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XAR Register Details

RISHIKESH BANSOD
Prodigy 90 points

What is use of upper 7 bits in XARn register, where are these 7 bits important. When we should consider them during address calculation?

Please reply.

Thanks 

  • 0
    TI__Mastermind 35645 points

    Hi,

    Team will address your request shortly.

    Thanks & regards,

    Sivaraj K

  • 0
    TI__Guru* 84285 points

    When performing integer arithmetic in the AR registers, the upper 7 bits can be ignored completely.  However, they are always used when you are using the XAR register as an address register.  Even though the instruction syntax typically shows *ARn when using an addressing mode, the whole XARn is actually used.  You must set the upper 7 bits correctly.  If all of your data exists in the first 64k, you can set the upper 7 bits to zero and forget about it.  Otherwise, you must take care to use the correct instructions to set the whole XAR.