4.44 beta

CPP/Common/CRC.cpp

@@ -0,0 +1,61 @@
+// Common/CRC.cpp
+
+#include "StdAfx.h"
+
+#include "CRC.h"
+
+static const UInt32 kCRCPoly = 0xEDB88320;
+
+UInt32 CCRC::Table[256];
+
+void CCRC::InitTable()
+{
+  for (UInt32 i = 0; i < 256; i++)
+  {
+    UInt32 r = i;
+    for (int j = 0; j < 8; j++)
+      if (r & 1) 
+        r = (r >> 1) ^ kCRCPoly;
+      else     
+        r >>= 1;
+    CCRC::Table[i] = r;
+  }
+}
+
+class CCRCTableInit
+{
+public:
+  CCRCTableInit() { CCRC::InitTable(); }
+} g_CRCTableInit;
+
+void CCRC::UpdateByte(Byte b)
+{
+  _value = Table[((Byte)(_value)) ^ b] ^ (_value >> 8);
+}
+
+void CCRC::UpdateUInt16(UInt16 v)
+{
+  UpdateByte(Byte(v));
+  UpdateByte(Byte(v >> 8));
+}
+
+void CCRC::UpdateUInt32(UInt32 v)
+{
+  for (int i = 0; i < 4; i++)
+    UpdateByte((Byte)(v >> (8 * i)));
+}
+
+void CCRC::UpdateUInt64(UInt64 v)
+{
+  for (int i = 0; i < 8; i++)
+    UpdateByte((Byte)(v >> (8 * i)));
+}
+
+void CCRC::Update(const void *data, size_t size)
+{
+  UInt32 v = _value;
+  const Byte *p = (const Byte *)data;
+  for (; size > 0 ; size--, p++)
+    v = Table[((Byte)(v)) ^ *p] ^ (v >> 8);
+  _value = v;
+}