linux network device driver Q: receiving packets

hi i'm working on network driver driver, totally confused by the existing code under driver/net/...

say i got RECV_COMPLETE interrupt, i need to move the received pkt into the SKB to pass up.

my plan is,
1. read the 1st 22 bytes for un-tagged ethernet frame,
that's preamble+SFD+src+dst+len,
2. from len, i know the total size of this frame,
data_len = len - 22;
read this number of bytes from hardware into buf1
3. the last 4 bytes is the frame check sequence
4. skb = netdev_alloc_skb,
skb_len = data_len - 4; // don't need the last 4 bytes
5. copy skb_len of bytes from buf1 into skb->data

is the above correct ?

also i saw netdev_alloc_skp_ip_align, ALIGN(len, 4), ...
each driver is doing things in different ways,

can someone give me a clear steps ?

thanks very much !

I don't know of any card that will give you the preamble or SFD. The first bytes of the frame delivered to you should be the dest. Typically there is no length field, the card reports that to you separately. You get ethertype in 12-13 (0-based) in most network protocols.