Changeset 00d7e1b in mainline for uspace/lib/net/generic/net_checksum.c

Timestamp:

2011-10-07T20:20:33Z (13 years ago)

Author:

Martin Decky <martin@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

49bd793b

Parents:

e2c50e1

Message:

networking improvements

• start the networking stack from init
• add loopback network interface driver (cherrypicked and sanitized from lp:~helenos-nicf/helenos/nicf)
• add libnic and various small pieces from lp:~helenos-nicf/helenos/nicf
• fix client side of NIC_GET_ADDRESS
• net binary overhaul

Note: "ping 127.0.0.1" works, but the first three pings timeout for some reason

File:

• uspace/lib/net/generic/net_checksum.c (modified) (2 diffs)

uspace/lib/net/generic/net_checksum.c

@@ -45 +45 @@
 #define CRC_DIVIDER_LE  0xedb88320
 
+/** Polynomial used in multicast address hashing */
+#define CRC_MCAST_POLYNOMIAL  0x04c11db6
+
 /** Compacts the computed checksum to the 16 bit number adding the carries.
  *
@@ -221 +224 @@
 }
 
+/** Compute the standard hash from MAC
+ *
+ * Hashing MAC into 64 possible values and using the value as index to
+ * 64bit number.
+ *
+ * The code is copied from qemu-0.13's implementation of ne2000 and rt8139
+ * drivers, but according to documentation there it originates in FreeBSD.
+ *
+ * @param[in] addr The 6-byte MAC address to be hashed
+ *
+ * @return 64-bit number with only single bit set to 1
+ *
+ */
+uint64_t multicast_hash(const uint8_t addr[6])
+{
+        uint32_t crc;
+    int carry, i, j;
+    uint8_t b;
+
+    crc = 0xffffffff;
+    for (i = 0; i < 6; i++) {
+        b = addr[i];
+        for (j = 0; j < 8; j++) {
+            carry = ((crc & 0x80000000L) ? 1 : 0) ^ (b & 0x01);
+            crc <<= 1;
+            b >>= 1;
+            if (carry)
+                crc = ((crc ^ CRC_MCAST_POLYNOMIAL) | carry);
+        }
+    }
+        
+    uint64_t one64 = 1;
+    return one64 << (crc >> 26);
+}
+
 /** @}
  */