##rev_execute
bits(datasize) result;
bits(6) V;
integer vbit;

case op of
    when RevOp_REV16 V = 001000;
    end
    when RevOp_REV32 V = 011000;
    end
    when RevOp_REV64 V = 111000;
    when RevOp_RBIT  V = if datasize == 64 then 111111 else 011111;

    end
result = X[n];
for vbit = 0 to 5
    // Swap pairs of 2^vbit bits in result
    if V<vbit> == 1 then
        bits(datasize) tmp = result;
        integer vsize = 1 << vbit;
        integer base = 0;
        while base < datasize do
            result<base+vsize-1:base> = tmp<base+(2*vsize)-1:base+vsize>;
            result<base+(2*vsize)-1:base+vsize> = tmp<base+vsize-1:base>;
            base = base + (2 * vsize);
    end
X[d] = result;
@@