Closes #178: Add LH angle streaming support

cflib/crazyflie/localization.py

@@ -35,6 +35,8 @@
 from cflib.crtp.crtpstack import CRTPPort
 from cflib.utils.callbacks import Caller
 
+from cflib.utils.fp16 import fp16_to_float
+
 __author__ = 'Bitcraze AB'
 __all__ = ['Localization', 'LocalizationPacket']
 
@@ -65,6 +67,7 @@ class Localization():
     COMM_GNSS_PROPRIETARY = 7
     EXT_POSE = 8
     EXT_POSE_PACKED = 9
+    LH_ANGLE_STREAM = 10
 
     def __init__(self, crazyflie=None):
         """
@@ -100,10 +103,31 @@ def _incoming(self, packet):
                 anchor_id, distance = struct.unpack('<Bf', raw_data[:5])
                 decoded_data[anchor_id] = distance
                 raw_data = raw_data[5:]
+        elif pk_type == self.LH_ANGLE_STREAM:
+            decoded_data = self._decode_lh_angle(data)
 
         pk = LocalizationPacket(pk_type, data, decoded_data)
         self.receivedLocationPacket.call(pk)
 
+    def _decode_lh_angle(self, data):
+        decoded_data = {}
+
+        raw_data = struct.unpack("<Bfhhhfhhh", data)
+
+        decoded_data['basestation'] = raw_data[0]
+        decoded_data['x'] = [0, 0, 0, 0]
+        decoded_data['x'][0] = raw_data[1]
+        decoded_data['x'][1] = raw_data[1] - fp16_to_float(raw_data[2])
+        decoded_data['x'][2] = raw_data[1] - fp16_to_float(raw_data[3])
+        decoded_data['x'][3] = raw_data[1] - fp16_to_float(raw_data[4])
+        decoded_data['y'] = [0, 0, 0, 0]
+        decoded_data['y'][0] = raw_data[5]
+        decoded_data['y'][1] = raw_data[5] - fp16_to_float(raw_data[6])
+        decoded_data['y'][2] = raw_data[5] - fp16_to_float(raw_data[7])
+        decoded_data['y'][3] = raw_data[5] - fp16_to_float(raw_data[8])
+
+        return decoded_data
+
     def send_extpos(self, pos):
         """
         Send the current Crazyflie X, Y, Z position. This is going to be

cflib/utils/fp16.py

@@ -0,0 +1,56 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+#
+#     ||          ____  _ __
+#  +------+      / __ )(_) /_______________ _____  ___
+#  | 0xBC |     / __  / / __/ ___/ ___/ __ `/_  / / _ \
+#  +------+    / /_/ / / /_/ /__/ /  / /_/ / / /_/  __/
+#   ||  ||    /_____/_/\__/\___/_/   \__,_/ /___/\___/
+#
+#  Copyright (C) 2020 Bitcraze AB
+#
+#  Crazyflie Nano Quadcopter Client
+#
+#  This program is free software; you can redistribute it and/or
+#  modify it under the terms of the GNU General Public License
+#  as published by the Free Software Foundation; either version 2
+#  of the License, or (at your option) any later version.
+#
+#  This program is distributed in the hope that it will be useful,
+#  but WITHOUT ANY WARRANTY; without even the implied warranty of
+#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#  GNU General Public License for more details.
+#  You should have received a copy of the GNU General Public License
+#  along with this program; if not, write to the Free Software
+#  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+#  MA  02110-1301, USA.
+
+import struct
+
+
+# Code from davidejones at https://gamedev.stackexchange.com/a/28756
+def fp16_to_float(float16):
+    s = int((float16 >> 15) & 0x00000001)    # sign
+    e = int((float16 >> 10) & 0x0000001f)    # exponent
+    f = int(float16 & 0x000003ff)            # fraction
+
+    if e == 0:
+        if f == 0:
+            return int(s << 31)
+        else:
+            while not (f & 0x00000400):
+                f = f << 1
+                e -= 1
+            e += 1
+            f &= ~0x00000400
+            # print(s,e,f)
+    elif e == 31:
+        if f == 0:
+            return int((s << 31) | 0x7f800000)
+        else:
+            return int((s << 31) | 0x7f800000 | (f << 13))
+
+    e = e + (127 - 15)
+    f = f << 13
+    result = int((s << 31) | (e << 23) | f)
+    return struct.unpack("f", struct.pack("I", result))[0]