From eed7aee495b7dd256ddd15f22513566706935857 Mon Sep 17 00:00:00 2001
From: pavelyakov <pavelyakov@kolibrios.org>
Date: Sat, 21 Mar 2020 10:59:27 +0000
Subject: [PATCH] Addition new function for crc32 checksum!

git-svn-id: svn://kolibrios.org@7740 a494cfbc-eb01-0410-851d-a64ba20cac60
---
 programs/cmm/lib/crc32.h | 58 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 58 insertions(+)
 create mode 100755 programs/cmm/lib/crc32.h

diff --git a/programs/cmm/lib/crc32.h b/programs/cmm/lib/crc32.h
new file mode 100755
index 0000000000..60a6cfca0a
--- /dev/null
+++ b/programs/cmm/lib/crc32.h
@@ -0,0 +1,58 @@
+/* CRC32 function; Author PaulCodeman */
+:dword crc32Table = 0;
+:dword makeCRCTable(void)
+{
+	dword i = 0;
+	dword c = 0;
+	dword ii = 0;
+	dword crcTable = 0;
+	IF (crc32Table) RETURN 0;
+	crc32Table = malloc(4*256);
+	crcTable = crc32Table;
+	WHILE (i < 256)
+	{
+		c = i;
+		ii = 0;
+		WHILE (ii < 8)
+		{
+			IF (c&1)
+			{
+				c >>= 1;
+				c ^= 0xEDB88320;
+			}
+			ELSE c >>= 1;
+			ii++;
+		}
+		DSDWORD[crcTable] = c;
+		crcTable += 4;
+		i++;
+	}
+}
+:dword crc32(dword bytes, length)
+{
+	dword crc = 0;
+	dword i = 0;
+	byte b = 0;
+	IF (!crc32Table) makeCRCTable();
+	crc = 0xFFFFFFFF;
+	WHILE (i < length)
+	{
+		b = DSBYTE[bytes];
+		bytes++;
+		EDX = crc^b;
+		EDX &= 0xFF;
+		EDX <<= 2;
+		EDX += crc32Table;
+		crc >>= 8;
+		crc ^= DSDWORD[EDX];
+		i++;
+	}
+	RETURN crc ^ 0xFFFFFFFF;
+}
+
+/* EXAMPLE
+dword str = 0;
+str = "Kevin van Zonneveld";
+crc32(str, strlen(str));
+IF (EAX == 1249991249) ExitProcess();
+*/
\ No newline at end of file