net: move compute_mcast_idx() to net.h
Reduce duplicated codes.
Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
diff --git a/net.c b/net.c
index c34474f..1922d8a 100644
--- a/net.c
+++ b/net.c
@@ -1475,3 +1475,26 @@
default_net = 0;
return 0;
}
+
+/* From FreeBSD */
+/* XXX: optimize */
+unsigned compute_mcast_idx(const uint8_t *ep)
+{
+ uint32_t crc;
+ int carry, i, j;
+ uint8_t b;
+
+ crc = 0xffffffff;
+ for (i = 0; i < 6; i++) {
+ b = *ep++;
+ for (j = 0; j < 8; j++) {
+ carry = ((crc & 0x80000000L) ? 1 : 0) ^ (b & 0x01);
+ crc <<= 1;
+ b >>= 1;
+ if (carry) {
+ crc = ((crc ^ POLYNOMIAL) | carry);
+ }
+ }
+ }
+ return crc >> 26;
+}