# Function core::arch::riscv32::xperm4

source ·

    pub unsafe fn xperm4(rs1: usize, rs2: usize) -> usize

🔬This is a nightly-only experimental API. (`riscv_ext_intrinsics` #114544)
Available on RISC-V RV32 and target feature `zbkx` only.
Expand description

Nibble-wise lookup of indicies into a vector.

The xperm4 instruction operates on nibbles. The rs1 register contains a vector of XLEN/4 4-bit elements. The rs2 register contains a vector of XLEN/4 4-bit indexes. The result is each element in rs2 replaced by the indexed element in rs1, or zero if the index into rs2 is out of bounds.

Source: RISC-V Cryptography Extensions Volume I: Scalar & Entropy Source Instructions

Version: v1.0.1

Section: 3.48

## §Safety

This function is safe to use if the `zbkx` target feature is present.