Add crc module.

1 files changed, 53 insertions, 0 deletions

diff --git a/lib/crc.h b/lib/crc.h
new file mode 100644
index 0000000000..ee13dafeed
--- /dev/null
+++ b/lib/crc.h
@@ -0,0 +1,53 @@
+/* crc.h -- cyclic redundancy checks
+   Copyright (C) 2005 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2, or (at your option)
+   any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software Foundation,
+   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
+
+/* Written by Simon Josefsson.  */
+
+#ifndef CRC_H
+# define CRC_H 1
+
+#include <stddef.h>
+#if HAVE_INTTYPES_H
+# include <inttypes.h>
+#endif
+#if HAVE_STDINT_H
+# include <stdint.h>
+#endif
+
+/* Compute CRC-32 value of LEN bytes long BUF, and return it. */
+extern uint32_t crc32 (const char *buf, size_t len);
+
+/* Incrementally update CRC-32 value CRC using LEN bytes long BUF.  In
+   the first call, use 0 as the value for CRC.  Return the updated
+   CRC-32 value.  */
+extern uint32_t crc32_update (uint32_t crc, const char *buf, size_t len);
+
+/* Compute modified-CRC-32 value of LEN bytes long BUF, and return it.
+   The "modification" is to avoid the initial and final XOR operation.
+   Due to historic implementation errors, this variant is sometimes
+   used (i.e., in RFC 3961). */
+extern uint32_t crc32_no_xor (const char *buf, size_t len);
+
+/* Incrementally update modified-CRC-32 value CRC using LEN bytes long
+   BUF.  In the first call, use 0 as the value for CRC.  Return the
+   updated modified-CRC-32 value.  The "modification" is to avoid the
+   initial and final XOR operation.  Due to historic implementation
+   errors, this variant is sometimes used (i.e., in RFC 3961).  */
+extern uint32_t
+crc32_update_no_xor (uint32_t crc, const char *buf, size_t len);
+
+#endif /* CRC_H */