Re: [lwip-users] Alignment problem i pbuf_alloc()

[Bill Knight]

Yes, that is what I am suggesting.

-Bill Knight



On 26 May 2004 11:07:56 +0100, K.J. Mansley wrote:

>On Tue, 2004-05-25 at 16:28, Bill Knight wrote:
>> I'll jump in here.  'payload' is declared as a void pointer.  If all
>> it is ever used for is to access bytes, then 'offset' does not need to
>> be taken into the alignment calc. when determining the address to
>> store into 'payload'.  If however, if is used to read or store 16 or
>> 32 bit values from and to the network device, and if it is aligned,
>> the data would not have to be broken into bytes and then reassembled.
>> I would suggest adding 'offset' into the alignment calc.

>Just for the avoidance of doubt, you suggest we use:

>p = mem_malloc(MEM_ALIGN_SIZE(sizeof(struct pbuf) + offset) + 
>MEM_ALIGN_SIZE(length));
>p->payload = MEM_ALIGN((void *)((u8_t *)p + sizeof(struct pbuf) + offset));

>rather than:

>p = mem_malloc(MEM_ALIGN_SIZE(sizeof(struct pbuf)) + MEM_ALIGN_SIZE(length + 
>offset));
>p->payload = MEM_ALIGN((void *)((u8_t *)p + sizeof(struct pbuf))) + offset;

>Is that correct?

>Kieran