import struct
import numpy as np

if __name__ == '__main__':
    '''
    # Data format: "%1B(Hours)%1B(Minutes)%4F(Seconds)%4U(ChipTimeUS)
    %4F(RawAccelX)%4F(RawAccelY)%4F(RawAccelZ)"

    The header string is 108 bytes long + CRLF\r\n (2bytes)
    Each valid data record is 22 bytes
    '''
    fname = '../Yost/data/data1.dat'
    dwidth = 22
    data = []
    with open(fname, 'rb') as file:
        file.seek(110) # skip header + newline = 110 bytes
        while True:
            bdata = file.read(dwidth)  # 22 bytes
            if len(bdata) < dwidth:
                break
            data.append(list(struct.unpack('>BBfIfff', bdata)))
    data = np.array(data)
    tm = (data[:, 3] - data[0, 3])/1e6
    dtm = np.diff(tm)
    print(1/np.mean(dtm))  # mean sample rate