Re: [microblaze-uclinux] xenet_FifoSend(struct sk_buff *orig_skb,structnet_device*dev)

["Jim Law" <jlaw@xxxxxxxxxxxxx>]

Hi,

Had a look at memmove - it uses memcpy for ascending moves and its own 
descending copy (with same basic algorithm) for descending moves.  I could 
re-write that in assembler (for generally faster moves), but I could also 
write a much faster "move_halfword_higher()" specific function for use in 
adapter.c, particularly if the following constraints are ok:

1. source is always word aligned
2. destination is always half-word aligned
3. the destination has enough extra room at the end to tolerate an extra 
half-word of data written past the end of active data (i.e. maximum 
(skb->len) + 2 bytes past skb->head+2).

I'm not fully understanding the relative position of skb->head and skb-> 
data -- can you clarify please?  I'm guessing that we start with skb->head 
and skb->data pointing to the same address and finish with skb->data and 
skb->tail adjusted two bytes higher, leaving skb->head unchanged.  Is this 
correct?

Jim

----- Original Message ----- 
From: "Brettschneider Falk" <fbrettschneider@xxxxxxxxxxxxxxx>
To: <microblaze-uclinux@xxxxxxxxxxxxxx>
Sent: Tuesday, April 29, 2008 1:10 PM
Subject: RE: [microblaze-uclinux] xenet_FifoSend(struct sk_buff 
*orig_skb,structnet_device*dev)


> Hi,
>
> Jim Law wrote:
> > Here is a new assembler memcpy for the MB.
> cool...trying that...stay tuned...
>
> > ... not sure what else I can add at this point. Is there any other
> > significant transfers or checksums that use other functions
> > that might benefit?
> drivers/net/xilinx_emac/adapter.c has that ugly memmove() in 
> FifoRecvHandler(). Maybe memmove() can also be faster in assembler... ;-)
>
> Cheers, Falk
>
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