The Intel® Streaming SIMD Extensions (Intel® SSE) provide a macro function to help create constants that describe shuffle operations. The macro takes four small integers (in the range of 0 to 3) and combines them into an 8-bit immediate value used by the SHUFPS instruction.
Shuffle Function Macro
You can view the four integers as selectors for choosing which two words from the first input operand and which two words from the second are to be put into the result word.
