If you can confine yourself to a table of 16 byte values, then Intel SSE3's instruction pshufb can let you have a table in a register, with 16 parallel lookups

If you can confine yourself to a table of 16 byte values, then Intel SSE3's instruction pshufb can let you have a table in a register, with 16 parallel lookups in one clock cycle (assuming your input are the low nibbles in another SSE3 register). More here: http://www.0x80.pl/notesen/2016-03-13-simd-lookup-pshufb.html http://www.0x80.pl/notesen/2016-03-13-simd-lookup-pshufb.htm...