Is there an easy way to build an interleaver in an 8 bit microcontroller,

>>61754011
Depends on how many bytes do you want to interleave. CPU cores usually don't allow you to use a quick way to do it unless they have built-in dedicated interleavers using CPU registers.

But if is 2 bytes you can try with an array.

void interleave(byte* input, byte* output)
{
    const byte ntable[] = {
        0b00000000,
        0b00000001,
        0b00000100,
        0b00000101,
        0b00010000,
        0b00010001,
        0b00010100,
        0b00010101,
        0b01000000,
        0b01000001,
        0b01000100,
        0b01000101,
        0b01010000,
        0b01010001,
        0b01010100,
        0b01010101
    };

    byte nibble[4];
    nibble[0] = input[0] & 0x0f;
    nibble[1] = input[0] >> 4;
    nibble[2] = input[1] & 0x0f;
    nibble[3] = input[1] >> 4;

    output[0] = (ntable[nibble[1]] << 1) | ntable[nibble[0]];
    output[1] = (ntable[nibble[3]] << 1) | ntable[nibble[2]];
}

>>61754196
Thanks. It's 250 bytes though, so I guess I better start typing shit.

>>61754228
This technique works better on 32-bit microcontrollers though.