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Additional documentation on the subtle difference of a 'pbuf chain' and a 'packet queue'.

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likewise 2003-06-06 08:34:37 +00:00
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src/core/pbuf.c
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@ -13,11 +13,18 @@
* Multiple packets may be queued, also using this singly linked list. * Multiple packets may be queued, also using this singly linked list.
* This is called a "packet queue". So, a packet queue consists of one * This is called a "packet queue". So, a packet queue consists of one
* or more pbuf chains, each of which consist of one or more pbufs. * or more pbuf chains, each of which consist of one or more pbufs.
* The differences between a pbuf chain and a packet queue are very
* subtle. Currently, queues are only supported in a limited section
* of lwIP, this is the etharp queueing code. Outside of this section
* no packet queues are supported as of yet.
* *
* The last pbuf of a packet has a ->tot_len field that equals the * The last pbuf of a packet has a ->tot_len field that equals the
* ->len field. It can be found by traversing the list. If the last * ->len field. It can be found by traversing the list. If the last
* pbuf of a packet has a ->next field other than NULL, more packets * pbuf of a packet has a ->next field other than NULL, more packets
* are on the queue. * are on the queue.
*
* Therefore, looping through a pbuf of a single packet, has an
* loop end condition (tot_len == p->len), NOT (next == NULL).
*/ */
/* /*