Andy Glew's comp-arch.net wiki, http://semipublic.comp-arch.net
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SIMD packed vector
SIMD packed vector is a redundant term for what might be more briefly called packed data representations.
I sometimes use the term SIMD packed vector because it combines all of the common names (that I am aware of) for this sort of data type:
- Operating on 1D vectors of data, A..A[N-1]
- In particular, operating on vectors that are packed into wide registers.
- See the difference between vector and packed vector.
- Because operations on vectors, and packed vectors in particular, are often SIMD (Single Instruction Multiple Data).
For example, the Intel MMX (MultiMedia Extension) was often called a SIMD instruction set extension while it was being designed - and, indeed, still is. And their follow-on instruction set extensions are called SSE (Streaming SIMD Extensions).
As a pedant and a stickler, I (Glew) have occasionally tried to correct the terminology: MMX, and SSE may have SIMD ALU instructions, but the do not have SIMD memory instructions (which essentially scatter/gather instructions) nor other SIMD instructions. So they can hardly be considered full SIMD instruction sets.