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NEON SIMD Dn Register and Parallel Operations

Thank you for your reply. A few more questions:

Is Dn a 128-bit wide register? Is Dd also a 128-bit wide register? (Referring to the diagram in the original question)

Also, the diagram shows 4 parallel operations. Is this the actual number of parallel operations that the hardware can execute?

As an example: If 4 parallel operations are executed, each operation would use 32-bits from each source register. Is this correct?

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  • Hello,


    D of Dn represents double (i.e. 64 bit).
    Also Qn represents quad (i.e. 128 bit).
    If you say about a source register by Dn, it can be both 64 bit or 128 bit (or 32 bit).
    If you say about a destination register by Dd, it can be both 64 bit or 128 bit (or 32 bit)..
    Please refer to ARM NEON programming quick reference .
    The parallelism of an operation would be 1, 2, 4 or 8.
    The unit of each operation depends on an instruction.


    Best regards,
    Yasuhiko Koumoto.

Reply
  • Hello,


    D of Dn represents double (i.e. 64 bit).
    Also Qn represents quad (i.e. 128 bit).
    If you say about a source register by Dn, it can be both 64 bit or 128 bit (or 32 bit).
    If you say about a destination register by Dd, it can be both 64 bit or 128 bit (or 32 bit)..
    Please refer to ARM NEON programming quick reference .
    The parallelism of an operation would be 1, 2, 4 or 8.
    The unit of each operation depends on an instruction.


    Best regards,
    Yasuhiko Koumoto.

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