DPP1 and DPP2 in Assembler Routines

Information in this article applies to:

  • C166


In the C166 Compiler manual, it states for the DPP1 and the DPP2 that "This DPP register may not be modified by assembler subroutines.". I would like to use either DPP1 or DPP2 in my assembler to speed up an operation. Is that possible?


Yes, you may use DPP1 and DPP2 in assembler routines provided that:

  1. You disable interrupts while using them.
  2. You restore the original values of the registers when you return to C or re-enable interrupts.


Last Reviewed: Thursday, February 25, 2021

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