MATLAB data receiver script can't handle "partial chunks"

[vladysor]

#10 must be solved first

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To maximize the USB efficiency, data transmission is arranged in chunks. Typical transmitter sketch looks like this:

// chunk_size in bytes, for OTG_FS "64" is passed
void transfer_serial_data(uint16_t* buf, const uint16_t buf_size, const uint16_t chunk_size) {
    for (uint16_t i = 0; i < (buf_size*2); i += chunk_size) {
        uint16_t cur_chunk_size = ((buf_size*2) - i < chunk_size) ? (buf_size*2 - i) : chunk_size;
        Serial.write((const uint8_t *) buf + i, cur_chunk_size);
    }
}

If data is not exactly the multiple of chunk_size, the last chunk is recalculated as (buf_size*2 - i), which allows to have a buf of any size.

However in MATLAB receiver script reads full chunk_size, regardless of data_length, typically like this:

function data = read_16bit_data(arduino, data_length)
    chunk_size = 32; % in bytes
    data_length_byte = data_length*2;

    raw_data_8bit = zeros(data_length_byte/chunk_size, chunk_size);
    raw_data_16bit = zeros(data_length_byte/chunk_size, chunk_size/2);
    
    % readings
    for i = 1:(data_length_byte/chunk_size)
        raw_data_8bit(i, :) = read(arduino, chunk_size, 'uint8');
        raw_data_16bit(i, :) = typecast_uint8(raw_data_8bit(i, :));
    end
    
    % rearrange by channel
    data = reshape(raw_data_16bit', 1, []);
end

function casted_data = typecast_uint8(data)
    reshaped_data = reshape(data, 2, []);
    casted_data = bitshift(uint16(reshaped_data(2, :)), 8) + uint16(reshaped_data(1, :));
end

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Improve the receiver script with better performance and ability to handle partial chunks. Implement this in /libraries/SensEdu/examples/Basic_UltraSound/matlab/Basic_UltraSound_ReadData.m, and test for different mic_data_size that are not multiple of 32bytes.