Added code for checksum calculation

2026-01-27 12:43:08 +00:00 · 2017-09-17 17:29:44 +02:00
parent 1fa361871c
commit 165fe55ce6
1 changed files with 56 additions and 0 deletions
--- a/Code/HanDebugger/HanDebugger/Crc16.cs
+++ b/Code/HanDebugger/HanDebugger/Crc16.cs
@@ -0,0 +1,56 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace HanDebugger
+{
+    public static class Crc16
+    {
+        private const ushort polynomial = 0x8408;
+        private static ushort[] table = new ushort[256];
+
+        static Crc16()
+        {
+            ushort value;
+            ushort temp;
+            for (ushort i = 0; i < table.Length; ++i)
+            {
+                value = 0;
+                temp = i;
+                for (byte j = 0; j < 8; ++j)
+                {
+                    if (((value ^ temp) & 0x0001) != 0)
+                    {
+                        value = (ushort)((value >> 1) ^ polynomial);
+                    }
+                    else
+                    {
+                        value >>= 1;
+                    }
+                    temp >>= 1;
+                }
+                table[i] = value;
+            }
+        }
+
+        public static ushort ComputeChecksum(byte[] data)
+        {
+            return ComputeChecksum(data, 0, data.Length);
+        }
+
+        public static ushort ComputeChecksum(byte[] data, int start, int length)
+        {
+            ushort fcs = 0xffff;
+            for (int i = start; i < (start + length); i++)
+            {
+                var index = (fcs ^ data[i]) & 0xff;
+                fcs = (ushort)((fcs >> 8) ^ table[index]);
+            }
+            fcs ^= 0xffff;
+            return fcs;
+        }
+    }
+}
+