Function decode_complete_quads 

fn decode_complete_quads(
    input: &[u8],
    input_index_start: usize,
    input_index_end: usize,
    decode_table: &[u8; 256],
    output: &mut [u8],
    output_index_start: usize,
) -> Result<(), DecodeSliceError>

Decode the complete non-terminal quads in input[input_index_start..input_index_end] (both bounds multiples of 4), writing to output starting at output_index_start, which must equal input_index_start / 4 * 3. Error offsets are reported in absolute input coordinates.