Распакуйте двоичный файл на PHP

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<?php

$file = "/tmp/kok.bin";

$fp = fopen ($file, 'rb')
    or die ("File $file cannot be opened.");


$data = fread ($fp, filesize($file));
    or die ("Could not read data from file $file");

# Create the format for unpacking the header data
$header_format = 
    'Cid/' .            # Grab 1 byte      
    'Cnumber/' .        # Grab 1 byte
    'CIdentifier/' .    # Grab 1 byte     
    'CTime/' .          # Grab 8 bytes 
    'L# of Records/' .  # Grab 1 byte , number of target in a packet
    'SHeader Size/' .   # Grab 4 bytes
    'SRecord Size';     # Grab 2 bytes

# Unpack the header data
$header = unpack ($header_format, $data);
$targetRecord =$header_format['L# of Records'];

    
# Create the format for unpacking the data that describes the format of the records in the file
$record_format = 
    'CField Name/' .    # Grab 1 byte
    'fField Type1/' .   # Grab 4 bytes 
    'fField Type2/' .   # Grab 4 bytes
    'fField Type3/' .   # Grab 4 bytes 
    'fField number/' .  # Grab 4 bytes           
    'fdistance/' .      # Grab 4 bytes
    'CField id /'       # Grab 1 byte 
    'iField Precision/' # Grab 4 bytes the size of the Field Data
    'SField Data';      # Grab x bytes 
for ($offset = 0; $offset < strlen ($data); $offset ++) {
    print_r (unpack ("$record_format", $data));
}
?>

1 first unpack $header_format to get 'L# of Records' for every packet.(have a total of 200 packets)
2 unpack  $record_format  'L# of Records' times
$record_format = 
     CField Name/' .    # Grab 1 byte
    'fField Type1/' .   # Grab 4 bytes 
    'fField Type2/' .   # Grab 4 bytes
    'fField Type3/' .   # Grab 4 bytes 
    'fField number/' .  # Grab 4 bytes           
    'fdistance/' .      # Grab 4 bytes
    'CField id /'       # Grab 1 byte 
    'iField Precision/' # Grab 4 bytes
    'SField Data';      # Grab x bytes 

3 Step 1 and 2 are for one packet from the file.
4 Repeat 1-3 until end of file is reached.  

Что я уже пробовал:

for ($offset = 0; $offset < strlen ($data); $offset += 32) {
    $unpackeddata= unpack ("@$offset/$header_format", $data);
    print "";
    print_r ($unpackeddata);
    print "";
}

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