Rust switchboxes.

switchboxes.rs

fn main()    
{
    //switch boxes
    let sbox_zero = [[1,0,3,2],
                     [3,2,1,0],
                     [0,2,1,3],
                     [3,1,3,2]];

    let sbox_one = [[0,1,2,3],
                    [2,0,1,3],
                    [3,0,1,0],
                    [2,1,0,3]];
                    
    let byte = 0b1111_0000;
    let mut result = 0b0000_0000;

    /* * * * * * *
     * SBOX ZERO *
     * * * * * * */
    let mut temp = 0;
    // row:
    if byte & (1 << 4) == 0b0001_0000 { temp = temp | 1 << 0; }
    if byte & (1 << 7) == 0b1000_0000 { temp = temp | 1 << 1; }
    let s_zero_row = temp;
    // column:
    temp = 0; // (reset)
    if byte & (1 << 6) == 0b0100_0000 { temp = temp | 1 << 1; }
    if byte & (1 << 5) == 0b0010_0000 { temp = temp | 1 << 0; }
    let s_zero_col = temp;

    /* * * * * * *
     *  SBOX ONE *
     * * * * * * */
    // row:
    temp = 0;
    if byte & (1 << 3) == 0b0000_1000 {  temp = temp | 1 << 1; }
    if byte & (1 << 0) == 0b0000_0001 {  temp = temp | 1 << 0; }
    let s_one_row = temp;
    // column:
    temp = 0;
    if byte & (1 << 2) == 0b0000_0100 {  temp = temp | 1 << 1; }
    if byte & (1 << 1) == 0b0000_0010 {  temp = temp | 1 << 0; }
    let s_one_col = temp;

    let sbox_zero_val = sbox_zero[s_zero_row][s_zero_col]; //2 bits
    let sbox_one_val  = sbox_one [s_one_row] [s_one_col];  //2 bits
    
    //join sbox_zero_val and sbox_one_val bits:
    // set bit 0 
    if sbox_one_val & (1 << 0) == 0b0000_0001 { result = result | 1 << 0; }
    // set bit 1
    if sbox_one_val & (1 << 1) == 0b0000_0010 { result = result | 1 << 1; }

    // set bit 2    
    if sbox_zero_val & (1 << 0) == 0b0000_0001 { result = result | 1 << 2; }
    //set bit 3
    if sbox_zero_val & (1 << 1) == 0b0000_0010 { result = result | 1 << 3; }
    
    println!("byte: {:08b}", byte);
    println!("switchbox-0: {:02b}, switchbox-1: {:02b}", sbox_zero_val, sbox_one_val);    
    println!("result: {:04b}", result);
}