vsext.vf4

{
  let SEW = get_sew();
  let LMUL_pow = get_lmul_pow();
  let num_elem = get_num_elem(LMUL_pow, SEW);
  let SEW_quart = SEW / 4;
  let LMUL_pow_quart = LMUL_pow - 2;

  if  illegal_variable_width(vd, vm, SEW_quart, LMUL_pow_quart) |
      not(valid_reg_overlap(vs2, vd, LMUL_pow_quart, LMUL_pow))
  then { handle_illegal(); return RETIRE_FAIL };

  let 'n = num_elem;
  let 'm = SEW;
  let 'o = SEW_quart;

  let vm_val  : vector('n, dec, bool)     = read_vmask(num_elem, vm, 0b00000);
  let vd_val  : vector('n, dec, bits('m)) = read_vreg(num_elem, SEW, LMUL_pow, vd);
  let vs2_val : vector('n, dec, bits('o)) = read_vreg(num_elem, SEW_quart, LMUL_pow_quart, vs2);
  result      : vector('n, dec, bits('m)) = undefined;
  mask        : vector('n, dec, bool)     = undefined;

  (result, mask) = init_masked_result(num_elem, SEW, LMUL_pow, vd_val, vm_val);

  assert(SEW > SEW_quart);
  foreach (i from 0 to (num_elem - 1)) {
    if mask[i] then {
      result[i] = match funct6 {
        VEXT4_ZVF4 => zero_extend(vs2_val[i]),
        VEXT4_SVF4 => sign_extend(vs2_val[i])
      }
    }
  };

  write_vreg(num_elem, SEW, LMUL_pow, vd, result);
  vstart = zeros();
  RETIRE_SUCCESS
}