On 28/05/15 13:58, Savolainen, Petri (Nokia - FI/Espoo) wrote:
How people think 0 is special or different from e.g. value 1?
Well, 0 is a special number in many ways, not just in mathematics and
computer science:
http://en.wikipedia.org/wiki/0_%28number%29
It is special in this case as well, because it's defined to be equal to:
pkt = odp_packet_alloc(pool, default_len);
odp_packet_reset(pkt, 0);
Which is not necessarily what you would expect. Most people had
different ideas what 0 should mean.
We can change documentation wording, but not add lengthy documentation for
value 0 as a special case (which is not).
-Petri
-----Original Message-----
From: ext Zoltan Kiss [mailto:[email protected]]
Sent: Thursday, May 28, 2015 3:51 PM
To: Savolainen, Petri (Nokia - FI/Espoo); ext Bill Fischofer
Cc: [email protected]
Subject: Re: [lng-odp] [API-NEXT PATCH 2/2] api-next: packet: clarify use
of 0 len on odp_packet_alloc()
I don't think so. There was a lengthy discussion on the arch meeting how
should you interpret that, I think that proves it's worth to clarify
what's the expected behaviour.
On 28/05/15 13:45, Savolainen, Petri (Nokia - FI/Espoo) wrote:
I think it should be enough to note that len can be 0. There’s no
special handling for value zero.
-Petri
*From:*ext Bill Fischofer [mailto:[email protected]]
*Sent:* Thursday, May 28, 2015 2:48 PM
*To:* Savolainen, Petri (Nokia - FI/Espoo)
*Cc:* [email protected]
*Subject:* Re: [lng-odp] [API-NEXT PATCH 2/2] api-next: packet: clarify
use of 0 len on odp_packet_alloc()
The purpose of the note was to expand on the case of len = 0. Are you
saying this is not needed? The consensus on the Wednesday arch call was
that it was, hence this patch.
On Thu, May 28, 2015 at 5:40 AM, Savolainen, Petri (Nokia - FI/Espoo)
<[email protected] <mailto:[email protected]>> wrote:
* ... The
* packet is initialized with data pointers and lengths set according
to the
* specified len, ...
The current documentation covers functionality also when len is 0. We
should minimize @note content over all the APIs, otherwise the actual
API spec gets fragmented. API documentation and functionality is the
same for len == 0, len == 1, ... In all the cases, implementation
decides on packet segmentation in limits of pool parameters.
If needed, we could add:
@note Zero is a valid 'len' value
-Petri
> -----Original Message-----
> From: lng-odp [mailto:[email protected]
<mailto:[email protected]>] On Behalf Of ext
> Bill Fischofer
> Sent: Wednesday, May 27, 2015 6:51 PM
> To: [email protected] <mailto:[email protected]>
> Subject: [lng-odp] [API-NEXT PATCH 2/2] api-next: packet: clarify use
of 0
> len on odp_packet_alloc()
>
> Signed-off-by: Bill Fischofer <[email protected]
<mailto:[email protected]>>
> ---
> include/odp/api/packet.h | 10 ++++++++++
> 1 file changed, 10 insertions(+)
>
> diff --git a/include/odp/api/packet.h b/include/odp/api/packet.h
> index 3a454b5..ea124df 100644
> --- a/include/odp/api/packet.h
> +++ b/include/odp/api/packet.h
> @@ -73,6 +73,16 @@ extern "C" {
> * @note The default headroom and tailroom used for packets is
specified
> by
> * the ODP_CONFIG_PACKET_HEADROOM and ODP_CONFIG_PACKET_TAILROOM
defines
> in
> * odp_config.h.
> + *
> + * @note The len parameter sets the initial length of the allocated
> packet.
> + * If specified as 0, the implementation will allocate a packet of a
> default
> + * length chosen by the implementation based on the pool create
> parameters
> + * and will then set the actual length of the packet to 0. The
result is
> + * the same as if the following sequence had been called by the
> application:
> + * @code
> + * pkt = odp_packet_alloc(pool, default_len);
> + * odp_packet_reset(pkt, 0);
> + * @endcode
> */
> odp_packet_t odp_packet_alloc(odp_pool_t pool, uint32_t len);
>
> --
> 2.1.0
>
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