Tools: added serial playback tool

for playing back serial data captured by ArduPilot

Tools/scripts/serial_playback.py

@@ -0,0 +1,65 @@
+#!/usr/bin/env python3
+'''
+playback a capture from ardupilot with timing
+the file format is a sequence of:
+
+  HEADER
+  DATA
+
+HEADER is:
+   uint32_t magic == 0x7fe53b04
+   uint32_t time_ms
+   uint32_t length
+'''
+
+import socket
+import time
+import struct
+from argparse import ArgumentParser
+
+parser = ArgumentParser(description="playback a capture file with ArduPilot timing headers")
+
+parser.add_argument("infile", default=None, help="input file")
+parser.add_argument("dest", default=None, help="TCP destination in ip:port format")
+parser.add_argument("--loop", action='store_true', help="loop to start of file at EOF")
+args = parser.parse_args()
+
+def open_socket(dest):
+    a = dest.split(':')
+    ip = a[0]
+    port = int(a[1])
+    tcp = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+    tcp.connect((ip, port))
+    return tcp
+
+f = open(args.infile,'rb')
+tcpsock = open_socket(args.dest)
+
+last_ms = None
+
+while True:
+    hdr_raw = f.read(12)
+    if len(hdr_raw) != 12:
+        if args.loop:
+            f.seek(0)
+            continue
+        print("EOF")
+        break
+    magic, t_ms, n = struct.unpack("<III", hdr_raw)
+    if magic != 0x7fe53b04:
+        print("Bad magic")
+        break
+    if last_ms is not None:
+        dt = t_ms - last_ms
+        if dt > 0:
+            time.sleep(dt*0.001)
+    last_ms = t_ms
+    data = f.read(n)
+    if len(data) != n:
+        if args.loop:
+            f.seek(0)
+            continue
+        print("short data, EOF")
+        break
+    tcpsock.send(data)
+    print("Wrote %u bytes t=%.3f" % (len(data), t_ms*0.001))