新增所有文件

middleware/checksum/crc4.c

@@ -0,0 +1,20 @@
+/********************************************************
+ *        Copyright(c) 2022    Semidrive                *
+ *        All rights reserved.                          *
+ ********************************************************/
+#include "crc4.h"
+
+const unsigned char CRC4_Table[16] = {0, 13, 7, 10, 14, 3, 9, 4,
+                                      1, 12, 6, 11, 15, 2, 8, 5};
+
+unsigned char crc4_calculate(unsigned char initial_value,
+                             const unsigned char *message, unsigned char len)
+{
+    unsigned char crc_val = initial_value;
+    int i = 0;
+    for (; i < len; i++) {
+        crc_val = CRC4_Table[crc_val] ^ message[i];
+    }
+    crc_val = 0 ^ CRC4_Table[crc_val];
+    return crc_val;
+}