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Example of instructions, doesn't use functional unit at all?

Hello to all,

I need a small help with the processor instructions. Can anybody provide me an example where during execution, the functional unit must not be used or it must be deactivated? 

All data-processing and data-transfer instruction need the functional unit. Initially, I thought the NOP instruction can be one of the examples, but while going through the documentations, I got to know that NOP instruction is nothing but the MOV R8,R8. 

I really want to measure the effect of functional unit activation and deactivation. So, is there any instruction example or any measurement technique, which will be helpful in our case?

I am working on ARM Cortex-M4.

Thanking you in advance,

Warm Regards,

Himanshu

Parents
  • Dear Mr. Yiu,

    Thank you very much for your quick reply. Therefore any of the NOP with 0xBF00 (16-bit NOP instruction) or NOP.W with 0xF3AF8000 (32-bit NOP instruction) can be used in our case (No usage of the functional unit), am I right?

      (generated from Cortex-M4)

    Thanking you once again,

    Kind Regards,

    Himanshu

Reply
  • Dear Mr. Yiu,

    Thank you very much for your quick reply. Therefore any of the NOP with 0xBF00 (16-bit NOP instruction) or NOP.W with 0xF3AF8000 (32-bit NOP instruction) can be used in our case (No usage of the functional unit), am I right?

      (generated from Cortex-M4)

    Thanking you once again,

    Kind Regards,

    Himanshu

Children