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Tried to improve pbuf_type, LWIP_SUPPORT_CUSTOM_PBUF and PBUF_FLAG_IS_CUSTOM documentation

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sg 2015-08-05 22:26:57 +02:00
parent e5e0a21fc6
commit 9352988c44
1 changed files with 27 additions and 8 deletions
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35
src/include/lwip/pbuf.h
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@ -40,8 +40,12 @@
extern "C" {
#endif
/** Currently, the pbuf_custom code is only needed for one specific configuration
* of IP_FRAG */
/** LWIP_SUPPORT_CUSTOM_PBUF==1: Custom pbufs behave much like their pbuf type
* but they are allocated by external code (initialised by calling
* pbuf_alloced_custom()) and when pbuf_free gives up their last reference, they
* are freed by calling pbuf_custom->custom_free_function().
* Currently, the pbuf_custom code is only needed for one specific configuration
* of IP_FRAG, unless required by external driver/application code. */
#ifndef LWIP_SUPPORT_CUSTOM_PBUF
#define LWIP_SUPPORT_CUSTOM_PBUF ((IP_FRAG && !IP_FRAG_USES_STATIC_BUF && !LWIP_NETIF_TX_SINGLE_PBUF) || (LWIP_IPV6 && LWIP_IPV6_FRAG))
#endif
@ -65,17 +69,32 @@ typedef enum {
} pbuf_layer;
typedef enum {
PBUF_RAM, /* pbuf data is stored in RAM */
PBUF_ROM, /* pbuf data is stored in ROM */
PBUF_REF, /* pbuf comes from the pbuf pool */
PBUF_POOL /* pbuf payload refers to RAM */
/** pbuf data is stored in RAM, used for TX mostly, struct pbuf and its payload
are allocated in one piece of contiguous memory (so the first payload byte
can be calculated from struct pbuf)
pbuf_alloc() allocates PBUF_RAM pbufs as unchained pbufs (although that might
change in future versions) */
PBUF_RAM,
/** pbuf data is stored in ROM, i.e. struct pbuf and its payload are located in
totally different memory areas. Since it points to ROM, payload does not
have to be copied when queued for transmission. */
PBUF_ROM,
/** pbuf comes from the pbuf pool. Much like PBUF_ROM but payload might change
so it has to be duplicated when queued before transmitting, depending on
who has a 'ref' to it. */
PBUF_REF,
/** pbuf payload refers to RAM. This one comes from a pool and should be used
for RX. Payload can be chained (scatter-gather RX) but like PBUF_RAM, struct
pbuf and its payload are allocated in one piece of contiguous memory (so
the first payload byte can be calculated from struct pbuf) */
PBUF_POOL
} pbuf_type;
/** indicates this packet's data should be immediately passed to the application */
#define PBUF_FLAG_PUSH 0x01U
/** indicates this is a custom pbuf: pbuf_free and pbuf_header handle such a
a pbuf differently */
/** indicates this is a custom pbuf: pbuf_free calls pbuf_custom->custom_free_function()
when the last reference is released (plus custom PBUF_RAM cannot be trimmed) */
#define PBUF_FLAG_IS_CUSTOM 0x02U
/** indicates this pbuf is UDP multicast to be looped back */
#define PBUF_FLAG_MCASTLOOP 0x04U