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[GNUnet-SVN] r18929 - in gnunet/src: include util
From: |
gnunet |
Subject: |
[GNUnet-SVN] r18929 - in gnunet/src: include util |
Date: |
Mon, 2 Jan 2012 11:22:17 +0100 |
Author: grothoff
Date: 2012-01-02 11:22:17 +0100 (Mon, 02 Jan 2012)
New Revision: 18929
Modified:
gnunet/src/include/gnunet_crypto_lib.h
gnunet/src/util/crypto_crc.c
Log:
adding crc16 to gnunet_crypto_lib.h
Modified: gnunet/src/include/gnunet_crypto_lib.h
===================================================================
--- gnunet/src/include/gnunet_crypto_lib.h 2012-01-02 09:59:38 UTC (rev
18928)
+++ gnunet/src/include/gnunet_crypto_lib.h 2012-01-02 10:22:17 UTC (rev
18929)
@@ -233,7 +233,41 @@
void
GNUNET_CRYPTO_seed_weak_random (int32_t seed);
+
/**
+ * Perform an incremental step in a CRC16 (for TCP/IP) calculation.
+ *
+ * @param sum current sum, initially 0
+ * @param hdr buffer to calculate CRC over (must be 16-bit aligned)
+ * @param len number of bytes in hdr, must be multiple of 2
+ * @return updated crc sum (must be subjected to GNUNET_CRYPTO_crc16_finish to
get actual crc16)
+ */
+uint32_t
+GNUNET_CRYPTO_crc16_step (uint32_t sum, uint16_t * hdr, size_t len);
+
+
+/**
+ * Convert results from GNUNET_CRYPTO_crc16_step to final crc16.
+ *
+ * @param sum cummulative sum
+ * @return crc16 value
+ */
+uint16_t
+GNUNET_CRYPTO_crc16_finish (uint32_t sum);
+
+
+/**
+ * Calculate the checksum of a buffer in one step.
+ *
+ * @param hdr buffer to calculate CRC over (must be 16-bit aligned)
+ * @param len number of bytes in hdr, must be multiple of 2
+ * @return crc16 value
+ */
+uint16_t
+GNUNET_CRYPTO_crc16_n (uint16_t *hdr, size_t len);
+
+
+/**
* Compute the CRC32 checksum for the first len
* bytes of the buffer.
*
Modified: gnunet/src/util/crypto_crc.c
===================================================================
--- gnunet/src/util/crypto_crc.c 2012-01-02 09:59:38 UTC (rev 18928)
+++ gnunet/src/util/crypto_crc.c 2012-01-02 10:22:17 UTC (rev 18929)
@@ -17,14 +17,14 @@
Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.
- For the actual CRC code:
+ For the actual CRC-32 code:
Copyright abandoned; this code is in the public domain.
Provided to GNUnet by address@hidden
*/
/**
* @file util/crypto_crc.c
- * @brief implementation of CRC32
+ * @brief implementation of CRC16 and CRC32
* @author Christian Grothoff
*/
@@ -113,4 +113,58 @@
return crc;
}
+
+
+/**
+ * Perform an incremental step in a CRC16 (for TCP/IP) calculation.
+ *
+ * @param sum current sum, initially 0
+ * @param hdr buffer to calculate CRC over (must be 16-bit aligned)
+ * @param len number of bytes in hdr, must be multiple of 2
+ * @return updated crc sum (must be subjected to GNUNET_CRYPTO_crc16_finish to
get actual crc16)
+ */
+uint32_t
+GNUNET_CRYPTO_crc16_step (uint32_t sum, uint16_t * hdr, size_t len)
+{
+ GNUNET_assert (0 == (len & 1));
+ for (; len >= 2; len -= 2)
+ sum += *(hdr++);
+ if (len == 1)
+ sum += *((unsigned char *) hdr);
+ return sum;
+}
+
+/**
+ * Convert results from GNUNET_CRYPTO_crc16_step to final crc16.
+ *
+ * @param sum cummulative sum
+ * @return crc16 value
+ */
+uint16_t
+GNUNET_CRYPTO_crc16_finish (uint32_t sum)
+{
+ sum = (sum >> 16) + (sum & 0xFFFF);
+ sum += (sum >> 16);
+
+ return ~sum;
+}
+
+
+/**
+ * Calculate the checksum of a buffer in one step.
+ *
+ * @param hdr buffer to calculate CRC over (must be 16-bit aligned)
+ * @param len number of bytes in hdr, must be multiple of 2
+ * @return crc16 value
+ */
+uint16_t
+GNUNET_CRYPTO_crc16_n (uint16_t *hdr, size_t len)
+{
+ uint32_t sum = GNUNET_CRYPTO_crc16_step (0, hdr, len);
+
+ return GNUNET_CRYPTO_crc16_finish (sum);
+}
+
+
+
/* end of crypto_crc.c */
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