bitbang module

2 files changed, 38 insertions, 16 deletions

diff --git a/kvmd/bitbang.py b/kvmd/bitbang.py
new file mode 100644
index 00000000..0f4a202f
--- /dev/null
+++ b/kvmd/bitbang.py
@@ -0,0 +1,34 @@
+# ========================================================================== #
+#                                                                            #
+#    KVMD - The main PiKVM daemon.                                           #
+#                                                                            #
+#    Copyright (C) 2018-2023  Maxim Devaev <[email protected]>               #
+#                                                                            #
+#    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 3 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, see <https://www.gnu.org/licenses/>.  #
+#                                                                            #
+# ========================================================================== #
+
+
+# =====
+def make_crc16(data: bytes) -> int:
+    crc = 0xFFFF
+    for byte in data:
+        crc = crc ^ byte
+        for _ in range(8):
+            if crc & 0x0001 == 0:
+                crc = crc >> 1
+            else:
+                crc = crc >> 1
+                crc = crc ^ 0xA001
+    return crc
diff --git a/kvmd/plugins/hid/_mcu/proto.py b/kvmd/plugins/hid/_mcu/proto.py
index e7bc165d..62d7497e 100644
--- a/kvmd/plugins/hid/_mcu/proto.py
+++ b/kvmd/plugins/hid/_mcu/proto.py
@@ -28,6 +28,7 @@ from ....keyboard.mappings import KEYMAP
 from ....mouse import MouseRange
 
 from .... import tools
+from .... import bitbang
 
 
 # =====
@@ -185,32 +186,19 @@ class MouseWheelEvent(BaseEvent):
 # =====
 def check_response(response: bytes) -> bool:
     assert len(response) in (4, 8), response
-    return (_make_crc16(response[:-2]) == struct.unpack(">H", response[-2:])[0])
+    return (bitbang.make_crc16(response[:-2]) == struct.unpack(">H", response[-2:])[0])
 
 
 def _make_request(command: bytes) -> bytes:
     assert len(command) == 5, command
     request = b"\x33" + command
-    request += struct.pack(">H", _make_crc16(request))
+    request += struct.pack(">H", bitbang.make_crc16(request))
     assert len(request) == 8, request
     return request
 
 
-def _make_crc16(data: bytes) -> int:
-    crc = 0xFFFF
-    for byte in data:
-        crc = crc ^ byte
-        for _ in range(8):
-            if crc & 0x0001 == 0:
-                crc = crc >> 1
-            else:
-                crc = crc >> 1
-                crc = crc ^ 0xA001
-    return crc
-
-
 # =====
 REQUEST_PING = _make_request(b"\x01\x00\x00\x00\x00")
 REQUEST_REPEAT = _make_request(b"\x02\x00\x00\x00\x00")
 
-RESPONSE_LEGACY_OK = b"\x33\x20" + struct.pack(">H", _make_crc16(b"\x33\x20"))
+RESPONSE_LEGACY_OK = b"\x33\x20" + struct.pack(">H", bitbang.make_crc16(b"\x33\x20"))