Date: Tue, 30 Mar 2010 08:58:21 +0800 (CST) From: jiani1012 <jiani1012@126.com> To: freebsd-net <freebsd-net@freebsd.org> Subject: space of ath_node Message-ID: <cba400.f3c8.127ac9383f3.Coremail.jiani1012@126.com>
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Hi,all
A problem puzzled me in ath code. The following code in function ath_node_alloc( ) shows the space allocated to an,
>struct ath_ratectrl {
>size_t arc_space; /* space required for per-node state */
>};
>const size_t space = sizeof(struct ath_node) + sc->sc_rc->arc_space;
>struct ath_node *an;
>an = malloc(space, M_80211_NODE, M_NOWAIT|M_ZERO);
but in the two lines below ,what is (an)[1]? Where is the initialization of (an)[1]? What does it contain? Can you show me? and how to get the content of sn?
>struct sample_node *sn = ATH_NODE_SAMPLE(an); /*in sample.c*/
>#define ATH_NODE_SAMPLE(an) ((struct sample_node *)&(an)[1]) /*in sample.h*/
Otherwise, the struct ath_ratectrl has been used in structures ath_softc, sample_softc and so on. Is there any relations between them?
Thank you!
Jeny
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