1 files changed, 31 insertions, 0 deletions
diff --git a/plugins/FileAsMessage/src/crc32.cpp b/plugins/FileAsMessage/src/crc32.cpp
new file mode 100644
index 0000000000..ab34393f8d
--- /dev/null
+++ b/plugins/FileAsMessage/src/crc32.cpp
@@ -0,0 +1,31 @@
+#include "main.h"
+
+const ulong CRCPoly = 0xEDB88320;
+ulong CRC32Table[256];
+
+void InitCRC32()
+{
+	for (UINT32 i = 0; i < 256; i++)
+	{
+		UINT32 r = i;
+		for (int j = 0; j < 8; j++)
+			if (r & 1) 
+				r = (r >> 1) ^ CRCPoly;
+			else     
+				r >>= 1;
+		CRC32Table[i] = r;
+	}
+}
+
+const ulong INITCRC = -1L;
+
+inline ulong UpdateCRC32(uchar val, ulong crc)
+{
+	return CRC32Table[(uchar)crc^val] ^ (crc>>8);
+}
+
+ulong memcrc32(uchar *ptr, int size, ulong crc )
+{
+	while(size--) crc = UpdateCRC32(*ptr++, crc);
+	return crc;
+}