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mbuf: add macro for offset arithmetic

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There are a number of instances in the code where rte_pktmbuf_mtod()
is used to get the mbuf data pointer, only to add an offset before
casting the result to some other header type.  This patch adds a new
rte_pktmbuf_mtod_offset() macro to eliminate these awful double cast
situations.

Signed-off-by: Cyril Chemparathy <cchemparathy@ezchip.com>
Acked-by: Olivier Matz <olivier.matz@6wind.com>
This commit is contained in:
Cyril Chemparathy 2015-06-22 11:34:21 -07:00 committed by Thomas Monjalon
parent e446bc731e
commit b2906abb0d
1 changed files with 21 additions and 3 deletions
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24
lib/librte_mbuf/rte_mbuf.h
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@ -54,6 +54,7 @@
*/
#include <stdint.h>
#include <rte_common.h>
#include <rte_mempool.h>
#include <rte_memory.h>
#include <rte_atomic.h>
@ -1079,19 +1080,36 @@ static inline struct rte_mbuf *rte_pktmbuf_lastseg(struct rte_mbuf *m)
return m2;
}
/**
* A macro that points to an offset into the data in the mbuf.
*
* The returned pointer is cast to type t. Before using this
* function, the user must ensure that the first segment is large
* enough to accommodate its data.
*
* @param m
* The packet mbuf.
* @param o
* The offset into the mbuf data.
* @param t
* The type to cast the result into.
*/
#define rte_pktmbuf_mtod_offset(m, t, o) \
((t)((char *)(m)->buf_addr + (m)->data_off + (o)))
/**
* A macro that points to the start of the data in the mbuf.
*
* The returned pointer is cast to type t. Before using this
* function, the user must ensure that m_headlen(m) is large enough to
* read its data.
* function, the user must ensure that the first segment is large
* enough to accommodate its data.
*
* @param m
* The packet mbuf.
* @param t
* The type to cast the result into.
*/
#define rte_pktmbuf_mtod(m, t) ((t)((char *)(m)->buf_addr + (m)->data_off))
#define rte_pktmbuf_mtod(m, t) rte_pktmbuf_mtod_offset(m, t, 0)
/**
* A macro that returns the length of the packet.