The xperm4 instruction operates on nibbles. The xs1 register contains a vector of XLEN/4 4-bit elements. The xs2 register contains a vector of XLEN/4 4-bit indexes. The result is each element in xs2 replaced by the indexed element in xs1, or zero if the index into xs2 is out of bounds.
xperm4 xd, xs1, xs2Type: R