crc_dir_test.py

import array
import operator
import os
import time

def CRC16_check(buf) :
    CRC=0
    CRC_poly=0x18005
    bits=16
    data=0
    CRCDIV = (CRC_poly & 0x7fffffff) * 32768 # << 15
    data = (buf[0] & 0x7fffffff) << 16
    len_buf = len(buf)
    for cnt in range(1,len_buf) :
        data = data + buf[cnt]
        for  cnt in range(bits) :
            if data & 0x80000000 :
                data = data ^ CRCDIV
            data = data & 0x7fffffff
            data = data * 2 # << 1
    CRC = data >> 16
    return CRC


def CRC32_check(buf) :
    CRC=0
    CRC_poly=0x104C11DB7    # 1 0000 0100 1100 0001 0001 1101 1011 0111 
    bits=16
    data=0
    CRCDIV = (CRC_poly & 0x7fffffffffff) * 32768 #<< 15
    data = buf[0]
    data = data & 0x7fffffffffff 
    data = data << 16
    data = data + buf[1]
    data = data & 0x7fffffffffff
    data = data << 16
    len_buf = len(buf)
    for cnt in range(2,len_buf) :
        data = data + buf[cnt]
        for  cnt in range(bits) :
            if data & 0x800000000000 :
                data = data ^ CRCDIV
            data = data & 0x7fffffffffff
            data = data * 2 # << 1
    CRC = int(data >> 16)
    return CRC
	 
# Open file for processing
def open_dir() :
        files = os.listdir('./prbs/.')
        files.sort()
        return files

def open_file(files, file_nr) :
        file_name = './prbs/' + files[file_nr][:]
        if files[file_nr][-3:] == 'dat':
                fileinfo = os.stat(file_name)
                size = int(fileinfo.st_size)
                f=open(file_name,'rb')
                max_frames = size/(88 + 1024*2 + 4)
                frames_to_proces=max_frames
        else :
                frames_to_proces=0
                f=open(file_name,'rb')
        return f, frames_to_proces


def read_frame(f, info_plot, frame_nr,f_log):
    CRC_ERROR=0
    header = array.array('H')
    data_in = array.array('H')
    data_crc = array.array('H')

    # READING HEADER INFORMATION
    header.fromfile(f,44)       # Bytes 0..88
    # remove SEQNR from header, this data is added after CRC calculations	
    header[2]=0   
    header[3]=0   
    if CRC16_check(header) :
        str_info = 'CRC ERROR HEADER '
        f_log.write(str_info + '\n')
        CRC_ERROR=1

    Station_id = header[0] & 0xFF
    RSP_id = header[0] >> 8
    RCU_id = header[1] &0xFF
    Sample_rate = header[1] >> 8
    Time = float((header[5] * 65536) + header[4])
    Sample_nr = (header[7] * 65536) + header[6]
    Samples = header[8]
    if (info_plot):
        time_string = time.ctime(Time)
        str_info =  'Frame nr %(FR)d Station %(ST)d  RSP %(RSP)d  RCU %(RCU)d  Sample rate %(S)d MHz  time of data  %(ti_D)s and %(SN)00.6f seconds'%\
            {"FR": frame_nr, "ST": Station_id ,"RSP": RSP_id, "RCU": RCU_id, "S": Sample_rate, "ti_D": time_string,"SN": float(Sample_nr)/float(200000000)}
    #               print string_info
        f_log.write(str_info + '\n')
    
    del(header)		
    # READ DATA SAMPLES
    data_in.fromfile(f,1024)
    data_crc.fromfile(f,2)
    data_list = data_in.tolist()
    for cnt in range(len(data_in)):
        data_in[cnt] = (data_in[cnt] & 0x0FFF)
    data_in.append(data_crc[1])
    data_in.append(data_crc[0])
    if CRC32_check(data_in):
        str_info = 'CRC ERROR DATA'
        f_log.write(str_info + '\n')
        CRC_ERROR=1
    return data_list,CRC_ERROR

def PRBS_CHECK(data_list, prev):
    samples_chk=0
    prbs_err=0
    for i in range(0,len(data_list)) :
        if prev == 0x0FFF :
            prev = data_list[i] & 0x07FF
        elif data_list[i] == 0xFFFF :
            prbs_err = prbs_err + 1
        elif data_list[i] == data_list[i-1] :
            prbs_err = prbs_err + 1
            samples_chk = samples_chk + 1
            prev = data_list[i] & 0x07FF
        else :
            cur = data_list[i] & 0x0FFE
            samples_chk = samples_chk + 1
            if cur != 2*prev :
                prbs_err = prbs_err + 1
#                print(str(i) + ' ' + hex(2*prev) + ' ' + hex(cur))
            prev = data_list[i] & 0x07FF
    return samples_chk, prbs_err, prev


	
def main() :
    files = open_dir()
    f_log = file('crc_dir_test.log', 'w')
    f_log.write('\n \n PRSB test \n \n')
    for file_cnt in range(len(files)) :
        prev = 0x0FFF;
        samples_chk=0
        prbs_err=0
        (f, frames_to_proces) = open_file(files, file_cnt)
        plot_info=1
        if frames_to_proces >0 :
            for frame_cnt in range(frames_to_proces):
                data_list,CRC_ERROR = read_frame(f,(frame_cnt==0),frame_cnt,f_log)
                if CRC_ERROR :
                    break
                r_samples_chk, r_prbs_err, prev = PRBS_CHECK(data_list, prev)
                samples_chk = samples_chk + r_samples_chk
                prbs_err = prbs_err + r_prbs_err
        # plot results
#            print 'Samples checked : ' + str(samples_chk) + ' PRBS errors: ' + str(prbs_err)
            f_log.write('Samples checked : ' + str(samples_chk) + ' PRBS errors: ' + str(prbs_err) + '\n')
        f.close
    f_log.close

main()