1 files changed, 57 insertions, 0 deletions

diff --git a/private/unimodem/new/mic/chksum.cpp b/private/unimodem/new/mic/chksum.cpp
new file mode 100644
index 000000000..55e936eaa
--- /dev/null
+++ b/private/unimodem/new/mic/chksum.cpp
@@ -0,0 +1,57 @@
+//
+//		Copyright (c) 1996 Microsoft Corporation
+//
+//
+//		CHKSUM.CPP		-- Implementation Checksum()
+//
+//		History:
+//			05/24/96	JosephJ		Created
+//
+//
+#include "common.h"
+
+//----------------	::Checksum -----------------------------------
+// Compute a 32-bit checksum of the specified bytes
+// 0 is retured if pb==NULL or cb==0 
+DWORD Checksum(const BYTE *pb, UINT cb)
+{
+	const UINT	MAXSIZE = 1024;
+	DWORD dwRet = 0;
+	//DWORD rgdwBuf[MAXSIZE/sizeof(DWORD)];
+
+
+	if (!pb) goto end;
+
+
+	// TODO: replace by crc32
+	while(cb--) {dwRet ^= dwRet<<1 ^ *pb++;}
+
+#if (TODO)
+	// If buffer not dword aligned, we copy it over to a buffer which is,
+	// and pad it 
+	if (cb & 0x3)
+	{
+		if (cb>=MAXSIZE)
+		{
+			ASSERT(FALSE);
+			goto end;
+		}
+		CopyMemory(rgdwBuf, pb, cb);
+	}
+#endif (TODO)
+
+end:
+	return dwRet;
+}
+
+
+//----------------	::AddToChecksumDW ----------------------------
+// Set *pdwChkSum to a new checksum, computed using it's previous value and dw.
+void AddToChecksumDW(DWORD *pdwChkSum, DWORD dw)
+{
+	DWORD rgdw[2];
+	rgdw[0] = *pdwChkSum;
+	rgdw[1] = dw;
+
+	*pdwChkSum  = Checksum((const BYTE *) rgdw, sizeof(rgdw));
+}