net: move CRC32 calculation from compute_mcast_idx() into its own net_crc32() function

Separate out the standard ethernet CRC32 calculation into a new net_crc32()
function, renaming the constant POLYNOMIAL to POLYNOMIAL_BE to make it clear
that this is a big-endian CRC32 calculation.

As part of the constant rename, remove the duplicate definition of POLYNOMIAL
from eepro100.c and use the new POLYNOMIAL_BE constant instead.

Once this is complete remove the existing CRC32 implementation from
compute_mcast_idx() and call the new net_crc32() function in its place.

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Jason Wang <jasowang@redhat.com>

1 files changed, 11 insertions, 5 deletions

diff --git a/net/net.c b/net/net.c
index 39ef546708..a14dc9910c 100644
--- a/net/net.c
+++ b/net/net.c
@@ -1581,25 +1581,31 @@ int net_client_parse(QemuOptsList *opts_list, const char *optarg)
 
 /* From FreeBSD */
 /* XXX: optimize */
-unsigned compute_mcast_idx(const uint8_t *ep)
+uint32_t net_crc32(const uint8_t *p, int len)
 {
     uint32_t crc;
     int carry, i, j;
     uint8_t b;
 
     crc = 0xffffffff;
-    for (i = 0; i < 6; i++) {
-        b = *ep++;
+    for (i = 0; i < len; i++) {
+        b = *p++;
         for (j = 0; j < 8; j++) {
             carry = ((crc & 0x80000000L) ? 1 : 0) ^ (b & 0x01);
             crc <<= 1;
             b >>= 1;
             if (carry) {
-                crc = ((crc ^ POLYNOMIAL) | carry);
+                crc = ((crc ^ POLYNOMIAL_BE) | carry);
             }
         }
     }
-    return crc >> 26;
+
+    return crc;
+}
+
+unsigned compute_mcast_idx(const uint8_t *ep)
+{
+    return net_crc32(ep, ETH_ALEN) >> 26;
 }
 
 QemuOptsList qemu_netdev_opts = {