[GNUnet-SVN] r36823 - in gnunet/src: include util

[gnunet]

Author: grothoff
Date: 2016-01-17 17:05:16 +0100 (Sun, 17 Jan 2016)
New Revision: 36823

Modified:
   gnunet/src/include/gnunet_crypto_lib.h
   gnunet/src/util/crypto_crc.c
Log:
add crc8

Modified: gnunet/src/include/gnunet_crypto_lib.h
===================================================================
--- gnunet/src/include/gnunet_crypto_lib.h      2016-01-17 16:04:53 UTC (rev 
36822)
+++ gnunet/src/include/gnunet_crypto_lib.h      2016-01-17 16:05:16 UTC (rev 
36823)
@@ -403,6 +403,19 @@
 
 
 /**
+ * @ingroup hash
+ * Calculate the checksum of a buffer in one step.
+ *
+ * @param buf buffer to calculate CRC over
+ * @param len number of bytes in @a buf
+ * @return crc8 value
+ */
+uint8_t
+GNUNET_CRYPTO_crc8_n (const void *buf,
+                      size_t len);
+
+
+/**
  * Perform an incremental step in a CRC16 (for TCP/IP) calculation.
  *
  * @param sum current sum, initially 0
@@ -439,6 +452,8 @@
                        size_t len);
 
 
+
+
 /**
  * @ingroup hash
  * Compute the CRC32 checksum for the first len

Modified: gnunet/src/util/crypto_crc.c
===================================================================
--- gnunet/src/util/crypto_crc.c        2016-01-17 16:04:53 UTC (rev 36822)
+++ gnunet/src/util/crypto_crc.c        2016-01-17 16:05:16 UTC (rev 36823)
@@ -165,5 +165,35 @@
 }
 
 
+/**
+ * @ingroup hash
+ * Calculate the checksum of a buffer in one step.
+ *
+ * @param buf buffer to calculate CRC over
+ * @param len number of bytes in @a buf
+ * @return crc8 value
+ */
+uint8_t
+GNUNET_CRYPTO_crc8_n (const void *buf,
+                      size_t len)
+{
+  const uint8_t *data = buf;
+  unsigned int crc = 0;
+  int i;
+  int j;
 
+  for (j = len; 0 != j; j--)
+  {
+    crc ^= (*data++ << 8);
+    for (i = 8; 0 != i; i--)
+    {
+      if (0 != (crc & 0x8000))
+        crc ^= (0x1070 << 3);
+      crc <<= 1;
+    }
+  }
+  return (uint8_t) (crc >> 8);
+}
+
+
 /* end of crypto_crc.c */