From 197fb2625a93838dad52ec137a79bde05384e763 Mon Sep 17 00:00:00 2001
From: Oliver Jowett <oliver@mutability.co.uk>
Date: Sat, 1 Oct 2016 15:06:02 +0100
Subject: [PATCH] Tool to replay beast captures with the right inter-message
 timing.

---
 tools/replay-beast.py | 136 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 136 insertions(+)
 create mode 100755 tools/replay-beast.py

diff --git a/tools/replay-beast.py b/tools/replay-beast.py
new file mode 100755
index 0000000..0f533bb
--- /dev/null
+++ b/tools/replay-beast.py
@@ -0,0 +1,136 @@
+#!/usr/bin/env python3
+
+#
+# Reads Beast-format input files and replays them to stdout
+# (either in their original form or in a human-readable form)
+# while maintaining the correct inter-message delays according
+# to the timestamps contained in the input file.
+#
+
+from contextlib import closing
+import time
+
+MODE_AC = 'MODE_AC'
+MODE_S_SHORT = 'MODE_S_SHORT'
+MODE_S_LONG = 'MODE_S_LONG'
+RADARCAPE_STATUS = 'RADARCAPE_STATUS'
+
+def parse(buf):
+    i = 0
+    messages = []
+    msglen = -1
+    start = 0
+
+    while i < len(buf):
+        if buf[i] != 0x1a:
+            i += 1
+            continue
+
+        i += 1
+        if i >= len(buf):
+            break
+
+        msglen = 1 + 6
+        if buf[i] == 0x31:
+            msglen += 2
+            msgtype = MODE_AC
+        elif buf[i] == 0x32:
+            msglen += 7
+            msgtype = MODE_S_SHORT
+        elif buf[i] == 0x33:
+            msglen += 14
+            msgtype = MODE_S_LONG
+        elif buf[i] == 0x34:
+            msglen += 14
+            msgtype = RADARCAPE_STATUS
+        else:
+            continue
+
+        i += 1
+        msgbytes = bytearray()
+        while i < len(buf) and len(msgbytes) < msglen:
+            if buf[i] == 0x1a:
+                i += 1
+                if i >= len(buf) or buf[i] != 0x1a:
+                    break
+
+            msgbytes.append(buf[i])
+            i += 1
+
+        if len(msgbytes) == msglen:
+            timestamp = (msgbytes[0] << 40) | (msgbytes[1] << 32) | (msgbytes[2] << 24) | (msgbytes[3] << 16) | (msgbytes[4] << 8) | (msgbytes[5])
+            signal = msgbytes[6]
+            data = msgbytes[7:]
+            raw = buf[start:i]
+            messages.append( (msgtype, timestamp, signal, data, raw) )
+            start = i
+
+    return (buf[start:], messages)
+
+def replay(filename, radarcape_mode, show_mode, delay_mode):
+    with closing(open(filename, 'rb')) as f:
+        buf = b''
+        last_timestamp = None
+        last_time = None
+
+        while True:
+            more = f.read(1024)
+            buf = buf + more
+
+            buf, messages = parse(buf)
+            if not messages and not more:
+                break
+
+            for msgtype, timestamp, signal, data, raw in messages:
+                if delay_mode:
+                    if radarcape_mode:
+                        secs = timestamp >> 30
+                        nanos = timestamp & 0x00003FFFFFFF
+                        adj_timestamp = nanos + secs * 1000000000
+                        freq = 1e9
+                    else:
+                        adj_timestamp = timestamp
+                        freq = 12e6
+
+                    if last_timestamp is None:
+                        last_timestamp = adj_timestamp
+                        last_time = time.time()
+                    elif adj_timestamp > last_timestamp:
+                        now = time.time()
+                        sched_delta = (adj_timestamp - last_timestamp) / freq
+                        delay = last_time + sched_delta - now
+                        if delay > 0.010:
+                            time.sleep(delay)
+                        last_timestamp = adj_timestamp
+                        last_time += sched_delta
+
+                if show_mode:
+                    h = ''
+                    for b in data:
+                        h += '{0:02X}'.format(b)
+                    print("Type: {0:16s} Time: {1:06X} Signal: {2:3d} Data: {3}".format(msgtype, timestamp, signal, h))
+                else:
+                    sys.stdout.buffer.write(raw)
+                    sys.stdout.buffer.flush()
+
+if __name__ == '__main__':
+    import sys
+
+    radarcape_mode = False
+    show_mode = False
+    delay_mode = True
+    for filename in sys.argv[1:]:
+        if filename == '--radarcape':
+            radarcape_mode = True
+        elif filename == '--beast':
+            radarcape_mode = False
+        elif filename == '--show':
+            show_mode = True
+        elif filename == '--raw':
+            show_mode = False
+        elif filename == '--delay':
+            delay_mode = True
+        elif filename == '--no-delay':
+            delay_mode = False
+        else:
+            replay(filename, radarcape_mode=radarcape_mode, show_mode=show_mode, delay_mode=delay_mode)