Replay: add example script for converting from cm to m in RRNI and RRNH messages

Tools/Replay/examples/rewrite-RFND-values-to-floats.py

@@ -0,0 +1,132 @@
+#!/usr/bin/env python
+'''In ArduPilot 4.7 the distance values were moved to float to
+facilitate supporting rangefinders with more than 327m of range.
+
+The dataflash Replay log messages changes to support this.
+
+This script will take an older log and convert those messages such
+that older logs can be replayed with newer code.
+
+AP_FLAKE8_CLEAN
+'''
+
+from argparse import ArgumentParser
+
+import struct
+
+from pymavlink import DFReader
+from pymavlink import mavutil
+
+new_RRNH_format = "ffB"
+new_RRNI_format = "ffffBBB"
+
+
+class Rewrite():
+    def __init__(self, rewrite_fmt, rewrite_fmtu, rewrite_instance):
+        self.rewrite_fmt = rewrite_fmt
+        self.rewrite_fmtu = rewrite_fmtu
+        self.rewrite_instance = rewrite_instance
+
+    def format_to_struct(fmt):
+        ret = bytes("<", 'ascii')
+        for c in fmt:
+            (s, mul, type) = DFReader.FORMAT_TO_STRUCT[c]
+            ret += bytes(s, 'ascii')
+        return bytes(ret)
+
+
+rewrites = {
+    # convert RRNI.distance_cm > RRNI.distance
+    "RRNH": Rewrite(
+        rewrite_fmt=lambda buf, m : buf[:3] + struct.pack(
+            Rewrite.format_to_struct("BBnNZ"),
+            m.Type,
+            struct.calcsize(Rewrite.format_to_struct(new_RRNH_format)) + 3,  # m.Length
+            bytes(m.Name, 'ascii'),
+            bytes(new_RRNH_format, 'ascii'),
+            bytes(m.Columns, 'ascii')
+        ),
+        rewrite_fmtu=lambda buf, m : buf[:3] + struct.pack(
+            Rewrite.format_to_struct("QBNN"),
+            m.TimeUS,
+            m.FmtType,
+            bytes("mm-", 'ascii'),  # new units
+            bytes("00-", 'ascii')  # new mults
+        ),
+        rewrite_instance=lambda buf, m : buf[:3] + struct.pack(
+            Rewrite.format_to_struct(new_RRNH_format),
+            m.GCl * 0.01,
+            m.MaxD * 0.01,
+            m.NumSensors
+        ),
+    ),
+    "RRNI": Rewrite(
+        rewrite_fmt=lambda buf, m : buf[:3] + struct.pack(
+            Rewrite.format_to_struct("BBnNZ"),
+            m.Type,
+            struct.calcsize(Rewrite.format_to_struct(new_RRNI_format)) + 3,  # m.Length
+            bytes(m.Name, 'ascii'),
+            bytes(new_RRNI_format, 'ascii'),
+            bytes(m.Columns, 'ascii')
+        ),
+        rewrite_fmtu=lambda buf, m : buf[:3] + struct.pack(
+            Rewrite.format_to_struct("QBNN"),
+            m.TimeUS,
+            m.FmtType,
+            bytes("???m--#", 'ascii'),  # new units
+            bytes("???0---", 'ascii')   # new mults
+        ),
+        rewrite_instance=lambda buf, m : buf[:3] + struct.pack(
+            Rewrite.format_to_struct(new_RRNI_format),
+            m.PX,
+            m.PY,
+            m.PZ,
+            m.Dist * 0.01,
+            m.Orient,
+            m.Status,
+            m.I
+        ),
+    ),
+}
+
+
+parser = ArgumentParser(description=__doc__)
+
+parser.add_argument("login")
+parser.add_argument("logout")
+
+args = parser.parse_args()
+
+login = mavutil.mavlink_connection(args.login)
+output = open(args.logout, mode='wb')
+
+type_name_map = {}
+
+
+def rewrite_message(m):
+    buf = bytearray(m.get_msgbuf())
+
+    mtype = m.get_type()
+    if mtype == 'FMT':
+        type_name_map[m.Type] = m.Name
+        if m.Name in rewrites:
+            return rewrites[m.Name].rewrite_fmt(buf, m)
+
+    if mtype == 'FMTU':
+        if m.FmtType not in type_name_map:
+            raise ValueError(f"Have not seen format for ID {m.FmtType}")
+        name = type_name_map[m.FmtType]
+        if name in rewrites:
+            return rewrites[name].rewrite_fmtu(buf, m)
+
+    if mtype in rewrites:
+        return rewrites[mtype].rewrite_instance(buf, m)
+
+    return buf
+
+
+while True:
+    m = login.recv_msg()
+    if m is None:
+        break
+    output.write(rewrite_message(m))

libraries/AP_RangeFinder/AP_RangeFinder_MAVLink.cpp

@@ -67,9 +67,9 @@ float AP_RangeFinder_MAVLink::min_distance() const
         return baseclass_min_distance;
     }
 
-    // return the smaller of the base class's distance and what we
+    // return the larger of the base class's distance and what we
     // receive from the network:
-    return MIN(baseclass_min_distance, _min_distance);
+    return MAX(baseclass_min_distance, _min_distance);
 }
 
 /*