reference

2026-08-15 09:04:38 +02:00
parent f6da346e18
commit a2387341bd
3 changed files with 556 additions and 0 deletions
--- a/reference/fit_crc.py
+++ b/reference/fit_crc.py
@@ -0,0 +1,39 @@
+from __future__ import annotations
+
+CRC_TABLE = (
+    0x0000,
+    0xCC01,
+    0xD801,
+    0x1400,
+    0xF001,
+    0x3C00,
+    0x2800,
+    0xE401,
+    0xA001,
+    0x6C00,
+    0x7800,
+    0xB401,
+    0x5000,
+    0x9C01,
+    0x8801,
+    0x4400,
+)
+
+
+def update_crc(crc: int, byte: int) -> int:
+    tmp = CRC_TABLE[crc & 0xF]
+    crc = (crc >> 4) & 0x0FFF
+    crc = crc ^ tmp ^ CRC_TABLE[byte & 0xF]
+
+    tmp = CRC_TABLE[crc & 0xF]
+    crc = (crc >> 4) & 0x0FFF
+    crc = crc ^ tmp ^ CRC_TABLE[(byte >> 4) & 0xF]
+    return crc & 0xFFFF
+
+
+def fit_crc(data: bytes | bytearray | memoryview) -> int:
+    crc = 0
+    for byte in data:
+        crc = update_crc(crc, byte)
+    return crc
+