Add built in t42 file playback mode

Author: ZXGuesser

README.md

@@ -2,14 +2,14 @@ Teletext TCP Packet Server
 --------------------------
 
 packet-server.py takes a teletext packet stream and serves it to multiple clients.  
-The script attempts to consume <lines per field> 42 byte packets from stdin every 20ms
+The script attempts to consume <lines per field> 42 byte packets from stdin every 20ms unless an input filename is specified with `-i`
 
 test.py is a test client which connects to the server and outputs packets to stdout
 
-The port is set using the -p argument, and the number of lines per field by -l
+The port is set using the `-p` argument, and the number of lines per field by `-l`
 
-The server can be tested using example.t42:  
-`(while cat example.t42; do :; done) | python3 packet-server.py -p 19761 -l 16`
+The server can be tested using example.t42: 
+`python3 packet-server.py -p 19761 -l 16 -i example.t42`
 
 A suitable packet stream can be generated using https://github.com/peterkvt80/vbit2  
-For example: `~/vbit2/vbit2 --dir ~/teletext | python3 packet-server.py -p 19761 -l 16`
+For example: `vbit2 --dir ~/teletext | python3 packet-server.py -p 19761 -l 16`

packet-server.py

@@ -54,9 +54,10 @@ def server6(PORT):
 if __name__ == "__main__":
     PORT = 0
     linesPerField = 0
+    inputfile = sys.stdin
 
     try:
-        opts, args = getopt.getopt(sys.argv[1:],"p:l:")
+        opts, args = getopt.getopt(sys.argv[1:],"p:l:i:")
     except getopt.GetoptError as err:
         print(err)
         sys.exit(2)
@@ -74,6 +75,12 @@ def server6(PORT):
             except:
                 print("invalid lines per field")
                 sys.exit(2)
+        elif opt in ('-i'):
+            try:
+                inputfile = open(arg, "r")
+            except:
+                print("failed to open file")
+                sys.exit(2)
 
     if PORT <= 1024 or PORT > 65535:
         print("invalid port, use -p <port>")
@@ -94,7 +101,9 @@ def server6(PORT):
     starttime=time.time()
 
     while(True):
-        data = bytearray(sys.stdin.buffer.read(42 * linesPerField))
+        data = bytearray(inputfile.buffer.read(42 * linesPerField))
+        if not data:
+            inputfile.seek(0) # loop input file
         if (linesPerField < 16):
             data.extend(bytearray(42*(16-linesPerField)))
         for q in clientQueues[:]: