add CitGardens basic support (only images now)

README.md

@@ -37,6 +37,7 @@ The following protocols are currently supported:
 * `AX.25`
 * `CSP` - [Cubesat Space Protocol](https://github.com/libcsp/libcsp)
 * `D-Star ONE` - [D-Star ONE Protocol](https://web.archive.org/web/20190807184852/http://www.d-star.one/downloads/D-Star%20ONE%20telemetry%20frame%20format.pdf)
+* `CitGardens-02` - [CIT Gardens-02 project](https://sites.google.com/view/gardens-02/english_ver/home)
 * `GreenCube` - [GreenCube](https://www.s5lab.space/index.php/decoding-ledsat-2/)
 * `Lucky-7` - [Lucky-7 Satellite protocol](https://www.lucky7satellite.org/radioamateurs)
 * `RoseyCubeSat`

SatsDecoder/systems/__init__.py

@@ -8,6 +8,7 @@
 import sys
 
 from SatsDecoder.systems.ax25 import *
+from SatsDecoder.systems.cit_gardens_02 import *
 from SatsDecoder.systems.csp import *
 from SatsDecoder.systems.dstar_one import *
 from SatsDecoder.systems.geoscan import *
@@ -27,6 +28,7 @@
         'geoscan',
         'usp',
         'ax25',
+        'cit_gardens_02',
         'csp',
         'greencube',
         'dstar_one',

SatsDecoder/systems/cit_gardens_02.py

@@ -0,0 +1,130 @@
+#  Copyright (c) 2024. Alexander Baskikh
+#
+#  MIT License (MIT), http://opensource.org/licenses/MIT
+#  Full license can be found in the LICENSE-MIT file
+#
+#  SPDX-License-Identifier: MIT
+
+import datetime as dt
+
+import construct
+
+from SatsDecoder.systems import common
+from SatsDecoder.systems.image_receiver import ImageReceiver
+
+__all__ = 'CitGardens02Protocol',
+
+proto_name = 'cit-gardens-02'
+
+"""
+https://sites.google.com/view/gardens-02/english_ver/home
+https://sites.google.com/view/gardens-02/english_ver/document/transmission-format
+https://x.com/CitGardens/status/1810292367527723258
+"""
+
+
+PKT_SEP = b'\xc0\xc0\x00'
+PKT_HDR = b'\xf0\xff\xf0\xff'
+packets = construct.Struct(
+    'tx_id' / construct.Hex(construct.Int8ub),
+    'p_num' / construct.Hex(construct.Int16ub),
+    'data' / construct.GreedyBytes,
+)
+
+hdrs = {
+    PKT_HDR: packets,
+    # b'\xf0\xaa\x03K': None,
+}
+
+gardens_len = 7 + 7 + 1 + 4
+gardens = construct.Struct(
+    'to_cs' / construct.PaddedString(7, 'ascii'),
+    'fr_cs' / construct.PaddedString(7, 'ascii'),
+    'const' / construct.Const(b'>', construct.Bytes(1)),
+    'hdr' / construct.Bytes(4),
+    'data' / construct.GreedyBytes,
+    # 'data' / construct.Switch(construct.this.hdr, hdrs, default=construct.GreedyBytes),
+)
+
+
+class Gardens02ImageReceiver(ImageReceiver):
+    PKT_SZ = 61
+
+    def __init__(self, outdir):
+        super().__init__(outdir, '.jpg')
+        self.unreliable_id = set()
+        self.last_id = -1
+
+    def generate_fid(self, force=0, name='Gardens-02', tx_id=0):
+        if force or not (self.current_fid and self.merge_mode):
+            self.last_date = now = dt.datetime.now()
+            self.current_fid = f'{name}_{now.strftime("%Y-%m-%d_%H-%M-%S,%f")}_{tx_id:02X}'
+        return self.current_fid
+
+    def push_data(self, pkt, name='Gardens-02', **kw):
+        tx_id = pkt.tx_id
+        p_num = pkt.p_num
+        soi = not p_num and pkt.data.startswith(b'\xff\xd8')
+
+        if not p_num and not soi:
+            # TODO: log it. it's not image
+            self.unreliable_id.add(tx_id)
+            return
+
+        if tx_id in self.unreliable_id:
+            # TODO: log it. no-image data
+            return
+
+        if soi:
+            self.unreliable_id.discard(tx_id)
+
+        force_new = self.last_id == -1 or self.last_id != tx_id
+        self.last_id = tx_id
+
+        img = self.get_image(force_new or soi, force=force_new, name=name, tx_id=tx_id)
+        with img.lock:
+            img.has_soi ^= soi
+            off = p_num * self.PKT_SZ
+            if off < img.first_data_offset:
+                img.first_data_offset = off
+
+            img.push_data(off, pkt.data)
+            if b'\xff\xd9' in pkt.data:
+                img.flush()
+                return 2
+
+        return 1
+
+
+class CitGardens02Protocol(common.Protocol):
+
+    @staticmethod
+    def get_sender_callsign(data):
+        return data.fr_cs
+
+    def __init__(self, outdir):
+        super().__init__(Gardens02ImageReceiver(outdir))
+
+    def recognize(self, bb):
+        try:
+            x = gardens.parse(bb)
+        except:
+            return
+        if not x:
+            return
+
+        name = self.get_sender_callsign(x)
+
+        if x.hdr == PKT_HDR:
+            h = bb[:gardens_len]
+            for i in bb.split(h)[1:]:
+                if i.endswith(PKT_SEP):     # py3.9 == .removesuffix()
+                    i = i[:-len(PKT_SEP)]
+                pkt = packets.parse(i)
+
+                if pkt.tx_id == 0xFF and pkt.p_num == 0xFFFF:
+                    # invalid packet
+                    continue
+
+                if len(pkt.data) == Gardens02ImageReceiver.PKT_SZ:  # image packet
+                    yield 'img', name, (self.ir.push_data(pkt, name), self.ir.cur_img)